Evaluation of the impact of APOC activities

African Programme for Onchocerciasis Control (APOC) Programme africain de lutte contre I'onchocercose JAF-FAC ht I a. JOINT ACTION FORUM Office of the Chairman JOINT ACTION FORUM Third session Liveroool. 4-5 December 1997 FORUM D'ACTION COMMUNE Bureau du Pr6sident JAF3/INF/DOC.2 ORIGINAL: ENGLISH October 1997 I I ,l EVALUATION OF THE IMPACT OF APOC ACTIVITIES Introduction Onchocerciasis is a disease of great Public Health importance in view of the medical and socioeconomic problems associated with the disease. The parasite Onchocerca volvulus causes itching and disfiguring skin disease, serious eye lesions and blindness in parts of tropical Africa as well as causing abandonment or preventing areas and fertile land. The disease has been largely controlled in most parts of West Africa following the successful implementation of Onchocerciasis Control Programme (OCP)1. Vector control in the original seven country area-started during the years 1974 - 1979. The availability of ivermectin in 1987 as a drug suitable for large scale treatment of onchocerciasis enabled OCP to adopt this as a means of reducing more rapidly the ocular morbidity from onchocerciasis. Post-control entomological surveillance and epidemiological evaluation have demonstrated a drastic fall in transmission of the disease in the 11 countries of OCP. The incidence of infection in children has been reduced by 99%. Considerable scientific evidence gathered during the life of OCP enabled the programme to quantify its impact including transmission potentials, parasitological prevalence studies, parasite loads in the community and ophthalmological studies. The intensity of infection as measured by the cornmunity microfilarial load (CMFL) declined in a linear fashion, reaching very low levels after 10 years of control. After 13 years of vector control, microfilariae were no longer seen in the eye, and there was no incidence of ocular lesions and onchocercal blindness. The African Programme for Onchocerciasis Control (APOC) has been established to extend the gains of OCP to new countries. APOC unlike OCP, will depend largely on the use of ivermectin to be distributed by a community directed strategy as the main control tool to eliminate onchocerciasis as a public health problem. Most countries have established National Onchocerciasis Task Forces to support the control activities and evaluation of impact is an essential activity to be considered at the beginning of the programme. JAF3 / tvy /ooc.z Page 2 STATEMBNT OF THE PROBLEM. OBJECTIVES OF APOC AND ITS EVALUATION The objective and the ultimate goal of APOC are To establish, within a period of 12 years, ffictive and self-sustainable community directed treatment with ivernrcctin (CDTI) throughout the remaining endemic areas in Africa and to eliminate the disease by vector control in few selected foci. Attainment of this objective will ultimately realize the goal of elimination of onchocerciasis as a disease of public health and socioeconomic impofiance throughout Africa The establishment of CDTI will be done through APOC-funded projects. Each project will have a monitoring component to assess whether CDTI has been effectively established in all target communities and to determine what treatment coverage has been achieved. Provisional guidelines for project monitoring have been provided by the Technical Consultative Committee of APOC. In order to evaluate whether APOC will achieve its ultimate objective of eliminating onchocerciasis as a problem of public health and socioeconomic importance throughout Africa, a separate epidemiological evaluation will be undertaken in a number of sites representative of the principal epidemiological patterns and which cover all endemic countries. The protocol for this evaluation of the impact of onchocerciasis control is provided in this document. The evaluation focuses on the effect of control on onchocerciasis disease burden, and particularly the ocular and skin