Agapitus Kato

Makerere University, College of Natural Sciences, Graduate Student

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RESEARCH Open Access

genetic divergence and geographic distance (r = 0.109, P = 0.185), and demographic tests provide ... more

A time-series approach to mapping livestock density using household survey data

Scientific Reports

More than one billion people rely on livestock for income, nutrition, and social cohesion, howeve... more More than one billion people rely on livestock for income, nutrition, and social cohesion, however livestock keeping can facilitate disease transmission and contribute to climate change. While data on the distribution of livestock have broad utility across a range of applications, efforts to map the distribution of livestock on a large scale are limited to the Gridded Livestock of the World (GLW) project. We present a complimentary effort to map the distribution of cattle and pigs in Malawi, Uganda, Democratic Republic of Congo, and South Sudan. In contrast to GLW, which uses dasymmetric modeling applied to census data to produce time-stratified estimates of livestock counts and spatial density, our work uses complex survey data and distinct modeling methods to generate a time-series of livestock distribution, defining livestock density as the ratio of animals to humans. In addition to favorable cross-validation results and general agreement with national density estimates derived f...

format_quoteFound strong positive correlation between livestock density estimates and GLW-3 data (coefficients > 100), highlighting mapping accuracy.format_quote

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Estimating the distribution of livestock in space and time: a time-series contribution to livestock density mapping

ABSTRACTMore than one billion people rely on livestock for income, nutrition, and social cohesion... more ABSTRACTMore than one billion people rely on livestock for income, nutrition, and social cohesion, however livestock keeping can facilitate disease transmission and contribute to climate change. While data on the distribution of livestock thus have broad utility across a range of applications, efforts to map the distribution of livestock on a large scale are limited to the Gridded Livestock of the World (GLW) project. We present a complimentary effort to map the distribution of cattle and pigs in Malawi, Uganda, Democratic Republic of Congo (DRC), and South Sudan. In contrast to GLW, which uses dasymmetric modeling applied to census data to produce time-stratified estimates of livestock counts and spatial density, our work uses complex survey data and distinct modeling methods to generate a time-series of livestock distribution, defining livestock density as the ratio of animals to humans. In addition to favorable cross-validation results and general agreement with national density ...

format_quoteProduced livestock density maps for Malawi, Uganda (2000-2020), and DRC (2008-2015) showing animals to humans ratio for longitudinal analysis.format_quote

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MOESM1 of Shared species of crocodilian trypanosomes carried by tabanid flies in Africa and South America, including the description of a new species from caimans, Trypanosoma kaiowa n. sp

Additional file 1: Table S1. Host species, geographical origin and gGAPDH and V7V8 SSU rRNA gene ... more

The effect of livestock density on Trypanosoma brucei gambiense and T. b. rhodesiense: a causal inference-based approach

Domestic and wild animals are important reservoirs of the rhodesiense form of human African trypa... more Domestic and wild animals are important reservoirs of the rhodesiense form of human African trypanosomiasis (rHAT), however quantification of this effect offers utility for deploying non-medical control activities, and anticipating their success when wildlife are excluded. Further, the uncertain role of animal reservoirs—particularly pigs—threatens elimination of transmission (EOT) targets set for the gambiense form (gHAT). Using a new time series of high-resolution cattle and pig density maps, HAT surveillance data collated by the WHO Atlas of HAT, and methods drawn from causal inference and spatial epidemiology, we conducted a retrospective ecological cohort study in Uganda, Malawi, Democratic Republic of Congo (DRC) and South Sudan to estimate the effect of cattle and pig density on HAT risk.For rHAT, we found a positive effect for cattle (RR 1.61, 95% CI 0.90, 2.99) and pigs (RR 2.07, 95% CI 1.15, 2.75) in Uganda, and a negative effect for cattle (RR 0.88, 95% CI 0.71, 1.10) and...

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Livestock, pathogens, vectors, and their environment: a causal inference-based approach to estimating the pathway-specific effect of livestock on human African trypanosomiasis risk

Livestock are important reservoirs for many diseases, and investigation of such zoonoses has long... more Livestock are important reservoirs for many diseases, and investigation of such zoonoses has long been the focus of One Health research. However, the effects of livestock on human and environmental health extend well beyond direct disease transmission. In this retrospective ecological cohort study we use pre-existing data and methods derived from causal inference and spatial epidemiology to estimate three hypothesized mechanisms by which livestock can come to bear on human African trypanosomiasis (HAT) risk: the reservoir effect, by which infected cattle and pigs are a source of infection to humans; the zooprophylactic effect, by which preference for livestock hosts exhibited by the tsetse fly vector of HAT means that their presence protects humans from infection; and the environmental change effect, by which livestock keeping activities modify the environment in such a way that habitat suitability for tsetse flies, and in turn human infection risk, is reduced. We conducted this st...

