REPORT OF A MISSION CARRIED OUT IN THE TUKUYUFOCUS SOUTH-WEST OF THE LTNITED REPUBLIC OF TANZANIA EAST AFRICA
2000 2
MISSION REPORT
onchocerciasis vector elimination proj ect in the Tukuyu focus, South-west of the united Republic of Tarzania, East Africa ' Re-evaluation of the entomological situation 'Planning of the ground larvicirling treatments - Susceptibility tests with temephos. - River trials of B.t. H-14 (Telmar)
I. INTRODUCTION
For the actual implernentation of the vector elimination campaign in the Tukuyu focus using ground larviciding, I carried out a mission in the South -Western part of Tanzania fro- ZttOltZObO to27/0912000.
2. OBJECTIVES OF THE MISSION
- To re-evaluate the entomological situation on the whole of the hydrographic network of the focus - To participate in the first two rounds of treatment - To train the national technicians in the practice of large scale ground larviciding - To carry out susceptibility tests on the Kiwira and Lufilyo rivers - To retrain the laboratory technicians (dissection of S damnosum s.l female flies, differentiation ofthe aquatic stages ofS. damnosum s.l, screening ofthe susceptibilitytest larvae, mounting of the onchocerca larvae ....) - River trials of Bacillus thurinqiensis H-|4
3. TRAVEL
13/07/2000 Odiennd - Abidjan t5/07/2000 Abidjan - Malabo 27/0712000 Malabo - Abidjan 28/07/2000 Abidjan - Dar Es Salaam 04/08/2000 Dar Es Salaam - Tukuyu t9/09/2000 Tukuyu - Dar Es Salaam 2U09t2000 Dar Es Salaam - Nairobi 22/09/2000 Nairobi - Abidjan 24/0912000 Abidjan - Ouagadougou 29/09t2000 Ouagadougou - Bobo-Dioulasso 30/0912000 Bobo-Dioulasso - Odiennd J
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4. MEETINGS AT\[D COURTESY VISITS iN DAR ES SALAAM AND AT TUKUYU
4.1. With Dr. Mwambazi, Resident Representative of WHO in Tanzania
On Monday 0ll08l2000,led by Dr. Mohamed Amri (deases prevention and control officer WHO Dar Es Salaam), Dr. Katenga (National Coordinator), Dr. B Maegga (NIMR station at Tukuyu) and myself paid a courtesy visit to Dr. Mwambazi, Representative of WHO.
During the meeting which the Representative granted to us, Dr. Amri in his brief introductory statement presented the onchocerciasis vector elimination project in the Tukuyu focus, in particular the work carried out last year.
In his answer, the Representative indicated that taking into account the general elections planned for the end October, the need for appropriate sensitization of all segments of the population of the focus, in particular the administrative authorities, the village leaders and the villagers was imperative before the beginning of larviciding operations to avoid any manipulation, wrong interpretation and exploitation of our activities for political purposes.
Dr. Simon B. Katenga informed Dr. Mwambazi that during the CDTI activities, sensitization campaigrs on vector elimination had been carried out. However, he supported and recommended better sensitization before the beginning of the larviciding activities. 4
4.2. With the lVlanagement of NIMR (National Institute for Medical Research)
On the same day, we were also received by:
- Dr. Mwelecele NR Malecela, Director for Research and Training NIMR) Tanzania - Dr. Andrew Y. Kitua, National Director General for Research (D.S.M.)
Dr. B Meagga briefed all these officers in charge about the objectives of my present mission
4.3. with the Director of the National Environmental Management council
In relation to the steps initiated by Dr. B Meagga to obtain the necessary authorization to use the insecticides selected, we were received by the National Director of the Environmental Management council,, Dr. Magnus Ngoile, National Director and Dr. R.u. Muheto, his assistant.
After the word of welcome by the director of the institution, Dr. Maegga briefly presented the vector elimination project by particularly explaining the use of temephos as the anti-blackfly larvicide selected.
In my intervention, I presented the qualities required fiom any insecticide used as an anti- blackfly larvicide i.e.: selectivity, biodegradability, non-toxicity for men and animals.
We also made a brief summary of the twenty five years vector control operations ofthe OCP Programm e, em phasizin g particularly the aquatic mon itorin g com ponent.
After exchanging views for about twenty minutes on the subject, the Director of the National Management Council observed that such activities were unknown in Tanzania.
Referring to specific cases, he said that in this pre-electoral period, as the products would be directly poured into the water of the rivers, negative reactions or even some complaints were to be feared, and even to be anticipated to come from all horizons : politicians, journalists (newspaper industry in particular), national or international organizations and institutions interested or involved in the managernent ofpesticides or the monitoring of the country's environment; hence the need for broad information of all the stakeholders.
