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Understanding the structure and drivers of parasite communities including species assembly patterns, diversity, abundance, and aggregation is crucial in assessing the health of wild populations and the dynamics of host-parasite interactions within ecosystems. This study analyzed tick communities parasitizing the critically endangered black rhinoceros and the near threatened white rhinoceros metapopulation in twelve sanctuaries in Kenya. A total of 14,302 ticks from 20 tick species across four genera, Dermacentor (1 species), Rhipicephalus (8 species), Amblyomma (8 species) and Hyalomma (3 species) were sampled from 372 rhinoceroses. The most dominant species included Amblyomma gemma (23.28 %), Amblyomma sparsum (22.28 %) and Rhipicephalus pulchellus (18.94 %). Six tick communities were identified based on similarity in relative tick species composition. Mean NDVI and temperature were the major drivers of tick communities. Asymptotic Hill-Shannon and Hill-Simpson tick diversity metrics were 8.12 and 6.26 respectively for the Kenyan rhinoceros metapopulation. Species diversity varied between sanctuaries with Nairobi National Park (NNP) having the highest diversity (Hill-Shannon: 6.35, Hill-Simpson: 5.8) and Sera Rhinoceros Sanctuary (SER) the lowest diversity, (1.83, 1.69). The Intensive Protection Zone (IPZ) and Nairobi National Park had the greatest species richness (14 and 13 respectively), while Sera Rhinoceros Sanctuary had the lowest (2). Spatial heterogeneity in NDVI and species abundance were major drivers of species richness and Hill-Shannon species diversity. The number of ticks per rhinoceros was highly variable with a mean (SD) of 38.53 + 40.59 ticks per host, indicating strong tick aggregation among hosts. Significant positive interspecies correlations suggest a great role of host factors in tick infestation. Environmental factors, including temperature, NDVI, and rainfall, influenced tick abundance. Host-related factors, such as age, and sex, also played critical roles. This research improves our understanding of rhinoceros tick communities, diversity, and abundance patterns, with implications for tick control, tick-borne disease surveillance and rhino conservation in Kenya.

Nairobi National Park (NNP) is among Kenya’s most vulnerable ecosystems, experiencing significant pressure from urbanization. Rodents, which are sensitive to environmental changes, are considered bioindicators of ecosystem health, and their population dynamics can be used to assess ecosystem pressures such as urbanization. This study assessed the rodent community structure in NNP to understand the effects of various urban pressures by examining the relationships between rodent diversity, richness, and abundance with vegetation types and metrics, seasonality, and habitat disturbances. The capture-mark-release method was used to trap rodents from 15 sites in Nairobi National Park’s savannah, forest, and riverine vegetation types during the dry and wet seasons. The diversity, species richness and abundance were determined from the trappings. From 56 rodents trapped, five species were identified namely: Lemniscomys striatus, Hylomyscus sp, Rattus rattus, Mus mus and Otomys tropicalis. Rodent diversity at NNP was low (Simpson=0.7130; Shannon Weiner=1.40; Brillouin index=1.27) while Pielou’s species evenness, was moderate=0.44 indicating near equity in species distribution. Univariate Generalised linear models showed that rodent abundance was influenced by season, vegetation type, and vegetation metrics. The multivariate model indicated that rodents were more abundant in the wet season compared to the dry season, and that abundance was also positively associated with increased tree and shrub densities. Rodent species richness was positively associated with higher tree density, while vegetation types influenced rodent species diversity. Rodent abundance was influenced by vegetation type, vegetation metrics (density and cover), and season. Human disturbance had no effect in both models. It was observed that the diverse anthropogenic activities occurring in NNP, do not significantly influence rodent abundance compared to the measured biotic and abiotic factors. This first rodent survey in this Park provides preliminary data for continued monitoring of this ecosystem.

