The economic cost of bovine trypanosomosis in pastoral and ago pastoral communities surrounding Murchision Falls National park, Buliisa district, Uganda.

BACKGROUND: Animal diseases that are endemic like tsetse transmitted trypanosomosis cause the continuous expenditure of financial resources of livestock farmers and loss of productivity of livestock. Estimating the cost of controlling animal trypanosomosis can provide evidence for priority setting and targeting cost-effective control strategies. METHODOLOGY: A cross-sectional survey to estimate the economic cost of bovine trypanosomosis was conducted in cattle-keeping communities living around Murchision falls National Park, in Buliisa district Uganda. Data was collected on herd structure, the cost of treatment and control, prevalence of morbidity and mortality rates due to trypanosomosis, and salvage sales losses in cattle herds in the last year. RESULTS: In this study, 55.4% (n = 87) of the households reported their cattle had been affected by trypanosomosis during the previous last year. There was a high economic cost of trypanosomosis (USD 653) per household in cattle-keeping communities in Buliisa district of which 83% and 9% were due to mortality and milk loss respectively/ High mortality loss was due to low investment in treatment. The study showed that prophylactic treatment 3 times a year of the whole herd of cattle using Samorin ® (Isometamidium chloride) at a cost of USD 110 could drastically reduce cattle mortality loss due to trypanosomosis due to trypanosomosis with a return on investment of USD 540 annually per herd. This could be coupled with strategic restricted insecticide spraying of cattle with deltamethrin products. CONCLUSION: The results show a high economic cost of trypanosomosis in cattle-keeping communities in Buliisa district, with cattle mortality contributing the largest proportion of the economic cost. The high mortality loss was due to low investment in treatment of sick cattle.

Knowledge, attitudes and practices on bovine trypanosomosis control in pastoral and agro pastoral communities surrounding Murchison Falls National Park, Uganda.

A mixed method survey was conducted among pastoral and agro pastoral communities surrounding Murchison Falls National Park, Uganda to assess knowledge, attitudes and practices about control of bovine trypanosomosis. A total of 96.8% (n = 152) of the participants had seen tsetse flies, and close to 91.7% (n = 116) of the participants had heard about bovine trypanosomosis. Bovine trypanosomosis was reported as a major disease in their area by about 73.9% (n = 116). There was a significant difference (P < 0.05) in the level of awareness and perception about tsetse and bovine trypanosomosis across the study sub counties. The majority of the farmers (60.5%) stated that grazing near national parks was the main cause of bovine trypanosomosis. A small proportion of farmers associated sharing grazing land and watering points with wildlife (19.1%) and grazing cattle in tsetse fly-infested areas (8.3%) as the causes of trypanosomosis. The communities in the study sub counties were aware of at least one or two clinical signs of bovine trypanosomosis. Spraying cattle with insecticide and avoiding grazing animals in tsetse-infested areas were the control practices. Curative trypanocides were mainly used to treat their cattle against trypanosomosis. Bush clearing, targets and traps as tsetse fly control measures were less practiced by the farmers. Treatment of cattle was based on observation of clinical signs due to absence of blood diagnostic facilities. Implementing regular tsetse fly population monitoring surveys and promotion of disease rapid diagnostic tools at farm level as long-term strategies are key for effective control of the disease.

Prevalence and control implications of bovine trypanosomes in endemic areas of northern Uganda.

