Report on focal vector elimination of S. neavei in Itwara focus, Kabarole district, Western Uganda: January- December 2000

.lr h) SCa/vLZ/BV ) r' REPORT ON FOCAL VECTOR ELIMINATION OF S. NEAVEI IN ITWARA FOCUS, KABAROLE DISTRICT WESTERN UGANDA JANUARY - DECEMBER 2OOO SUBMITTED BY NOTF . UGANDA SUMMARY Focal vector elimination of Simulium neavei s.s in ltwara focus, northern Kabarole District continued since its inception in September 1998. The two years' operations registered tremendous progress. Activities involved in monitoring were crab trapping and examination, supervised and unsupervised adult catches in the six established catching sites and support supervision by various cadres of staff. It was observed that in ltwara main focus and Siisa sub-focus, out of the 5Bg and 1,479 crabs caught and examined respectively, all were negative for S. neaveiimmature stages. ltwara main focus has been free of S. neavei vector for the last 41 months since river treatment was suspended whereas for Siisa sub-focus it is 14 months since the last positive crab was encountered. However, for the Aswa sub-focus, out of the 3,674 crabs caught and examined, 116 (3.2%) were infested with S. neavei immature stages. The situation in Aswa sub-focus has been attributed to the focal breeding of S. neavei in R. tVusabira which was only discovered in August 2000. Post - treatment data on this river revealed a tremendous reduction in crab infestation from 65.6% to 0% after four treatment cycles. During the period under review, a total of 58.75 litres of temephos (Abate) was used in the two sub-foci. lt is anticipated that with the encouraging progress in Aswa sub- focus we expect a re-adjustment to 8 - weekly treatment in February 2001 and suspension of treatment in [Vay 2001. All the adult catches conducted by vector collectors in the six sites registered no adult fly caught an indication of low vector population. However, during prospection of R. [Vlusabira, the seven S. neaveicaught none was infected on dissection. Support supervision was increased by the vector control officers to ensure proper record keeping and timely submission of forms. t'. 1. l t ( t INTRODUCTION Focal vector elimination of Simulium neavei s.s. in ltwara focus, northem Kabarole District has been ongoing since September 1998 under the support of APoc Trust Fund. Prior, inception of the APoc programme the pre-and post control operations in this focus was conducted under the support of the GTZ Basic Health Services. Their support was both on Simulium research and mass ivermectin distribution to the affected communities. They achieved a lot in terms of S. neavei control to the extent that river treatment was suspended in one of the areas in the focus (ltwara main focus). The financial support from the APOC programme which came later when the GTZ Basic Health Services ceased to support vector control was aimed at completing the elimination activities. A total of USD 16,157$ was disbursed by APOC management in 1998 and 1999 to facilitate activities in this focus. We expect the final instalment of USD 23,009$ to be disbursed and after executing the planned activities, this project should be evaluated. The project has now operated for 26 months. The operations were smooth in the first year, but in the second year there had been several interruptions in activities due to insecurity. ln view of this the project could not meet its expected target time frame of 2 years. This present report reviews activities that have been accomplished from January to December 2000. fri MATERIALS AND METHODS 1. Project Area The ltwara focus is located around the ltwara forest reserve about 25 kms North East of the District town of Fort Portal. The reserve covers 87 KtM2 of steeply undulating terrain, 22% of which is grassland (Howard, 1991). lt is bordered to West, South and East by large tea estates, which are economically important. To the north it is bordered by subsistence farms with some large cattle ranches along lower