Objectives: Dengue virus (DENV) is a global public health concern owing to its widespread distribution, significant morbidity, and potentially severe outcomes. Although not yet reported in Rwanda, this study aimed to explore the DENV seroprevalence in selected health facilities. Methods: Serum samples from 2286 patients who visited 11 health facilities nationwide were investigated for DENV and Zika virus immunoglobulin G. Bivariate and multivariate logistic regression analyses were performed to determine the predictors. Results: The DENV seroprevalence was 30.4 %, but Zika virus immunoglobulin G was not detected. Participants’ mean age was 40.5 ± 16.3 years; 62.2 % were females and 37.8 % were males. In total, 85.8 % were farmers, 4.7 % were office workers, and 3 % were vocational professionals. Farmers had a higher risk of past DENV infections than other professionals. No significant differences in past infections were observed between sexes or age groups. Conclusions: These findings indicate past DENV infections in Rwanda, highlighting the need for DENV surveillance and enhanced diagnostic capacity. Strengthening these efforts will help prevent infectious diseases, reduce unnecessary treatments, and mitigate the risk of antimicrobial resistance.

Sindbis virus (SINV) is a zoonotic arbovirus transmitted by mosquitoes and maintained by wild birds with an expanding distribution globally. Despite its importance, surveillance efforts are low or lacking in many areas, especially in Africa. Our study aimed to highlight the epidemiology of SINV in wild birds in a West African country – Nigeria – with implications for human health. Blood samples were collected from wild resident Afrotropical and migrant Palearctic birds over two years. RT-qPCR was used to detect SINV RNA positive samples, followed by confirmatory conventional PCR and Sanger sequencing targeting the non-structural protein gene. Three out of 504 samples (0.6%; 95% CI: 0.12–1.73%) were positive for SINV, all from individuals of a single species, the African Thrush (Turdus pelios). We successfully generated the whole genome sequence of one sample. Phylogenetic analysis revealed it was closely related to strains from Algeria, Spain and Kenya in the SINV-I genotype. The study suggests that SINV is enzootic in the region and that the African Thrush may be a putative reservoir species.

Fences are increasingly used globally as a management tool in conservation to reduce wildlife depredations, disease transmission, and wildlife mortality. There are a limited number of studies on the genetic effects of perimeter fencing of protected areas on megaherbivores. Using population genetic analyses on 226 sequences of a 400 bp fragment of the mtDNA Dloop from 10 East African buffalo populations (3 fenced and 7 unfenced), the influence of spatial isolation and fencing on buffalo population genetic diversity and genetic differentiation was examined. Mean gene diversity between fenced and unfenced buffalo populations was not different (fenced: 0.978 +/- 0.003, unfenced: 0.973 +/- 0.004, p = 0.300), but nucleotide diversity was higher in fenced than unfenced populations (fenced: 0.038 +/- 0.019, unfenced: 0.030 +/- 0.015, p = 0.005). Genetic differentiation among buffalo populations based on haplotype frequencies and model-based genetic distance was weak (FST = 0.08, Phi ST = 0.06) and contributed to 6.2% and 8.5% of total genetic variance, respectively. Ninety-three percent of population pairs were genetically differentiated by distances determined from haplotype frequencies, but only 51% of population pairs were differentiated using modeled distances, suggesting recent differentiation. There was no correlation between linearized FST and geographical distance (r = -0.005, p = 0.52), but linearized Phi ST was moderately correlated with geographic distance (r = 0.329, p = 0.03). The distance effect was greater when fenced populations were excluded (Phi ST: r = 0.464, p = 0.05), suggesting that insularization due to fencing is distorting isolation by distance. SSD analyses revealed that 2 of 3 fenced populations and 2 of 7 unfenced populations had non-unimodal distributions, suggesting demographically declining populations. Our study reveals the high genetic diversity but warns that genetic erosion due to isolation, including fencing, is likely setting in and will have an impact on East African buffalo populations.

