Biology subjects

Boulange, A.

Publications and source records attributed to Boulange, A..

3 recordsLinked to original sources

bioRxiv2026

Spatial distribution and habitat suitability of tsetse (Glossina spp.) in Cote dIvoire: An ensemble modeling approach to support targeted disease control

Background Tsetse are vectors of trypanosomes responsible for African animal trypanosomosis (AAT) and human African trypanosomiasis (HAT). While Cote dIvoire has successfully eliminated HAT as a public health problem and approaches elimination of transmission, AAT remains a major obstacle to agriculture and livestock production. Understanding the spatial distribution of tsetse is essential for prioritizing and sustaining disease control and elimination efforts. Methodology/Principal Findings Using 1,702 occurrence records from the national tsetse atlas we modeled the habitat suitability of the nine tsetse species present in Cote dIvoire. We identified suitable habitats in unsampled areas and quantified environmental constraints on tsetse distribution. Resampling the data to a 1km x 1km grid produced spatially explicit outputs at a resolution more relevant for operational planning. An ensemble modeling approach was employed integrating four algorithms--Random Forest, XGBoost, Maximum Entropy (MaxEnt), and Generalized Additive Models (GAM)-- with satellite-derived environmental and anthropogenic predictors--which achieved high predictive accuracy, area under the curve and True Skill Statistics 0.80 and 0.83, respectively. Distance to waterbodies, soil moisture, distance to protected areas, maximum land surface temperature, and sheep density were key drivers of habitat suitability. Importantly, the models identified suitable habitats in 11 administrative regions not covered by the atlas, providing an improved national tsetse risk profile. Conclusions/Significance These results provide a detailed assessment of the ecological suitability of tsetse across Cote dIvoire and their persistence in agroecological mosaics with high human and livestock densities. We offer a high-resolution blueprint for vector and disease control, particularly in areas where field data are currently lacking. We provide a robust framework for evidence-based decision-making within the Progressive Control Pathway (PCP) for AAT by enabling the identification of priority areas and resource allocation optimization to improve livestock productivity through more effective AAT control and reduce the risk of resurgence of HAT.

ecology↗

bioRxiv2025

Evaluation of the vectorial competence of Glossina brevipalpis in the transmission of Trypanosoma congolense-savannah type, in the Matutuine District, Maputo Province, Mozambique

African Animal Trypanosomosis (AAT) is a parasitic disease caused by trypanosome species, posing a major challenge to animal health and production in Africa. In the Matutuine District, southern Mozambique, where Glossina brevipalpis is prevalent, AAT is endemic. Previous research conducted in South Africa suggested that G. brevipalpis plays a marginal role in the transmission of Trypanosoma congolense. However, considering the wide distribution of G. brevipalpis in Southeast Africa and the major epidemiological implications of the aforementioned observations, this study was designed to re-assess the vectorial competence of G. brevipalpis in the transmission of T. congolense-savannah type. The research involved 915 G. brevipalpis flies, fed six times on two cattle infected with T. congolense. After 48 hours, the flies were later fed on a non-infected animal to clean the proboscis, followed by extended feeding on four susceptible cattle for 22 days. These five clean animals were monitored for 60 days based on body temperature, packed cell volume, buffy coat technique and polymerase chain reaction. In the meantime, flies were dissected weekly to observe the development of trypanosomes in the midgut and proboscis. To discard any possible mechanical transmission by G. brevipalpis 48 hours after an infected blood meal, 97 flies from a colony were fed once on two infected cattle and once on a susceptible bovine. The Spearman correlation and Mann-Whitney U tests were used to analyse the data. Results showed that the four susceptible cattle became infected with T. congolense, while the animal used for proboscis cleaning and discard any mechanical transmission remained uninfected. Dissections revealed that 89% of flies were positive for trypanosome through microscopy and 100% through PCR. These findings confirm that G. brevipalpis is a competent biological vector for transmitting T. congolense, challenging earlier assumptions and emphasizing its role in AAT dynamics.

ecology↗

bioRxiv2021

Molecular epidemiology of Animal African Trypanosomosis in southwest Burkina Faso

BackgroundAnimal African Trypanosomosis (AAT) is a parasitic disease of livestock that has a major socio-economic impact in the affected areas. It is caused by several species of uniflagellate extracellular protists of the genus Trypanosoma mainly transmitted by tsetse flies: T. congolense, T. vivax and T. brucei brucei. In Burkina Faso, AAT hampers the proper economic development of the southwestern part of the country, which is yet the best watered area particularly conducive to agriculture and animal production. It was therefore important to investigate the extend of the infection in order to better control the disease. The objective of the present study was to assess the prevalence of trypanosome infections and collect data on the presence of tsetse flies. MethodsBuffy coat, Trypanosoma species-specific PCR, Indirect ELISA Trypanosoma sp and trypanolysis techniques were used on 1898 samples collected. An entomological survey was also carried out. ResultsThe parasitological prevalence of AAT was 1.1%, and all observed parasites were T. vivax. In contrast, the molecular prevalence was 23%, of which T. vivax was predominant (89%) followed by T. congolense (12%) and T. brucei s.l. (7.3%) with a sizable proportion as mixed infections (9.1%). T. brucei gambiense, responsible of sleeping sickness in humans, was not detected. The serological prevalence reached 49%. Once again T. vivax predominated (86.2%), but followed by T. brucei (9.6%) and T. congolense (4.2%), while 34.6% of positive samples tested positive for at least two trypanosome species. Seven samples, from six cattle and one pig, were found positive by trypanolysis. The density per trap of Glossina tachinoides and G. palpalis gambiensis was about three flies. Conclusions/SignificanceOverall, our study showed a high prevalence of trypanosome infection in the area, pointing out an ongoing inadequacy of control measures. Authors summaryIn Burkina Faso, like in most countries of sub-Saharan Africa, Animal African Trypanosomosis (AAT) is hampering economic development. It was therefore important to investigate the extent of trypanosome infections after years of control. This study examined circulating trypanosomes in domestic animals using parasitological, molecular and serological tools in southwest Burkina Faso. The prevalence levels observed show that the known epidemiological situation in the region has not really changed. The trypanosome species usually found in the area such as T. congolense, T. vivax and T. brucei s.l. have remained the same, with a stronger presence of T. vivax. The low occurrence of tsetse fly and the predominance of T. vivax attests to the role of the mechanical vectors in maintaining the disease. Although no cases of T. brucei gambiense infection was encountered in the animals examined, trypanolysis tests suggest that there are contact cases in this historical focus of sleeping sickness. Efforts are therefore necessary to reduce or even eliminate the trypanosome burden, and the data provided by this study can assist the decision making.

microbiology↗