African animal trypanosomiasis (AAT), a disease complex caused by tsetse fly-transmitted Trypanosoma brucei brucei, T. congolense savannah ITS, and T. vivax, continues to inflict heavy losses to the animal industry in terms of decreased livestock production and productivity. Live bait technology and chemotherapy have been used as a control strategy in northern Uganda since 2006 with minimal success. Here, we report the results of a cross-sectional study carried out in Lango subregion, Uganda, to assess the species prevalence of bovine trypanosome in cattle using the internal transcribed spacer (ITS) of trypanosome ribosomal DNA (rDNA). Blood samples were collected from 1090 cattle by ear vein puncture and screened using a single pair of primers designed to amplify ITS ribosomal DNA (rDNA). Our results indicate an overall prevalence of 40.18% (438/1090, 95% CI 30.82-54.51). T. vivax constituted 32.66% (356/1090), T. congolense 2.39% (26/1090), T. brucei 1.28% (14/1090), T. godfreyi 0.09%(1/1090), T. brucei and T. congolense 0.36% (4/1090), T. brucei and T. vivax 1.47% (16/1090), T. vivax and T. congolense 1.65% (18/1090), T. vivax and T. simiae 0.18% (2/1090), and T. vivax and T. godfreyi 0.09% (1/1090) of infections. Over 91.7% of infections involved single species, while 9.5% were mixed infections. Over 90.2% (37/41) of the mixed infections involved T. vivax as one of the species, while 53.7% (22/41) involved T. congolense. The high prevalence of AAT and the continued presence of T. brucei raise public health concerns because of the zoonotic implications. An integrated approach that involves mass treatment of cattle, vector, and animal movement control should be adopted to reduce the risk of both AAT and HAT.

Factors associated with persistence of African animal trypanosomiasis in Lango subregion, northern Uganda.

African animal trypanosomiasis (AAT) continues to inflict heavy losses on livestock production especially cattle in terms of decreased production and productivity in Uganda. AAT is a disease complex caused by tsetse fly-transmitted Trypanosoma brucei brucei, Trypanosoma brucei rhodesiense, Trypanosoma congolense, and Trypanosoma vivax. The disease is most important in cattle but also known to cause serious losses in pigs, camels, goats, and sheep. Several control measures including live bait technology, mass treatment of cattle with trypanocidal drugs, and deployment of tsetse traps have been used in the past 10 years, but the problem still persists in some areas. This necessitated an exploration of the factors associated with continued trypanosome infections in cattle, which are also known reservoirs for the zoonotic trypanosomiasis. A structured questionnaire was administered to 286 animal owners from 20 villages purposively selected from Lira, Kole, and Alebtong districts of Lango subregion to obtain information on the factors associated with persistence of infection. Over 50% of the respondents reported trypanosomiasis as a major challenge to their livestock. Land ownership (P = 0.029), type of livestock kept (P = 0.000), disease control strategy employed (P = 0.000), source of drugs (P = 0.046), and drug preparation (P = 0.017) were associated with persistent AAT infection. We recommend continued farmer sensitization on the threat of AAT and the available prevention and control options. The use of isometamidium chloride for prophylaxis against trypanosomiasis is highly recommended. There is also a need to foster qualified private veterinary drug supply in the region.

High intensity of Tunga penetrans infection causing severe disease among pigs in Busoga, South Eastern Uganda.

BACKGROUND: Towards the improvement of stakeholders' awareness of animal tungiasis, we report 10 unusual severe clinical cases of pig tungiasis which were associated with very high infection intensities of T. penetrans in an endemic area. RESULTS: Morbidity of ten pigs with high sand flea intensities detected during high transmission seasons in an endemic area in Busoga sub region, Uganda is described in detail. The cases of pigs presented with a very high number of embedded sand fleas (median = 276, range = 141-838). Acute manifestations due to severe tungiasis included ulcerations (n = 10), abscess formation (n = 6) and lameness (n = 9). Chronic morphopathological presentations were overgrowth of claws (n = 5), lateral deviation of dew claws (n = 6), detachment (n = 5) or loss of dew claws (n = 1). Treatment of severe cases with a topical insecticidal aerosol containing chlorfenvinphos, dichlorvos and gentian violet resolved acute morbidity and facilitated healing by re-epithelialisation. CONCLUSIONS: The presentations of tungiasis highlighted in this report show that high intensities of embedded T. penetrans can cause a severe clinical disease in pigs. Effective tungiasis preventive measures and early diagnosis for treatment could be crucial to minimize its effects on animal health.

Two Severe Cases of Tungiasis in Goat Kids in Uganda.