Therefore, he invited us:
- to contact the institutions and organizations involved in the management of pesticides in Tanzania.
- to address to him, as soon as possible, a correspondence relating to the use of these pesticides; he would forward the letter to all the appropriate levels of the hierarchy concerned.
He further pointed out that in general the problems or difficulties occurring with the use or following the use of insecticides resulted from an inappropriate sensitization of the authorities and population concerned. Consequently, he advised us to await the various answers to the aforementioned correspondence before the effective implementation of our larviciding campaign.
4.4. With The District Commissioner
In the absence of the Head of the district, we were received by his dputy, Mr. Ntupwa. This time, I was accompanied by Dr. Maegga's Assistant, Mr. Karoli D. Malley who, after the usual introductions, explained the subject of our visit. Following Mr. Malley, I specified the reasons of my current visit toTukuyu. Then, we wished to have the support of the district officials for the success of the onchocerciasis vector elimination campaign in the Tukuyu focus, in particular for the sensitization of all the officers in charge in the district (village chiefs, political representatives) living near the rivers where our sprayings would be carried out.
Mr. Ntupwa, the District Administrative Secretary and deputy to the Head of the district said he had some knowledge of onchocerciasis because he attended a seminar dealing with this plague. 5
PROSPECTI0I flarval checkl
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Following the presentation of his district (geography, economy, in particular agricultural economy and tourism), the deputy in his answer congratulated us for the work already accomplished and urged us to continue with it not only for the benefit of the bordering populations, and even of all the inhabitants of the Tukuyu district, but also of all the Tanzanian people as a whole because Tukuyu is one of the big foodsrufr producing areas of the country. For sensitization, we shatl make every effort to inform the population concerned as well as all administrative officers and political leaders he concluded.
5. TECHNICAL ACTIVITIES
5.1. Preparatory meeting
A meeting to prepare for the field activities connected with the effective start up of ground larviciding for the elimination of S. damnosum from the Tukuyu focus of onchocerciasis was held on 05/08/2000 in the NIMR station office at Tukuyu. The capturers, the laboratory technicians, the scientist (biologist), the bio statistician serving as deputy to Dr. Maegga, the head of the station on mission in Dar Es Salaam, attended the meeting. The meeting reviewed all the questions relating to the practical organization of the work, in particular the logistics, the equipment for collection, susceptibility tests, river trials, mapping etc... The work plan, as well as the composition of the team which would be responsible for carrying out the work was also discussed. It was thus agreed that all the planning of the activities would be done by the consultant. We seized this occasion to strongly sensitize the capturers and technicians on the importance oftheirjob, each in his specific area of intervention, with examples and actual facts. Particular emphasis was put on the catches. In concluding the meeting, each participant promised to give the best of himself for the success of the project.
5.2. Planning of the activities
Based on the discussions we had during the meeting of 05/08/2000, and the plan of action drawn on 2l/06/2000, the work plan was established as follows:
- Coding of the rivers - Mapping of the points of application ofthe larvicides according to the data available - Susceptibility tests on the Kiwira and Lufilyo rivers - Prospection and search for access roads to the points oflarvicide spraying - River trials of Teknar on the Mbaka Lufilyo rivers - Training of the technicians in actual scale ground larviciding 6
- Make up of the treatment teams, drawing up of the circuits - Re-training of the laboratory technicians (dissection of the female flies, identification of the aquatic stages of the vector, determination of the various larval stages of S. damnosum g,!.).
5.3. Coding of the rivers
We carried out the coding of the rivers and of their tibutaries (see table and map in appendix).
5.4. Mapping of the points of application (see map)
5..5. Susceptibility tests on the Kiwira and Lufilyo rivers
Two susceptibility tests were carried out on the Kiwira and Lufilyo rivers (see results in appendix). With a CL95 of 0.384 mg/l for high mortality, the results indicate a good susceptibility to temephos on these two rivers. However, an increased presence of dying larvae on the Kiwira river was noted. In addition to the observations made during the first tests, it should be noted tl:a;t a plant for the treatment of coal extracted from the surrounding mountains is located upstream of the breeding sites where the collection of larvae was carried out. As a matter of fact, chemicals are used in agriculture in the area, including organophosphorous compounds (see list in appendix).