Sogohi and Muzizi rivers(Fig 2). The area is densely populated and onchocerciasis is highly endemic. About B0% of the population of 45,000, living around the ltwara forest reserve is estimated to be infected with Onchocerca Volvulus (Garms, 1997). The situation has greatly changed since ivermectin treatment started in 1991. Besides, there are two secondary foci on the Siisa and Aswa river systems and these lie to the East. The Siisa river area is mainly Savannah type of vegetation with subsistence farming being practiced. However, recent agricultural development in this area has degraded the existing gallery forest along the river systems. FIELD OPERATIONS (a) ltwara Main focus River treatment in this focus was suspended in June 1997. lVonitoring for any S. neaveire-infestation had been through crab trapping and examination at the key check points. During thrs period under review a total of eight prospections were made at various check points in the focus. Supervised and .t i unsupervised adult catches were regularly conducted in the three catching sites (sogohi, Kijura , Busasa) situated in this focus. A total of 39 s. damnosum caught from Sogohi site were dissected. Support supervision by various categories of staff were also undertaken. (b) Siisa and Aswa sub-foci Crab trapping and examination, and river treatment on a 4 - weekly interval using temephos (Abate) continued in the above sub-foci. However, due to the persistent positive crabs encountered at some two points on R. Aswa, a comprehensive prospection was conducted at three sites on R. Musabira in late August 2000. This is one of the tributaries joining R. Aswa to the west at the upper point (Fig 1). Four treatment cycles were conducted at one point along R. [t/usabira from September 2000. Because it is a small stream an application rate of 0.1ppm (300 ml.) of temephos (Abate) was used. Supervised and unsupervised adult catches continued in the three sites in the sub-foci. Seven S .neavei and 111 S. damnosum adult flies were caught along R. N/usabira and at Andrew's point, respectively were dissected. Support supervision by the various categories of Health staff was conducted during the period under review. RESULTS (a) ltwara Main focus The results of crab trapping and examination is shown in Tablel. In the six prospections, a total of 589 crabs were caught, and all were negative of immature stages of S. neavel. lt has been observed that the crab population are getting much reduced in streams flowing to the Toro Game Reserve. lt is not clear whether this is associated with ecological changes in their habitat, however, this has to be further investigated.. In the supervised and unsupervised adult catches no adult S. neavei was caught in any of the three catching sites (Table 2). At Sogohi catching site the 39 S. damnosum dissected were all negative. (b) Siisa and Aswa sub-foci Out of the 1 ,479 crabs caught and examined in Siisa sub-focus, all were negative for immature stages of S. neavei. Whereas in Aswa sub-focus, 116 (3.2o/o) out of the 3,674 crabs caught had infestation with S. neaveiimmature stages (Table 1). The persistent positivity of crabs for the six month during the period under review had been attributed to S. neavei breeding in R. 1t/usabira (Fig 1). Crab infestation ranged from 1.2%- 19.9o/" with the mean of 3.2%. Pre-treatment data for R. Musabira indicated that out of the 92 crabs caught, 74 (BO.4Yo) were positive of S. neavel immature stages. Post- treatment data revealed a tremendous reduction in crab infestation from BO.4o/o to 0.0% after four treatment cycles. There has been tremendous reduction in the number of larvae from 470 to 0, an indication of effective river treatment (Table 3). All the points close to R. Musabira are now free of S. neavet A total of 39.15 litres of temephos had been used during the twelve treatment cycles rn the sub-foci Despite the insecurity prevailing in the district, efforts () r'\L/ (r .r( were made to maintain river treatment except in