manifestations of the disease. With respect to the socioeconomic consequences of onchocerciasis, the evaluation will be based on the premise that once the disease manifestations have been eliminated, its socioeconomic consequences will also have disappeared. The importance of onchocercal skin disease has been shrdied by a multicountry study group. The prevalence of itching showed a positive correlation with prevalence of skin nodules though prevalence of Ieopard skin lesion showed weak but positive relationship. Unfortunately, most of the onchocercal skin lesions vary with age. Acute papular onchodermatitis was most prevalent in the younger age group, whilst chronic papular oncho dermatitis, atrophy and depigmentation decreased with age. This could make trend analysis difficult if age groups are not linked in the analysis stage. Oncho eye disease and blindness have been studied extensively in various ecological zones where onchocerciasis is hyper or mesoendemic. Major pathways to blindness from this disease which are sclerosing keratitis in the anterior segment and optic nerve disease and chorioretinitis in the posterior segment still abound in endemic communities. Appearance of new corneal haze or regression of an already existing haze will constitute the change in sclerosing keratitis as well as appearance of new or worsening of existing chorioretinal lesions. The present non invasive indicators considered in this proposal were not used during OCP to assess changes in eye disease and the only source of information on onchocercal skin disease is from the multi-country snrdy. Literature review In a multi-country study of the importance of onchocercal skin lesions, it was concluded that over 30% of the population in the endemic communities had onchocercal skin lesions. The most prevalent among them being chronic papular onchodermatitis affecting 13. 1 % of the population. The data showed JAF3 / tNs /ooc . z Page 3 a strong correlation between the prevalence and severity of onchocercal skin disease and the level of endemiciry in the communiry. Troublesome itching as a result of onchocerciasis was reported by more than half of the population of hyperendemic populations. The results of the study indicated that there was a significant difference between the prevalence of the onchocercal skin lesions in the hyperendemic areas and non endemic areas. Thus if the APOC operations were to be successful, the period of treatment could be considered as making the area of treatment non endemic. In this case the results of the multi-country study could be applicable. It is hoped that with treatment, transmission of the parasite will be diminished as a result of low community microfilarial load. Published reports indicate that most onchocercal blindness and morbidity in the meso endemic savanna and forest savanna areas are from optic nerve disease and chorioretinitis in the posterior segment whilst in the anterior segment, sclerosing keratitis and uveitis along with secondary glaucoma are the blinding pathways. It has been shown that ivermectin produces an 80Vo reduction in new cases of optic nerve disease as well as 45% reduction in incidence of further visual field deterioration in individuals with optic atrophy. It also has beneficial effect on other onchocercal eye lesions including punctate keratitis and iridocyclitis. Ivermectin prevents or delays the onset of optic atrophy as well as slowing down the progression of the disease. General Objective To evaluate the opthalmological and dermatological impact of onchocerciasis control in APOC countries and to evaluate the effect of ivermectin on disease burden. Specific Objectives SKIN LESIONS 1. To determine the change in prevalence of onchocercal reactive skin lesions and depigmentation (DPM) 2. To determine the change in the proportion of the population with symptoms/signs of severe itching. 3. To determine the incidence of onchocercal depigmentation (DPM). 