5.6. River trials of B.t. H-14 Teknar
The first tests carried out on the Mbaka and Lufilyo rivers aimed at studying the actual carry of the larvicide. The first targetted breeding sites were respectively at 4.5 km and 6 km away from the application point. 3/t At the normal dose of 0.72 I per m und at a discharg e rate of 2.5 rn "t on the Mbaka river, very little falling offover 4.5 km was noted ;41.3%o falling off of the old larvae was observed. 3/t 3/t At the dose of 0.54 I per m ut th" discharge rate of 8.586 m on th" Lufilyo river, only a mortality rate of l6.2Yo of the mature larvae was observed. 7
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5.7. Re-evaluation of the entomological situation
Prospections and search for access roads to the points ofapplication
a) Distribution of S. damnosum s.l. and current situation of the prospections
The prospections we carried out during our last mission in connection with the planned river trials of temephos had revealed the presence of S. damnoszrn s./. upstream of the limits indicated in the report by Dr. f Watsh and B.T.A. Maegga entitled " Planning of focal vector eradication in onchocerciasis foci in ianzania ". Therefore, it appeared to us that for an elimination of the vector, it was essential to locate all the breeding sites of S. damnoiim s./. in the focus to supplement the existing data for a total coverage with the larvicides to be used. Consequently, on all the watercourses prospected, we went upstream as far as possible to detect the last breeding site and much further downstream of the limits of distribution of S. damnosum described in the aforementioned report.
Kiwira River
Main course KI 100 to KI 102
14 points visited, of which 6 were found to be positive (see map).
We could not reach the main course fiom the civil prison to the merging point with the Lubangalala river. In the absence of any proof attesting to the absence of S. damnosum s.1., we chose to assume u porri-bl" presence. From this merging point ofthe Lubangalala river to Kyela, S. damnosum s./. is present with a prevalence of species like S. hargreavesi, S. vorm.
Tributaries
l5 points visited, 4 positive points (see map). 8
Except for the Mwalisi river, the tributaries only shelter S. dqmnosum s./. at their merging point with the Kiwira river. As for the Mwalisi river, it is positive from its confluence with the Kiwira river to its merging point with the Kisyesye river. The Kisyesye tributary itself shelter s S. damnosum s.l. lt could be that the Mwalisi river as well as the Kisyesye river are positive further upstream. It is to be feared that all the small tributaries of the Mwalisi river (KI 600) and of the Kisyesye river, its main tibutary, are colonized by S. damnosum s./. Hence the need for meticulous prospections to allow for an appropriate treatment of this watercourse and all its permanently flowing tributaries.
Mbaka River
Maincourse MB 100
7 breeding sites prospected,4 found positive (see map)
WedidnotfindS.dqmnosums./.upstreamofthe Mbakabridge. The presenceof ,S. damnosum on this river is located between the Masoko primary school upstream and Ipande downstream.
Tributaries
Our prospections on the tributaries of the Mbaka river revealed the presence of S domnosum only on the MB 300 (R. Mwalisi). The limit of the distribution of the yector on this river is at the Masoko bridge (Tukuyu - Matema road).
Lufilyo River
Main course
5 points checked, of which 2 sheltered aquatic stages of S. damnosum s./. Previous data indicated the merging point of tributary R. Rumakali as the upstream limit of the presence of S. damnosum s.l. and at approximately I to} km downstream from the Tapio catching point.
Our investigations revealed the presence of S. damnosum s.l. at more than ten kilometers downstream. As on the river Kiwira, the speed of the water even after this point, the last accelerations are fast enough to favour a breeding site for S. damnosum s./ when there is an obstacle (man made fish trap, tree fallen into the bed of the river or simply a narrowing of the bed, division into several arms)'
Tributaries
The two most important tributaries are: the R. Kasyabona and the R. Rumakali. The R Kasyabona was positive in three points (see map of shelters). The limit of distribution of the vector of onchocerciasis is at the merging point with Magubwa, its upstream tributary, downstream from the kasyabona village primary school.
It should be noted that the Kasyabona river is no longer accessible from the last breeding site located near the Kasyabona village primary school to its merging point with the main course of the R. Lufilyo where no current is perceptible.
The R. Rumakali is accessible only in two points, at its merging point with the R. Lufilyo and at the local bridge on bulongwa track. S. damnosum s./. is present only at the merging point.
Lumbira River
The only point that we were able to visit on this river is located a few kilometers (approximately 3 km) from the point where it flows into Lake Nyasa. S. damnosum s./. is present there. 9
b) Search for access roads
River Kiwira and its tributaries
Upstream
From the bridge on the R. Kiwira upstream of Kiwira village on the asphalt road to Tukuyu- Mbeya at the level of the civil prison, access to the main course is easy. From the civil prison to the merging point with the R. Lubangalala, there is no track leading to the main course.
