IIMPACT ASSESSMENT OF ACPOC ACTIVITMS IN UGANDA: ENTOMOLOGICAL BASELINE DATA COLLECTION, AUGUST 4m - 23m 1998 BTA Maeega 1. EXECUTIVE STiMMARY Field work was conductd n Simulium (Lewisellum) neavel transmission area. After arrival on August 2il,the nert 2 days were used for literature searching on onchocerciasis and its vector in Uganda in general, and in the proposed study area in particular. Much assistance was received from the national entomological team of three persons, one from the Vector Control Division in Kampala and two entomology technologists from Fort Portal in Kabarole district, bordering Bushenyi district to the north. While awaiting arrival of essential supplies from APOC in Ouagadougou, the national entomoloy team provided all that was necessary, and sometimes imprwised. Field work was conducted from August 106 to 206. All the known S. neavei vectors live in phoretic association with fresh water crabs of the genus Potarnonoures in their larval and pupae stages. Thus search for the S. neavei immature stages always begins with catching crabs and then inspecting them for infestation with immature stages of the potential vectors ofthe S. newei goup. The first site selected for vector sampling was in Nyabubare Parish of Buhinda County, 36 km from Ishaka township. Rutoto (Lutoto) streanL tributary of the Kyambura river was surveyed for the presence of crabs and subsequerfi S. neqvel breeding. No crabs were captured by basket traps, set at 2 discrete sampling sites, each for a duration of at least hour. Since even the "substrate" crabs were absent in Rutoto streanL no further sampling was conducted in the upper Kyambura river system. The stream was considered too slow for S. dnnnorm breeding. No adult simuliid females were caught landing on humans. Entomological work shifted to Katerera sub-county further norttq to an area adjoining the Kicheche onchocerciasis sub-focus in the southern portion of Kabarole district. Crab collections were productive in the 2 streams of Rutondo and Ngoro closest to human settlements; and 2 rivers, Buhindaji and Kitomi, wherever trapping was done. Majority of crabs were infested with immature stages of S. neavel, with an average infestation rate of 8 or above larvae and pupae (including pupal cases of emerged flies). Simultaneous attempts at adult human bait collections were not equally productive. Only I or 2 flies were caught landing on trouser legs, at 3 different points on the Rutondo and Ngoro streams. Four and 5 flies respectively, were caught at 2 other points, one on the Buhindaji R. and the other on the Ngoro streanL before or after rain showers, when many were observed just hovering over human bait without landing. The scarcity of fly human biting observation may be attributed to unsuitable weather conditions, exacerbated by human environmental degradation through extensive slash and burn bush clearing ongoing at the time ofvisit Furthermore, it will be necessary to determine the species identity ofthe vectors and / or whatever other species of the S. newei is endemic in the strearns. The fast changing physical environment demand that vector species identification be done as soon as possible, lest a vector displacement occurs in the future. 2 On the Kitomi river at Kyarwera bridge, 67 flies were caught within 2.25trs of late morning. In comparison to the Buhindaji river systenq this was high fly biting rate. 2, INTRODUCTION 2.1 General overview From emerging evidence, large scale treatment of onchocerciasis using ivermectin reduces transmission considerably over a period of time (Taylor et al, 1990; Remme et al 1989). There is further evidence that repeated treatment with ivermectin may have cumulative negative effects on the female fecundity of Onchocerca volwlus (Katholi et al 1995). The strategy of the African Programme for Onchocerciasis Control (APOC) is to introduce "Community Directed treated with Ivermectin" CDTI in hyper and mesoendemic areas, so as sustain onchocerciasis control for some decades, til it ceases to be a public health problem. Although there is emerging evidence of reduction of adult female O. volwlus reproductive capacity and that of parasite transmission following repeated treatment raises hope for a possibility of intemrpting transmission at some stage, this crucial threshold, assuming there is one, needs to be established. However, it is unlikely that complete intemrption of transmission will be auained in many areas for a while following treatment. As a consequence of uncertainity over how long treatment must continue, at what coverage rate in different areas of varying levels of endemicities, coupled with the geographical variability of the important epidemiological factors which influence transmission and the impact of CDTI on it, it is essential for transmission indices to be evaluated at regular intervals for the duration of any treatment prograrnme. To establish any operational implications of intemrpted transmissiorL APOC needed to follow up the impact of CDTI on transmission in representative "foci". Baseline data on vector infectivity rate is required as a yardsick to "measure" the impact of ivermectin treatment after 5 - 10 years and beyond. Representative ofthe main epidemiological patterns and the principal vector - parasite complexes in the APOC covered regioq study sites where not much systematic, large scale ivermectin treatment has been done were selected. As a principal criteriaq the sites should be meso or hyperendemic, in which the level of infectivity ofthe vector is then used as an appropriate entomological indicatoq to be evaluated at regular intervals. 2.2 Vector - parasite complexes In Eastern Africa, onchocerciasis is generally focal in distribution, being found in mountainous areas, where steep hillslopes drained by fast flowing streams provide ideal breeding sites for vector 3 Simuliid species. On regional basis, main vectors belong to the Simulium (fulwardsellum) dsmnosum complex and members of the S (cwisellum) neavei goup. Instead of submerged vegetation or rocks, the Simulium neavei goup species live on fresh water crabs in what is generally known as "phoretic association". In Ugand4 in the majoriry ofthe foci straddling the Rift Valley drainage system - such as our the current study area, the disease is presumably transmitted by S. neavel s.s., although the precise species identification was never confirmed. In a recent study on O. volwhs genetic strains variations, the parasite showed greater heterogeneity in 4 sampled foci in Tanzarua than in Cameroon and Sierra Leone (Oskarn, et al. 1997). The four foci showed ditrering clinicat picture of the skin disease, with the forest and or cooler upland having milder skin lesions compared to the lower altitude, warner areas which had more severe disease, associated with elevated prevalence of epilepsy, high prevalence of severe skin lesions and general body weakness. However, these variations have never been studied in detail enough to establish a consistent vector - parasite relationships as has been done for the West African savana and forest vector - parasite complexes. Nevertheless, there are obvious variations in the clinical presentation of the disease in different foci, hence the study of one focus may not represent the rest of the endemic areas in a country. 3. OBJECTIVES 3.1 Broad Objective To evaluate the long term impact of "community directed treatment with ivermectin - CDTI on O. volvu lu s transmi ssion. 3.2 Specific Objectives To determine the long term reduction in vector infectivity as measured by the number of infective flies (flies with L3 in the head) per 1000 parous flies. In order to achieve this main objective, it is necessary:- To collect out baseline data for one year pre-treatment in order to establish peak fly biting times and transmission in an untreated area; ii) To collect evaluation data at the most suitable "fly biting peaks", at 5 and l0 year intervals following the beginning of a CDTI progra.mme. iii) Standard entomological protocols established by the OCP be adopted as far as possible where feasible and relevant. i) 4 4. MATERIALS A}[D METHODOLOGY 4.1 Materials 4.1.1 Background information of the study area Uganda is administratively dMded into 39 districts. Bushenyi district is one of the 17 onchocerciasis endemic districts in the whole country, and one of the 13 in western districts along the rift valley escarpment (Mutabuzi and Duke, 1998; Walsh et al., 1996). The main vector in the area is Simulium neovei which prefers forested river valleys to open country. Slightly over one million people are reportedly infected with onchocerciasis (W.HO, 1995 quoted in Walsh et al ree6). Bushenyi district is fairly densely populated in the south but it seems less so in the north (actual data population not obtained). It is transversed by Kasyoha - Kitomi forest reserve from which arise many streams draining into Lakes Edward, George and many smaller crater lakes. Queen F,lizabeth National Park and Kalinzu forest are located on the district's North Western shoulder. The study area is in the upper reaches of the Buhindaji river, which runs into lake George after confluence with Kitomi river, that marks the southern boundary of Kabarole distriCI. The small forest streams form ideal breeding sites ofthe S. neavei s.q the presumed main local onchocerciasis vector. 