AN OVERVIEW OF TSETSE AND TRYPANOSOMOSIS CONTROL IN TANZANIA 2003-2005

UN APERÇU DE LA LUTTE CONTRE LES TSETSE ET LA TRYPANOSOMOSE EN TANZANIE (2003 – 2005)

J.W.Daffa¹,  P. Z. Njau¹,  H. Mbwambo & M. Byamungu³

¹ Directorate of Veterinary Services, Ministry of Water and Livestock Development, DAR ES SALAAM, Tanzania.
² Animal Disease Research Institute (ADRI), DAR ES SALAAM, Tanzania
³ Tsetse and Trypanosomosis Research Institute (TTRI), TANGA, Tanzania

Introduction

            Tanzania occupies a total area of 945,027 square kilometers and has a human population of 34.5 million people with annual growth rate of 2.9%.  Out of 886,000 square kilometres of land in Tanzania, only 6% is currently cropped, while 40% is occupied by permanent pasture with the remaining 54% mostly forest and woodland (NRI, 1991).   The country has 49,979,000 ha suitable for grazing of which 26,143,000 ha are in use but 13,127,000 ha are infested by tsetse. Over 80% of the population lives in rural areas; their livelihoods depends on agriculture (i.e. crops, livestock, fisheries and forestry) which accounts for 50% of the Gross Domestic Product (GDP).  The contribution of the livestock sector to both agriculture and national gross domestic product is 30% and 18% respectively. These figures do not include domestic consumption and across the border trade. About 40% of the Livestock GDP originates from beef production, about 30% from dairy products and about 30% from poultry and small stock production.

            The country has about 17.7 million cattle, 12.5 million goats, 3.5 million sheep, 0.8million pigs and about 27 million local chickens (2002, MAFS). The largest concentrations of small stock are to be found in more or less the same areas, which have high cattle numbers. The small ruminant population (goats and sheep) consists almost entirely of local breeds and they have significant contributions to local consumption and incomes in the rural areas. There are estimated 3.5 million farming households, 58% of which own poultry, 19% own small stock and 17% own cattle. About 80% of the livestock keepers are also crop farmers and the rest (20%) are pastoralists. Livestock production is largely subsistence and mostly is for the local market and wealth is limited to the livestock ownership in most of the livestock keeping communities.

            Tsetse infestation and trypanosomosis are high challenges to the Tanzanian economy since they are major constraints to livestock and crop production. About 50% of total rangeland in use in Tanzania is tsetse infested putting about 4 million people and 7 million cattle at risk. Tsetse-transmitted trypanosomosis has sociological, medical and veterinary importance. Infested vast areas of humid, sub-humid to semi-arid zones of Tanzania, have great potential for increased crop and livestock production. While Nagana is much more widespread in Tanzania, sleeping sickness outbreaks are also a reality especially in the tsetse-infested western zone. The disease leads to decreased human labour and livestock losses due to mortality and morbidity. The impacts of tsetse and trypanosomosis include reduced food production in the affected areas, increased cost of livestock production, loss of livestock, and loss of foreign currency at the national level as more drugs are imported and less animal products exported, all together contributing towards aggravating poverty in the affected rural areas and to the nation at large. Losses due to mortality and reduced milk yield are estimated at US$ 7.98 million annually.

            There are seven species of Glossina of economic importance affecting both human and livestock, namely, Glossina morsitans, G. pallidipes, G. swynnertoni, G. brevipalpis, G. austeni, G. fuscipes and G. longipennis, inorder of importance.  These tsetse flies have excluded cattle from a large portion of good grazing lands due to animal trypanosomosis which they transmit, leading to problems of over grazing and soil degradation of tsetse free lands.  Furthermore, there is forced migration of livestock keepers in search of pasture causing a great impact on social relations, environmental degradation and transmission of other livestock diseases.

            The Tsetse and Trypanosomosis Research Institute (TTRI) – Tanga, conducts research on tsetse (Glossina spp) and tsetse-borne diseases (trypanosomosis) that will lead to sustainable control and eradication of the disease. The institute advocates the use of environmentally and user-friendly methods like the Sterile Insect Technique (SIT). This is conducted through rearing of tsetse flies in the laboratory and producing surplus males that are irradiated by Gamma rays and released in tsetse infested areas. The irradiated males mate with the wild females, which will never produce offspring till death. Through this process permanent eradication of tsetse in infested areas is assured. Other tsetse control methods recommended by the institute include the use of odor-baited traps and insecticide impregnated targets and screens. The institute offers advice to stakeholders on best traps for different species and their habitats and insecticides to use in tsetse suppression. Fly production activities continued at the institute with three Glossina species, G. austeni, G. pallidipes and G. brevipalpis. There are scientists with long experience and ability to test the efficacy of various insecticides both in the laboratory and in field.