September 2000 when this could not be conducted in Siisa sub-focus. Adult catches also continued in the three sites in the sub-foci. No adult S. neaveiwas caught during the period under review. However, in Aswa sub- focus at Andrew's site, 1 1 1 S. damnosum dissected wer all negative for filarial infection. lnvestigation for the occurrence of this species revealed that they use screw pine vegetation (Pandanus chiliocapus) as substrate for breeding and these are common plants along R. Aswa. The seven S. neaveidissected were all negative. (c ) Support supervision The supervisory visits made by various categories of staff is shown in Table 4. There has been an increase in supervision from t\tlay 2000, especially in the two sub-foci. This was achieved due to the improvement in he procurement of funds for field activities. Collection of adult fly catching forms from the various catching sites improved. DISCUSSION The results of monitoring activities from ltwara main focus and Siisa is a strong indication that S. neaveielimination can be achieved in this focus. This success would have been achieved throughout the focus if there had been no interruption in treatment cycles due to the prevailing insecurity. However, we believe that since past control efforts against S. neaveigroup in Uganda had some success in Budongo focus (Prentice, 1974) with few 1 \J I, treatment cycles, therefore the current one in ltwara focus has great prospects. It has been noted that to achieve any success in elimination process, comprehensive pre-control survey is very paramount. The recent discovery of S. neavei breeding in R. [Vusabira, a tributary of R. Aswa was an indication that pre-control survey overlooked this small stream. Roberts and Highton (1974) also pointed out that the success of any control campaign stem from a thorough pre-control survey. lt is therefore now certain that since this problem has been un-earthed, elimination in Aswa sub-focus will be achieved. This is evidenced by the fact that from September 2000, there has been a tremendous reduction in the number of larvae to zero, an indication of effective treatment. The consideration for a B - weekly treatment which was planned for August 2000 could not be done under this scenario. However, this is now planned for February 2001 since progressive decline in infestation had been observed in the Aswa sub-focus. The S. damnosum species encountered at Sogohi and Andrew's points may not be a vector according to dissection results. Recent studies by Kruger et. Al (1998) do suggest that they are more ornithophilic than antropophilic. Finally, the strength of elimination success in this focus which are based on the brology of the vector, their slow rate of population build up and the ongoing deforestation makes us believe that S. neavei is vulnerable and will be eliminated rn this focus. C-; (t L] ii )(. AGHIEVEMENTS a Itwara main focus and Siisa sub-focus are still free of S. neavei. Discovery of S. neayei breeding in R. Musabira in Aswa sub-focus lmproved support supervision a a a a CONTRAINTS lnsecurity interrupted operations in the focus in some months Lack of efficient portable flow meter. Lack of a computer. CHALLENGES . ls the S. damnosum encountered in Aswa sub-focus and R. Sogohi a vector? CONCLUSION The ltwara main focus and Siisa sub-focus are still free from S. neavei, this is a strong indication that elimination can be achieved in the whole focus. The focal breeding of S. neayei on of R. Musabira, in Aswa sub-focus, which has been unearthed now gives very high prospects for achieving elimination. PLAN OF ACTIVITIES (Refer to Table 5) The way forward . Re-adjust river treatment to B-weekly in February 2001 . Suspend river treatment in IVlay 2001 . Procurement of efficient flowmeter' a 9 a lncrease support supervision at all levels to ensure the goal of elimination is achieved. () f---tLJ -{ A)5 o I .o 0) o{i D) o =. 6' a o a o o o g 3.) o) =F.o =' = €ql ql o o -o xq) u A) -to 6- g a =.or €o a o) C(o q, o. o) o =>. o' a --lo)ul 5G)N I I I 5l I (D o - o o o) 3 of =' =o N) aCg I o a. ;n.DCOC(D -iZoca,.l.5o!