4.1.2 Climate and vegetation Rainfall pattern is shown in Table 1A, for 1994 - 1997 for the tea growing highlands to the South of the study area. Temperatures were not available, but during the study visit, the "sdy site had day time temperatures oiabove 300C while the highlands were lower by from 2uC - 5uC. Rainfall pattem in this cooler, and probably wetter area than the study are4 is expected to be similar, although most likely would vary in magnitude. Heavy rains fall in March - May and September to December. Drier weather is experienced in January / February and July / August, the latter coinciding with this study visit. There are two main forest reserves and a National Park (Fig l) The north and northwestem part have the Rift Valley with its characteristic features, and many crateu depressions and crater lakes. 4.1.3 Human setflements and socioeconomic activities. Bushenyi district is more densely populated in the southern ha$ where the higilands are covered with banana farmers, tea plantations, some coffee, sweet potatoes and various other domestically used crops. The long harmed Ankole cattle, and goats are common domestic animals. The Northern portion of the district seems drier, with some homesteads and associated farm plots 5 currently pushing the edge of the forest reserve further into the hills. Here goats seem to be more visible. Besides the traditional sweet potatoes and plantain, cassava" groundnuts beans form seasonal crops. Robusta coffee is grown as a cash crop. During the visit, some timber harvesting from the forest reserve was observed. 4.1.4 Onchocerciasis and Ivermectin Treatment Ivermectin treatment for Bushenyi district onchocerciasis endemic areas, including the study area, is planned to take place in October 1998. Considering there have been 6 previous treatment cycles of ieasonably good rou.ruge in the area, it is strongly recommended that an intensified entomological data collection be carried out between September and December, 1998, which exercise (or preferably during the latter part), the expert entomologist pay the second visit to terrain. The fate bf entomologrcal aspect of impact Assessment of CDTI will only be decided thery that is, whether it will Ue mJaningful to continue entomologicat data collection or not. A detailed discussion is provided to emphasize on recommendations for the immediate future. Onchocerciasis is hyperendemic in several counties ofBushenyi district. Since 1992 there has been a vertical ivermectin treatment programme, supported by Christofel Blindenmission (CBM), operating out of Mbarara, for the two districts of Mbarara and Bushenyi. According to the report oithe CgN4 project Coordinator treatment coverages is between 70 - \ff/o generally. Treatment for l99g has been postponed until October, 1998, in order to prepare for its rarganization to a community directed treatment with ivermectin (CDTI) to replace the initial community based approach so far run through a vertical mobile team. 4.2 Methodolory 4.2.L General outline A 14 day field work was initially scheduled. Outlined activities include sample site selectiorq sampling of immature stages for species identification, selection of suitable sites for human bait fly cat"ires, *hole day fly catches (dawn to dusk), fly dissections for parity (age), dissections and examination for infection with filarial stages and staining of and finally dissections of stained parous flies for examination for filarial infections. The schedule also includes training of the national stafi if not already familiar with the required techniques. 4.2.2 Siteselection Nyabubare parish in Buhinda county was first tried, since the preceding sociological surveys corre.ed this area (Fig l,site A). Rutoto stream was checked for riverine crabs, which support the vector pre-imaginal irg.r The search for potential vectors was abandoned after the first day, as the stream yielJed ro .iub.. The rest of the field activities were conducted in Katerera Sub-county, Mugombwa parish (Fig.l site B), and a comparative observation made in southern onchocerciasis 6 focus ofKabarole district (Fig. ! site C). Crab sampling was done at 3 points eactr, on the Rutondo and Ngoro streams; the former is a tributary of the Buhindaji river, while the latter that of the Katerer4 both flow through human settlements. Two sites were chosen from larger rivers, one on the Buhindaji approximately 2 km from Kagarama uillage and for comparisorq one site on the Kitomi, at Kyarwera just on the edge of the Kasyoha-Kitomi Forest Reserve north-eastern fringes (Fig.l at C). 4.2.3 Crab trapping and sampling for immature stage of Simulium n eovei species Crab trapping and collection of,S. neavei immature stages were conducted using basket traps, a set of 2 each time, using fresh meat as crab bait. Crabs were sexually differentiated, carapace size measured with calipers and examined for immature stages of S. neavel, including pupal cases. All data was entered onto a chart @ef Appendix IA), provided by the entomolory technologists from Fort Portal. 4.2.4 Sampling for other potential vector spp immature stages Only once were S. dsmnosum s.l. immatures observed in and collected from Buhindaji river. These were preserved n 80% Ethanol (for lack of cold Carnoys' solution for cytogenetic preservation), and later used in identification demonstration. 4.2.5 Human bait fty catching Adult human bait captures were attempted at all sites where crab trapping was done and found positive. Since fly human landing catches were very poor during the whole field trip, whole day catches from 7.00 to 18.00 hours were not established at any one site. AgaitL for fly catching recording form 2A and28 were used as shown below. 4.2.6 Fty dissection for age determination and filarial infection The protocol of OCP was used for fresh dissection and staining with Maye/s haemulum in the very limited number of flies caught. However, this was done only as a "stage rehearsal", since the number of flies was too small. Some adult flies were preserved for identification specimens, either dry pinned or in 80% alcohol. 4.2.7 Training in Simulium vector species identification Field work was conducted by 4 people, with a plan of locally recruiting vector collectors once '7 suitable catching sites are established. Although the exact vector identity of the local species in the study site is not knowrU it is generally assumed to be S. neavei. The two national Entomology Technologists were very experienced in sampling and dissection of the S. neavei s.s. from previous work on the GTZ run entomological study conducted by Prof Rolf Garms in Invara onchocerciasis focus near Fort Portal. Specimen preservation methods and identification of immature and imaginal stages for the two major v@tor groups in eastern Africa were discussed. Larval and pupal materials were examined using a light microscope for illustration of essential features. Adult demonstrations were not done for lack of appropriately mounted specimens. Cytogenetic identification technique was discussed, as well as the more current DNA / PCR technology. The national team was very much interested in acquianting themselves with vector identification methods. 