2.0.      Policy And Strategy Issues

The overall objective of the Livestock Policy of Tanzania 2005 is to improve the well-being of the rural population whose principal occupation and way of life is based on livestock by promoting a competitive and efficient livestock industry.

The objective is to improve the feeding and health of livestock through adoption of appropriate technologies of tsetse control in order to eradicate trypanosomosis and hence increase production and productivity

2.1       Policy Statements

• The Government in collaboration with other stakeholders will promote, sensitize, and advocate on tsetse control and eradication.

• The Government in collaboration with other stakeholders will strengthen research, extension and human resource development.

• The Government in collaboration with other stakeholders will promote and support the development of affordable, manageable and effective tsetse control techniques.

• The Government in collaboration with other stakeholders will promote application of environmentally friendly integrated tsetse control and eradication methods such as Sterile Insect Technique (SIT), Insecticide Treated Cattle (ITC) and Insecticide Treated Nets (ITN).

• The Government will establish partnership and strengthen multi-sectoral coordination for tsetse control and eradication.

• The Government in collaboration with other stakeholders will harmonize National and Regional policies such as those of East African Community and SADC on tsetse control and eradication.

• The Government in collaboration with other stakeholders will support monitoring and survey for tsetse.

            The Agriculture and Livestock Policy of 1997 addressed the problems associated with the centralized support system, the deterioration of livestock infrastructure and the provision of technical field services. The Agriculture and Livestock Policy proposed radical changes consistent with a liberalized and market-oriented economy shifting from a centralized state-controlled and dominated economy to a situation where the private sector becomes more actively involved.  The Government hived off the delivery of animal health services to private sector but retaining regulatory role and providing enabling environment for the private veterinary sector to take-off.

            Over years, the control of trypanosomosis has been through extensive use of prophylactic and curative trypanocidal drugs. Use of trypanocides has been the major method of control of trypanosomosis. Unfortunately, trypanocidal drug resistance has been reported in Tanzania and, furthermore new effective trypanocidal drugs are unlikely to be available in the near future due to high costs of development and production. Therefore, rational use of the available drugs is advocated for improvement of livestock production and productivity for growth of national economy.

            Over the past decade in the absence of any significant community involvement in tsetse and trypanosomosis, sustainable control has not been achieved. Cattle owners dip or spray their cattle when they find it necessary, if they have access to the facilities and when they can obtain insecticides especially synthetic pyrethroids which kill both ticks and tsetse flies. 

            With trade liberalization, there is no effective control over importation, registration, use, testing and quality control of trypanocides and they are haphazardly being used and sold throughout the country. Furthermore, privatization of veterinary services including distribution of drugs and insecticides has denied the rural areas of this service. Most of the private practices are still concentrated in urban areas. The decline of dipping services has however encouraged tsetse and tick control by hand spraying or use of pour-on formulations, making the livestock owners directly responsible/accountable at farm level.

2.2     Tsetse And Trypanosomosis Strategy Objective Of The Strategy

            The objective of the strategy is to ensure food security, increase income of livestock keepers, and contribute to poverty reduction in rural areas. The strategy intends to institute a coordinated and integrated control approach involving all stakeholders. The  strategy intends to institute a co ordinated and integrated control approach involving all stake holders.

Strategic Interventions

            Tsetse infestation is one among the major constraints affecting not only livestock development in Tanzania but also human health. The proposed interventions however, will require medium to long-term implementation periods.

Interventions will include the following:-

         The implementation of tsetse and trypanosomosis control programmes and activities involve many stakeholders but there has been no established institutional coordination mechanism. Consequently, there are undefined roles of the stakeholders. A framework for co-ordination will be developed that will take into account the coverage of all tsetse and trypanosomosis activities.

Review of the existing laws and regulations.

The legislation governing tsetse and trypanosomosis control is the Tsetse Fly Control Ordinance (Cap. 100 of 1943). As a solution to the problem of out-dated, lack of harmonized and uncoordinated laws and regulations, the Government, in collaboration and consultation with wide spectrum of actors will review/update and harmonize the laws and regulations that concern tsetse and trypanosomosis.

