Molecular Detection of Tick-Borne Pathogen Diversities in Ticks from Livestock and Reptiles along the Shores and Adjacent Islands of Lake Victoria and Lake Baringo, Kenya

Abstract

Although diverse tick-borne pathogens (TBPs) are endemic to East Africa, with recognized impact on human and livestock health, their diversity and specific interactions with tick and vertebrate host species remain poorly understood in the region. In particular, the role of reptiles in TBP epidemiology remains unknown, despite having been implicated with TBPs of livestock among exported tortoises and lizards. Understanding TBP ecologies, and the potential role of common reptiles, is critical for the development of targeted transmission control strategies for these neglected tropical disease agents. During the wet months (April–May; October–December) of 2012–2013, we surveyed TBP diversity among 4,126 ticks parasitizing livestock and reptiles at homesteads along the shores and islands of Lake Baringo and Lake Victoria in Kenya, regions endemic to diverse neglected tick-borne diseases. After morphological identification of 13 distinct Rhipicephalus, Amblyomma, and Hyalomma tick species, ticks were pooled (≤8 individuals) by species, host, sampling site, and collection date into 585 tick pools. By supplementing previously established molecular assays for TBP detection with high-resolution melting analysis of PCR products before sequencing, we identified high frequencies of potential disease agents of ehrlichiosis (12.48% Ehrlichia ruminantium, 9.06% Ehrlichia canis), anaplasmosis (6.32% Anaplasma ovis, 14.36% Anaplasma platys, and 3.08% Anaplasma bovis,), and rickettsiosis (6.15% Rickettsia africae, 2.22% Rickettsia aeschlimannii, 4.27% Rickettsia rhipicephali, and 4.95% Rickettsia spp.), as well as Paracoccus sp. and apicomplexan hemoparasites (0.51% Theileria sp., 2.56% Hepatozoon fitzsimonsi, and 1.37% Babesia caballi) among tick pools. Notably, we identified E. ruminantium in both Amblyomma and Rhipicephalus pools of ticks sampled from livestock in both study areas as well as in Amblyomma falsomarmoreum (66.7%) and Amblyomma nuttalli (100%) sampled from tortoises and Amblyomma sparsum (63.6%) sampled in both cattle and tortoises at Lake Baringo. Similarly, we identified E. canis in rhipicephaline ticks sampled from livestock and dogs in both regions and Amblyomma latum (75%) sampled from monitor lizards at Lake Victoria. These novel tick–host–pathogen interactions have implications on the risk of disease transmission to humans and domestic animals and highlight the complexity of TBP ecologies, which may include reptiles as reservoir species, in sub-Saharan Africa.

Molecular prevalence of emerging Anaplasma and Ehrlichia pathogens in apparently healthy dairy cattle in peri-urban Nairobi, Kenya

“…Anaplasma bovis which is a monocytic pathogen of ruminants was also detected in this study. Different tick species in the genera Amblyomma and Rhipicephalus have been documented to transmit this pathogen [6]. Similar studies have detected this pathogen in Kenya [7], China [37], South Korea [3] Tunisia [38] and Algeria [39].…”

“…Anaplasma centrale whose only known vector is Rhipicephalus simus [4] causes mild anaplasmosis in cattle [5] but has not been reported in Kenya possibly because the tick vector is absent. Anaplasma bovis transmitted by various species of Amblyomma and Rhipicephalus ticks [6] causes sub-clinical disease in cattle and has been recently been reported in indigenous calves in Kenya [7].…”

Pathogens, endosymbionts, and blood-meal sources of host-seeking ticks in the fast-changing Maasai Mara wildlife ecosystem

“…endosymbiont from an Am. eburneum nymph, but not from other tick samples from the coastal region of Kenya [21] or from the Lake Victoria region [49]. This suggests that the prevalence of Coxiella sp.…”

Review of challenges and opportunities for dairy cattle farming under mixed system of Homa Bay County, Western Kenya

“…The diseases of cattle reported in these areas include Anaplasmosis, Babesiosis, and Heart water, in addition to East Coast fever and trypanosomiasis, of which majority of the diseases were tick-borne infections. Indeed, from a study on molecular detection of tick-borne pathogen diversities in ticks from livestock and reptiles along the shores and adjacent islands of Lake Victoria and Baringo in Kenya, disease causing pathogens responsible for causation of the listed diseases were identified (Omondi et al, 2017). These diseases have been reported to occur with a high frequency across Table 5.…”