At mid-course
From its merging point with the R. Lubangalala, the river is accessible in several points virtually all the way up to the lake. However, at mid-course, we had to spend one and a half to two hours scrambling up or down the stiffand abrupt slopes of the mountain peaks surrounding it.
Downstream
On its downstream stretch, the river is definitely more accessible starting from the Lwangwa Masoko catching point to the Ipyana bridge.
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Apart from the Lubangalala (KI 400), Lumbe, (KI 200) and Mosiya (KI300) tributaries which are of easy access, the points of application on the other tributaries are of very difficult access requiring sometimes more than two hours walking in the mountains.
Rivers Mbaka and Lufilvo
The accessibility to all the application points on these two rivers and their tributaries does not present any particular difficulty except for the point located on the Rumakali which requires approximately an hour's walk.
c) Altitude
focus, the maximum altitude at which we found Over the whole of the hydrographic network of the ^S. damnosum was approximately 1000 m. S. damnosum s.l. is found between 472 m and 1000 m approximately. The presence of S. damnosum s.l. in relation to altitude appeared variable according to the different basins. ln the basin of the R. Kiwira, the vector is present up to 878 m on the main course while on its main tributary, the Mwalisi (KI 600), one still finds it at 973 m.
On the river Mbaka , S. damnosum s.l. is no longer found at 726 m. However, on its tributary the Mwalisi (MB 300), the human onchocerciais vector species is present up to 77 | m. At 7 I I meters of altitude, S. damnosum s./. is still present on the main course of the R. Lufilyo. The tributaries LU 200 (Rumakali) and LU 300 (Kasyabona) shelter S. damnosum s.l. at 682 m and 638 m, respectively.
focus is From our observations, it appears that the distribution of ^S. damnosum s./ in the Tukuyu determined by the topography of the terrain.
d) River temperature
According to our investigations, two situations emerge : one related to the climate, and the other related to the topography ofthe terrain.
- Situation related to the climate:
The first three weeks of August were very cold. The tempsrature of the rivers varied from the between 14 and 24 degreeswith an average of tZ to l8 degrees. With the return of the sun starting last week of August, it"was even hot somJtimes. Sometimis the ternperature reached 25 degrees in the mid- course and downstream stretches ofthe rivers.
- Situation related to the topography
If in the mountains the water remains cool whatever the climate, in the valleys and in the rice fields temperatures are higher, particularly during the hottest hours of the day. They could reach above 25 degrees centigrade during the hottest days.
e) Breeding sites
In the mountains, they are discontinuous lines of breeding sites strewn with cascades and of the falls. In the valleys where the flow becomes more homogeneous but always fast, th9 breeding sites are traditional type (exposed rocks, narrowing of the river bed, etc...). On some of the rivers, the current velocity remains ni!t, piu"iicully all the *ay down to the lake; thus on the occasion of an artificial or natural obstacle (man madeh.h t tree fallen intothe bed ofthe river, ect...), the conditions for reproduction ofthe vector can "p, be met (see map). ll
I) Discharge rates
As a consequence of insufficient rainfall during the last rainy season, the discharges of the rivers were lower. The rates measured were:
3/s - for the middle course of the R. Mbaka : 2.5 m3ls on 17/Og/2000 against 4.3 m on 6/10 / 99 (measurement taken at the same place)
3/s 3ls - for the upstream stretch of the Lufilyo river : 5.275 m on 1710912000 against 6.3 m on 13/10/99.
g) Identification of the aquatic stages of S. damnosum s.L (see results in appendix)
REMARKS
In the mountains, the population of S. domnosum s.l. is minority compared to the other simulium species like S. vorac and S. hargreovesi.
At mid-course, the population of S. damnosum s./. becomes more important, but remains minority in the majority of cases. The predominant species is S. hargreavesi.
Downstream, S. damnosum s./. becomes really significant, even predominant in some cases.
The presence in the focus of other species like S. mcmahoni, S. shoudeni, S. cerviconutum, S. unicornutum is also noted
On the Luswisi river and its tributary R. Kawalisi, we encountered a species morphologically close to S. damnosum s./.. The only differences were:
- a smooth thoracic pseudopode (total absence ofscales).
- early stages of pupal gills whose pattern is different from that of S. damnosum.
- apparently smaller larvae than those of S. domnosum s-1.
This species was collected only on the R. Luswisi (KI 500) and its tributary R. Kawalisi. In the breeding site located near Luswisi village at the bridge, it cohabits with S. vorm and S. hargreavesi while on the R. Kiwalisi at its merging point with the R Luswisi, it exclusively seems to colonize this breeding site.