Capacity building

         There is few skilled staff to effectively implement the control programmes. In order to overcome this problem, human resource development and deployment by both the public and private sector is necessary.  In order to overcome this problem the capacity of the lead ministries will be strengthened through training and recruitment of well trained personnel.

Developing a comprehensive National Tsetse and Trypanosomosis Research Framework.

         There are several research and training Institutions carrying out research on tsetse and trypanosomosis (Tropical Pesticides Research Institute, Tsetse and Trypanosomosis Research Institute, National Institute of Medical Research, Sokoine University of Agriculture and Animal Disease Research Institute). However, there is lack of coordination in the tsetse and trypanosomosis research being conducted in the country. In order to overcome the above problem, research activities will be coordinated to focus on development, acquiring and transfer of appropriate technologies for the control and eradication of tsetse and trypanosomosis.

         Active involvement and effective participation of various stakeholders, including private and public service providers and the target communities in implementing control interventions is important.  Sustained participation and contribution of communities will be encouraged from the planning to implementation stages through training, motivation, awareness creation and advocacy of tsetse and trypanosomosis control. Training should be provided to all stakeholders as per identified needs.

• Sensitization and advocacy of tsetse and trypanosomosis control.
• Strengthening collaboration of stakeholders and integration of tsetse and trypanosomosis control methods.
• Up-dated relevant data and information that is crucial for successful control.

Financial arrangements

         The implementation of the strategy will require sufficient financial resources from a number of sources. Financial inputs will be derived from the Government, the private sector and development partners.

Monitoring and evaluation

         The lead ministries and the National Tsetse and Trypanosomosis Control Committee will be responsible for developing a comprehensive and suitable framework for monitoring and evaluation of tsetse and trypanosomosis control programmes. This will enable measurement of achievement and contribution of the programmes towards poverty reduction, economic growth and improvements of the welfare of the rural communities.

3.0       Tsetse And Trypanosomosis Control

3.1 Tsetse Control activities 2003 -2005

            Tsetse flies are found in all regions of Tanzania with exception of the high altitudes such as the Eastern and Western Usambaras and the Southern highlands (Map 1). The degree of infestation varies from one area to another.  Tanzania recognizes the problem of tsetse and trypanosomosis as it cuts across many sectors as an obstacle to rural development.

            The total rangelands have the capacity to carry a total of 20 million livestock units but presently only 17 million livestock units are available, thus 3 million livestock units can be accommodated. There is therefore, a potential for expansion of the livestock industry to increase the contribution of livestock to the national GDP and producers' income. In order to realize the above potential, deliberate efforts must be directed to the control of tsetse in the arable and potential grazing area covering 50 million hectares.

3.1.1    Awareness raising, Training and Community involvement.

            The goal of community based tsetse control programme is to contribute to poverty reduction at household and national levels through increased agricultural and livestock productivity in tsetse infested areas. The specific objectives are to empower pastoral communities in tsetse and trypanosomosis management, promote use of environmentally friendly tsetse and trypanosomosis control techniques (odour-baited targets and spraying pyrethroids on livestock), promote improved land use plans, livestock and crop husbandry technologies that reduce tsetse population, strengthen tsetse and trypanosomosis surveillance and control through collaboration between public and private service providers for the purpose of  improving human and animal health for food security and poverty alleviation in tsetse infested areas.

            During sensitization campaigns and demonstration/training of tsetse and trypanosomosis control techniques a total of 1,812 villagers were reached. This raised their knowledge and led to contribution and participation in tsetse and trypanosomosis control activities in their areas. Livestock keepers and crop farmers contributed about 845 targets while the government under the ministries of Livestock and Health in collaboration with WHO supported them by insecticide of Glossinex and 2,695 targets to Kigoma, Tabora and Rukwa regions where there was outbreak of sleeping sickness from 2003-2004.

            A total of 49 public service providers from 49 districts were trained between 2003 and 2004. Two training workshop were conducted aimed at updating the knowledge of district tsetse field officers on various topics pertaining to tsetse and trypanosomosis control such as land use in tsetse controlled areas, epidemiology of sleeping sickness, pesticides, GIS, early warning systems and pasture management, Project cycle and management, ITN, ITC and screens/targets. A total of 27 private service providers, 10 farmer motivators and 10 Farmer Field School (FFS) for livestock FFS groups were established under the FITCA project. A total of  2500 posters and 9000 leaflets and three types of tsetse training manuals at farmers, primary school and extension levels were produced and disseminated to affected regions.