Mosquitoes are known to vector arthropod-borne viruses (arboviruses) that pose a global public health issue in the form of mosquito-borne viral diseases such as chikungunya fever, dengue fever, Japanese encephalitis, yellow fever, and Zika. Besides, mosquitoes may also carry insect-specific viruses (ISVs), which are evolutionarily alike arboviruses yet do not infect vertebrates. These ISVs have been shown to affect the ability of mosquitoes to transmit arboviruses, as well as potentially inhibit arbovirus infections in vertebrate hosts. Yet, ISVs still constitute a relatively new and little-researched area where further studies may yield new knowledge regarding their distribution, their future importance in the control of mosquito-borne viral disease and potential role in biological control of mosquitoes. This review provides insights into ISV classification, transmission, and biology, as well as historical and future aspects. It mainly focuses on the characterization of the transmission dynamics of ISVs to highlight the various potential arboviral pathogen transmission blocking mechanisms along with evolution and host tropism. The review also provides additional information on the potential use of ISVs as a method of biological control in comparison to other proposed methods as well as delving into current research into arbovirus-based vaccines and antiviral drug development.

Arthropod-borne (arbo) viruses cause emerging diseases that affect the livelihoods of people around the world. They are linked to disease outbreaks resulting in high morbidity, mortality, and economic loss. In sub-Saharan Africa, numerous arbovirus outbreaks have been documented, but the circulation and magnitude of illness caused by these viruses during inter-epidemic periods remains unknown in many regions. In Rwanda, there is limited knowledge on the presence and distribution of arboviruses. This study aimed at determining the occurrence and distribution of selected arboviruses, i.e., chikungunya virus (CHIKV), o’nyong-nyong virus (ONNV), dengue virus (DENV), West Nile virus (WNV), Zika virus (ZIKV), Rift Valley fever virus (RVFV) and Crimean-Congo haemorrhagic fever virus (CCHFV), among febrile patients visiting health centres in Rwanda. A total of 2294 dry blood spots (DBS) were collected on filter papers during August 2019 – December 2020. Reverse-transcription polymerase chain reaction (RT-PCR) was performed on samples in pools of ten, using both quantitative (DENV, ZIKV, RVFV) and conventional PCR (CHIKV, ONNV, WNV, CCHFV) with virus specific primers, followed by sequencing. Demographic data and clinical manifestations of illness were analysed. ONNV infection was detected in 12 of 230 pools (5.2%) and ZIKV in three pools (1.3%). The other arboviruses were not detected. All ONNV cases were found in the Rwaniro health centre, while ZIKV infection was found among patients visiting the Kirinda and Zaza health centres. There was temporal variability in ONNV infections with most cases being recorded during the long dry season, while ZIKV infection occurred during both dry and wet seasons. Patients with ONNV were older and more were females. In conclusion, ONNV and ZIKV infection were detected in acute patients and can explain some of the feverish diseases in Rwanda.

African Swine Fever (ASF) is caused by a DNA virus (AFSV) maintained and transmitted by the Argasid ticks. The re-emergence of the disease in Africa coupled with its rapid spread globally is a threat to the pig industry, food security and livelihoods. The ecology and epidemiology of the ASFV sylvatic cycle, especially in the face of changing land use and land cover, further compounds the menace and impacts of this disease in Kenya. The study aimed to determine the occurrence and distribution of ASFV seroprevalence in warthog populations, the tick vectors and extent of tick infestation of warthog burrows, and the genotypes of ASFV in soft ticks in Kenya. Warthogs from different parts of Kenya were captured and venous blood was centrifuged to harvest sera. Warthog burrows were examined for their conditions and to extract ticks. Sera were analyzed for antibodies against ASFV using a commercial ELISA kit coated with p32 ASFV recombinant protein. Ticks were pooled, DNA extracted and the p72 gene of the ASFV was amplified by qPCR and conventional PCR. The overall seroprevalence of ASFV in warthogs was 87.5 %. A total of 228 warthog burrows were examined and 2154 argasid ticks were extracted from the burrows. Tick pools from Kigio Farm and Lewa Wildlife Conservancies were ASFV-positive by qPCR and conventional PCR. ASFV was further confirmed by the Twist Comprehensive Viral Research Panel (TCVRP), which also identified the argasid ticks as Ornithodoros porcinus. The ticks were infected with virus genotype IX, and their occurrence overlaps with regions of previous ASF outbreaks in domestic pigs. Further, Viruses that could be tick endosymbionts/commensals or due to bloodmeal were detected in ticks by TCVRP; Porcine type-C oncovirus; Pandoravirus neocaledonia; Choristoneura fumiferana granulovirus; Enterobacteria phage p7; Leporid herpesvirus 4 isolate; 5; Human Lymphotropic virus; Human herpesvirus 5. In conclusion, our results suggest that infected Ornithodoros spp. seems to have a rich virome, which has not been explored but could be exploited to inform ASF control in Kenya. Further, the ecology of Ornithodoros spp. and burrow-use dynamics are complex and more studies are needed to understand these dynamics, specifically in the spread of ASFV at the interface of wild and domestic pigs. Further, our results provide evidence of genotype IX ASFV sylvatic cycle which through O. porcinus tick transmission has resulted in high exposure of adult common warthogs. Finally, the co-circulation of ASFV genotype IX in the same location with past ASF outbreaks in domestic pigs and presently in ticks brings to focus the role of the interface and ticks on virus transmission to pigs and warthogs.