5.8. Ground larviciding
5.8.1. Water gauges
Overall, there are 4 water gauges in the whole ofthe hydrographic network ofthe focus : 2 on the Kiwira river (l upstream at the level of the civil prison and I downstream from Kyela); 1 on the river Mbaka (downstream at the level of the bridge) and I on the upper Lufilyo (at Lufilyo village).
Only the 2 water gauges on the Kiwira river are functional. They could be exploited for the treatments of some stretches of the aforementioned river (KI 100 and KI 102).
5.8.2. Discharge measurement by the float method
Except for the few stretches of the R. Kiwira whose discharges could be obtained thanks to the two water gauges mentioned above, it would be necessary for determining the quantity of larvicide to be applied, to obtain the discharge rate through the float method (see list of the points of application). q.."."_1__f t2
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5.8.3. The insecticide
The larvicide to be used is ternephos at the dosage of 0.4 I per m "t or". a l0 mn application time.
Because of the cycle of larval development which could vary according to water temperature, i.e. longer in the mountains where the water is always cooler (14' C to 19" C) than in the valleys (24' C to 25" C or even higher), we recommend a l0 day cycle of treatment.
5.8.4. Treatment teams
a) the technical staff
In addition to the biologist who will fuIfilI the functions of organizing the operations and superuision, 7 technicians will be needed for the ground treatments of the focus : 3 teams of 2 people; 1 team of 2 people for larval checks and 3 drivers. l3
b) vehicles
The Tukuyu research station for onchocerciasis control activities has:
- 2 Hilux pick ups -1 Vitara (4 wheel drive, 3 doors) - 3 Yamaha 250 cross country motor bikes (to be equipped with luggage racks)
5.8.5. Treatmentcycles
2 or 3 teams for a l0 day cycle (see appendix) 3 teams for a7 day cycle (see appendix)
5.8.6. Lanal checks
As much as possible, 24 to 48 hours after the first cycle of larviciding, a general prospection will have to be undertaken to evaluate the efficacy of the treatments on the one hand, but also for an appreciation of the points of application on the other, for possible readjustment. For the main courses of the rivers, this checking should initially concern the breeding sites located immediately upstream of the points of application. For the tributaries, this checking should primarily be conducted at the merging points.
5.9. Catches
On the whole of the focus, there are currently 6 catching points dishibuted as follows:
- R. Lufilyo : 3 catching points (Lufilyo village, Crater and Tapio) - R. Mbaka : 2 catching points (Kambasegela and dwanga) - R. Kiwira : I catching point (Lwangamasoko)
For an assessment of the future vector elimination campaign, it appears useful to strengthen the catching network by:
- R. Kiwira : 3 catching points (1 at the natural bridge or the civil prison, I catching point at the confluence with R. Luswisi, I catching point at Ipyana downstream from Kyela) - R. Mwalisi (KI600) : I catching point at the level of Bwipa village - R. Mbaka : I catching point (at the level of the Masoko primary school) - R. Mwalisi (MB300) : at Kiloba village - R. Lufilyo : 2 catching points (Lusongo village, Ndobo) - R. Kasyabona : I catching point at the primary school of Kaslabona village - R. Lumbira : I catching point (at the level of the catholic mission)
The catches could be weekly for the first 2 months and twice-weekly thereafter. t4
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6. TRAINING
As in the preyious y@r, all the field and laboratory activities were conducted in the presence 9f t!9 : trained in: laboratory assistants and the bioiogist of the NIMR Tukuyu station. This team of 4 people was thus
- Ground larviciding of S. damnosum s.l.larval breeding sites - Carrying out susceptibility tests (for the biologist) - Screening the larvae for the susceptibilitytests - Mountin! the onchocerca larvae for laboratory examination (the biologist)
a refresher course will be organized soon for the As for the dissection and other laboratory-has techniques, course in biology laboratory assitants by Mr. Kalinga Akili who just successfully completed a training (OCP). ecology of the vector and vector control at the onchocerciasis control Programme the firs! The training in ground larviciding for blackfly control has in fact started since last year with constitute the base of tests with the temephos. The 4 technicians who diligently participated in these activities can in no doubt ensure the teams which wiil be called upon to conduct the vector elimination campaign. They the training of other technicians in this field.