Map 1              Tsetse Distribution Map

3.1.2    Tsetse Control in Game Reserve Areas

            Tourism industry (Map 2) is also threatened by the nuisance of tsetse and sleeping sickness challenge.  Tanzania National Parks Authority deployed a total of 3226 insecticide treated targets (1573 - Serengeti, 750 –

Mikumi, 553 – Katavi, 350 in Ruaha National parks) and 1244 vehicles were sprayed with insecticides.

3.1.3    Tsetse survey and mapping

            Surveys for re-mapping of tsetse distribution in Tanzania has been done in six (6) regions namely Tanga, Kilimanjaro, Arusha, Manyara, Mara and Shinyanga in the period between 2003 -2005. The locations were recorded by using the Geographical Positioning System (GPS). Tsetse trapping was done using biconical/ NGU traps and sticky panel mounted on moving vehicle. All trapping devices used were efficient especially in areas with high tsetse infestation; in areas with low tsetse density, panels were the most efficient. The distribution of tsetse flies is discrete and of low population due the expansion of settlements and farms. Consequently, there is a limited grazing land and animals are illegally forced to graze in parks with wild animals such that they come in contact with tsetse flies especially during dry season. In some areas the cause of low tsetse catches was due to dryness which had forced the game animals to move deep into the forest park and game reserve.

            The tsetse species found in these regions include G. swynnertoni, G. brevipalpis G. fuscipes, G. morsitans, and G. pallidipes. In addition, G. swynnertoni was found mainly in the game reserve while G. pallidipes wasfound in villages within the buffer zone.

            Tsetse infestation in the area is very high and efforts need to be done to control the vector. The community should be educated on the danger of grazing their animals in the park where there is a high concentration of tsetse to avoid loosing there animals as a result of trypanosomosis. It is also important to strengthen tsetse control programs within the game reserve and around settlements in buffer zones.

Map 2 Tanzania National Parks And Game Reserves

3.2.      Trpanosomosis Control

3.2.1    Animal African Trypanosomosis (AAT) diagnosis and surveillance in Tanzania

            Animal African Trypanosomosis known as “Nagana”, ranks second to East Coast Fever (ECF) in terms of morbidity and mortality among the vector borne diseases and is one of the major constraints in the development of rural communities and livestock industry in Tanzania. It is also an important factor affecting pastoral community settlements. To protect animals from trypanosomosis, livestock keepers are forced to keep stocks of anti-trypanocidal drugs to cure them, which sometimes, are done improperly thereby in the long run causing resistance of trypanosomes to trypanocidal drugs used.

            AAT is largely based on clinical signs and parasitological diagnosis (blood smear and buffy coat examination and mouse inoculation). Serological methods (e.g. ELISA) are used in research and surveillance studies. Some bio molecular studies on field collected samples are carried out at Sokoine University of Agriculture. “Shotgun” treatments are often carried out due to lack of laboratory diagnosis

            It is estimated that about 7 million livestock and 4 million people are at risk of contracting trypanosomosis. Although accurate data on the incidence of trypanosomosis is lacking (table 1), it is estimated that on average, each year 150,000 cattle are affected by trypanosomosis. It is estimated that losses due to mortality and reduced milk yield is about US$ 7.98 million annually. These losses do not include other production parameters and control costs.

Table 1:    Animal trypanosomosis surveillance report from 1998 to 2004

Source: MWLD Epidemiology Unit monthly reports

3.2.2    Human African Trypanosomosis (HAT)

            Human African Trypanosomosis (HAT) or Sleeping Sickness (S.S) is one of the major public health problems with about 300 people are affected by the disease each year (Figure 1). Sleeping sickness seriously affects the workforce and cost households in terms of treatment and time spent in taking care of sick members of the family. Convalescing individuals take long before re-engaging in substantial productive work.

4.0       Tsetse And Trypanosomosis Research Institute Activities

4.1       Trypanosomosis prevalence in cattle on Mafia Island Tanzania

            Tsetse surveys were initiated and conducted for eradication by the sterile insect technique (SIT) on Mafia Island where Glossina brevipalpis has been found to be the only species. Mass production for SIT application is being done at Tsetse & Trypanosomosis Research Institute (TTRI). Baseline data on trypanosomosis prevalence was done in collaboration with the Animal Disease Research Institute (ADRI).