Tungiasis ensues from the penetration and burrowing of female sand fleas (Tunga spp.; Siphonaptera: Tungidae) in the skin of mammals. There are few case reports of severe tungiasis in goats and in these cases the Tunga species were not in most cases clearly identified. Two cases of severe tungiasis caused by Tunga penetrans in goat kids from tungiasis-endemic rural Uganda are reported. These are the first severe cases of tungiasis in goats reported from outside South America.

Prevalence of porcine cysticercosis in the Lake Kyoga Basin, Uganda.

BACKGROUND: Taenia solium is a zoonotic helminth with the potential to cause life threatening epilepsy in people through the aberrant larval infection of the brain called Neurocysticercosis (NCC). The pig is the intermediate host for T. solium where the larval form, cysticercus cellulosae, normally develops after the pig eats eggs of the parasite. Humans are the definitive host where the adult tapeworm develops and are infected through the consumption of poorly cooked, infected meat. T. solium has been acknowledged by the World Health Organization (WHO), Food and Agriculture Organization (FAO) and UK Department for International Development (DFID) as being a neglected zoonotic disease, and was recently included in the WHO roadmap for control of neglected tropical diseases. This neglect encompasses a lack of epidemiological data and a lack of validated, effective control strategies being adopted. Understanding the epidemiology of this parasite in the intermediate host is the first step towards designing suitable intervention strategies for the improvement of public health. This study was undertaken to provide an accurate and up-to-date estimate for the prevalence of porcine cysticercosis in the Lake Kyoga basin. RESULTS: Sera from 378 pigs were analysed with the HP10 Antigen Enzyme Linked Immunosorbant Assay (ELISA) and the prevalence was found to be 25.7% (95% confidence interval 21.0% to 30.0%). Previous sero- surveillance in this region, using the B158/B60 Ag Elisa had indicated a prevalence of 8.6% in 2005 indicating a dramatic increase in prevalence (J. Parasitol Res, Article ID 375493, 2009) within a 6 year period. CONCLUSION: This increasing prevalence in the disease indicates to us that there is currently no effective control of this parasite and that in this region of Uganda at least; cysticercosis remains a neglected zoonotic disease.

Seasonal Monitoring of Glossina Species Occurrence, Infection Rates, and Trypanosoma Species Infections in Pigs in West Nile Region, Uganda.

Introduction: Trypanosomiasis is a parasitic infection caused by the protozoa Trypanosoma. It is exclusively associated with Glossina species habitats and, therefore, restricted to specific geographical settings. It affects a wide range of hosts, including humans. Animals may carry different Trypanosoma spp. while being asymptomatic. They are, therefore, potentially important in unpremeditated disease transmission. Aim: The aim of this study was to study the potential impact of the government tsetse fly control program, and to elucidate the role of pigs in the Trypanosoma epidemiology in the West Nile region in Uganda. Methods: A historically important human African trypanosomiasis (HAT) hotspot was selected, with sampling in sites with and without a government tsetse fly control program. Pigs were screened for infection with Trypanosoma and tsetse traps were deployed to monitor vector occurrence, followed by tsetse fly dissection and microscopy to establish infection rates with Trypanosoma. Pig blood samples were further analyzed to identify possible Trypanosoma infections using internal transcribed spacer (ITS)-PCR. Results: Using microscopy, Trypanosoma was detected in 0.56% (7/1262) of the sampled pigs. Using ITS-PCR, 114 of 341 (33.4%) pig samples were shown to be Trypanosoma vivax positive. Of the 360 dissected tsetse flies, 13 (3.8%) were positive for Trypanosoma under the microscope. The difference in captured tsetse flies in the government intervention sites in comparison with the control sites was significant (p < 0.05). Seasonality did not play a substantial role in the tsetse fly density (p > 0.05). Conclusion: This study illustrated the impact of a government control program with low vector abundance in a historical HAT hotspot in Uganda. The study could not verify that pigs in the area were carriers for the causative agent for HAT, but showed a high prevalence of the animal infectious agent T. vivax.

Systematic Review and Meta-Analysis on Knowledge Attitude and Practices on African Animal Trypanocide Resistance.