The mosquito Culex pipiens occurs in two ecotypes differing in their mating and overwintering behavior: pipiens mate in open environments and diapause, and molestus also mate in small spaces and is active throughout the year. Cx. pipiens carry Wolbachia endosymbionts of the wPip strain, but the frequency of infection differs between studied populations. Wolbachia infection affects the host reproductive success through cytoplasmic incompatibility. wPip Wolbachia is divided into five types, wPip I–V. The type of wPip carried varies among Cx. pipiens populations. In northern European locations different wPip types are found in the two ecotypes, whereas in southern locations, they often carry the same type, indicating differences in hybridization between ecotypes. In this study, Cx. pipiens specimens of both ecotypes were collected from Sweden and compared to specimens from Norway, England, Italy, and the Netherlands, as well as Cx. quinquefasciatus from Mali and Thailand. The abundance varied, but all specimens were infected by Wolbachia, while the tested specimens of other mosquito species were often uninfected. The wPip strains were determined through the sequence analysis of Wolbachia genes ank2 and pk1, showing that Cx. pipiens ecotypes in Scandinavia carry different wPip strains. The observed differences in wPip strains indicate that hybridization is not frequent and may contribute to barriers against hybridization of the ecotypes in Sweden and Norway.

Objectives: The recent detection and expansion of West Nile virus (WNV) and Usutu virus (USUV) in the Netherlands, Germany, and Austria point to the likelihood of the viruses spreading to Northern Europe. Migratory birds and ornithophilic mosquitoes may spread these viruses to new areas. We sampled birds during the spring and autumn bird migration of 2021 in Southern Sweden to investigate the risk of the introduction of mosquito-borne zoonotic avian viruses like WNV and USUV.

Methods: We collected blood samples from 1775 birds comprising 59 species and determined the seroprevalence of WNV using a competitive enzyme-linked immunosorbent assay (ELISA). WNV and USUV belong to the Japanese encephalitis serocomplex, and antibodies against both viruses are detected in the WNV ELISA. Focus-forming assays or fluorescence-based neutralization assays were performed to verify ELISA results and to differentiate between antibodies against WNV and USUV.

Results: We found nine (0.51%) samples to be WNV-antibody-positive. Cross-neutralization experiments with WNV and USUV confirmed that seven (0.41%) had WNV-neutralizing antibodies and two (0.11%) had USUV-neutralizing antibodies. Interestingly, the two samples had neutralizing antibodies of both viruses. All samples but one with anti-flavivirus antibodies came from long-distance migrants wintering in sub-Saharan Africa. Antibodies were detected in samples taken during spring and autumn and only in adult birds.

Conclusion: The findings show that migratory birds in Sweden have been exposed to WNV and USUV.