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Mitochondrial DNA (mtDNA) markers reveal low genetic variation and the presence of two honey bee races in Uganda’s agro-ecological zones

Journal of Apicultural Research, 2017

As plant pollinators, honey bees (Apis mellifera) play a very important role in agricultural and ... more As plant pollinators, honey bees (Apis mellifera) play a very important role in agricultural and non agricultural crop production. In addition, honey bee products are of nutritional, medicinal, cosmetic and economic value to society. With the current changing trends in Uganda’s farming systems, it is important to determine the level of genetic variation, and extent of differentiation in the honey bee population. This will be crucial for a successful honey bee management system for improved productivity and conservation of the honey bees in the different agro-ecological zones of Uganda. To achieve this, we investigated the genetic variation in honey bees from ten agro-ecological zones of Uganda by sequencing the intergenic region of the Mitochondrial DNA (mtDNA) COI-COII. We observed high haplotype diversity (Hd > 0.530) within a majority of the agro-ecological zones except the Southern Highland agro-ecological zone (Hd = 0.154). Both the population structure and the phylogenetic analyses revealed the presence of two honey bee races (A. m. adansonii and A. m. scutellata) in Uganda. A. m. adansonii is more widespread in the agro-ecological zones in the northern and eastern parts of Uganda while A. m. scutellata is more spread in the southern and western parts of the country. This is the first exhaustive population genetics research on bees in Uganda, and provides results that are useful to the beekeeping industry for effective management of the honey bee population. These results should be considered while planning beekeeping activities in the country.

Mitochondrial DNA sequence divergence and diversity of Glossina fuscipes fuscipes in the Lake Victoria basin of Uganda: implications for control

Parasites & Vectors, 2015

Background: Glossina fuscipes fuscipes is the main vector of African Trypanosomiasis affecting bo... more Background: Glossina fuscipes fuscipes is the main vector of African Trypanosomiasis affecting both humans and livestock in Uganda. The human disease (sleeping sickness) manifests itself in two forms: acute and chronic. The Lake Victoria basin in Uganda has the acute form and a history of tsetse re-emergence despite concerted efforts to control tsetse. The government of Uganda has targeted the basin for tsetse eradication. To provide empirical data for this initiative, we screened tsetse flies from the basin for genetic variation at the mitochondrial DNA cytochrome oxidase II (mtDNA COII) gene with the goal of investigating genetic diversity and gene flow among tsetse, tsetse demographic history; and compare these results with results from a previous study based on microsatellite loci data in the same area. Methods: We collected 429 Gff tsetse fly samples from 14 localities in the entire Ugandan portion of the Lake Victoria coast, covering 40,000 km 2. We performed genetic analyses on them and added data collected for 56 Gff individuals from 4 additional sampling sites in the basin. The 529pb partial mitochondrial DNA cytochrome oxidase II (mtDNA COII) sequences totaling 485 were analysed for genetic differentiation, structuring and demographic history. The results were compared with findings from a previous study based on microsatellite loci data from the basin. Results: The differences within sampling sites explained a significant proportion of the genetic variation. We found three very closely related mtDNA population clusters, which co-occurred in multiple sites. Although Φ ST (0-0.592; P < 0.05) and Bayesian analyses suggest some level of weak genetic differentiation, there is no correlation between genetic divergence and geographic distance (r = 0.109, P = 0.185), and demographic tests provide evidence of locality-based demographic history. Conclusion: The mtDNA data analysed here complement inferences made in a previous study based on microsatellite data. Given the differences in mutation rates, mtDNA afforded a look further back in time than microsatellites and revealed that Gff populations were more connected in the past. Microsatellite data revealed more genetic structuring than mtDNA. The differences in connectedness and structuring over time could be related to vector control efforts. Tsetse re-emergence after control interventions may be due to re-invasions from outside the treated areas, which emphasizes the need for an integrated area-wide tsetse eradication strategy for sustainable removal of the tsetse and trypanosomiasis problem from this area.