7. COMMENTS
7.1. The prospections from these The three basins forming the hydrographic network of the focus were prospected. It results presented' prospections that the distribution of the vectoi of onchocerciasis is much wider than was initially in the various irrO"bA, according to our investigations, S. damnosum s.l. exists well beyond the limits, indicated of the main rivers as of documents and reports. It shouli be noted that we found many small tributaries as well season. the tributaries and sub-tributaries not often shown on the maps which continued to flow during this stretchs sheltering S. These tiny watercourses certainly shelter the vector at their merging points with the river nec€ssary damnosums./. A complete identification of these backwaters is an essential long-term undertaking Moreover, the for the treatment of ali the breeding sites in order to achieve total elimination of the vector. l5
Songwe river, the natural border between Tanzania and Malawi in its downstream stretch, shelters S. damnosum s./. upstream of the border post over a significant stretch according to the distribution map presented in the report by the NOTF of Tanzania dated May 2000. Tributaries of this river take their source on the territory of the focus along the main tributary of R. Kiwira, the Mwalisi (KI 600) and merge into its part sheltering S. damnosum s./.. A good number of these tributaries of the Songwe river are dry in this season. The flowing in those that continue to flow is not very significant in this season. However, as soon as the rains resume, these backwaters will also resume flowing, thus constituting corridors of contamination of the R. Mwalisi from the Songwe river. Practically from the border post to Lake Nyasa, the Songwe river flows next to the Kiwira and rurs alongside it.
7.2. Larual checks
The points of applications were selected by taking into account:
- the effective carry of temephos - the changes in discharge rates due to the water brought in by the tributaries - the accessibility to the sites - the distribution of S. damnosum s.l.
The treatments are planned to take place during the dry season. At the beginning of the season, the flow of the rivers will be more significant but it will be in constant decrease.
A systematic larval check over the whole of the network after each cycle of treatment to evaluate the effectiveness of the larviciding will allow for a possible readjustment of the application points. This checking is particularly relevant for the breeding sites immediately located upstream of the points of application. 16
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7.3. Susceptibility tests
A CL 95 susceptibility of S. damnosum s.l.larvae to temephos on the R. Kiwira is comparable to that on the Mbaka and Lufilyo rivers with the same comments. However, at the dose of 0.625 mg / l, one notes a higher number of dying larvae. It must be noted that :
- rumy chemical products, including organophosphorous compounds, are used in agriculture in the focus area (see list attached).
- a plant for the treatment of coal extracted from the surrounding mountains is located upstream of the merging point of R. Mwalisi (KI 600).
7.4. River trials of B.t. H-14 (Teknar)
The performance ofTeknar according to the results ofthese first tests is not better than that recorded in West Africa. The carry of lkm obtained during the low water period requires practically a breeding site by breeding site treatment. The objective being an elimination of the vector from all of the focus, this implies the treatmeit of all the breeding sites. However, the topography of the terrain makes it impossible to reach all the breeding sites. Consequently, the use of Teknar as the larvicide of choice in this focus cannot be recommended. NonethJless, since ground iarviciding is the control method to be used, we think that more tests at higher discharges and highir doses in order to better understand the behavior of Teknar in this area would be useful. For yrn 3/t these future tests, we considered concentrations of 1.6 mg/l (0.96 ) and2.4 mg/l (l '44y."t ) during the low water period, then at higher discharge rates (at the beginning ofthe dry season). t7
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8. CONCLUSIONS, SUGGESTIONS AI{D RECOMMENDATIONS
8.1. Conclusion l8
8.1.1. Entomological activities
The susceptibilitlt tests
The results obtained indicate a good susceptibility to temephos. 100% mortality at the dose of 0.625 mgfl was observed.
The river trials of bacillus thurinsiensis H- l4 (feknar)
At the dose of 0.72 | per cubic meter second, the maximum carry observed during these preliminary tests was I km approximately.
At the dose of 0.54 I per cubic meter second, the effectiveness of Teknar was almost null at 6 km.
The prospections : application points and accessibili\t
Following our prospections, it appears that the distribution of S. damnosum s.l. in the focus is much more significant and wider than previously presented.
lndeed the vector ofonchocerciasis is found upstream as well as downstream from the pre-established limits.
In addition, the main tributaries (KI 600 R. Mwalisi, a tributary of R. Kiwira and the MB 300, a tributary of the R. Mbaka) are almost entirely colonized by S. damnosum s.l. Moreover, the small rivers which flow into either the main rivers or their tributaries over the stretches sheltering S. domnosum s.l. are colonized at their merging points. We discovered small tributaries and subtributaries which are not represented o1 tfe maps but *t i"n no* certainly all year round. In general, in the mountain ranges, all the rivers of the hydrographic network of the focus show a line of breeding sites without discontinuity all the way down to their eiit fiom these mountains. In the valleys, the current becomes more homogeneous but rather fast, punctuated^ with some accelerations favourable to the reproduction of S. damnosum s./.. In the immediate surroundings of S. the lake, the terrain is definitely flat ; therefore the current becomes slower and unsuitable for the breeding of damnosum s.1..