5. OBSERVATIONS 5.1 Site selection Nyabubare Parish in Country Buhinda was abandoned for absence of crabs, Katerera sub-county, close by Kagarama and Nyabubale villages, in Mugombwa Parish was chosen. Rutoto and Ngoro strearns were favourable breeding sites, with their abundant crab populatiorq as well as main rivers ofBuhindaji and Kitomi, which originate in the Kasyoha - Kitomi Forest Reserve. Three sites each were selected on Rutondo and Ngoro streams; the former is a tributary of the Buhindaji river. One site each was chosen from 2 larger rivers, on the Buhindaji about 2 km from Kagarama village; one site on the Kitomi river, at Kyarwer4 just on the edge of the Kasyoha- Kitomi Forest Reserve. Under normal circumstances, it appeared that most of the selected larval habitats would favourable for adult human biting catches as well. 5.2 Crab trapping and sampling for immature stages of Simulium nearyi species All the selected sites yielded abundant crabs which were heavily infested with S. newei preimaginal stages, an average of 8 or more per indMdual crab. Results of the crab trapping and S. neavei "immatures" sampling are shown in Table l. B CRABS SneaveiSITE # MEAN S,^,84'EI /CRAB SLY NO I-ARVA PUPAE PCs DATE WATERCOT]RSE 0.25MALE FEMAL 4 5 0 0 0 0 I 0 1*r 0.119 0 0 ry8l98 R RUTONM/KAGARAMA TOTAL 3.M 2.20 MALE FEMAL 24 10 67 15 a ,' 4 5 I 9 2.79TOTAL 34 82 4 6 5 2.q 1.,18 2 MALE FEMAL 25 ,( 523t a I ll 1.94TOTAL 50 83 3 a 0 2.N 4.00 3 MATT, FEMAL 7 3 t2 1l 0 I I ) 2.60TOTAL l0 23 12t8/98 R. RLTTONDO/KAGARAI\,IA 1.90 4.82 I MALE FEMAL 9 t7 l7 68 0 6 6 8 3.81TOTAL 26 85 t3l8D8 R BL'HINDAJI,'KAGARAMA 8 37 t9 4l 9.93 t2.u I I\,IALE FEMAL l5 3l 122 320 442 45 & I 1.89TOTAL 46 l3/8D8 RNGORO/ NGOROVILI-AGE 17 47 I 1 0 I 3.6 12.25 2 MLE FEMAL 5 4 9 64 a I 7.44TOTAL 5 t1 4l 125 0 a 0 l0 8.20 12.45 3 MAI-E, FEMAL tt.t2t6 t6 l0 l,l/8D8 RNC,ORO/ NGOROVILI-AGE TOTAL 29 2t 252 t64 9 8 37 34 10.28 9.81 I MALE FEMAL 10.0850 416 t7 7lTOTAL 6.0 11.75 6 4 29 4l I 1 6 5 t7t8D8 R KITOMI/KYARWERA lr MAIE FEMAL Table 1 : Crab Carches and Infestation by immature stages of Szz lium neavei s.l. TOTAL l0 70 a t1 8.30 9 0 8 t7t8/98 R BUHINDAJYKAGARAMA I MAIT, FEMAL 1 8 13 20 3 a 4 2.4t 3.38 TOTAL l5 33 5 6 2.93 l8/8,98 RNGORO/ NGOROVIII.AGE I MALE FEMAL 20 30 131 2t6 7 38 l4q 7.60 9.80 TOTAL 50 347 45 54 8.92 tegatd: Sanplingsessims differof, d same sitg Trial sanptingfcr 15- 20 minu€s, u/hile dher sanplestakar over I-2 hour drdlm 10 s. neaveiinfestation rate per crab per site ranged from 1.9 to 2.6 for Rutondo stream' 2'93 to 3'81 for Buhindaj i;7.4 to lZ forNgoro stream ,f,d Kito,oi .iu"t, 8'3 and 10 per sampling session' Ngoro stream had high crab catche, *J the highes infestation rates at the village spot, with infestation rates of 9 to l2,and yet there was no ,tiong evidence of fly human biting activity' Since this heavy infestation compares with the Kitomi/I(yarwera of g to 10, some fly human-biting would be expected in Ngoro village or at any of the 3- sampling sitel, s-rnc9. on the Kitomi at Kyarwer4 fly landing reached over 70. 'n 2i minutes from'9:45 to 2:00 o'clock' Absence of human landing flies on the Ngoro may imply that the cra! i1{estins species was not human-biting' oi rfr. atmosp-heric conditions were a severe deterrent to the biting activity 5.3 Sampting for other potential vector spp immature stages s. domnorums./. immature stages were collected from Buhindaji river in for.est remnant nearby Kagaramavillage. No other stream surveyed had preimaginal stages ofthis species complex' S.4Humanbaitflycatchingdissectionsforagedeterminationandfilarialinfection Adult human bait captures were conducted at all sites where crab trapping was done, these obtained I or Zf*airi ni"t after several hours' of waiting' However, on two sepa'rate occasions' 4 flies were caught in l; afternoon on the Buhindaji, just before a rain shower, and on a second one' 5 flies were caught on the Ngoro site, this time rouowing a rain shower. The biggest single fly catch was made on the Kitomi river at ry**".4 wtrere zs flies were caught between 9:45 and 14:00 hours. This site was cool, shaied and humid, and was only used for comparative observations, because it is just outside the study area' Since fly human landing catches were extremely poor during the whole field trip, thus whole day catches from 7:00 - t8:00 hours was not estabtisnea at any site on either river as intended' The protocol of ocP was used for fresh dissections and staining with Mayer,s haemulum in the very limited number of flies caught, including the Kitomi river sample, done as a "stage rehearsal"' since the number of flies was too small foibaseline "impact asseisment" data. . Some adult flies were preserved for identification ,p"ri*.nf "itft", dry pinned or in 80% alcohol' (h--.'X Z4 ) ZA S.5Traininginsimuliumvectorspeciesidentification Tkee potential local "vector collectors" were shown the flies and how to collect them' Except for the one on the Kitomi river, none succeeded in collecting any due to scarcity of human landing flies' Discussions were held on handling of specimens. General specimen pr-eservation methods and identification of immature and imad; stages for the sub-genus Lewisellum neavei and Mwardseltum damnoxtm,the two -;j- ,"iot gfoups in eastern Africa were discussed and 11- demonstrated. Thus whenever ice could be secured, larval samples of potential vector(s) were preserved in Carnoys for possible chromosomal characterisation. However, constant electricity disruptions limited ice making, thus hampering even this effort. S. neavei larval samples. During the l0 days, only t'wice did the group succecd in saving ice cubes for field. Few crabs were separately preserved for identification and/or identification confirmation. Examination of posterior dorsal abdominal tubercles and cuticular setae showed a close affinity to the S. squamowm / yahense and the eastern Africa 'T.{yamagasani" form. Many Eastern African S. domnosum forms, the majority of them nonanthropopffic, fit in this general morphological category. Without the benefit of simultaneous chromosomal characterisatioq it is impossible to determine its specific identity (Maeggq 1992). Cytogenetic identification technique was discussed, as well as the more current DNA / PCR technology. Whenever ice could be secured, larval samples of potential vector(s) were preserved in Carnoys for possible chromosomal characterisation. Few S. neavei larval samples and crabs were separately preserved for identification and / or identification confirmation. Adult distinguishing characters were not demonstrated for lack of suitably mounted specimens. In the absence of entomological pins, some material was pinned with too large pins that distorted the regular characteristics of the fly specimen to be ofany good in morphological identification. 6. DISCUS$ON AND RECOMMENDATIONS 6.1 Discussion Immature stages of the S. newei goup members in Eastern Africa live attached to fresh water crabs in phoretic association. [n many streams where they occur, fresh water crabs carry numerous larvae and pupae of the S. neavei species (Walsh et aL,1996). However, S. neavei spp breeding is limited by factors other than availability of host crabs, as in many instances, fresh water crabs occur in a wider range of stream habitats where S. neavei spp do not (Raybould and White, 1979). The same crab species may harbour more than one member of the species goup (Raybould, 1969; Raybould & Yagunga, 1969). Whether the immature stages of S. neavel currently found on the crabs are human - biting i.e. potential or actual vectors, has to be determined. The first step will be a broader sampling and specific characterisation by a combination of methods, including cytogenetics as done nthe S.nyaxlandicum (Amani form) and S. wodi @rocunier, et al 1988). All populations of .9. neavei in the onchocerciasis areas, where they are seemingly the main v@tor appear to have no distinguishing morphological characters, and according to Walsh et al. (1996), they are currently assigned to S. newel s.s. until definite cytogenetic characterisation is done. In the study area, which is part of the Albertine Rift Valley escarpment, the species occurs at about 1000 to 1500 m altitude, and usually in well forested streams (Walstt, et aI. 1996). The immature stages are found on Potamonmttes aloysiisabaudiae. l2 It has been observed that in more deforested stream valleys, there is already a rapid decline in fly human biting activity, reportedly on the Nkurungu river to the immedate north of the study area (Garms, 1997, Wamani and Tukesig4 personal communication). Whether the scarcity of human biting phenomenon at the time of our visit is due to adverse climatic factors which inhibit fly feedind behaviour, or the immature stages observed actually belong to nonanthoropophilic S. neavei species is not clear, thus has to be determined. In two brief occassions, slight increase in fly landing was observed, both immediately before or soon after rain showers. These observations strengthen the suspicion of a possible rainy season fly biting phenomenon. Some villagers claimed that the flies were numerous in wet season; some adding - especially in presence of monkeys. It is therefore imperative to intensiS entomological observations during the coming 4 months of rainy season, from September to December, 1998. Following this exercise, a decision will then be made as to whether obtained data is of practical used for impact assessment in APOC activities in years to come. The national team was very much interested in acquiating themselves with vector identification methods. There both the S. neavei and S. dsmnontm vector species whose identities are yet unknown in Uganda. Training of the interested national experts, using own locally collected materialwill be great asset. 