4. To determine the change in prevalence of onchocercal skin nodules . EYB LESIONS 3. To determine the change in the prevalence of onchocercal eye lesions, visual function defects and blindness using the standard clinical methods for eye examination and the Wu-Jones Computerized Visual Function Tests (CVFT). 4. To determine the incidence of onchocercal eye lesions, visual field defects and blindness JAF3 /tNr /ooc.z Page 4 Working hypothesis Regular ivermectin treatment will: D reduce severe itching, prevent the development of onchocercal skin disease and may regress early skin lesions; ii) prevent the development or delay progression of onchocercal eye lesions and blindness; and may regress early stages of ocular lesions. APOC activities should thereby lead to marked reduction in morbidity of onchocerciasis. Methodology. Determination of Prevalence of nodules and skin lesions A cross- sectional study design will be used. Two studies will be carried out, first at baseline and the second, 4-5 years after. A sample of a population in the target study site will be selected and subjected to interviews using a questionnaire and physical examination. The number of sites for evaluation within a country will be determined by the geographical zones and the size of the country. Cohort analysis will be done to determine incidence. Skin examination will be done according to examination methodology as described by Murdoch et al (Bri. J of Dermatology) and subsequently simplified for the multi-country study. The sample size determination For a successful programme of operations, there should be a demonstrable difference in prevalence of skin lesions of about l0% or more between the two point estimations for all the target population within 5 years. Alternatively, at the end point for evaluation, the age-group specific prevalence data should show increasing trends with age for skin nodules and chronic onchocercal skin lesions. However, for conditions expected to regress, such as itching, microfilarial loads in the eyes, early lesions of the anterior segment of the eye and early lesions of the skin such as acute papular onchodermatitis, the age group specific effect of the treatment is not expected to be significant. The aim of each cross sectional study will be to estimate the prevalence of onchocercal skin and eye lesion by age. It is expected that onchocercal skin lesions would drop from a prevalence of about 15% to 10%, severe itching could drop from30% to 15% and prevalence of microfilarial in the anterior chamber from l0% to 5%. Using a drop in prevalence rate of 10% resulting from the activities of the programme, a sample of about 750 inhabitants will be required at each evaluation site. Criteria for selection of evaluation sites. The study sites should be: 1. representative of all major epidemiological and ecological zones 2. hyperendemic for oncho within APOC project areas 3. reasonably accessible as frequently as possible during the year. Sites should not be JAF3 /tNr /ooc.z Page 5 4. co-endemic for onchocerciasis and loasis. 6. Epidemiological criteria 1. REMO should have been or about to be completed 2. Areas should not have been previously subjected to Mectizan 3. Ecology of the country should be taken into account Savanna Forest-savanna mosaic Forest Sample selection. The evaluation will be carried out in up to 22 selected sites in APOC countries. Potential sites should be identified in Nigeria, Cameroon, Chad, Central African Republic, Sudan, Ethiopia, Uganda, Tanzania, Malawi, Angola, Congo, Gabon, Democratic Republic of Congo (see appendix 1). The sample will be obtained by selecting rural communities around the selected evaluation site. The target population will be interviewed and examined within the selected households. For the eye examinations, all the interviewed individuals above the age of 10 years will be examined. Enough information will be collected to enable the linkage of individuals between studies. If a village is too large, a subsection will be selected on the basis of local organization (subchief, cell leaders