BACKGROUND: African trypanocide resistance is an emerging public health emergency whose control requires a revisit on farmer's knowledge, attitudes, and practices in developing countries. African animal trypanocide resistance (AATr) is rife in an environment where drug use and policy decisions are disjointed. The objective of the study was to identify community factors responsible for the development of AATr. This was important since diminazene aceturate (DA), isometamidium chloride (ISM), and homidium bromide (HB) have existed for over 30 years and no new drugs have been provided to farmers. METHODS: An electronic keyword search across 12 databases was conducted using a search criterion from 1806 to June 2022. This generated a total of 24 publications, but after removing duplicates, review articles, and nonrelated articles, a total of eight papers were included in the analysis by following the PRISMA checklist. A meta-analysis was conducted on the data extracted and the risk ratio and inverse variance at 95% confidence interval were calculated using RevMan®. RESULTS: All the eight articles in the study showed that DA was the most preferred trypanocide in both West and Eastern Africa. Poor farmer knowledge of AATr and limited drug options were major drivers for trypanocide resistance. In addition, farmer treatments, use of untrained personnel, poor administration, poor dosing, and preparation of trypanocides were major drivers for the development of AATr and similarities were identified in DA and ISM practices (P = 0.13). CONCLUSIONS: AATr is spread in developing countries due to a lack of community knowledge, attitudes, and drug-use practices. This situation could be reversed through interdisciplinary collaborations in endemic communities by promoting effective treatments and responsible drug handling.

Scaling up of tsetse control to eliminate Gambian sleeping sickness in northern Uganda.

BACKGROUND: Tsetse flies (Glossina) transmit Trypanosoma brucei gambiense which causes Gambian human African trypanosomiasis (gHAT) in Central and West Africa. Several countries use Tiny Targets, comprising insecticide-treated panels of material which attract and kill tsetse, as part of their national programmes to eliminate gHAT. We studied how the scale and arrangement of target deployment affected the efficacy of control. METHODOLOGY AND PRINCIPAL FINDINGS: Between 2012 and 2016, Tiny Targets were deployed biannually along the larger rivers of Arua, Maracha, Koboko and Yumbe districts in North West Uganda with the aim of reducing the abundance of tsetse to interrupt transmission. The extent of these deployments increased from ~250 km2 in 2012 to ~1600 km2 in 2015. The impact of Tiny Targets on tsetse populations was assessed by analysing catches of tsetse from a network of monitoring traps; sub-samples of captured tsetse were dissected to estimate their age and infection status. In addition, the condition of 780 targets (~195/district) was assessed for up to six months after deployment. In each district, mean daily catches of tsetse (G. fuscipes fuscipes) from monitoring traps declined significantly by >80% following the deployment of targets. The reduction was apparent for several kilometres on adjacent lengths of the same river but not in other rivers a kilometre or so away. Expansion of the operational area did not always produce higher levels of suppression or detectable change in the age structure or infection rates of the population, perhaps due to the failure to treat the smaller streams and/or invasion from adjacent untreated areas. The median effective life of a Tiny Target was 61 (41.8-80.2, 95% CI) days. CONCLUSIONS: Scaling-up of tsetse control reduced the population of tsetse by >80% across the intervention area. Even better control might be achievable by tackling invasion of flies from infested areas within and outside the current intervention area. This might involve deploying more targets, especially along smaller rivers, and extending the effective life of Tiny Targets.

Herd prevalence of bovine brucellosis and analysis of risk factors in cattle in urban and peri-urban areas of the Kampala economic zone, Uganda.