             During two consecutive surveys (February and August/Sept 2002), a total of 970 cattle from the cattle population of Mafia Island were randomly blood- sampled. All blood samples were microscopically screened for the presence of trypanosomes and a portion of these were checked for the antibodies with an Antibody ELISA and for the presence of trypanosomal DNA with PCR. Microscopic evidence of trypanosomes of the congolense group (sub-genus nannomonas) was found in only two animals and the species were identified by PCR analysis as T. congolense savannah type. Non-pathogenic Trypanosoma theileri were detected in 3.2% (31/970) of the samples using the Dark Ground-Buffy Coat (DG-BC) technique. For survey 1 (S1), detection of antibodies (ELISA) against pathogenic trypanosomes indicated a sero-prevalence of 14.2% (68/480). Only 5 out of 59 samples which were either DG positive or with a PCV lower than 25 (selected from 970 samples) and examined by PCR, were found positive for T. congolense. Although no animals from survey 2 (S2) were found positive using Dark Ground-Buffy Coat technique (DG-BC) on the collected blood, further tests indicated two animals positive for T. congolense, one by using the PCR technique the other by mouse inoculation.

            The low prevalence of pathogenic trypanosomes on Mafia Island is intriguing, especially in view of the omnipresence of the tsetse fly G. brevipalpis. Although the presence of detected trypanosomal antibodies does not necessarily indicate a current infection, the combination of serological/parasitological and the PCR technique do support this low prevalence of trypanosomosis in cattle.

            Further baseline information was collected in April/May 2004, September/October 2004 and May/June 2005 using a sentinel herd of 85 cattle which were followed up for Packed Cell Volume, presence/absence of trypanosomes by Buffy coat/blood slide examinations and mouse inoculation. One animal was found to be infected with pathogenic Trypanosoma congolense by parasitological technique. It remains however a fact that pathogenic trypanosomes are present on Mafia Island and from a research and scientific point of view it will be interesting to further investigate the link between the Glossina species present, the transmission risk and the trypanosomes found in the cattle including PCR test on all positive samples.

Figure 1:    Number of Sleeping Sickness incidences diagnosed from District Hospitals in nine districts of

                   Tanzania from 1995 to 2004

Source: NIMR reports, Ministry of Health 2005

            The low prevalence of pathogenic trypanosomes is somewhat surprising in view of the island-wide distribution of the tsetse fly, G. brevipalpis being the only tsetse fly species so far encountered on the island (IAEA, 2001). This low prevalence might be attributed to a possible combination of factors such as (1) the frequent prophylactic treatment of the cattle with trypanocidal drugs, (2) a low feeding frequency of the tsetse fly G. brevipalpis on cattle or (3) the low vectorial capacity of G. brevipalpis for either T. vivax and/or T. congolense. It seems that the farmers treat their animals often themselves with drugs that are freely available on the market. Regular prophylactic treatments with trypanocidal drugs will obviously mask the true epidemiological situation of the disease trypanosomosis

            Future surveys should therefore include data on treatment records of cattle with trypanocidal drugs, screening by PCR of all blood samples either positive for trypanosomes or with PCV lower than 25, blood meal analysis of captured G. brevipalpis flies in order to identify host-preference in feeding and data on the prevalence of trypanosomosis species in G. brevipalpis using PCR-tests for identification.

4.2.      Quality Control Of Blood Collected Under Local Conditions For Feeding Tsetse Flies

            Successful SIT programs for tsetse eradication require mass production of tsetse flies in the laboratory. In mass production, among other factors, tsetse diet (good quality blood) is very important. Good quality blood is vital in the maintenance of healthy flies with good survival and good production. Therefore, before blood collection the health status of slaughtered animals should be taken into consideration. Also blood collection procedures, including handling and storage should be done under hygienic conditions to minimize contamination.

            During the period under review seasonal sampling of blood obtained from different abattoirs was done and the following tests were carried out on the collected blood; PCV values, bacterial screening and 30-day bioassays were performed to determine the quality factor (QF).  Flies used were Glossina austeni kept under TTRI rearing standards. In most of the collected samples the PCV was above the acceptable value of 25 and the QF was above 1.