Application points
The application points selected according to the carry oftemephos, the discharge rate, the accessibility and the distribution of S. damnosum s.l. number 35 against 26 accordtng to the report by Dr. F Walsh and Dr. B.T.A. Maegga (Planning of vector eradication in onchocercasis foci in Tanzania) ; this number could increase after the prospection of the small tributaries and subtributaries. "ssertiul
Accessibili0t
All the application points are accessible. In the upstream parts of the R. Kiwira and R. Lumbira, the access is much more dimcuh and requires long hours of walking in the hills.
The sround treatmenls
Overall, approximately 283 km of river are to be treated over all of the hydrographic network of the foi6. There are only 2 functional water gauges on the sole Kiwira river. Most of the discharge rates needed for the treatments will b€ obtained through the float method of measurement. The selected insecticide remains temephos at the dosage of 0.4 I I cubic meter second. We suggest a l0 day cycle of treatment.
The treatment cYcle
We considered two scenarios for the treatment cycle. One with two teams and the other with three teams (see appendix) t9
8.1.2. The importation of temephos
From the talks relating to this subject, it emerged that there is no barrier, but constraints exist on the approval and importation of pesticides in Tanzania. Compliance with certain provisions is essential, namely:
stating the quantity of insecticide to be imported
providing the relevant information on the use of the pesticide (toxicity, environmental impact)
providing the basic data about the effectiveness and environmental impact, along with documents and publications on the product.
It seems that the procedures for obtaining this approval can be long (6 months to 3 years). The persons in charge of the project would like to receive as soon as possible the necessary information and documents so that they can initiate the process at the earliest.
8.1.3. Sensitization
Sensitization is an indispensable prerequisite for the implementation of the ground larviciding campaign. It should be directed at all the stakeholders (Ministries, national and international organizations, local institutions, the press, administrative authorities, traditional chiefs, village leaders and finally, all the bordering populations of the rivers to be treated in the focus)
8.1.4. Training
4 technicians of the NIMR station were introduced to the practice of ground larviciding for the control of the simulium vector; they can in no doubt effectively carry out the ground larviciding of the focus.
9. SOME OBSERVATIONS
9.1. The catches
The catching of the fernales of S. damnosum s./. is one of the most effective methods used for the evaluation, the study-of simulium populations dynamics and the transmission of human onchocerciasis.
During our stay, we noted a great inadequacy and even carelessness in the catches but above all a in the disarming o, it part of the capturers which denotes a lack of professional conscientiousness performance"urr-uln"r. of their duties. "
9.2. The supervision
The total absence of supervision of entomological activities in the field, the almost non-involvernent of the co.ordinating entomologist will, in the long.*, b" prejudicial to the completion of the work and ultimately to the reliabitity if ttre result=s and will constitute an obstacle to achieving the expected success. 20
10. SUGGESTIONS AND RECOMMEIIDATIONS
r0.1. Suggestions
l. The catching of the females flies as a method of evaluation before and after the vector elimination campaign is of critical importance. Taking into account our observations in the field, we suggest:
a) the training, awareness raising through a more sustained sensitizatioq supervision or simply the replacement of those capturers lacking diligence and efficiency in the performance of their duties.
b) regular supervision of the teams of capturers by the scientist (for example by participating in whole days of catching activities every time this is possible).
2. For a better knowledge of the performance of Teknar in the focus, we suggest the continuation of the river trials with Teknar at higher discharge rates and dosages (1.2 mdl; 1.6 mg/l; 2.a mgll).
3. The water gauges on the R. Kiwira should be used to obtain the discharge rates for the calculation of the quantities of larvicide to be sprayed. The repairing of the other water gauges or even the installation of new ones would relieve and frcilitate the work of the treatment teams. Consequently, we suggest:
a) the training of all the technicians who will be called upon to carry out the ground larviciding treatrnents in the use ofthe gauges.
b) the updating ofthe taring curves ofthe existing gauges.
4. When the ground larviciding campaign is started, any disturbance of the cycle or round will be prejudicial to the results expected ; therefore, we recomlnend that the material and logistical means required for the vector elimination project be actually made available for its implementation.
we 5. So that dissections can continue without any disturbance due to the ground larviciding campaign, suggest training one of the capturers in the dissection of the females of S. damnosum s-1.
