Putative bloodmeal sources in Glossina austeni tsetse fly of Arabuko Sokoke National Reserve in Kenya.

Tsetse flies, the sole biological vectors of trypanosomiasis, are predominantly controlled using visual traps and targets baited with attractant lures. Formulation of the lures is informed by compositions of odors from vertebrate hosts preferred by specific tsetse species. However, there are no effective lures for Glossina austeni, a major vector of trypanosomiasis along eastern-coastal region of Africa. Formulation of the lure can be informed by knowledge of G. austeni, preferred vertebrate hosts. We thus sought to understand these hosts by assessment of putative bloodmeal sources of this tsetse fly in Arabuko Sokoke National Reserve where this species is naturally present. We sampled tsetse flies using NGU traps, isolated non-teneral G. austeni flies based on their feeding status, and identified vertebrate source of bloodmeals in their midgut contents using vertebrate 16S rRNA-PCR High-Resolution Melting analysis. We analyzed the relative vertebrate species frequencies in the bloodmeals using Fisher's exact tests. Overall, we trapped 122 flies, most of which (66.39%) were non-teneral, among which we successfully identified the vertebrate bloodmeals in 30 samples. Specifically, we detected putative suni antelope (Neotragus moschatus), harnessed bushbuck (Tragelaphus scriptus), buffalo (Syncerus caffer) and cattle (Bos taurus) derived bloodmeals. Putative suni antelope bloodmeals were significantly more frequent (63.22%), than those of the harnessed bushbuck (23.33%), buffalo (10.00%) or cattle (3.33%) (p < 0.05 Fisher's exact tests) among the samples analyzed. Suni antelope thus appears to predominate vertebrate bloodmeal source for G. austeni in the reserve, coincident with findings reported elsewhere, and is therefore a viable candidate for bioprospecting for G. austeni responsive attractants.

Effectiveness of a community-centered Newcastle disease vaccine delivery model under paid and free vaccination frameworks in southeastern Kenya.

In the absence of effective drugs, vaccines constitute the cornerstone for the prevention of Newcastle disease (ND). Different strategies have been implemented to increase vaccination, but uptake remains low, underscoring the need for novel vaccine delivery methods. We designed and assessed the effectiveness of a community-centered ND vaccine delivery model in southeastern Kenya. Under the model, we sensitized smallholder chicken farmers (SCFs) through structured training on chicken husbandry, biosecurity, ND, and its vaccination, among other aspects. We subsequently engaged trained community vaccinators (CVs) to deliver vaccines and/or provide vaccination services to SCFs at a cost on one hand and, at no cost on the other, in selected sites to address challenges of inadequate service providers, vaccine unavailability, and inaccessibility. We tested this model under paid and free vaccination frameworks over one year and assessed the model's effect on vaccine uptake, ND-related deaths, and vaccine accessibility, among other aspects. Overall, we vaccinated more chickens at free sites compared to paid sites. However, we vaccinated a significantly higher mean number of chickens per household at paid (49.4±38.5) compared to free (28.4±25.9) sites (t = 8.4, p<0.0001). We recorded a significant increase in the proportion of SCFs who vaccinated their chickens from 31.3% to 68.4% (χ2(1, N = 399) = 58.3, p<0.0001) in paid and from 19.9% to 74.9% (χ2(1, N = 403) = 115.7, p<0.0001) in free sites pre- and post-intervention, respectively. The mean number of ND-related deaths reported per household decreased from 18.1±31.6 pre-intervention to 7.5±22.3 post-intervention (t = 5.4, p = 0.000), with higher reductions recorded in paid sites (20.9±37.7 to 4.5±11.2) compared to free sites (15.0±22.6 to 10.7±29.7) pre- and post-intervention, respectively. Farmers with access to vaccines increased significantly from 61.1% to 85.4% (χ2(1, N = 399) = 31.7, p<0.0001) in paid and 43.6% to 74.9% (χ2(1, N = 403) = 38.4, p = 0.0001) in free sites pre- and post-intervention, respectively. We established that type of intervention framework, gender of household head, if the household head attended training on chicken production in the last 12 months, access to information on ND vaccination, and the number of chickens lost to the previous ND outbreak were significant predictors of ND vaccine uptake. Our findings indicate the model has a broader reach and benefits for SCFs. However, policies should be enacted to regulate the integration of CVs into the formal animal health sector.

Bloodmeal host identities among sympatric Glossina austeni and Glossina pallidipes tsetse flies in Shimba Hills National Reserve, Kwale, Kenya.

Odor from preferred/non-preferred tsetse fly vertebrate hosts have been exploited in R&D of attractants/repellents of the fly for human and livestock protection. Odors from vertebrate hosts of Glossina austeni and Glossina pallidipes tsetse flies can facilitate formulation of novel attractants effective against G. austeni or improvement of existing attractant blends for G. pallidipes. We compared vertebrate blood meal sources of both fly species at Shimba Hills National Reserve, Kenya, to establish putative preferred host of either species, hence potential source of G. austeni or G. pallidipes specific odors. We trapped sympatric adult flies in 2021 and 2022 using NGU traps/sticky panels baited with POCA, collected their blood meals and characterize the meals using HRM vertebrate 16S rRNA- PCR (for host identification), and compared host profiles using GLM and Fisher's exact tests. We collected 168 and 62 sympatric G. pallidipes and G. austeni with bloodmeal, respectively in 2021 and, 230 and 142 respectively in 2022. In 2021, we identified putative hosts of 65.48 and 69.35 % of the G. pallidipes and G. austeni respectively and 82.61 and 80.28%, respectively in 2022. In 2021, we detected harnessed bushbuck, buffalo, common warthog and cattle putative host bloodmeals, and additionally bushpig and suni antelope bloodmeals in 2022. Putative vertebrate bloodmeal sources were significantly different by tsetse fly species (χ2(1, N=457) = 43.215, p < 0.001) and sampling year (χ2(1, N=457) = 8.044, p = 0.005). Frequency of common warthog bloodmeals was higher in G. pallidipes (65.79 %) than G. austeni (38.60%), and that of suni antelope and harnessed bushbuck putative bloodmeals higher in G. austeni (21.05-28.07%) than in G. pallidipes (6.84 - 17.37%) in 2022. There was an apparent change in putative feeding preference/host choices in both fly species between 2021 and 2022. Host bloodmeals in G. pallidipes or G. austeni predominantly from putative harnessed bushbuck, suni antelope or common warthog reveal these vertebrates with potential odors that can be harnessed and formulated into appropriate attractants for respective species and integrated into routine control regiment for G. pallidipes and/or G. austeni.