4.3       Trapping Of Glossina Pallidipes Austeni And Their Adaptation Into In Vitro Feeding System

            Trapping of Glossina pallidipes for adaptation in the laboratory on an in vitro feeding system has been tried at TTRI 3 times prior to this project with very limited success. In these past trials, although many flies were caught in the traps, many of them died within the collection devices or during transportation. The collecting devices of the traps made flies to be stuck in collapsible areas of the netting and failed to get out hence could not move and as a result they could not escape heat and wind which affected them to death. Replacement of the collection cage with a holding cage has significantly improved fly survival of caught flies. The suitability of the new collecting device is that it is not collapsible and the rigid plastic sides of the cage offer as barrier for wind and heat to the flies captured in the cage.

            Captured flies are fed on site on an artificial membrane after warming the blood with warm water. The cages containing the flies are wrapped in a wet cloth and shipped to the laboratory in Tanga.  Flies that have been already maintained in the laboratory produce some pupae but there are severe abortions of larvae and eggs, which signify stress in the system yet. However, currently, modification of fly collection device of the trap, transportation and feeding system show some breakthrough on numbers of flies that are shipped to the institute every collection day. This observation indicates that the previous collection cage is not suitable for collecting flies for laboratory adaptation. Probably what is important now is to perfect the system to achieve adaptation of field flies into artificial conditions and feeding system in future.

4.4       Trials On The Control Of Trypanosomosis By Using Tsetse Fly Traps In Mngeta And Mlimba Divisions

            A brief report is presented on tasks carried out in pastoral areas of Mngeta and Mlimba divisions as preparations for control of trypanosomosis. The specific objectives carried out were:

• To conduct tsetse species survey
• To locate tsetse fly traps to preferable habitat
• To conduct training to Village Extension Officers (VEOs) on how to use the traps and assess tsetse fly density
• To discuss with pastoral communities their responsibility to the traps.

            The surveys of tsetse flies were carried out in pastoral areas listed by pastoral communities in Mngeta and Mlimba divisions. Specifically, pastoral areas surveyed are Miomboni (Mofu ward), Mgudeni (Mchombe ward), Merera (Chita ward) Makirika (Mlimba ward), Ngalimila (Utengule ward) and Mfiriga/Kichangani (Utengule ward). The areas sampled are infested with Glossina morsitans, G. pallidipes and G. brevipalpis and endemic to human Trypanosomosis according to  the tsetse infestation map of Africa (Ford & Katondo, 1977). The survey was carried out by locating (setting) different conventional retaining traps and sticky panels baited with 1:4:8 mixtures of 4-methylpropylnol sachets in areas suspected of being infested with tsetse with the help of the youth found in the respective areas. Some elders also participated in the field activities.

            The vegetation in the survey areas was found to be typical savanna and Miombo woodland.  The soil in all areas was very wet and grass (Panicum spp) was very tall. Wild animals common in the areas are Buffalo and antelopes.

            Traps used in the sampling were Biconical, Modified Pyramidal, H-trap and the Sticky Panel. These traps were selected for survey in these areas because they are very efficient in catching all species of tsetse found in the country. The traps stayed in each place for one day and thereafter emptied and contents analyzed on site.

            Training to VEOs and agricultural/pastoral communities were conducted as field classes at centres proposed by respective groups. The training involved lectures and practical. All the different traps, targets and odour attractants were displayed and their relative attractiveness and capability to catch flies taught. Further training included the use of the blue/black/blue cloth target that kills flies after impregnation with a persistent insecticide. After Lectures on the traps and their applicability, the groups were invited for discussions and views on responsibility to the traps.

Results

            In all the areas surveyed, no tsetse fly was caught in the traps or the sticky panel. However, few Stomoxys and Tabanids entered the traps and were stuck on the glued surface of the panels. The response of all the focus groups during lectures, locating of traps and discussions were very positive; shown by active participations for most of them. In all groups, pastoral communities showed readiness to participate fully in tsetse control should the programme start. Moreover, they were willing to contribute money to purchase more targets. At Merera, one participant offered to contribute 10 targets alone. This shows that pastoral communities are eager to have trypanosomosis affecting their animals controlled.