etc), and examine all eligible members. A detailed census will be taken and used 5 years later for matching- Annexe 1, (Edited by Smith and Morrow, 1991 In "Methods for field trials of interventions against tropical diseases"). Skin examination will be undertaken to detect Skin Lesions Four clinical morphological types of onchocercal skin lesions will be classified : (i) Chronic Papular Onchodermatitis (CPOD), (ii) Depigmentation (DPM), (iii) Acute Papular Onchodermatitis (APOD) and (iv) Atrophy (ATR). Skin Nodules 1. Palpable nodules, the number and distribution will be recorded Itching 1. Troublesome itching as evidenced by scratch marks on the body and responses to health survey questions. A questionnaire will be designed to collect information from members of the selected families in each community. After introducing the purpose of the study, questions will be asked regarding severe itching. A skin examination form will be used to identify the skin lesions and the results recorded for each person. JAF3 / tNr /ooc .z Page 6 Eye examination All standard eye examinations will be performed by an ophthalmologist and one resident ophthalmologist trained especially for the study. The Wu-Jones tests will be performed by two trained assistants. All subjects will do the Wu-Jones tests while half of this number will undergo detailed standard clinical methods for eye examination. Yisual Acuity Visual acuity will be measured using the Standard Snellen's illiterate "E" chart for distance (in addition to the Computerized Visual Acuiry Test (CVAT). The test is to be conducted with the chart placed at a distance of 6 metres from the subject in broad daylight with source of light coming from behind the chart. One eye is tested at a time with the other occluded after clearly explaining the procedure to the patient. Wu-Jones Test Subjects will be examined further using the Wu-Jones test. Testing will be carried out in a room darkened with black curtains or plastic drapes to cut out natural light. One red light will be provided to give dim red light "dark room" conditions to enable patient and examiner observe the computer screen, recording by the examiner and movement by other subjects. CVAT With subject seated comfortably and test explained to him or her at the computer programme prompting, the examiner selects the eye to be tested. Subject sits at a distance of 1 metre from the screen (standard arms length or measured with a one-metre twine which all examiners should have, patient is asked to indicate with the wave of his or her hand the direction the "E" appearing on the screen faces. The computer records each point scored by the patient until he goes through "8" letters he can identify. This is automatically recorded by the computer and stored into the hard disk. The fellow eye is tested in a similar way. The Motion Sensitivity Screening Test (MSST). A series of vertical lines are displayed on the computer screen. As preliminary training, subject is asked whether he sees them and if so to count them. This is to ensure that he actually understands the instructions. He is then asked to watch the lines and to press abuzzer, to be handed over to him, as soon as he perceives movement of any of the lines. When the examiner is certain that the subject has understood the test, he (subject) is then asked to rest his chin on the chin rest in a specially made box that contains the computer. The chin rest is 40 cm away from the screen. When subject is seated comfortably, one eye is occluded and he is asked to fix the open eye on a central white target on the screen all the time and to press the buzzer whenever he sees from the corner of the open eye, any movement of the lines. At the end of the test, which lasts about 2.2 minutes, the computer displays the results on the screen. This is again registered on to the hard disk. A recording form for the test is also completed by the examiner. This serves as a check and an additional follow-up record for the particular