6.2 Recommendations Available information on vectors of onchocerciasis in the study area needs further investigation. From observations made during the current study it is not possible establish whether substantial fly biting activity occurs, sufficient to sustain O. volwtlus transmissioq in order to fufill the selection criteria for APOC impact assessment purpose. It is therefore recoflrmended that:- i) A 7 day monthly vector sampling sessions be conducted by the national entomological team between September and December, 1998. ii) The December 7 day data collection trip be joined by the external entomologist, this will be the second field trip for the latter, in the fust year ofbaseline data collection. iii) From these "rainy'' season observations, a decision will be made, as to whether the site is suitable for evaluation of transmission indices for impact assessment of CDTI. Furthermore, during this period various samples for vector identification will be collected and preserved by the national tearry ready for processing and analysing whenever reagents become available. ,r)* From the above recommendatioq there is a request for a small budgetary increase for which a review estimate is attached. This is because it is absolutely necessary for the local 13 entomological team to have private transport in order to reach the out of the way tracks that are remote from public transport routes. The NOTF is willing to provide a motor vehicle, but cannot carter for fuel and oil. It is further requested that the entomolory technologists be allowed 7 and not 5 days for the next very crucial4 months (refer to Table 1A below), to give the team sufEcient time to trap crabs and also catch flies in most suitable sites. The terrain is difficult, thus five days will cut the real working days to 2 -3, which are considered insufficient in the absence of other sources of supporting information. v)* Considering that most communities in accessible, onchocerciasis areas of Uganda have been under large scale ivermectin treatment for the past 6-7 years, it is hereby recommended that prior to the next treatment cycle, which marks the biginning of CDTI in our study are4 the villages of Kagaram4 Nyabubale and Ngoro be skin snipped to determine current skin mf rates. The observation on skin mf rates can then be used as a starting point for CDTI, comparable to whatever entomological transmission indices will be observed pre-treatment. 7. CONCLUSION More entomological data is required before the selected site is judged as suitable for impact assessment of CDTI on transmission indeces. REFERENCES: Garms, R (1997). Eradication of the vector Sirmilium neavei from the northern onchocerciasis focus of Kabarole district - situation in March 1997 Unpublished report to GTZ Basic Health Services, Fort Portal, 31.03.1997 ; pp20. Katholi, CR, L Tog A Meriweather &TR Unnasch (1995). Determining the prevalence of Orrchrcerca volwlus infection in vector populations by polymerase chain reaction screening of pools of black flies. Journal of Infectious Diseases 172.1414-7. Maegga, BT (1992).Identification of Sirrulium damnosum vectors of Onchocerca volwtlus in the Tukuyu Valley of Southwest Tanzana. A PhD Dissertation submitted to Cornell University Graduate School, Ithaca, New York USA, Ian1992) pp xiv + 269. Mutabazi, D & BOL Duke (1998). Onchocerciasis control in Uganda: How can self-sustaining, community-based treatment with ivermectin be achieved? Ann. Trop. Med. Parasitol.92(2).195- 203. OskanLL.,GLMwaiko,BMaegg4ASame-Ekobo,FIr{iokou,CBellec&SHerder(1996). Genetic variation in Onchocerca volvulus from Cameroor; Tanzana and Sierra Leone. Unpublished Report of the Royal Tropical Institute Amsterdam, Department of Biomedical Researcll Amsterdarn, The Netherlands (pp.28; (presented as Mwaiko, et al 1996, at the KVth International Congress for Tropical Medicine and Malari4 Nagasaki, Japarr,lT-22 Nov. 1996; and L4 APPENDICES L6 6 bF c q oN F- {$ cl o raz! a.{rlf l i FT z ! v:G v? O rr2 c{ al GI vl rio ct o s \Dd \r al F. o\(ld F o\ Eoa G t:\a nN v) o\ i oo r) !+ o\ r: € \o & ri o;\o € di N ts = € ei N € q \o\o t N r1 R Nr- a oi + o rf + :f, t- d a N F..\o 6 2 q €o \ o\6 e{ t-- € o 5ofl c! o\o \ \o € F.t'. € \o € € r) f; € €l o\F E * o\ o\ o\o\ \o o\ o\ a-. o\ o\ u lD CI (t) tn o (l) (E It E] o o .Y f (B o. E oU d 6)F E G! o0 LoN (D B& o d.-(s GtE -(tl ftlil q) p CBF -, )-,. I og'---ot- :c rh Catches of River and Place ; 14 R rVtrcrit i Traps set Date ' t+l *l1e Trarps reooved Date: . crabs (Potamona ut s) Mtront<> 'Jtr-/-A'hi ! lf Eour; /i,, ou f'u Eour t 444" Px^ X rya.LuL,<[.a l,io. of traPs: P Mode or trapprng I fll-aasrecs I Hand-traps E uy nana E c"g' yraLer texperaLure oC, ConducEl.vrLy: i.rS/crn, pH Hour No. S. neavelI^I:-dth ( ctn) .No. S. neaveiWidth (cm) P PCsLNo 66P PCsd6 ?? LNo I F ,)3 I C t7 tt 26 2, ?o '!, ltsI I 2'l l1:Il;ll I U iL, 1t: + t+t> 4?o 1 ) -i-- I 7 I 23 .ro28 "(+ 5 ',34.gc 3 +tl c2, 60f) o 2964 4oo a'tI 30 ,+ qr) I780?o ,7 I I i 5 + Do 31 3, ocd Cr-+ tc I \-)6 o oi I L32 l,f3IL c I7 3.71- oI 33 4 >b| o& IOI 3.3(, I zI9 I \-r: /- 5 S n I I 34 -{' 2c .j ,30IIi I Ir l l10 I I 4 rc o l3, 80 6O 2 36rl .io (11l II(, C l).1. -(f\t2 I t)3' 3c' tGt2 IZ r^L- ot .1 J i- -,) qJ 7r) ()(r 1L c) 41 >f, 31 39 38 tq14 i4to to o o40 .3 .6o+ + I3'sb 15 I DII41 3' +r> 3J II I C t1-15 13 su t3 C r^)3 I l ,1 .,1\tt Ir 6r>1? D o38o ,6l o 433' 80 718 3,30 te lI {47o --t'5))19 I I ,y'- D i :L ,c 46 i/ / ll I l:[Ll tL, 20 a! '1, r1{) ,r,\)) ? L S'r c, 4't lLt D I3' 7o 48 ,.s l350 2? ,7, I + 49tI:l ,f24 I + 50 _s ac 3' 3'c .: - .''.1 -i-"'- t^.-.,,.., 0 .'l M. ^,- n ,l-)y:/t-,Qrl .,:*lil 'rAI Nn- 99 I i I t u( C t"t) A Sfeesu'x r A fu.-^-.-r n".r/ 14\ t?,qt;re-N1 i Uf fRr c-t Catch of Sirmrl ium Srrrulium damnosum s .1. catching site: t2rjroru[o- t.a_Aq&pn+n.^ Dates: \l_ lorlqf Rtver : Qtr.;zrlif\o - B.a rr_, ,..,r i) A.t r Narres of vector collectors: l) )\ 1! 't Hour' No . iR flies i a ri n 3- 1 15 I I '1 I I eave L Datc' ,) .l e)?. Date: Date: Date: R aj. n T No.flies Hour R a i n i I I I I I R a i n Hour I No. flies 07- Hour I I No. f Ii-es 07 08 11 L2 11 L2 0 -09 0- 12-13 I L2-L3 tc i I I .J 1d 1.3 - 14 13-1{ 14 --15- 15 6 15 16 15 16 16 l7 16 L7 1?-18 oe - lc-;- 10 - 1l ' 'cl rrl a7 0e - 09 09- 10 12-13 Oo 1? - r, L' t. 16 ct ot) 18 1A - 19 0 r I 11 - 12 | 12 14 - i5 L7 1 r6- r 08 i7 15 18-19 re - r7 rz- - ra- - 191 ToLrI r-) - To brI I I lot,aI f- TotaI II Rema-rks il i'tt^^* +t^{ s \-J^^ O\-SQ=A \N1'fL Rn* q C.atd^o.8, r t 07 OB 10 I -18 18- I I 1 I I ( A*eersen* aR tlC*rrlbA ' hr--( -- St * Catch of S catching site , ('1fr4L0a{U kta\aa Rrrrer, Q R.t-toua' Najaes of vector colleetors: 1 t E .7. 2) J.w Da.te: 1f-.c)8.?r Ho'.:r No. f .Iies O7 - Oti 0?-08 irmrl i near.';i Sirmrlium darnnosum s.1. FL l/-*8,fttzc)e€ Dns Tr-_tLi t111gtb 3) T't Datea: R CL i l) Date: -0 -,, )--, .i -de .. o e- '----- 09(t tt,& \n e-z\ 08*0e i':li I -10 I I I10-11 I-L - D- 15 .rg - rn ra - r5 otr - 0:) f '{_i- I i -,----'- -"-'-'--' c-1 I It5 )s 09-1A 1 10-11 l_1 - 12 l_0 - i.I 11 -1 l- -1' I 1 I I L LIll ----1..i3 I ir;ld 13)I L--__l12 - 13 L2-l, j'i'-:'-; ;' + - "---- -- td - 15'- rs - ro i J.3-L 1 -id 1.4 - ..-_-i .15 I i I -.1 ia'r i, -1 16 - J. 'r tS9r he b *,V J. i1 - 1o rB - il ___-._ _ _t_..l7-18 -:T0-l To?cL e-2 \Renrarks : \ \,..,-l O4.^a_O^ L? -1Al t3 '!oi,irl, 1:) O l,^* U^Ja\ e-{e-ckl +ho0j Date:Date: IIour )io flies R u. i n R a i n Hour No le sf.1 Ra ir n Hour No. flies 15 1.6 15 L7 L7 19 1. 1 I I I ! I T I I Tot:aI :-I l I I iI 'l{^" D (* ssse L- P hSa!^, ,-! I I -_l'-- i_-_ I l / I I
