Molecular detection of selected tick-borne pathogens infecting cattle at the wildlife-livestock interface of Queen Elizabeth National Park in Kasese District, Uganda

An ecological and epidemiological single-season survey of Anaplasma and Ehrlichia positive ticks in Victoria Falls National Park, Zimbabwe

There is an urgent need for continued research on the ecology of tick-borne diseases in Africa. Our objective was to provide a preliminary description of the ecology and epidemiology of tick species, tick-borne pathogens, and animal hosts in Zimbabwe, focusing efforts at Victoria Falls National Park, for a single season. We tested the hypothesis that tick surveillance and pathogen screening data can be used to model associations among ticks, hosts, and pathogens. We collected ticks from domesticated animals and wildlife in Zimbabwe and screened the ticks for the presence of Anaplasma and Ehrlichia bacteria. Nearly 30% of the screened ticks were PCR-positive; 89% of tick species were PCR-positive, and 88% of animal species carried at least one PCR-positive tick. We sequenced a subset of amplicons that were similar to three Anaplasma species and three Ehrlichia species. The odds of a tick being PCR-positive increased when many ticks were collected from the host or the tick was collected from a cow (domesticated animal). Tick species shared host species more often than expected. We demonstrate that ticks in northwestern Zimbabwe present a One Health problem for nearby wildlife and humans.

Anaplasma Species in Africa-A Century of Discovery: A Review on Molecular Epidemiology, Genetic Diversity, and Control

Anaplasma species, belonging to the family Anaplasmataceae in the order Rickettsiales, are obligate intracellular bacteria responsible for various tick-borne diseases of veterinary and human significance worldwide. With advancements in molecular techniques, seven formal species of Anaplasma and numerous unclassified species have been described. In Africa, several Anaplasma species and strains have been identified in different animals and tick species. This review aims to provide an overview of the current understanding of the molecular epidemiology and genetic diversity of classified and unclassified Anaplasma species detected in animals and ticks across Africa. The review also covers control measures that have been taken to prevent anaplasmosis transmission on the continent. This information is critical when developing anaplasmosis management and control programs in Africa.

First molecular identification of multiple tick-borne pathogens in livestock within Kassena-Nankana, Ghana

The risk of pathogen transmission continues to increase significantly in the presence of tick vectors due to the trade of livestock across countries. In Ghana, there is a lack of data on the incidence of tick-borne pathogens that are of zoonotic and veterinary importance. This study, therefore, aimed to determine the prevalence of such pathogens in livestock using molecular approaches. A total of 276 dry blood spots were collected from cattle (100), sheep (95) and goats (81) in the Kassena-Nankana Districts. The samples were analyzed using Polymerase Chain Reaction (qPCR) and conventional assays and Sanger sequencing that targeted pathogens including Rickettsia, Coxiella, Babesia, Theileria, Ehrlichia and Anaplasma. An overall prevalence of 36.96% was recorded from the livestock DBS, with mixed infections seen in 7.97% samples. Furthermore, the prevalence of infections in livestock was recorded to be 19.21% in sheep, 14.13% in cattle, and 3.62% in goats. The pathogens identified were Rickettsia spp. (3.26%), Babesia sp. Lintan (8.70%), Theileria orientalis (2.17%), Theileria parva (0.36%), Anaplasma capra (18.48%), Anaplasma phagocytophilum (1.81%), Anaplasma marginale (3.26%) and Anaplasma ovis (7.25%). This study reports the first molecular identification of the above-mentioned pathogens in livestock in Ghana and highlights the use of dry blood spots in resource-limited settings. In addition, this research provides an update on tick-borne pathogens in Ghana, suggesting risks to livestock production and human health. Further studies will be essential to establish the distribution and epidemiology of these pathogens in Ghana.