individual. JAF3/rllp/noc.z Page 1 Anterior segment examination Subject is first asked to bend his head down between his knees for at least 2 minutes . The procedure is to allow for the emergence of microfilariae into the anterior chamber. Subject is then examined on the slit lamp biomicroscope (x 25 magnification) and count of microf,rlariae in the cornea and anterior chamber noted. Cornea is examined for dead microfilaria, punctate or sclerosing keratitis. Other corneal pathology is looked for. Pupillary reaction to light as well as the shape of pupil is examined. Anterior chamber and iris are examined for signs of inflammation and for opacities in the lens, luxation or dislocation of the lens. Posterior segment examination This is carried out after dilation with mydrilate l% or phenylephrine l0%, with the direct and/or indirect ophthalmoscope. Fundus examination Optic disc changes such as pallor of the disc, changes at the disc margins, sheathing of retinal blood vessels and pathological cupping of the disc will be looked for. Oncho chorioretinitis Presence and distribution of the typical oncho signs of chorioretinitis- atrophy of the retinal pigment epithelium, atrophy of choriocapillaries will be noted. Other chorioretinal signs of possible oncho origin. The non-typical onchoretinal signs- pigment hyperplasia, pseudo-drusen, which will be looked for are designed to test their probable association with onchocerciasis. Training and standardization of research team members. It is crucial to provide adequate training and standardization for all the examining members of the team to minimize observer variation. JAF3 / tNp /ooc . z Page I EPIDEMIOLOGICAL EVALUATION: SKIN EXAMINATION FORM 1. Study Centre Code 4. House hold Code 6. Name of respondent Name of Village Individual Number 7 Age -(yrs) 8. Sex_ 9. Name of Head Household 10 In School _ (Y/ N) If no, why ?, 11.Date 12. PERSONAL EXPERIENCE OF ILLNESS "We are especially interested in your health. How have you been feeling since last month ? 13. Have you been troubled by any particular health problems ? 14. PHYSICALEXAMINATION 2 5 Record spontaneous answers DISEASES ANSWERS When PROMPTED 1. Headache/ Cough 2. JoinrBone pain / Backache 3. Fatigue / Weakness 4. Severe / troublesome Itching 5. Insomnia 6. Concern for appearance 7. Diarrhoea and others Skin condition Absent : 0 Present : I COMMENTS With scratch marks With excoriation With superinfection : excoriation & superinf. : 1 2 J 4 Acute Papular Onchodermatitis (APOD) Chronic Papular Onchodermatitis (CPOD) Lichenified Onchodermatitis (LOD) Onchocercal Depigmentation (DPM) Palpable Onchocercal Nodules Village. rD N'trtr trtr Site N' tr tr Name of Subject. Examiner. Name of Head of Household I. Visual Acuity Aided/Unaided-Acuity Pinhole-Acuity EVALUATION OF EPIDEMIOLOGICAL IMPACT OF APOC ACTIVITIES EYE EXAMINATION FORM JAF3/rur'/noc.z Page 9 ...village code Etr trtr ....compound Notrtr trtr ....Surname Date:DD/MM/YY. Codes 01 : 6/18 ;05 : 3/60 02 : 6124 ;07 : HM/CF/PL 03 : 6136; 08 : NPL 04 : 6160 ;99 : Unable to assess Use Pinhole if VA : <6118 Do not use if : PL or NPL I : Absent 2:ExactCount-1-100 3: >100-Estimatecount 1 : Absent 2:Exactcountl-50 3: )50-Estimatecount 1 : Absent 2:Exactcounti-20 3 : )20 - Estimate Count 1 : Absent 2:9and3O'clo"f.C 3 : Confluent Inferior Semiluar pupil free C 4 : Confluent, pupil obscured 5 : Unable to assess. District/LGA Left trtr trtr 2. Microfilarial DMFC trtr (Dead microfilarial in cornea) MFAC (Mf in anterior chamber after head down 2 mns) Right trtr trn trn 3. Cornea (a) Punctate Keratitis (b) Sclerosing Keratitis tr tr o JAF3 / tNr /ooc .z Page 10 @ Other corneal Signs Right Left 4. Pupil (a) Shape (b)Light Response Iridocyclitis (a) Torpid (Flare +/- cells .Pigmented KPS Iris atrophy . No injection (b) Acute tr tr (Ciliary Injection, Flare )+/- cells . KPs. Often Pigmented Codes 1 : Absent 2: Comeal Oedema (Any degree) 3 : Central Opacify associated with reduced visual acuity 4 : Trachomatous Pannus (Any degree) 5 : 2+3 ; 