IIMPACT ASSESSMENT OF ACPOC ACTIVITMS IN UGANDA: ENTOMOLOGICAL BASELINE DATA COLLECTION, AUGUST 4m - 23m 1998 BTA Maeega 1. EXECUTIVE STiMMARY Field work was conductd n Simulium (Lewisellum) neavel transmission area. After arrival on August 2il,the nert 2 days were used for literature searching on onchocerciasis and its vector in Uganda in general, and in the proposed study area in particular. Much assistance was received from the national entomological team of three persons, one from the Vector Control Division in Kampala and two entomology technologists from Fort Portal in Kabarole district, bordering Bushenyi district to the north. While awaiting arrival of essential supplies from APOC in Ouagadougou, the national entomoloy team provided all that was necessary, and sometimes imprwised. Field work was conducted from August 106 to 206. All the known S. neavei vectors live in phoretic association with fresh water crabs of the genus Potarnonoures in their larval and pupae stages. Thus search for the S. neavei immature stages always begins with catching crabs and then inspecting them for infestation with immature stages of the potential vectors ofthe S. newei goup. The first site selected for vector sampling was in Nyabubare Parish of Buhinda County, 36 km from Ishaka township. Rutoto (Lutoto) streanL tributary of the Kyambura river was surveyed for the presence of crabs and subsequerfi S. neqvel breeding. No crabs were captured by basket traps, set at 2 discrete sampling sites, each for a duration of at least hour. Since even the "substrate" crabs were absent in Rutoto streanL no further sampling was conducted in the upper Kyambura river system. The stream was considered too slow for S. dnnnorm breeding. No adult simuliid females were caught landing on humans. Entomological work shifted to Katerera sub-county further norttq to an area adjoining the Kicheche onchocerciasis sub-focus in the southern portion of Kabarole district. Crab collections were productive in the 2 streams of Rutondo and Ngoro closest to human settlements; and 2 rivers, Buhindaji and Kitomi, wherever trapping was done. Majority of crabs were infested with immature stages of S. neavel, with an average infestation rate of 8 or above larvae and pupae (including pupal cases of emerged flies). Simultaneous attempts at adult human bait collections were not equally productive. Only I or 2 flies were caught landing on trouser legs, at 3 different points on the Rutondo and Ngoro streams. Four and 5 flies respectively, were caught at 2 other points, one on the Buhindaji R. and the other on the Ngoro streanL before or after rain showers, when many were observed just hovering over human bait without landing. The scarcity of fly human biting observation may be attributed to unsuitable weather conditions, exacerbated by human environmental degradation through extensive slash and burn bush clearing ongoing at the time ofvisit Furthermore, it will be necessary to determine the species identity ofthe vectors and / or whatever other species of the S. newei is endemic in the strearns. The fast changing physical environment demand that vector species identification be done as soon as possible, lest a vector displacement occurs in the future. 2 On the Kitomi river at Kyarwera bridge, 67 flies were caught within 2.25trs of late morning. In comparison to the Buhindaji river systenq this was high fly biting rate. 2, INTRODUCTION 2.1 General overview From emerging evidence, large scale treatment of onchocerciasis using ivermectin reduces transmission considerably over a period of time (Taylor et al, 1990; Remme et al 1989). There is further evidence that repeated treatment with ivermectin may have cumulative negative effects on the female fecundity of Onchocerca volwlus (Katholi et al 1995). The strategy of the African Programme for Onchocerciasis Control (APOC) is to introduce "Community Directed treated with Ivermectin" CDTI in hyper and mesoendemic areas, so as sustain onchocerciasis control for some decades, til it ceases to be a public health problem. Although there is emerging evidence of reduction of adult female O. volwlus reproductive capacity and that of parasite transmission following repeated treatment raises hope for a possibility of intemrpting transmission at some stage, this crucial threshold, assuming there is one, needs to be established. However, it is unlikely that complete intemrption of transmission will be auained in many areas for a while following treatment. As a consequence of uncertainity over how long treatment must continue, at what coverage rate in different areas of varying levels of endemicities, coupled with the geographical variability of the important epidemiological factors which influence transmission and the impact of CDTI on it, it is essential for transmission indices to be evaluated at regular intervals for the duration of any treatment prograrnme. To establish any operational implications of intemrpted transmissiorL APOC needed to follow up the impact of CDTI on transmission in representative "foci". Baseline data on vector infectivity rate is required as a yardsick to "measure" the impact of ivermectin treatment after 5 - 10 years and beyond. Representative ofthe main epidemiological patterns and the principal vector - parasite complexes in the APOC covered regioq study sites where not much systematic, large scale ivermectin treatment has been done were selected. As a principal criteriaq the sites should be meso or hyperendemic, in which the level of infectivity ofthe vector is then used as an appropriate entomological indicatoq to be evaluated at regular intervals. 2.2 Vector - parasite complexes In Eastern Africa, onchocerciasis is generally focal in distribution, being found in mountainous areas, where steep hillslopes drained by fast flowing streams provide ideal breeding sites for vector 3 Simuliid species. On regional basis, main vectors belong to the Simulium (fulwardsellum) dsmnosum complex and members of the S (cwisellum) neavei goup. Instead of submerged vegetation or rocks, the Simulium neavei goup species live on fresh water crabs in what is generally known as "phoretic association". In Ugand4 in the majoriry ofthe foci straddling the Rift Valley drainage system - such as our the current study area, the disease is presumably transmitted by S. neavel s.s., although the precise species identification was never confirmed. In a recent study on O. volwhs genetic strains variations, the parasite showed greater heterogeneity in 4 sampled foci in Tanzarua than in Cameroon and Sierra Leone (Oskarn, et al. 1997). The four foci showed ditrering clinicat picture of the skin disease, with the forest and or cooler upland having milder skin lesions compared to the lower altitude, warner areas which had more severe disease, associated with elevated prevalence of epilepsy, high prevalence of severe skin lesions and general body weakness. However, these variations have never been studied in detail enough to establish a consistent vector - parasite relationships as has been done for the West African savana and forest vector - parasite complexes. Nevertheless, there are obvious variations in the clinical presentation of the disease in different foci, hence the study of one focus may not represent the rest of the endemic areas in a country. 3. OBJECTIVES 3.1 Broad Objective To evaluate the long term impact of "community directed treatment with ivermectin - CDTI on O. volvu lu s transmi ssion. 3.2 Specific Objectives To determine the long term reduction in vector infectivity as measured by the number of infective flies (flies with L3 in the head) per 1000 parous flies. In order to achieve this main objective, it is necessary:- To collect out baseline data for one year pre-treatment in order to establish peak fly biting times and transmission in an untreated area; ii) To collect evaluation data at the most suitable "fly biting peaks", at 5 and l0 year intervals following the beginning of a CDTI progra.mme. iii) Standard entomological protocols established by the OCP be adopted as far as possible where feasible and relevant. i) 4 4. MATERIALS A}[D METHODOLOGY 4.1 Materials 4.1.1 Background information of the study area Uganda is administratively dMded into 39 districts. Bushenyi district is one of the 17 onchocerciasis endemic districts in the whole country, and one of the 13 in western districts along the rift valley escarpment (Mutabuzi and Duke, 1998; Walsh et al., 1996). The main vector in the area is Simulium neovei which prefers forested river valleys to open country. Slightly over one million people are reportedly infected with onchocerciasis (W.HO, 1995 quoted in Walsh et al ree6). Bushenyi district is fairly densely populated in the south but it seems less so in the north (actual data population not obtained). It is transversed by Kasyoha - Kitomi forest reserve from which arise many streams draining into Lakes Edward, George and many smaller crater lakes. Queen F,lizabeth National Park and Kalinzu forest are located on the district's North Western shoulder. The study area is in the upper reaches of the Buhindaji river, which runs into lake George after confluence with Kitomi river, that marks the southern boundary of Kabarole distriCI. The small forest streams form ideal breeding sites ofthe S. neavei s.q the presumed main local onchocerciasis vector. 