6. The ground larviciding treatments in the Tukuyu focus will be particularly arduous because of the geography of the terrain.
To ensure and maintain the dynamisnL enthusiasm and efficiency of the technicians who will be in charge of the treatments and prospections, we suggest that a special incentive which would motivate them more be granted to them so that this personnel would give the best of temselves during the whole campaign.
7. The elimination of the vector will be dependent on a total effectiveness of the larviciding treatments of all the reproduction sites of the vector identified beforehand, over a sufficiently long period of time.
Because of the complexity of the entomological situation, we do not think that this noble objective can be achieved in only on" .*io., of heatment. We suggest 3 consecutive seasons of larviciding.
10.2. Recommendations
l Taking into account:
- the proximity of the river Songwe, the natural border between Tanzania and Malawi, which virtually runs alongside the Kiwira river from the border post to the lake,
- the presence of many small tributaries of this river flowing from the focus area, 2t a
a the fact that a distribution map presented in the report by the NOTF Tanzania entitled: " Tukuyu focus vector elimination. Nine months technical progress and financial reports: july 1999- April 2000 ' attests a colonization of the middle part of the R. Songwe, we recommend:
an entomological re-evaluation of the the Songwe river basin
2. The elimination of the vector implies treating all the breeding sites of S. damnosum s.1.. To do so, it is necessary to identi$ all the habitats of the vector ; yet, the tributaries and sub.tributaries which flow into the colonized portions of the main rivers or their tributaries and which surely shelter S. damnosum s.l. at their merging points have not all been recorded. Therefore, we recommend the continuation and refinement of the prospections to detect these tiny backwaters which are not often represented on the maps but which do not dry up, and their systematic treatment.
3. Taking into account:
- that our recommendation relating to the monitoring of the entomofauna before the implementation of the ground larviciding campaign was not acted upon,
- the conditions required for the importation and the use of pesticides in Tanzania, we recommend:
* that all useful information regarding the use of temephos as a larvicide for the control of blackflies be transmitted as soon as possible to all the structures managing the vector elimination project (documentation from the manufacturer, environmental impact in the countries where ternephos was used, total quantity to import into Tanzania).
* that studies on the impact of the larvicide on the non-target fauna be undertaken in the hydrographic network of the focus.
4. Vector control is an unknown activity in Tanzania. To avoid any hostile, or even aggressive reaction of the population, of national or local authorities on the one hand, of national or international institutions, or even of the press on the other hand, we recommend:
- wide publicizing of the vector elimination project by the medias
- an intensive sensitization ofthe local and regional authorities, and especially ofthe populations bordering the rivers ofthe focus.
5. For a better planning, organization, and execution ofall the technical field and laboratory activities, we recommend that the coordinator olthe project delegate his responsibilities in the technical and practical fields to the biologist who has just successfully completed training in biology ecology and onchocerciasis vector control at OCP, and this on account of the experience we gained during our mission.
11. ACKNOWLEDGEMENTS
We wish to express here our sincere gratitude to all those who, one way or another, have contributed to the accomplishment oiour mission; in particular the staffof the National Institute for Medical Research at the Tukuyu station. 22 I
Our sincere thanks to the valiant entomological team which showed not only excellent t conscientiousness, but above all a real willingness to learn and to apply in the field the knowledge acquired during their training. Always driven by the desire to do better, it did not spare any effort to make our mission a succes. This dynamic team was made up of:
Mr. Kalinga Akili, the biologist of the team Mwaikonyole Adam, Senior Laboratory assistant Kibweja Addow, Laboratory assistant Donald Charles, Laboratory Technician
Our recognition and gratitude also go to Mr. Karoli D. Malley for the assistance in all kinds he provided us during our entire mission.
We also thank Dr. Bertha T A. Maegga, the Coordinator of the project.
Would the officers in charge listed below:
Dr. A. Sdkdtdli, Director of APOC, Ouagadougou Dr. L Yameogo, Chief of the Vecor Control Unit, Ouagadougou Dr. M. Noma, CEV APOC, Ouagadougou Dr. Akpoboua L.K.B., Administrative and Technical Officer (ATO), Ouagadougou Mr. Sarr Mamadou, Chief of the Administrative and Technical Services of the Western Zone at Odienn6, C6te d'Ivoire Dr. Y. Bissan, Coordinator of Entomological and lnsecticide Research at Odiennd
please find here the expression of our recognition and sincere thanks for the useful recommendations and especially for the confidence they placed in us for carrying out this important mission.
Written at Odiennd, 19 October 2000
Mr. Tele Barro Entomological and Insecticide ResearchAssistan I/OCP- Odiennd