BACKGROUND: Human brucellosis has been found to be prevalent in the urban areas of Kampala, the capital city of Uganda. A cross-sectional study was designed to generate precise information on the prevalence of brucellosis in cattle and risk factors for the disease in its urban and peri-urban dairy farming systems. RESULTS: The adjusted herd prevalence of brucellosis was 6.5% (11/177, 95% CI: 3.6%-10.0%) and the adjusted individual animal prevalence was 5.0% (21/423, 95% CI: 2.7%-9.3%) based on diagnosis using commercial kits of the competitive enzyme-linked immunosorbent assay (CELISA) for Brucella abortus antibodies. Mean within-herd prevalence was found to be 25.9% (95% CI: 9.7%-53.1%) and brucellosis prevalence in an infected herd ranged from 9.1% to 50%. A risk factor could not be identified at the animal level but two risk factors were identified at the herd level: large herd size and history of abortion. The mean number of milking cows in a free-grazing herd (5.0) was significantly larger than a herd with a movement restricted (1.7, p < 0.001). CONCLUSIONS: Vaccination should be targeted at commercial large-scale farms with free-grazing farming to control brucellosis in cattle in and around Kampala city.

Spatial epidemiology of hospital-diagnosed brucellosis in Kampala, Uganda.

BACKGROUND: A retrospective case-control study was undertaken to examine the spatial risk factors for human brucellosis in Kampala, Uganda. METHODS: Information on age, sex and month of diagnosis was derived from records from plate agglutination tests undertaken at Mulago Hospital, Kampala. Information on Parishes (LC2s) where patients reside was sourced from the outpatient registration book. In-patient fracture cases were selected for use as controls using 1:1 matching based on the age, sex and month of diagnosis. The locations of cases and controls were obtained by calculating Cartesian coordinates of the centroids of Parish level (LC2) polygons and a spatial scan statistic was applied to test for disease clustering. Parishes were classified according to the level of urbanization as urban, peri-urban or rural. RESULTS: Significantly more females than males were found to show sero-positivity for brucellosis when compared with the sex ratio of total outpatients, in addition female brucellosis patients were found to be significantly older than the male patients. Spatial clustering of brucellosis cases was observed including around Mulago Hospital (radius = 6.8 km, p = 0.001). The influence of proximity to the hospital that was observed for brucellosis cases was not significantly different from that observed in the controls. The disease cluster was confounded by the different catchment areas between cases and controls. The level of urbanization was not associated with the incidence of brucellosis but living in a slum area was a significant risk factor among urban dwellers (odds ratio 1.97, 95% CI: 1.10-3.61). CONCLUSIONS: Being female was observed to be a risk factor for brucellosis sero-positvity and among urban dwellers, living in slum areas was also a risk factor although the overall risk was not different among urban, peri-urban and rural areas of the Kampala economic zone.

Controlling Tsetse Flies and Ticks Using Insecticide Treatment of Cattle in Tororo District Uganda: Cost Benefit Analysis.

Background: The endemic vector-borne diseases transmitted by tsetse and ticks impose heavy burdens on the livestock keepers in Africa. Applying deltamethrin to the belly, legs, and ears of cattle offers a possibility of mitigating these losses at a cost affordable to livestock keepers. Although studies have quantified the impacts of individual diseases on livestock productivity, little is known about the dual economic benefits of controlling both tsetse and ticks, nor about the number of cattle that need to be treated to confer these benefits. Alongside an epidemiological study in south-east Uganda, a farm level assessment was done to investigate the benefits and costs of spraying different proportions of the village cattle population using this restricted application protocol. Methods: A study comprising 1,902 semi-structured interviews was undertaken over a period of 18 months. Financial data on household income and expenditure on cattle was collected, and cost-benefit analysis was done pre- and post-intervention and for different spraying regimes. The total cost of the intervention was obtained from the implementation costs of the epidemiological study and from expenses incurred by participating farmers enabling examination of benefit-cost ratios and incremental benefit-cost ratios for each treatment regime. Results: The benefit-cost analysis of spraying 25%, 50%, and 75% of the cattle population yielded average benefit-cost ratios of 3.85, 4.51, and 4.46. The incremental benefit-cost ratios from spraying each additional 25% of the cattle population were 11.38, 3.89, and 0.79, showing a very high return on investment for spraying 50% of the population, with returns reducing thereafter. Conclusion: Comparing the gross margins per bovine, the study found that increasing the proportion of cattle sprayed yielded increasing benefits to the farmers, but that these benefits were subject to diminishing returns. From a practical viewpoint, this study recommends spraying only draft cattle to control trypanosomiasis and tick-borne diseases in this area as they make 38.62% of the cattle population, approaching the 50% threshold. In areas with a lower proportion of draft males, farmers could be advised to also include cows.