4.1.2 Climate and vegetation Rainfall pattern is shown in Table 1A, for 1994 - 1997 for the tea growing highlands to the South of the study area. Temperatures were not available, but during the study visit, the "sdy site had day time temperatures oiabove 300C while the highlands were lower by from 2uC - 5uC. Rainfall pattem in this cooler, and probably wetter area than the study are4 is expected to be similar, although most likely would vary in magnitude. Heavy rains fall in March - May and September to December. Drier weather is experienced in January / February and July / August, the latter coinciding with this study visit. There are two main forest reserves and a National Park (Fig l) The north and northwestem part have the Rift Valley with its characteristic features, and many crateu depressions and crater lakes. 4.1.3 Human setflements and socioeconomic activities. Bushenyi district is more densely populated in the southern ha$ where the higilands are covered with banana farmers, tea plantations, some coffee, sweet potatoes and various other domestically used crops. The long harmed Ankole cattle, and goats are common domestic animals. The Northern portion of the district seems drier, with some homesteads and associated farm plots 5 currently pushing the edge of the forest reserve further into the hills. Here goats seem to be more visible. Besides the traditional sweet potatoes and plantain, cassava" groundnuts beans form seasonal crops. Robusta coffee is grown as a cash crop. During the visit, some timber harvesting from the forest reserve was observed. 4.1.4 Onchocerciasis and Ivermectin Treatment Ivermectin treatment for Bushenyi district onchocerciasis endemic areas, including the study area, is planned to take place in October 1998. Considering there have been 6 previous treatment cycles of ieasonably good rou.ruge in the area, it is strongly recommended that an intensified entomological data collection be carried out between September and December, 1998, which exercise (or preferably during the latter part), the expert entomologist pay the second visit to terrain. The fate bf entomologrcal aspect of impact Assessment of CDTI will only be decided thery that is, whether it will Ue mJaningful to continue entomologicat data collection or not. A detailed discussion is provided to emphasize on recommendations for the immediate future. Onchocerciasis is hyperendemic in several counties ofBushenyi district. Since 1992 there has been a vertical ivermectin treatment programme, supported by Christofel Blindenmission (CBM), operating out of Mbarara, for the two districts of Mbarara and Bushenyi. According to the report oithe CgN4 project Coordinator treatment coverages is between 70 - \ff/o generally. Treatment for l99g has been postponed until October, 1998, in order to prepare for its rarganization to a community directed treatment with ivermectin (CDTI) to replace the initial community based approach so far run through a vertical mobile team. 4.2 Methodolory 4.2.L General outline A 14 day field work was initially scheduled. Outlined activities include sample site selectiorq sampling of immature stages for species identification, selection of suitable sites for human bait fly cat"ires, *hole day fly catches (dawn to dusk), fly dissections for parity (age), dissections and examination for infection with filarial stages and staining of and finally dissections of stained parous flies for examination for filarial infections. The schedule also includes training of the national stafi if not already familiar with the required techniques. 4.2.2 Siteselection Nyabubare parish in Buhinda county was first tried, since the preceding sociological surveys corre.ed this area (Fig l,site A). Rutoto stream was checked for riverine crabs, which support the vector pre-imaginal irg.r The search for potential vectors was abandoned after the first day, as the stream yielJed ro .iub.. The rest of the field activities were conducted in Katerera Sub-county, Mugombwa parish (Fig.l site B), and a comparative observation made in southern onchocerciasis 6 focus ofKabarole district (Fig. ! site C). Crab sampling was done at 3 points eactr, on the Rutondo and Ngoro streams; the former is a tributary of the Buhindaji river, while the latter that of the Katerer4 both flow through human settlements. Two sites were chosen from larger rivers, one on the Buhindaji approximately 2 km from Kagarama uillage and for comparisorq one site on the Kitomi, at Kyarwera just on the edge of the Kasyoha-Kitomi Forest Reserve north-eastern fringes (Fig.l at C). 4.2.3 Crab trapping and sampling for immature stage of Simulium n eovei species Crab trapping and collection of,S. neavei immature stages were conducted using basket traps, a set of 2 each time, using fresh meat as crab bait. Crabs were sexually differentiated, carapace size measured with calipers and examined for immature stages of S. neavel, including pupal cases. All data was entered onto a chart @ef Appendix IA), provided by the entomolory technologists from Fort Portal. 4.2.4 Sampling for other potential vector spp immature stages Only once were S. dsmnosum s.l. immatures observed in and collected from Buhindaji river. These were preserved n 80% Ethanol (for lack of cold Carnoys' solution for cytogenetic preservation), and later used in identification demonstration. 4.2.5 Human bait fty catching Adult human bait captures were attempted at all sites where crab trapping was done and found positive. Since fly human landing catches were very poor during the whole field trip, whole day catches from 7.00 to 18.00 hours were not established at any one site. AgaitL for fly catching recording form 2A and28 were used as shown below. 4.2.6 Fty dissection for age determination and filarial infection The protocol of OCP was used for fresh dissection and staining with Maye/s haemulum in the very limited number of flies caught. However, this was done only as a "stage rehearsal", since the number of flies was too small. Some adult flies were preserved for identification specimens, either dry pinned or in 80% alcohol. 4.2.7 Training in Simulium vector species identification Field work was conducted by 4 people, with a plan of locally recruiting vector collectors once '7 suitable catching sites are established. Although the exact vector identity of the local species in the study site is not knowrU it is generally assumed to be S. neavei. The two national Entomology Technologists were very experienced in sampling and dissection of the S. neavei s.s. from previous work on the GTZ run entomological study conducted by Prof Rolf Garms in Invara onchocerciasis focus near Fort Portal. Specimen preservation methods and identification of immature and imaginal stages for the two major v@tor groups in eastern Africa were discussed. Larval and pupal materials were examined using a light microscope for illustration of essential features. Adult demonstrations were not done for lack of appropriately mounted specimens. Cytogenetic identification technique was discussed, as well as the more current DNA / PCR technology. The national team was very much interested in acquianting themselves with vector identification methods. 