Probable reasons for non availability of tsetse:

            Parameters of success in a tsetse fly control programme is based on baseline data collected before the project e.g. population density of the pest and level of trypanosomosis infection in livestock.  Tabanids could transmit trypanosomosis in livestock mechanically. However, an intermediate host mainly facilitates sustainability of the disease, which is the tsetse. This suggests that wherever trypanosomosis is prevalent or endemic, there must be tsetse flies. Unfortunately, although it has been establishment by other stakeholders that abortions in cattle were caused by trypanosomosis and despite that vegetation in the surveyed areas is typical for tsetse, infestation and curative measure using anti-trypanocidal drugs is very high, which suggests presence of tsetse. No tsetse fly was caught in the surveys conducted in Mngeta and Mlimba divisions from 22 – 31 January 2005.  Possible reasons for failure to catch tsetse in the areas are that:

• The ground cover was very wet that it could not serve as breeding ground and therefore flies could have shrunken to an unknown area for this season where they could breed on dry soil under logs or rocks etc and raid livestock periodically from a sustainable habitat. For example one of the habitats believed to sustain tsetse is between Utengule and Taweta. This area was not visited because the road connecting it was not passable at the time of study.

• Normally, tsetse flies are rare during middle of wet and dry seasons and common at beginning and end of rains.

Recommendations and suggestions

            Since it has been established that abortion in cattle were caused by trypanosomosis in the months of May to July when it is dry, more sampling of tsetse species infestation be implemented at this period coupled with blood screening for trypanosomes to establish index of the problem for use in assessment of control success during and after the control programme. In the survey, more efforts must be put to identify areas that serve as tsetse sustaining areas.  If available data on abortions is conclusive, then that can be the index and therefore control programme be planned using blue/black/blue targets impregnated with Glossinex and baited with synthetic odour attractants or cow urine under specialized supervision. Monitoring of control success should be based on reduction of abortion and infection rates in cattle.

            Because wild animals which are carriers of trypanosomes cross from conserved areas into livestock pasture areas, it is recommended that odour-baited insecticide-treated targets and traps be set on the buffer zones as barriers for tsetse flies that are sustained in the game conservation areas and cross into livestock grazing areas. 

Future plans

            More sampling of tsetse infestation to be carried out in the dry season to identify species of tsetse found in the areas and their relative abundance to establish a suitable monitoring trap during control campaign. Animals diagnosed positive to trypanosomosis should be treated to assess if there will be any new transmission rates after the control campaign which will show presence of tsetse.

• Tsetse sustainable areas to be identified for intensification of control devices and where these areas are in the game conserved areas, areas for barrier systems are determined to reduce movement of flies into livestock pastures.
• For sustainability of the tsetse and trypanosomosis campaign the approach should be self-help. When the-would be beneficiaries of the output are involved, the motivation is high.
• A regression line should be drawn during tsetse and trypanosomosis control campaign to show trend of success.
• Supervision and monitoring of the projects is necessary.

4.5       Trials On The Control Of Trypanosomosis At Safi Dairy Farm Tanga District

            SAFI Dairy Farm is situated in the Tanga district. The area of the farm is 300 square km. The farm has 175 dairy cattle.  It is bordered to the south and south east with bushes suspected of being infested with tsetse.  To the north and west, the farm borders with farmlands and settlements. The climate of the area is coastal and vegetation is thicketed grassland. Tanga region is infested with 4 species of tsetse: Glossina morsitans, G. pallidipes. G. austeni and G. brevipalpis. Tanga district is one of the districts infested with these species of tsetse.  The distribution of the species is not well known because there has been a big change in farming systems and settlement since the existing map was developed. However, trypanosomosis infection in cattle is common in most areas of the district especially where cattle husbandry is traditional, i.e. grazing outdoors.   

            According to the farm management of the SAFI Dairy Farm, trypanosomosis cases have been regularly recorded in the cattle. This has necessitated sustaining the animals with anti-trypanocidal drugs (Berenil and Samorin mainly). In January 2005, tsetse traps (conventional and sticky panels) were located around the farm for about 2 weeks with the objective of identification of tsetse found in the area and their relative densities. Unfortunately, no tsetse was caught. Many biting flies (Tabanids) and stomoxys were however caught in the traps. Although biting flies can transmit trypanosomes mechanically, they are not able to sustain the disease in animals in the total absence of tsetse flies.  Therefore prevalence of the disease in the farm suggests the presence of tsetse flies. The farm management has no skills of fighting against the tsetse. 

In order to solve the tsetse and tsetse borne problem at SAFI farm, The farm management was advised to implement the following: -

• Establish levels of the disease in the cattle and trypanosome species infecting the cattle (animal blood screening)
• Identify areas sustaining tsetse that raid the farm - (further trapping at the beginning of the rainy season when flies normally disperse from sustainable areas
• Establish tsetse control strategy based on item 2 above.

