Makwatta, J. O. | bioRxiv Science

bioRxiv2024

Stomoxys flies (Diptera, Muscidae) are competent vectors of multiple livestock hemopathogens

Stomoxys flies are widely distributed and economically significant vectors of various livestock pathogens of veterinary importance. However, the role of Stomoxys spp. in pathogen transmission is poorly understood. Therefore, we studied the feeding patterns of these blood feeders collected from specific locations in Kenya, to identify various vertebrate hosts they fed on, and the livestock hemopathogens they carried, to elucidate their role in pathogens transmission. Our findings show that field-collected Stomoxys flies carried several pathogens including Trypanosoma spp., Anaplasma spp., and Theileria spp. that were also found in the blood of sampled livestock, namely camels and cattle. The findings on blood meal analysis show that Stomoxys flies fed on a variety of domestic and wild vertebrate hosts. We further determined whether Stomoxys spp. are vectors of hemopathogens they harbored by studying the vector competence of S. calcitrans, S. niger niger, and S. boueti species complex, through laboratory and natural experimental in vivo studies. We show that in the process of blood feeding Stomoxys spp. complexes can transmit T. evansi (8.3%) and T. vivax (30%) to Swiss white mice. In addition, field-collected Stomoxy spp. were exposed to healthy mice for blood meal acquisition, and in the process of feeding, they transmitted Theileria mutans and Anaplasma spp. to Swiss white mice (100% infection in the test mice group). All mice infected with both trypanosomes via stomoxys bite died while those infected with Theileria and Anaplasma species did not, demonstrating virulence difference between pathogens. The key finding of this study showing broad feeding host range, cosmopolitan, plethora of pathogens harboured, and efficient vector competence in spreading multiple pathogens suggests profound role of Stomoxys on pathogen transmission and infection prevalence in livestock. Author summaryStomoxys flies are highly adaptable to several ecological settings, including metropolitan areas. In contrast, tsetse flies (genus Glossina), the main biological vectors of African trypanosomes, have a limited distribution to parks and other conservation areas. Stomoxys flies could play a significant role in the spread of animal African trypanosomes, among other hemopathogens, particularly in areas with or without tsetse infestation. Although there have been speculations about the potential role of Stomoxys flies in the transmission of various pathogens, there is lack of data to link hemopathogens occurring in both bloodmeal hosts of Stomoxys and in the flies, and further in vivo experimental studies to confirm the vector competence of Stomoxyine flies. Here, we explored a host and pathogens network, and investigated species diversity at various ecologies, and demonstrated that Stomoxys flies feed on diverse vertebrate hosts and are infected with a plethora of pathogens. We also showed experimentally that they could transmit some of these hemopathogens to mice, for instance, T. vivax, T. evansi, Theileria mutans, and Anaplasma spp. with varying infection success rates. Stomoxys flies could play a significant role in transmitting and spreading various hemopathogens of veterinary importance and possibly maintaining their circulation in livestock, which could explain the occurrence of animal African trypanosomes in the regions outside the tsetse belts.

pathology↗

bioRxiv2024

Exploring the dynamic ticks-camel-pathogens interaction

The ability of ticks to interact and adapt to different ecologies and hosts determines their vectorial competence for various pathogens, however ticks-livestock-pathogens interaction studies are limited. With our ticks-hosts-pathogens interface studies, we found 14 species of ticks feeding on various livestock. Ticks showed a strong preference for one-humped camels (Camelus dromedarius). The camel nostril was the most preferred predilection site. The most prevalent tick species on camels was Hyalomma rufipes. We found two novel Amblyomma gemma variants which are distinct both morphologically and genetically from previously described Amblyomma gemma. The signature odors from camel breath and body were attractive to H. rufipes; demonstrating ticks utilize camel-derived metabolites to find their host. Our research shows that H. rufipes and camel hosts have unique and shared pathogens showing H. rufipes vector and camels reservoir host qualities. Our study unravels the dynamic interactions between ticks, pathogens, and camels that all influence the likelihood of pathogen adaptation and transmission dynamics. IMPORTANCETicks are obligatory hematophagous arachnids, serving as vectors for a wide array of pathogens that can be transmitted to animals and humans. The ability of ticks to acquire and transmit various pathogens depends on its attraction to quality reservoir host and the survival of the pathogens in ticks gut and other tissues. However, the complex dynamics of tick-pathogens interaction and host-seeking behavior remains understudied. This investigation revealed notable variation in tick preference for domestic animals, camel being the most preferred host. Moreover, our spatial analysis about tick attachment sites showed nostril is the most preferred sites by various tick species. Our epidemiology data showed variation in the pathogens harbored by camel (host) and vector (H. rufipes), demonstrating the camels efficiency as reservoir host and ticks vector competence for various pathogens. With our behavioral experiment using H. rufipes and its preferred hosts (camel) breath and body signature odors, we identified novel attractants for H. rufipes, thus offering new avenues for combating TBDs. Overall, our study presents novel insights into how multiple factors shape tick-host-pathogens interaction.

ecology↗