5. OBSERVATIONS 5.1 Site selection Nyabubare Parish in Country Buhinda was abandoned for absence of crabs, Katerera sub-county, close by Kagarama and Nyabubale villages, in Mugombwa Parish was chosen. Rutoto and Ngoro strearns were favourable breeding sites, with their abundant crab populatiorq as well as main rivers ofBuhindaji and Kitomi, which originate in the Kasyoha - Kitomi Forest Reserve. Three sites each were selected on Rutondo and Ngoro streams; the former is a tributary of the Buhindaji river. One site each was chosen from 2 larger rivers, on the Buhindaji about 2 km from Kagarama village; one site on the Kitomi river, at Kyarwer4 just on the edge of the Kasyoha- Kitomi Forest Reserve. Under normal circumstances, it appeared that most of the selected larval habitats would favourable for adult human biting catches as well. 5.2 Crab trapping and sampling for immature stages of Simulium nearyi species All the selected sites yielded abundant crabs which were heavily infested with S. newei preimaginal stages, an average of 8 or more per indMdual crab. Results of the crab trapping and S. neavei "immatures" sampling are shown in Table l. B CRABS SneaveiSITE # MEAN S,^,84'EI /CRAB SLY NO I-ARVA PUPAE PCs DATE WATERCOT]RSE 0.25MALE FEMAL 4 5 0 0 0 0 I 0 1*r 0.119 0 0 ry8l98 R RUTONM/KAGARAMA TOTAL 3.M 2.20 MALE FEMAL 24 10 67 15 a ,' 4 5 I 9 2.79TOTAL 34 82 4 6 5 2.q 1.,18 2 MALE FEMAL 25 ,( 523t a I ll 1.94TOTAL 50 83 3 a 0 2.N 4.00 3 MATT, FEMAL 7 3 t2 1l 0 I I ) 2.60TOTAL l0 23 12t8/98 R. RLTTONDO/KAGARAI\,IA 1.90 4.82 I MALE FEMAL 9 t7 l7 68 0 6 6 8 3.81TOTAL 26 85 t3l8D8 R BL'HINDAJI,'KAGARAMA 8 37 t9 4l 9.93 t2.u I I\,IALE FEMAL l5 3l 122 320 442 45 & I 1.89TOTAL 46 l3/8D8 RNGORO/ NGOROVILI-AGE 17 47 I 1 0 I 3.6 12.25 2 MLE FEMAL 5 4 9 64 a I 7.44TOTAL 5 t1 4l 125 0 a 0 l0 8.20 12.45 3 MAI-E, FEMAL tt.t2t6 t6 l0 l,l/8D8 RNC,ORO/ NGOROVILI-AGE TOTAL 29 2t 252 t64 9 8 37 34 10.28 9.81 I MALE FEMAL 10.0850 416 t7 7lTOTAL 6.0 11.75 6 4 29 4l I 1 6 5 t7t8D8 R KITOMI/KYARWERA lr MAIE FEMAL Table 1 : Crab Carches and Infestation by immature stages of Szz lium neavei s.l. TOTAL l0 70 a t1 8.30 9 0 8 t7t8/98 R BUHINDAJYKAGARAMA I MAIT, FEMAL 1 8 13 20 3 a 4 2.4t 3.38 TOTAL l5 33 5 6 2.93 l8/8,98 RNGORO/ NGOROVIII.AGE I MALE FEMAL 20 30 131 2t6 7 38 l4q 7.60 9.80 TOTAL 50 347 45 54 8.92 tegatd: Sanplingsessims differof, d same sitg Trial sanptingfcr 15- 20 minu€s, u/hile dher sanplestakar over I-2 hour drdlm 10 s. neaveiinfestation rate per crab per site ranged from 1.9 to 2.6 for Rutondo stream' 2'93 to 3'81 for Buhindaj i;7.4 to lZ forNgoro stream ,f,d Kito,oi .iu"t, 8'3 and 10 per sampling session' Ngoro stream had high crab catche, *J the highes infestation rates at the village spot, with infestation rates of 9 to l2,and yet there was no ,tiong evidence of fly human biting activity' Since this heavy infestation compares with the Kitomi/I(yarwera of g to 10, some fly human-biting would be expected in Ngoro village or at any of the 3- sampling sitel, s-rnc9. on the Kitomi at Kyarwer4 fly landing reached over 70. 'n 2i minutes from'9:45 to 2:00 o'clock' Absence of human landing flies on the Ngoro may imply that the cra! i1{estins species was not human-biting' oi rfr. atmosp-heric conditions were a severe deterrent to the biting activity 5.3 Sampting for other potential vector spp immature stages s. domnorums./. immature stages were collected from Buhindaji river in for.est remnant nearby Kagaramavillage. No other stream surveyed had preimaginal stages ofthis species complex' S.4Humanbaitflycatchingdissectionsforagedeterminationandfilarialinfection Adult human bait captures were conducted at all sites where crab trapping was done, these obtained I or Zf*airi ni"t after several hours' of waiting' However, on two sepa'rate occasions' 4 flies were caught in l; afternoon on the Buhindaji, just before a rain shower, and on a second one' 5 flies were caught on the Ngoro site, this time rouowing a rain shower. The biggest single fly catch was made on the Kitomi river at ry**".4 wtrere zs flies were caught between 9:45 and 14:00 hours. This site was cool, shaied and humid, and was only used for comparative observations, because it is just outside the study area' Since fly human landing catches were extremely poor during the whole field trip, thus whole day catches from 7:00 - t8:00 hours was not estabtisnea at any site on either river as intended' The protocol of ocP was used for fresh dissections and staining with Mayer,s haemulum in the very limited number of flies caught, including the Kitomi river sample, done as a "stage rehearsal"' since the number of flies was too small foibaseline "impact asseisment" data. . Some adult flies were preserved for identification ,p"ri*.nf "itft", dry pinned or in 80% alcohol' (h--.'X Z4 ) ZA S.5Traininginsimuliumvectorspeciesidentification Tkee potential local "vector collectors" were shown the flies and how to collect them' Except for the one on the Kitomi river, none succeeded in collecting any due to scarcity of human landing flies' Discussions were held on handling of specimens. General specimen pr-eservation methods and identification of immature and imad; stages for the sub-genus Lewisellum neavei and Mwardseltum damnoxtm,the two -;j- ,"iot gfoups in eastern Africa were discussed and 11- demonstrated. Thus whenever ice could be secured, larval samples of potential vector(s) were preserved in Carnoys for possible chromosomal characterisation. However, constant electricity disruptions limited ice making, thus hampering even this effort. S. neavei larval samples. During the l0 days, only t'wice did the group succecd in saving ice cubes for field. Few crabs were separately preserved for identification and/or identification confirmation. Examination of posterior dorsal abdominal tubercles and cuticular setae showed a close affinity to the S. squamowm / yahense and the eastern Africa 'T.{yamagasani" form. Many Eastern African S. domnosum forms, the majority of them nonanthropopffic, fit in this general morphological category. Without the benefit of simultaneous chromosomal characterisatioq it is impossible to determine its specific identity (Maeggq 1992). Cytogenetic identification technique was discussed, as well as the more current DNA / PCR technology. Whenever ice could be secured, larval samples of potential vector(s) were preserved in Carnoys for possible chromosomal characterisation. Few S. neavei larval samples and crabs were separately preserved for identification and / or identification confirmation. Adult distinguishing characters were not demonstrated for lack of suitably mounted specimens. In the absence of entomological pins, some material was pinned with too large pins that distorted the regular characteristics of the fly specimen to be ofany good in morphological identification. 6. DISCUS$ON AND RECOMMENDATIONS 6.1 Discussion Immature stages of the S. newei goup members in Eastern Africa live attached to fresh water crabs in phoretic association. [n many streams where they occur, fresh water crabs carry numerous larvae and pupae of the S. neavei species (Walsh et aL,1996). However, S. neavei spp breeding is limited by factors other than availability of host crabs, as in many instances, fresh water crabs occur in a wider range of stream habitats where S. neavei spp do not (Raybould and White, 1979). The same crab species may harbour more than one member of the species goup (Raybould, 1969; Raybould & Yagunga, 1969). Whether the immature stages of S. neavel currently found on the crabs are human - biting i.e. potential or actual vectors, has to be determined. The first step will be a broader sampling and specific characterisation by a combination of methods, including cytogenetics as done nthe S.nyaxlandicum (Amani form) and S. wodi @rocunier, et al 1988). All populations of .9. neavei in the onchocerciasis areas, where they are seemingly the main v@tor appear to have no distinguishing morphological characters, and according to Walsh et al. (1996), they are currently assigned to S. newel s.s. until definite cytogenetic characterisation is done. In the study area, which is part of the Albertine Rift Valley escarpment, the species occurs at about 1000 to 1500 m altitude, and usually in well forested streams (Walstt, et aI. 1996). The immature stages are found on Potamonmttes aloysiisabaudiae. l2 It has been observed that in more deforested stream valleys, there is already a rapid decline in fly human biting activity, reportedly on the Nkurungu river to the immedate north of the study area (Garms, 1997, Wamani and Tukesig4 personal communication). Whether the scarcity of human biting phenomenon at the time of our visit is due to adverse climatic factors which inhibit fly feedind behaviour, or the immature stages observed actually belong to nonanthoropophilic S. neavei species is not clear, thus has to be determined. In two brief occassions, slight increase in fly landing was observed, both immediately before or soon after rain showers. These observations strengthen the suspicion of a possible rainy season fly biting phenomenon. Some villagers claimed that the flies were numerous in wet season; some adding - especially in presence of monkeys. It is therefore imperative to intensiS entomological observations during the coming 4 months of rainy season, from September to December, 1998. Following this exercise, a decision will then be made as to whether obtained data is of practical used for impact assessment in APOC activities in years to come. The national team was very much interested in acquiating themselves with vector identification methods. There both the S. neavei and S. dsmnontm vector species whose identities are yet unknown in Uganda. Training of the interested national experts, using own locally collected materialwill be great asset. 