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Does a One Health Approach to Human African Trypanosomiasis Control Hasten Elimination? A Stochastic Compartmental Modeling Approach

Background: In response to large strides in the control of human African trypanosomiasis (HAT), i... more Background: In response to large strides in the control of human African trypanosomiasis (HAT), in the early 2000s the WHO set targets for elimination of both the gambiense (gHAT) and rhodesiense (rHAT) forms as a public health (EPHP) problem by 2020, and elimination of gHAT transmisson (EOT) by 2030. While global EPHP targets have been met, and EOT appears within reach, there is ample evidence that current control strategies will not achieve gHAT EOT in the presence of animal reservoirs, the role of which is currently uncertain. Furthermore, rHAT is not targeted for EOT due to the known importance of animal reservoirs for this form. Methods: To evaluate the utility of a One Health approach to gHAT and rHAT EOT, we built and parameterized a compartmental stochastic model, using the Institute for Disease Modeling's Compartmental Modeling Software, to six HAT epidemics: the national rHAT epidemics in Uganda and Malawi, the national gHAT epidemics in Uganda and South Sudan, and two...

Shared species of crocodilian trypanosomes carried by tabanid flies in Africa and South America, including the description of a new species from caimans, Trypanosoma kaiowa n. sp

Parasites & Vectors, May 14, 2019

Background: The genus Trypanosoma Gruby, 1843 is constituted by terrestrial and aquatic phylogene... more Background: The genus Trypanosoma Gruby, 1843 is constituted by terrestrial and aquatic phylogenetic lineages both harboring understudied trypanosomes from reptiles including an increasing diversity of crocodilian trypanosomes. Trypanosoma clandestinus Teixeira & Camargo, 2016 of the aquatic lineage is transmitted by leeches to caimans. Trypanosoma grayi Novy, 1906 of the terrestrial lineage is transmitted by tsetse flies to crocodiles in Africa, but the vectors of Neotropical caiman trypanosomes nested in this lineage remain unknown. Results: Our phylogenetic analyses uncovered crocodilian trypanosomes in tabanids from South America and Africa, and trypanosomes other than T. grayi in tsetse flies. All trypanosomes found in tabanids clustered in the crocodilian clade (terrestrial lineage) forming six clades: Grayi (African trypanosomes from crocodiles and tsetse flies); Ralphi (trypanosomes from caimans, African and Brazilian tabanids and tsetse flies); Terena (caimans); Cay03 (caimans and Brazilian tabanids); and two new clades, Tab01 (Brazilian tabanid and tsetse flies) and Kaiowa. The clade Kaiowa comprises Trypanosoma kaiowa n. sp. and trypanosomes from African and Brazilian tabanids, caimans, tsetse flies and the African dwarf crocodile. Trypanosoma kaiowa n. sp. heavily colonises tabanid guts and differs remarkably in morphology from other caiman trypanosomes. This species multiplied predominantly as promastigotes on log-phase cultures showing scarce epimastigotes and exhibited very long flagellates in old cultures. Analyses of growth behavior revealed that insect cells allow the intracellular development of Trypanosoma kaiowa n. sp. Conclusions: Prior to this description of Trypanosoma kaiowa n. sp., no crocodilian trypanosome parasitic in tabanid flies had been cultured, morphologically examined by light, scanning and transmission microscopy, and phylogenetically compared with other crocodilian trypanosomes. Additionally, trypanosomes thought to be restricted to caimans were identified in Brazilian and African tabanids, tsetse flies and the dwarf crocodile. Similar repertoires of trypanosomes found in South American caimans, African crocodiles and tabanids from both continents support the recent diversification of these transcontinental trypanosomes. Our findings are consistent with trypanosome host-switching likely mediated by tabanid flies between caimans and transoceanic migrant crocodiles co-inhabiting South American wetlands at the Miocene.

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The population structure of Glossina fuscipes fuscipes in the Lake Victoria basin in Uganda: implications for vector control