6: 2+4 ;7 : 3+4; 8: Others (speci$, measles, Band Keratitis) 9 : Unable to assess. I : Normal 2 : Distorted - Specify (Down-drawn, Nasally-drawn) 1 : Normal (Brisk) 2: Small & fixed 3:Dilated&fixed 4: Sluggish 5 : Unable to assess 1 : Absent 2 : Without Anterior or Posterior Synechiae 3 : With Anterior or Posterior Synechiae 4: Signs of previous Iridocyclitis without Ant. or Post Synechiae 5: Signs of previous Iridocyclitis with Ant. or Post Synechiae 9: Unable to assess 1 : Absent 2: Without Anterior or Posterior Synechiae 3 : With Anterior or Posterior Synechiae 4 : Signs of previous Iridocyclitis with Ant. or Post Synechial 9 : Unable to assess 5 JAF3 /tNp /ooc .z Page 11 Right 6. CATARACT (Reflex: rr) 7. OPHTHALMOSCOPY Optic DISC (a) Vertical cup/Disc Ratio (b) Colour @ View of Disc 8. Chorioretinitis (a) Morphology (b) Distribution 9. Other Choroidoretinal Signs of Oncho (Non typical Oncho Signs) tr I : Clear red reflex (rr) 2 : impaired rr <l12 obscured 3 : Impaired rr ) 1/z obscured 4: No rr 5 : Aphakia 6 : Displaced lens 9 : Unable to assess I : <0.5 2: >0.5 1 : Normal 2 : Pale 3 : Primary Optic Atrophy 4: Consecutive Optic Atrophy with/without sheathing ofvessels 5 : Abnormally Pink 1 : clear 2 : Obscured 3 : Uncooperative 1 : Absent 2: Mottling of retinal pigment epithelium 3 : Confluent atrophy of retinal pigment epithelium 4 : 2+3 + choriocapillaris atrophy 9 : Unable to assess I : Temporal 2 : Nasal )- LAZ 4: Generalized 9 : Unable to assess I : Absent 2 : Pseudo- drusen 3 : Pigment Hyperplasia tr Left Codes tr tr tr tr tr JAF3 /tvp /ooc.z Page 72 10. Other Fundus Lesions I 1. Intraocular Pressure (In mm Hg) Using Glaucotest 12. Right Left Codes Main Cause of Visual Impairment tr 1 : Absent 2 : Focal chorioretinitis (typical toxoplasmosis) 3 : Vascular Retinopathy (Diabetic, Hypertensive) 4: Drusen 9 : Unable to assess trtr 99 : Unable to test I : Normal 2 : Onchopathology of anterior segment 3 : Oncho pathology of posterior segment 4 : Non Oncho Cataract 5 : Glaucoma (non-Oncho) 6: Phthisis bulbi 7: Trachoma 8 : Others (trauma, measles ) 9: Unable to determine tr tr JAF3 / tNp /ooc . z Page 13 CVAT & MSST RECORD FORM TIME ZERO 1" FOLLOW UP 2M FOLLOW UP Logmar Right Left Right Left Right Left 0.0r 0.1 0.2 0.3 0.4 0.5 0.6 0.1 0.8 0.9 1.0 1.1 t.2 1.3 t.+ I.5 1.6 Sensitivity % 100 90 80 10 60 50 40 30 20 10 Reliability % 100 90 80 '70 60 50 40 30 Time in seconds WORK PLAN JAF3 / tNr /ooc.z Page L4 TIME FRAME FOR THE EPIDEMIOLOGICAL IMPACT ASSESSMENT. It is suggested that as soon as possible, all APOC countries should conduct the epidemiological impact assessment study in the appropriate sites in the country. Four teams should be formed to carry out the evaluation in 22 sites in 13 APOC countries. Each team will consist of one or two ophthalmologists, one or two dermatologist/ clinicians, two assistants for the Wu-Jones machines, a coordinator and a local helper. The professionals in each team should be assembled and trained for standardization of techniques and procedures soon (not later than October 1997) for about 14 days. The venue for the workshop should allow easy access to both patients and materials, facilitate training and provide adequate administrative and secretarial support. A pilot study will be organized as part of or following the training It may be necessary to include a social scientist in some of the sites to collect data on the community's views and acceptance of the APOC activities while the possibility of conducting a more detailed social impact assessment study is being considered. A list of potential skin and eye professionals including epidemiologists has been prepared. Trainers have been identified. In order to facilitate the training, it is important to assemble patients and materials. The22 sites and 13 countries have been identified. These are listed in this report. It is suggested that following the baseline evaluation, the next assessment should take place after five years MAIN ACTIVITIES Field preparation Contact