=E& a(J+)-ou)(o:aao+gH *6 5 dl\uf=:f =(n'@6dtso'99coO:f+ft u)oyRcu'++ a ><' g) t-C)=\ U)+-(t(D u?3q o-oooq)f=cD=co =l$:*f+ +- ,'n):-r/ o t v Al t v t Y (_l ol f -n oo o) a a o) (_ Cf (- c c a o o o Noo I t'- --t o) (J 6- 5 a o 5. (o 3(t o ofr a io o s. a o s. a o J = €!) q, oo I x 0)6!) o 6- 9. o =.o (- q) q, a I z o o 3 L.) o t9ooo o N)oOO a- o)1llclo: l< I I I 1 t, ^, UJ C)l=fL; l- ! I i (_ C f o (_ CC E a a oC o 3U o (Jo o Z o o 3U o -lo -{ r O) o o o .l o o q o 6' o ao @ -{ O) 5 5 s so,N --l O) O) (}) o o I o O I O O J O O al o 6' m J o 3q o(o -o' (.) o I o o o o J o o O J T' =. 9.E A) m J o 3 o o(o 6' 'lr I -lo)u o 3 o a o)u o 9_ 6- ot o ; xq) =. )g) f. o A) J o- o B' 3 o o ? =o o)g: P o € A) a (t I oo I x 0)uq) o 6- I a =.o o = N)oOo c U c U) N O o_ 9. l(o o o o a o o 3o o NOOO N o o u). f(o o o o oo U o N)OO o_ o 9. =(o o C) o Z o CDI o N) OO 5 o C) o U o o 3U o N OO {'\ CCg) u,$0)qq: $o) -to + CC @@oq)g: 9. 0)O) n o CCAU'N0) 9: o: o)o) { o -{ r CEa u')oa)q: q. $o) o -{ -to -{ t- CC@aoo)qg: $0) -{o -{ t- (t, o TZooctco)f _Joo AZ$oOEo3 oo xz_o)ooc$3 oo t Zg)c) 5C o_3 OU AZ$ouc0)_3 OU JI o)5 i" i"OOOO (,N9l @@bbOO o 0) o JI 90 90 N) N)bbOO N)rO(n OOOO I JN) 90P PPOOOO o, N5 { (,5 (,l NO.) -ZooEoo o 55 O) N5 o{ CN CNAo) (oct) c, o)(Jit r (oN r\l@5 o BI (o(o5 J!-{ --t @(, --l O(n@ + o o OO Jo O Jo .fN O N) o)(.) r .N.@(Jl {5 (rl O)(o (os J!! --l {(, --.t (O(r@ (0(rl (,t5: .9. (.)(.) JJ--l O) o I(.a) (rl I o z o o o o, cro o oo (0 o(o o oo (Jr O(JI 5{o so)-{ c, !) ? A) o o OO o OO o oo o,s I (Jil50 5o 5oo ! E!l o o OO o o(, {{ o !! N)f\)o) A(,tN(rs N).s{ N)Io\l o A)o oa z o o Io oobb lrt(rl o(obbo N l\)o-bs o) s, o, (Jl \.1 -G)Abo @oL 1\) (O :P@N Jo\ o o A)f. o IJ l\\.J ,r' -l0)(t o N ? oq) o 0) o- =o A) o o a) o oi' oo qlg -a' o o- o o o = €q) 1 A) o otrI xq)ttq) o o o -o' =.or C(o 0)) o- AI o f 68fii=i6qrdqx 6.9g= dK _.6 r cY oo i rr- o)3 6 a:r. - g;q6 -{o -{ r a o(o o)o OOOOOOOOOOO x ql o OOOOOOOOOOO TD a!, o A) o OOOOOOOOOOO o OOOOOOOOOOO 9.6'q) J o. o{ o ooooooooooo o { o =.o o 0) o o oo ooooooooooo )' -t c o(g= -ct E<-: oo@ cf) oo(o ro ooo$ o ros$ oot-lo ooF-s ooo$ ooo(o ooo(o oo r(o ooN(o OoN(o o ro r- @ 1() (U 3o c o GI Q o \oc c.i q o q O ol r q o q O eo r c\i q o) c!$ oq N q O ol (v) o I (o @ r @ sO) CY)1r)N (v) cf) .{- o c)N @lr) cf) (Y)(o ro (o o)N N .d- c.) o) @ c) @NN @ ro ro (f, o + .f, q o o cf) o o O N r $F.- ro o (o b8 ogZ.) o o) @ $O) r (o rr) N cr) cr)$ o cr)N @lr) cf) to r- ro NN cf) f,- ro co oo$ @NN !tt-(0(9 o J o o -o =lololol:= la c o cl oo roC q o q o q o q o q o q o q o q o I q O q O q O q o o I @(o ror N N @ (o o) NN c{)ce t-o r O)(o r I NoN lJ) @ o,t-v o + O o O O O o o O I o O O o Eg oSZ.) @(o LO N N @ (o O) f--N cr)co r--O o)rf) r I NON rO @ oo o)t,-t o G a o roE I I q O q o q O q o q O I q O I q o q O q o (I) I I I N o) rorO lt.-O) rotr) (o$r I O ro I .{- rr) Os o,@ ro o + I I O O O O O I O O O o L(U fL ! 0) LL N O) -c.O L(o : L o_ LO LO ro LO (o$ > =--) I O LO Lq) _o o o C o 'o o I _of U) (tr =a !c(U (E ,9 U) L o E c) G :fo (U o 0) (U _o a o _c o_ 0) E o C =(J E I o, @ ro J F oF Os L c) _o C q) C) oo $ LO L 0) _o E(D oZ Lq) _o E 0) U) U)f O) f C)c l ---) f-- o) (o (U =E(o ---) a -o(! L o oz ah o o '6 E(! L(! = c o i.ooo o{ o -o E o oz I b G Ga o t- .9 o o ot- G' -oGY o J o o (It (! 3 = .; o GI .s E GI x o E (g o 'a o o E o -o(g L o o) !(oF ! I f,q t qno,.ring the breeding stretch on river musobiro ln Asws sub-focus, KEY = Breeding stretch on river musobirq o G Gouging point Rood & Swomp Scole t:50,000 Y ,'{uSA q s'1 t I N I t, Yl q l{ n I I , 34 <-- 33 <-32 <- 31 G D) , muzizi3k. tif tr u,.__ o =ca'6 O) o- =o) :aooOO o\ 9co0)OE FoDvo3 co()OO EeLAOco o'. P889 O@-Zo -L-goJ ci 'a9 oLog N: .e6 Z{-- ciN 6 Al ,, I Nf *.! 7 o + eaSv T o t,t '',I( I I I I i- : '/ 3 -/y'*,^. o a Y N I? Rv € oo I N c o3 Y :v + NtF f N N i s,/ L)o t qC O1Z *J a1 i Y (-o 1/ ?'.(: /:r\;r{I I 1., Nill ov I ! ) c0 b6. \_- uc x I I/./9 o'9 t \6 e\ t o )(,