Molecular Investigation of Tick-Borne Haemoparasites Isolated from Indigenous Zebu Cattle in the Tanga Region, Tanzania

Tick-borne diseases (TBDs) are a major hindrance to livestock production in pastoral communities of Africa. Although information on tick-borne infections is necessary for setting up control measures, this information is limited in the pastoral communities of Tanzania. Therefore, this study aimed to provide an overview of the tick-borne infections in the indigenous cattle of Tanzania. A total of 250 blood samples were collected from the indigenous zebu cattle in the Tanga region, Tanzania. Then, we conducted a molecular survey using the polymerase chain reaction (PCR) and gene sequencing to detect and identify the selected tick-borne pathogens. The PCR was conducted using assays, based on Theileria spp. (18S rRNA), Theileria parva (p104), Theileria mutans and T. taurotragi (V4 region of the 18S rRNA), Babesia bigemina (RAP-1a), B. bovis (SBP-2), Anaplasma marginale (heat shock protein groEL) and Ehrlichia ruminantium (pCS20). The PCR screening revealed an overall infection rate of (120/250, 48%) for T. mutans, (64/250, 25.6%) for T. parva, (52/250, 20.8%) for T. taurotragi, (33/250, 13.2%) for B. bigemina and (81/250, 32.4%) for A. marginale. Co-infections of up to four pathogens were revealed in 44.8% of the cattle samples. A sequence analysis indicated that T. parva p104 and A. marginale groEL genes were conserved among the sampled animals with sequence identity values of 98.92−100% and 99.88−100%, respectively. Moreover, the B. bigemina RAP-1a gene and the V4 region of the 18S rRNA of T. mutans genes were diverse among the sampled cattle, indicating the sequence identity values of 99.27−100% and 22.45−60.77%, respectively. The phylogenetic analyses revealed that the T. parva (p104) and A. marginale (groEL) gene sequences of this study were clustered in the same clade. In contrast, the B. bigemina (RAP-1a) and the T. mutans V4 region of the 18S rRNA gene sequences appeared in the different clades. This study provides important basement data for understanding the epidemiology of tick-borne diseases and will serve as a scientific basis for planning future control strategies in the study area.

Epidemiology of Ticks and Tick-Borne Pathogens in Domestic Ruminants across Southern African Development Community (SADC) Region from 1980 until 2021: A Systematic Review and Meta-Analysis

Ticks are hematophagous ectoparasites that are capable of infesting a wide range of mammals, including domestic animals, ruminants, wildlife, and humans across the world, and they transmit disease-causing pathogens. Numerous individual epidemiological studies have been conducted on the distribution and prevalence of ticks and tick-borne diseases (TBDs) in the Southern African Developing Community (SADC) region, but no effort has been undertaken to synchronize findings, which would be helpful in the implementation of consolidated tick control measures. With the aim of generating consolidated pooled prevalence estimates of ticks and TBDs in the SADC region, we performed a systematic review and meta-analysis of published articles using the PRISMA 2020 guidelines. A deep search was performed on five electronic databases, namely, PubMed, ScienceDirect, Google Scholar, AJOL, and Springer Link. Of the 347 articles identified, only 61 of the articles were eligible for inclusion. In total, 18,355 tick specimens were collected, belonging to the genera Amblyomma, Haemaphysalis, Hyalomma, and Rhipicephalus (including Boophilus) across several countries, including South Africa (n = 8), Tanzania (n = 3), Zambia (n = 2), Zimbabwe (n = 2), Madagascar (n = 2), Angola (n = 2), Mozambique (n = 1), and Comoros (n = 1). The overall pooled prevalence estimate (PPE) of TBPs in livestock was 52.2%, with the highest PPE in cattle [51.2%], followed by sheep [45.4%], and goats [29.9%]. For bacteria-like and rickettsial TBPs, Anaplasma marginale had the highest PPE of 45.9%, followed by A. centrale [14.7%], A. phagocytophilum [2.52%], and A. bovis [0.88%], whilst Ehrlichia ruminantium had a PPE of 4.2%. For piroplasmids, Babesia bigemina and B. bovis had PPEs of 20.8% and 20.3%, respectively. Theileria velifera had the highest PPE of 43.0%, followed by T. mutans [29.1%], T. parva [25.0%], and other Theileria spp. [14.06%]. Findings from this study suggest the need for a consolidated scientific approach in the investigation of ticks, TBPs, and TBDs in the whole SADC region, as most of the TBDs are transboundary and require a regional control strategy.