The TTRI consultants deployed traps in the area for two weeks and caught no tsetse. Following these results the TTRI team has recommended to conduct cattle blood screening to establish trypanosome infection status in the different groups of cattle kept in the farm. The outcome of the infection rate screening will determine practical strategies that will be applied to control the disease in the farm.

4.6       Genetic Studies On G. Swynnertoni

            We understand that PCR-based analysis of the nuclear and mitochondria DNA of the tsetse can be used to provide information of gene flow between populations and therefore determine level of population isolation. The work is a collaborative effort between TTRI and Iowa State University USA. During this work four collections of G. swynnertoni (N = 216) were made. Of seven mitochondrial haplotypes, the commonest was found in 95% of the flies, indicating a low diversity in this species, diminishing resolution of genetic differentiation and dispersion. Our estimates indicated that subpopulations were only weakly differentiated.

            In another tsetse species, four collections were made from G. pallidipes in Serengeti and Tarangire. 268 flies were examined at two mitochondrial loci (ribosomal 16S2 and cytochrome c oxidase sub-unit I) by means of the single strand conformation polymorphism method. Also, 152 flies were examined at 8 micro satellite loci. Seven mitochondrial haplotypes were found one of which was common to all samples. The most common haplotype was found in 70% of the flies. However, the genetic differentiation between Tarangire and Serengeti was minimal. Analysis of nuclear genes (micro satellites) supported the mitochondrial data. Mitochondrial diversity and gene flow in Tanzania for G. pallidipes is comparable to that observed in and among Southern African, Kenyan and Ethiopian populations.

            We conclude that the gene flow among Tanzanian G. swynnertoni is more dispersed but the mitochondrial diversity was too little to provide a good test. Hence more sampling needs to continue from other areas in the G. swynnertoni belt. In the case of G. pallidipes the species demonstrates high mitochondrial diversities over most of its range. Populations, however, generally seem to be fairly localized and gene flow among them is rather less than one would assume from published ecological research.

4.7       Future Research Plans

4.7.1 Tsetse And Trypanosomosis Research Activities (Ttri & Adri)

• To continue with tsetse fly adaptation of other species which are not in our labs
• To continue rearing adapted species (G. austeni, G. pallidipes, G. brevipalpis & G. m. morsitans) as seeds for SIT application if need and for research purposes.
• To continue with Tsetse and Trypanosomosis surveys in Mafia Island
• To continue research on Quality Control for blood collection under local conditions.
• Trapping of Glossina pallidipes austeni and their adaptation into in vitro feeding system
• To develop Mivumoni ranch to enable supply of reliable & good quality blood for feeding mass reared flies at TTRI laboratories for use on eradication campaigns.
• To continue strengthening TTRI physical capacity to enable fully participation in AU (African Union) campaign for tsetse eradication in the whole of Africa
• To continue with genetic studies of tsetse flies
• To strengthen molecular diagnosis of tsetse borne diseases activities.

4.7.2    National Institute For Medical Research (NIMR)

• Drug resistance for T.b. rhodesiense –suramin, melarsoprol.
• Role of the P2 adenosine transporter in T.b. rhodesiense in resistance to arsenics.

5.0       The Way Forward

• Continue with the control of tsetse and trypanosomosis in the arable and potential grazing area covering 50 million hectares to allow utilization of the tsetse infested rangeland for livestock production, agriculture and habitation. The long-term goal to the trypanosomosis problem is to eradicate tsetse flies. Eradication will be undertaken under area-wide approach taking in consideration  Land Use Plan to ensure areas cleared of the fly are properly utilized and do not get re-infested.

• Tsetse eradication programme will be accompanied by range development through land use plans and proper livestock stocking (as per carrying capacity) of cleared areas.

• Community participatory approaches will be used at grassroots level for sustainable tsetse and trypanosomosis control.

• Use of the advanced technology of Sterile Insect Technique (SIT) will be employed for eradication.

• Research directed to develop and sustain sensitive, specific and easy to use diagnostic techniques should be addressed in order to intervene with appropriate treatment as part of the integrated tsetse and trypanosomosis control and eradication strategy. 
  
  
• To continue strengthening TTRI physical capacity to enable fully participation in AU (African Union) campaign for tsetse eradication in the whole of Africa.
  
• PATTEC project implementation