Molecular identification of bloodmeal sources and trypanosomes in Glossina spp., Tabanus spp. and Stomoxys spp. trapped on cattle farm settlements in southwest Nigeria

Abstract

The interactions of host, vector and parasite in bovine trypanosomiasis transmission cycles in southwest Nigeria are not yet well understood. Trypanosoma (Trypanosomatida: Trypanosomatidae) species infection prevalences and bloodmeal sources were determined in transmitting vectors of the genera Glossina (Diptera: Glossinidae), Tabanus (Diptera: Tabanidae) and Stomoxys (Diptera: Muscidae) collected using Nzi traps in cattle settlements in southwest Nigeria. Sequenced cytochrome B mitochondrial DNA segments obtained from vector digestive tracts identified bloodmeal sources from eight host species, namely human, cattle, hippopotamus, giraffe, gazelle, spotted hyena, long-tailed rat and one unidentified species. Overall, 71.1% [95% confidence interval (CI) 63.0-78.1], 33.3% (95% CI 21.9-47.0) and 22.2% (95% CI 16.2-29.9), respectively, of Glossina, Tabanus and Stomoxys flies were positive for trypanosomes. The observed trypanosome species were Trypanosoma vivax, Trypanosoma congolense, Trypanosoma brucei, Trypanosoma evansi, Trypanosoma simiae and Trypanosoma godfreyi. Trypanosome DNA was more prevalent in tsetse (34.8% Tr. vivax, 51.1% Tr. b. brucei, 5.2% Tr. congolense, 4.4% Tr. simiae and 24.4%mixed infections) than in other flies and the main determinants in all flies were seasonal factors and host availability. To the best of the present group's knowledge, this is the first report of Trypanosoma species in Tabanus and Stomoxys flies in Nigeria. It indicates that vector control programmes should always consider biting flies along with tsetse flies in the control of human and animal trypanosomiasis.

Genetic diversity of trypanosome species in tsetse flies (Glossina spp.) in Nigeria

“…Interestingly, T. b. brucei was highly prevalent in tsetse (approximately 50%) collected in close proximity to cattle farms in Oyo State, while T. vivax and T. congolense were detected less frequently [14]. During our surveys, we detected no DNA originating from T. brucei ( s.l.…”

“…Prevalence of T. b. brucei was generally low compared to T. vivax and T. congolense . The only exception is provided by a study in southern Nigeria where it was highly prevalent in tsetse (> 50%) [14], while in northern Nigeria this parasite was not detected at all [13]. To our knowledge, an overview of parasites present in different tsetse populations from different regions in Nigeria collected within the same time and analysed with the same molecular methods has not yet been undertaken.…”

Mathematical modelling and control of African animal trypanosomosis with interacting populations in West Africa—Could biting flies be important in main taining the disease endemicity?

“…Progression rate of exposed cattle α k 0.516 [3] Proportion of effective treatment ρ 0.12 [19] Recovery rate r k 0.1 [19] Death rate of tsetse fly σ t 0.212 [19] Progression rate of exposed tsetse fly γ t 0.028 [31] Stomoxys [3]…”

“…Transmission of infection to Stomoxys α 2 0.031 [31] Transmission of infection to cattle φ k1 0.29 [3] Transmission of infection from Tabanus to cattle φ k2 0.33 [31] Small ruminants disease induced death rate ϕ 0. [22], which is considered in the model.…”

Zoonotic parasites of dromedary camels: so important, so ignored

“…Traditionally tabanids, muscids and hippoboscids are considered to be mechanical vectors of T. evansi , and several species of the genera Ancala , Atylotus , Chrysops , Haematobia , Haematopota , Hippobosca , Pangonia , Philoliche , Stomoxys and Tabanus have been collected directly from camels or their surroundings [9, 72–74]. Stomoxys calcitrans , Stomoxys niger , Tabanus taeniola , Tabanus par and Tabanus subangustus collected on cattle have been identified to be infected with T. evansi [75]. However, there is no molecular confirmation on the role of definite fly species as vectors of T. evansi in camels.…”