Livestock Network Analysis for Rhodesiense Human African Trypanosomiasis Control in Uganda.

Background: Infected cattle sourced from districts with established foci for Trypanosoma brucei rhodesiense human African trypanosomiasis (rHAT) migrating to previously unaffected districts, have resulted in a significant expansion of the disease in Uganda. This study explores livestock movement data to describe cattle trade network topology and assess the effects of disease control interventions on the transmission of rHAT infectiousness. Methods: Network analysis was used to generate a cattle trade network with livestock data which was collected from cattle traders (n = 197) and validated using random graph methods. Additionally, the cattle trade network was combined with a susceptible, infected, recovered (SIR) compartmental model to simulate spread of rHAT (R o 1.287), hence regarded as "slow" pathogen, and evaluate the effects of disease interventions. Results: The cattle trade network exhibited a low clustering coefficient (0.5) with most cattle markets being weakly connected and a few being highly connected. Also, analysis of the cattle movement data revealed a core group comprising of cattle markets from both eastern (rHAT endemic) and northwest regions (rHAT unaffected area). Presence of a core group may result in rHAT spread to unaffected districts and occurrence of super spreader cattle market or markets in case of an outbreak. The key cattle markets that may be targeted for routine rHAT surveillance and control included Namutumba, Soroti, and Molo, all of which were in southeast Uganda. Using effective trypanosomiasis such as integrated cattle injection with trypanocides and spraying can sufficiently slow the spread of rHAT in the network. Conclusion: Cattle trade network analysis indicated a pathway along which T. b. rhodesiense could spread northward from eastern Uganda. Targeted T. b. rhodesiense surveillance and control in eastern Uganda, through enhanced public-private partnerships, would serve to limit its spread.

Prevalence and risk factors for trypanosome infection in cattle from communities surrounding the Murchison Falls National Park, Uganda.

BACKGROUND: Bovine trypanosomosis transmitted by tsetse flies is a major constraint to cattle health and productivity in all sub-Saharan countries, including Uganda. The objectives of this study were to determine the prevalence of bovine trypanosomosis and identify its associated risk factors and the species of trypanosomes associated with the disease. METHODOLOGY: A cross-sectional study was conducted around Murchison Falls National Park, Uganda from January 2020 to April 2020. Trypanosomes were detected in blood samples by PCR analysis targeting the internal transcribed spacer 1 (ITS-PCR assays), and trypanosomes in positive blood samples were sequenced. RESULTS: Of 460 blood samples collected and tested, 136 (29.6%) were positive for trypanosome infections and 324 (70.4%) were negative. The overall trypanosome prevalence was 29.6% (95% confidence interval 25.4-33.8%), attributed to three trypanosome species. Of these three species, Trypanosoma vivax was the most prevalent (n = 130, 28.3%) while the others were detected as mixed infections: T. vivax + Trypanosoma congolense (n = 2, 0.4%) and T. vivax + Trypanosoma evansi (n = 1, 0.2%). There were significant differences in trypanosome prevalence according to sex (χ2 = 62, df = 1, P < 0.05), age (χ2 = 6.28, df = 2, P = 0.0043) and cattle breed (χ2 = 10.61, df = 1, P = 0.001). CONCLUSIONS: Trypanosomosis remains a major limitation to cattle production around Murchison Falls National Park and interventions are urgently needed. In our study, the prevalence of trypanosome infections was high, with T. vivax identified as the most prevalent species. Age, sex and breed of cattle were risk factors for trypanosome infection.

Critical Linkages Between Livestock Production, Livestock Trade and Potential Spread of Human African Trypanosomiasis in Uganda: Bioeconomic Herd Modeling and Livestock Trade Analysis.