by Agapitus Kato and Chaz Hyseni

Parasites & Vectors, 2012

Background: Glossina fuscipes fuscipes is the primary vector of trypanosomiasis in humans and liv... more Background: Glossina fuscipes fuscipes is the primary vector of trypanosomiasis in humans and livestock in Uganda. The Lake Victoria basin has been targeted for tsetse eradication using a rolling carpet initiative, from west to east, with four operational blocks (3 in Uganda and 1 in Kenya), under a Pan-African Tsetse and Trypanosomiasis Eradication Campaign (PATTEC). We screened tsetse flies from the three Ugandan PATTEC blocks for genetic diversity at 15 microsatellite loci from continental and offshore populations to provide empirical data to support this initiative. Methods: We collected tsetse samples from 11 sites across the Lake Victoria basin in Uganda. We performed genetic analyses on 409 of the collected tsetse flies and added data collected for 278 individuals in a previous study. The flies were screened across 15 microsatellite loci and the resulting data were used to assess the temporal stability of populations, to analyze patterns of genetic exchange and structuring, to estimate dispersal rates and evaluate the sex bias in dispersal, as well as to estimate demographic parameters (N E and N C ). Results: We found that tsetse populations in this region were stable over 4-16 generations and belong to 4 genetic clusters. Two genetic clusters (1 and 2) corresponded approximately to PATTEC blocks 1 and 2, while the other two (3 and 4) fell within PATTEC block 3. Island populations grouped into the same genetic clusters as neighboring mainland sites, suggesting presence of gene flow between these sites. There was no evidence of the stretch of water separating islands from the mainland forming a significant barrier to dispersal. Dispersal rates ranged from 2.5 km per generation in cluster 1 to 14 km per generation in clusters 3 and 4. We found evidence of male-biased dispersal. Few breeders are successfully dispersing over large distances. Effective population size estimates were low (33-310 individuals), while census size estimates ranged from 1200 (cluster 1) to 4100 (clusters 3 and 4). We present here a novel technique that adapts an existing census size estimation method to sampling without replacement, the scheme used in sampling tsetse flies.

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Mitochondrial DNA sequence divergence and diversity of Glossina fuscipes fuscipes in the Lake Victoria basin of Uganda: implications for control

by Agapitus Kato, Loyce Okedi, and Chaz Hyseni

Background: Glossina fuscipes fuscipes is the main vector of African Trypanosomiasis affecting bo... more Background: Glossina fuscipes fuscipes is the main vector of African Trypanosomiasis affecting both humans and
livestock in Uganda. The human disease (sleeping sickness) manifests itself in two forms: acute and chronic. The
Lake Victoria basin in Uganda has the acute form and a history of tsetse re-emergence despite concerted efforts to
control tsetse. The government of Uganda has targeted the basin for tsetse eradication. To provide empirical data
for this initiative, we screened tsetse flies from the basin for genetic variation at the mitochondrial DNA cytochrome
oxidase II (mtDNA COII) gene with the goal of investigating genetic diversity and gene flow among tsetse, tsetse
demographic history; and compare these results with results from a previous study based on microsatellite loci data
in the same area.
Methods: We collected 429 Gff tsetse fly samples from 14 localities in the entire Ugandan portion of the Lake
Victoria coast, covering 40,000 km2. We performed genetic analyses on them and added data collected for 56 Gff
individuals from 4 additional sampling sites in the basin. The 529pb partial mitochondrial DNA cytochrome oxidase
II (mtDNA COII) sequences totaling 485 were analysed for genetic differentiation, structuring and demographic
history. The results were compared with findings from a previous study based on microsatellite loci data from the
basin.
Results: The differences within sampling sites explained a significant proportion of the genetic variation. We found
three very closely related mtDNA population clusters, which co-occurred in multiple sites. Although ΦST (0 – 0.592;
P < 0.05) and Bayesian analyses suggest some level of weak genetic differentiation, there is no correlation between
genetic divergence and geographic distance (r = 0.109, P = 0.185), and demographic tests provide evidence of
locality-based demographic history.
Conclusion: The mtDNA data analysed here complement inferences made in a previous study based on
microsatellite data. Given the differences in mutation rates, mtDNA afforded a look further back in time than
microsatellites and revealed that Gff populations were more connected in the past. Microsatellite data revealed
more genetic structuring than mtDNA. The differences in connectedness and structuring over time could be related
to vector control efforts. Tsetse re-emergence after control interventions may be due to re-invasions from outside
the treated areas, which emphasizes the need for an integrated area-wide tsetse eradication strategy for sustainable
removal of the tsetse and trypanosomiasis problem from this area.

format_quotePATTEC initiatives against Gff began in 2008 to eliminate the acute form of HAT in Uganda's Lake Victoria basin, amidst continuing tsetse re-emergence.format_quote

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The population structure of Glossina fuscipes fuscipes in the Lake Victoria basin in Uganda: implications for vector control

by Agapitus Kato, Johnson Ouma, and Loyce Okedi

Parasites & …, Jan 1, 2012

Glossina fuscipes fuscipes is the primary vector of trypanosomiasis in humans and livestock in Ug... more Glossina fuscipes fuscipes is the primary vector of trypanosomiasis in humans and livestock in Uganda. The Lake Victoria basin has been targeted for tsetse eradication using a rolling carpet initiative, from west to east, with four operational blocks (3 in Uganda and 1 in Kenya), under a Pan-African Tsetse and Trypanosomiasis Eradication Campaign (PATTEC). We genetically screened tsetse flies from the three Ugandan PATTEC blocks for genetic diversity at 15 microsatellite loci from continental and offshore populations to provide empirical data to support this initiative.

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