should be made with the chief and the elders of the villages selected. Study timetable should be discussed and be fixed. It is envisaged that each village would need about 3 days for interview and examination. Travel time must be worked out differently. Time of training of research team and the identification of local counterpart should be considered Data analysis. Prevalence will be calculated as the number of all persons examined that has the condition of interest divided by the total number examined. Prevalence would be compared across time periods or between age groups. Incidence will be calculated using the linked data. JAF3/rNr'/noc.z Page 15 BUDGET PER SITE FOR EVALUATION ITEM 1. Personnel Local per diem and salary for 3 professionals (two ophthalmologists, one dermatologist, (at maximum $100.00) for 14 days per site - 3x14x100 2 computer assistants and $ 50 x 14 days One driver for $ 30 x 21 days One local persons $10 x 14 days Sub total 2. EQUIPMENT Quantity Slit Lamp (Haag Streit or Topcon) Notebook Computer Ophthalmoscope - Direct Ophthalmoscope -Indirect *20D lens Snellens "8" chart Glaucotest Sub total 3. STIPPLIES US DOLLARS. 4,200.00 1,400.00 630.00 140.00 6.370.00 1 1 1 1) 2 each s,000.00 1,700.00 700.00 1,400.00 20.00 40.00 Spare bulbs Batteries (Alkaline) 2 20 pairs 8,860.00 10.00 10.00 20.00 s0.00 Sub total 4. DRUGS OPHTHALMIC Phenylephrine l0% 20 bottles Mydrllate l% 20 bottles Amethocaine 1% 10 bottles Chloramphenicol eye, drops & ointment 100 tubes/bottles Flourescein Strips 10 packets Sub total a a a a a a a aa a a a JAF3 / tvr /ooc . z Page 15 5. DRUGS GENERAL ParaceLamol Chloroquine phosphate Tetracyclines capsules Fersolate tablets Vitamin A capsules Others . Plastic wash basin . Water can and soap Sub total 6. TRANSPORTATION Vehicle hire x 21 days Fuel & Oil/Lubricant x 21 days Electric Generator hire Sub total 7. AIR FARES 3. STATIONERY Five reams of A,4 paper Photocopy of questionnaire Pens/clips/etc Sub total 9. DATA ENTRY AND REPORTING TOTAL COST OF STUDY PER SITE 1000 tablets 1000 tablets 1000 tablets 1000 tablets 1000 tablets Ia a a s0.00 2.000.00 s0.00 100.00 70.00 220.00 500.00 20,070.00 000 600 400 2,000.00 a a JAF3/rur/noc.z Page 7'7 References 1. WHO Expert Committee on Onchocerciasis Control. Onchocerciasis and its control, WHO Technical Report Series 852, Geneva, 1995. 2. Remme J et al. The predicted and observed decline in onchocerciasis infection during 14 years of successful control of Simulium spp. in West Africa. Bulletin of the World Health Organization, 1900, 68:331-339. 3. The Pan-African Study Group on Onchocercal Skin Disease. The importance of Onchocercal Skin Disease Applied Field Research Reports No. 1 TDR/AFR/RP/95.1 4. Abiose A et al : Reduction in incidence of optic revue disease with annual ivermectin to control onchocerciasis. 5. Umeh RE, et al : Eye Disease in an onchocerciasis endemic area of the forest Savanna mosaic region of Nigeria. Bulletin of the World Health Organization 1996,74(I) :95 - 100 6. Prost A : The burden of blindness in about males in Savanna villages of west Africa onchocerciasis. Transactions of the Royal Society of Tropical Medicine & Hygiene. 1986, 80 7. Cousens et al : Impact of annual ivermectin on onchocercal visual field loss. In press. exposed to 525-7 8. Dadzie K.Y. et al : Changes in ocular onchocerciasis four and twelve months after community based treatment with ivermectin in a hypoendemic onchocerciasis focus Transactions of the Royal Society of Tropical Medicine & Hygiene, 1990,84 103 - 108. a JAF3/INF/DOC. e Page 18 Censuses ANNEX 1 &rrvey form number u of D Mllage Name: m m lnterviewec.---ffl Compound Head: No. Date: JJ-JJ trl-lsM Person Names Relat. Sex Blrth Date Resld5fmtrtr tILI 5f fI[f t,.]trtr 5f LI mtr m[t SlLr EJtI G]LI E]LI EJL.] f,]LI 5]LI 5f rrl Eltrl tl trJJJi tr tr tr D D JJJ-J tr ! D tr JJJJ JJJJ JJJJ D f'-r-rrf ! tr ! tr ! tr D tr tr ! n ! tr JJJJ tr EJJ-I tr JJJJ tr EfD EJJJJ] D JJJJ tr u D ! ! 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