Background: Tsetse-transmitted human African trypanosomiasis (HAT) remains endemic in Uganda. The chronic form caused by Trypanosoma brucei gambiense (gHAT) is found in north-western Uganda, whereas the acute zoonotic form of the disease, caused by T. b. brucei rhodesiense (rHAT), occurs in the eastern region. Cattle is the major reservoir of rHAT in Uganda. These two forms of HAT are likely to converge resulting in a public health disaster. This study examines the intricate and intrinsic links between cattle herd dynamics, livestock trade and potential risk of spread of rHAT northwards. Methods: A bio-economic cattle herd model was developed to simulate herd dynamics at the farm level. Semi-structured interviews (n = 310), focus group discussions (n = 9) and key informant interviews (n = 9) were used to evaluate livestock markets (n = 9) as part of the cattle supply chain analysis. The cattle market data was used for stochastic risk analysis. Results: Cattle trade in eastern and northern Uganda is dominated by sale of draft and adult male cattle as well as exportation of young male cattle. The study found that the need to import draft cattle at the farm level was to cover deficits because of the herd structure, which is mostly geared towards animal traction. The importation and exportation of draft cattle and disposal of old adult male cattle formed the major basis of livestock movement and could result in the spread of rHAT northwards. The risk of rHAT infected cattle being introduced to northern Uganda from the eastern region via cattle trade was found to be high (i.e. probability of 1). Conclusion: Through deterministic and stochastic modelling of cattle herd and cattle trade dynamics, this study identifies critical links between livestock production and trade as well as potential risk of rHAT spread in eastern and northern Uganda. The findings highlight the need for targeted and routine surveillance and control of zoonotic diseases such as rHAT.

Spatial analysis of G.f.fuscipes abundance in Uganda using Poisson and Zero-Inflated Poisson regression models.

BACKGROUND: Tsetse flies are the major vectors of human trypanosomiasis of the form Trypanosoma brucei rhodesiense and T.b.gambiense. They are widely spread across the sub-Saharan Africa and rendering a lot of challenges to both human and animal health. This stresses effective agricultural production and productivity in Africa. Delimiting the extent and magnitude of tsetse coverage has been a challenge over decades due to limited resources and unsatisfactory technology. In a bid to overcome these limitations, this study attempted to explore modelling skills that can be applied to spatially estimate tsetse abundance in the country using limited tsetse data and a set of remote-sensed environmental variables. METHODOLOGY: Entomological data for the period 2008-2018 as used in the model were obtained from various sources and systematically assembled using a structured protocol. Data harmonisation for the purposes of responsiveness and matching was carried out. The key tool for tsetse trapping was itemized as pyramidal trap in many instances and biconical trap in others. Based on the spatially explicit assembled data, we ran two regression models; standard Poisson and Zero-Inflated Poisson (ZIP), to explore the associations between tsetse abundance in Uganda and several environmental and climatic covariates. The covariate data were constituted largely by satellite sensor data in form of meteorological and vegetation surrogates in association with elevation and land cover data. We finally used the Zero-Inflated Poisson (ZIP) regression model to predict tsetse abundance due to its superiority over the standard Poisson after model fitting and testing using the Vuong Non-Nested statistic. RESULTS: A total of 1,187 tsetse sampling points were identified and considered as representative for the country. The model results indicated the significance and level of responsiveness of each covariate in influencing tsetse abundance across the study area. Woodland vegetation, elevation, temperature, rainfall, and dry season normalised difference vegetation index (NDVI) were important in determining tsetse abundance and spatial distribution at varied scales. The resultant prediction map shows scaled tsetse abundance with estimated fitted numbers ranging from 0 to 59 flies per trap per day (FTD). Tsetse abundance was found to be largest at low elevations, in areas of high vegetative activity, in game parks, forests and shrubs during the dry season. There was very limited responsiveness of selected predictors to tsetse abundance during the wet season, matching the known fact that tsetse disperse most significantly during wet season. CONCLUSIONS: A methodology was advanced to enable compilation of entomological data for 10 years, which supported the generation of tsetse abundance maps for Uganda through modelling. Our findings indicate the spatial distribution of the G. f. fuscipes as; low 0-5 FTD (48%), medium 5.1-35 FTD (18%) and high 35.1-60 FTD (34%) grounded on seasonality. This approach, amidst entomological data shortages due to limited resources and absence of expertise, can be adopted to enable mapping of the vector to provide better decision support towards designing and implementing targeted tsetse and tsetse-transmitted African trypanosomiasis control strategies.