6.2 Recommendations Available information on vectors of onchocerciasis in the study area needs further investigation. From observations made during the current study it is not possible establish whether substantial fly biting activity occurs, sufficient to sustain O. volwtlus transmissioq in order to fufill the selection criteria for APOC impact assessment purpose. It is therefore recoflrmended that:- i) A 7 day monthly vector sampling sessions be conducted by the national entomological team between September and December, 1998. ii) The December 7 day data collection trip be joined by the external entomologist, this will be the second field trip for the latter, in the fust year ofbaseline data collection. iii) From these "rainy'' season observations, a decision will be made, as to whether the site is suitable for evaluation of transmission indices for impact assessment of CDTI. Furthermore, during this period various samples for vector identification will be collected and preserved by the national tearry ready for processing and analysing whenever reagents become available. ,r)* From the above recommendatioq there is a request for a small budgetary increase for which a review estimate is attached. This is because it is absolutely necessary for the local 13 entomological team to have private transport in order to reach the out of the way tracks that are remote from public transport routes. The NOTF is willing to provide a motor vehicle, but cannot carter for fuel and oil. It is further requested that the entomolory technologists be allowed 7 and not 5 days for the next very crucial4 months (refer to Table 1A below), to give the team sufEcient time to trap crabs and also catch flies in most suitable sites. The terrain is difficult, thus five days will cut the real working days to 2 -3, which are considered insufficient in the absence of other sources of supporting information. v)* Considering that most communities in accessible, onchocerciasis areas of Uganda have been under large scale ivermectin treatment for the past 6-7 years, it is hereby recommended that prior to the next treatment cycle, which marks the biginning of CDTI in our study are4 the villages of Kagaram4 Nyabubale and Ngoro be skin snipped to determine current skin mf rates. The observation on skin mf rates can then be used as a starting point for CDTI, comparable to whatever entomological transmission indices will be observed pre-treatment. 7. CONCLUSION More entomological data is required before the selected site is judged as suitable for impact assessment of CDTI on transmission indeces. REFERENCES: Garms, R (1997). Eradication of the vector Sirmilium neavei from the northern onchocerciasis focus of Kabarole district - situation in March 1997 Unpublished report to GTZ Basic Health Services, Fort Portal, 31.03.1997 ; pp20. Katholi, CR, L Tog A Meriweather &TR Unnasch (1995). Determining the prevalence of Orrchrcerca volwlus infection in vector populations by polymerase chain reaction screening of pools of black flies. Journal of Infectious Diseases 172.1414-7. Maegga, BT (1992).Identification of Sirrulium damnosum vectors of Onchocerca volwtlus in the Tukuyu Valley of Southwest Tanzana. A PhD Dissertation submitted to Cornell University Graduate School, Ithaca, New York USA, Ian1992) pp xiv + 269. Mutabazi, D & BOL Duke (1998). Onchocerciasis control in Uganda: How can self-sustaining, community-based treatment with ivermectin be achieved? Ann. Trop. Med. Parasitol.92(2).195- 203. OskanLL.,GLMwaiko,BMaegg4ASame-Ekobo,FIr{iokou,CBellec&SHerder(1996). Genetic variation in Onchocerca volvulus from Cameroor; Tanzana and Sierra Leone. Unpublished Report of the Royal Tropical Institute Amsterdam, Department of Biomedical Researcll Amsterdarn, The Netherlands (pp.28; (presented as Mwaiko, et al 1996, at the KVth International Congress for Tropical Medicine and Malari4 Nagasaki, Japarr,lT-22 Nov. 1996; and L4 APPENDICES L6 6 bF c q oN F- {$ cl o raz! a.{rlf l i FT z ! v:G v? O rr2 c{ al GI vl rio ct o s \Dd \r al F. o\(ld F o\ Eoa G t:\a nN v) o\ i oo r) !+ o\ r: € \o & ri o;\o € di N ts = € ei N € q \o\o t N r1 R Nr- a oi + o rf + :f, t- d a N F..\o 6 2 q €o \ o\6 e{ t-- € o 5ofl c! o\o \ \o € F.t'. € \o € € r) f; € €l o\F E * o\ o\ o\o\ \o o\ o\ a-. o\ o\ u lD CI (t) tn o (l) (E It E] o o .Y f (B o. E oU d 6)F E G! o0 LoN (D B& o d.-(s GtE -(tl ftlil q) p CBF -, )-,. I og'---ot- :c rh Catches of River and Place ; 14 R rVtrcrit i Traps set Date ' t+l *l1e Trarps reooved Date: . crabs (Potamona ut s) Mtront<> 'Jtr-/-A'hi ! lf Eour; /i,, ou f'u Eour t 444" Px^ X rya.LuL,<[.a l,io. of traPs: P Mode or trapprng I fll-aasrecs I Hand-traps E uy nana E c"g' yraLer texperaLure oC, ConducEl.vrLy: i.rS/crn, pH Hour No. S. neavelI^I:-dth ( ctn) .No. S. neaveiWidth (cm) P PCsLNo 66P PCsd6 ?? LNo I F ,)3 I C t7 tt 26 2, ?o '!, ltsI I 2'l l1:Il;ll I U iL, 1t: + t+t> 4?o 1 ) -i-- I 7 I 23 .ro28 "(+ 5 ',34.gc 3 +tl c2, 60f) o 2964 4oo a'tI 30 ,+ qr) I780?o ,7 I I i 5 + Do 31 3, ocd Cr-+ tc I \-)6 o oi I L32 l,f3IL c I7 3.71- oI 33 4 >b| o& IOI 3.3(, I zI9 I \-r: /- 5 S n I I 34 -{' 2c .j ,30IIi I Ir l l10 I I 4 rc o l3, 80 6O 2 36rl .io (11l II(, C l).1. -(f\t2 I t)3' 3c' tGt2 IZ r^L- ot .1 J i- -,) qJ 7r) ()(r 1L c) 41 >f, 31 39 38 tq14 i4to to o o40 .3 .6o+ + I3'sb 15 I DII41 3' +r> 3J II I C t1-15 13 su t3 C r^)3 I l ,1 .,1\tt Ir 6r>1? D o38o ,6l o 433' 80 718 3,30 te lI {47o --t'5))19 I I ,y'- D i :L ,c 46 i/ / ll I l:[Ll tL, 20 a! '1, r1{) ,r,\)) ? L S'r c, 4't lLt D I3' 7o 48 ,.s l350 2? ,7, I + 49tI:l ,f24 I + 50 _s ac 3' 3'c .: - .''.1 -i-"'- t^.-.,,.., 0 .'l M. ^,- n ,l-)y:/t-,Qrl .,:*lil 'rAI Nn- 99 I i I t u( C t"t) A Sfeesu'x r A fu.-^-.-r n".r/ 14\ t?,qt;re-N1 i Uf fRr c-t Catch of Sirmrl ium Srrrulium damnosum s .1. catching site: t2rjroru[o- t.a_Aq&pn+n.^ Dates: \l_ lorlqf Rtver : Qtr.;zrlif\o - B.a rr_, ,..,r i) A.t r Narres of vector collectors: l) )\ 1! 't Hour' No . iR flies i a ri n 3- 1 15 I I '1 I I eave L Datc' ,) .l e)?. Date: Date: Date: R aj. n T No.flies Hour R a i n i I I I I I R a i n Hour I No. flies 07- Hour I I No. f Ii-es 07 08 11 L2 11 L2 0 -09 0- 12-13 I L2-L3 tc i I I .J 1d 1.3 - 14 13-1{ 14 --15- 15 6 15 16 15 16 16 l7 16 L7 1?-18 oe - lc-;- 10 - 1l ' 'cl rrl a7 0e - 09 09- 10 12-13 Oo 1? - r, L' t. 16 ct ot) 18 1A - 19 0 r I 11 - 12 | 12 14 - i5 L7 1 r6- r 08 i7 15 18-19 re - r7 rz- - ra- - 191 ToLrI r-) - To brI I I lot,aI f- TotaI II Rema-rks il i'tt^^* +t^{ s \-J^^ O\-SQ=A \N1'fL Rn* q C.atd^o.8, r t 07 OB 10 I -18 18- I I 1 I I ( A*eersen* aR tlC*rrlbA ' hr--( -- St * Catch of S catching site , ('1fr4L0a{U kta\aa Rrrrer, Q R.t-toua' Najaes of vector colleetors: 1 t E .7. 2) J.w Da.te: 1f-.c)8.?r Ho'.:r No. f .Iies O7 - Oti 0?-08 irmrl i near.';i Sirmrlium darnnosum s.1. FL l/-*8,fttzc)e€ Dns Tr-_tLi t111gtb 3) T't Datea: R CL i l) Date: -0 -,, )--, .i -de .. o e- '----- 09(t tt,& \n e-z\ 08*0e i':li I -10 I I I10-11 I-L - D- 15 .rg - rn ra - r5 otr - 0:) f '{_i- I i -,----'- -"-'-'--' c-1 I It5 )s 09-1A 1 10-11 l_1 - 12 l_0 - i.I 11 -1 l- -1' I 1 I I L LIll ----1..i3 I ir;ld 13)I L--__l12 - 13 L2-l, j'i'-:'-; ;' + - "---- -- td - 15'- rs - ro i J.3-L 1 -id 1.4 - ..-_-i .15 I i I -.1 ia'r i, -1 16 - J. 'r tS9r he b *,V J. i1 - 1o rB - il ___-._ _ _t_..l7-18 -:T0-l To?cL e-2 \Renrarks : \ \,..,-l O4.^a_O^ L? -1Al t3 '!oi,irl, 1:) O l,^* U^Ja\ e-{e-ckl +ho0j Date:Date: IIour )io flies R u. i n R a i n Hour No le sf.1 Ra ir n Hour No. flies 15 1.6 15 L7 L7 19 1. 1 I I I ! I T I I Tot:aI :-I l I I iI 'l{^" D (* ssse L- P hSa!^, ,-! I I -_l'-- i_-_ I l / I I