Harnessing technology and portability to conduct molecular epidemiology of endemic pathogens in resource-limited settings.

Improvements in genetic and genomic technology have enabled field-deployable molecular laboratories and these have been deployed in a variety of epidemics that capture headlines. In this editorial, we highlight the importance of building physical and personnel capacity in low and middle income countries to deploy these technologies to improve diagnostics, understand transmission dynamics and provide feedback to endemic communities on actionable timelines. We describe our experiences with molecular field research on schistosomiasis, trypanosomiasis and rabies and urge the wider tropical medicine community to embrace these methods and help build capacity to benefit communities affected by endemic infectious diseases.

Estimating the impact of Tiny Targets in reducing the incidence of Gambian sleeping sickness in the North-west Uganda focus.

BACKGROUND: Riverine species of tsetse (Glossina) transmit Trypanosoma brucei gambiense, which causes Gambian human African trypanosomiasis (gHAT), a neglected tropical disease. Uganda aims to eliminate gHAT as a public health problem through detection and treatment of human cases and vector control. The latter is being achieved through the deployment of 'Tiny Targets', insecticide-impregnated panels of material which attract and kill tsetse. We analysed the spatial and temporal distribution of cases of gHAT in Uganda during the period 2010-2019 to assess whether Tiny Targets have had an impact on disease incidence. METHODS: To quantify the deployment of Tiny Targets, we mapped the rivers and their associated watersheds in the intervention area. We then categorised each of these on a scale of 0-3 according to whether Tiny Targets were absent (0), present only in neighbouring watersheds (1), present in the watersheds but not all neighbours (2), or present in the watershed and all neighbours (3). We overlaid all cases that were diagnosed between 2000 and 2020 and assessed whether the probability of finding cases in a watershed changed following the deployment of targets. We also estimated the number of cases averted through tsetse control. RESULTS: We found that following the deployment of Tiny Targets in a watershed, there were fewer cases of HAT, with a sampled error probability of 0.007. We estimate that during the intervention period 2012-2019 we should have expected 48 cases (95% confidence intervals = 40-57) compared to the 36 cases observed. The results are robust to a range of sensitivity analyses. CONCLUSIONS: Tiny Targets have reduced the incidence of gHAT by 25% in north-western Uganda.

Experiences with an in-training community service model in the control of zoonotic sleeping sickness in Uganda.

By 2006, the acute and zoonotic Tripanosoma brucei rhodesiense sleeping sickness in Uganda was spreading northward, leading to fear of a merger with the chronic Tripanosoma brucei gambiese type that affects people in the northwest of the country. Eliminating infection in cattle was urgent because they had been confirmed to be spreading the zoonotic type, and eliminating infection would reduce the animal reservoir and subsequently reduce transmission of sleeping sickness. In this article, we describe how the staff and students of the Faculty of Veterinary Medicine, Makerere University, adjusted their approach to training veterinary students who could provide the urgently needed manpower to enable the community to halt the disease's spread. Because it was not usual for university staff and students to implement disease control activities, the government of Uganda had to delegate this responsibility to Makerere University. In turn, the university had to explore available opportunities in its training and outreach mandates. A model was developed that proved to be an effective hands-on training strategy while helping to control a disease that was threatening the health of people in a community that was just recovering from an armed rebellion. In total, 66 students and supervisors participated in the 10-week-long mass treatment activities in the target area and treated more than 190,000 out of 220,000 targeted (>86%) cattle with diminazene aceturate and deltamethrin. Also, the graduates' performance improved, as indicated by 43.5% of graduates securing employment within less than a month after completing the course.