Isolation of the causative agent of heartwater (<i>Cowdria ruminantium</i>) from three <i>Amblyomma</i> species in eight Districts of Kenya

Ngumi, P.N.; Rumberia, R.M.; Williamson, Susanna; Sumption, Keith; Lesan, A.C.; Kariuki, D. P.

doi:10.1136/vr.140.1.13

Cited by 9 publications

(8 citation statements)

References 9 publications

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“…The low prevalence of E. ruminantium estimated from the RLB results was surprising, given previous reports of the prevalence of this pathogen in Kenya ( Ngumi et al, 1997 ). To confirm the RLB results, all samples were analyzed with the E. ruminantium -specific qPCR assay based on the pCS20 gene region.…”

Section: Resultsmentioning

confidence: 61%

“…We also observed a very low prevalence of E. ruminantium , the causative agent of heartwater, by both RLB and the pCS20 qPCR assay . E. ruminantium has previously been isolated in eight districts across Kenya, suggesting that this organism is widely distributed across the country ( Ngumi et al, 1997 ). It is possible that the sequences of the primers and probes used in the RLB assay are not sufficiently similar to those in the corresponding regions in the genomes of the E. ruminantium organisms in the study site to allow for detection.…”

Section: Discussionmentioning

confidence: 99%

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The epidemiology of tick-borne haemoparasites as determined by the reverse line blot hybridization assay in an intensively studied cohort of calves in western Kenya

Njiiri

Bronsvoort

Collins

et al. 2015

Veterinary Parasitology

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HighlightsA reverse line blot assay was used to estimate tick-borne haemoparasite prevalence in an intensively studied cohort of indigenous cattle in western Kenya.There were high prevalences of Theileria mutans (71.6%), T. velifera (62.8%), Anaplasma sp. Omatjenne (42.7%), A. bovis (39.9%), Theileria sp. (sable) (32.7%), T. parva (12.9%) and T. taurotragi (8.5%), with minor occurrences of eight other haemoparasites.The most prevalent haemoparasites were mostly present as coinfections, with strong associations between several of the Theileria parasites, in particular T. velifera with Theileria sp. sable and T. mutans, and T. parva with T. taurotragi.Comparison of RLB and serological results indicated that indigenous cattle seem capable of clearing infections of three pathogenic parasites (T. parva, A. marginale and B. bigemina), whereas infections with the mostly benign T. mutans are more persistent.

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Section: Resultsmentioning

confidence: 61%

Section: Discussionmentioning

confidence: 99%

The epidemiology of tick-borne haemoparasites as determined by the reverse line blot hybridization assay in an intensively studied cohort of calves in western Kenya

Njiiri

Bronsvoort

Collins

et al. 2015

Veterinary Parasitology

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“…with a DNA sequence close to E. ruminantium in Moyale Constituency, which is part of the study area in 2016 [ 18 ], and the isolation of the pathogen from Amblyomma spp. in eight districts across Kenya [ 69 ] suggest that there is continuous circulation of E. ruminantium across the country. Since 2016 and during the entire study period in 2020, no clinical heartwater cases were reported from camels, sheep and goats in Marsabit (Boku Bodha, unpublished observations).…”

Section: Discussionmentioning

confidence: 99%

Ticks and Tick-Borne Pathogens Associated with Dromedary Camels (Camelus dromedarius) in Northern Kenya

et al. 2021

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Ticks and tick-borne pathogens (TBPs) are major constraints to camel health and production, yet epidemiological data on their diversity and impact on dromedary camels remain limited. We surveyed the diversity of ticks and TBPs associated with camels and co-grazing sheep at 12 sites in Marsabit County, northern Kenya. We screened blood and ticks (858 pools) from 296 camels and 77 sheep for bacterial and protozoan TBPs by high-resolution melting analysis and sequencing of PCR products. Hyalomma (75.7%), Amblyomma (17.6%) and Rhipicephalus (6.7%) spp. ticks were morphologically identified and confirmed by molecular analyses. We detected TBP DNA in 80.1% of blood samples from 296 healthy camels. “Candidatus Anaplasma camelii”, “Candidatus Ehrlichia regneryi” and Coxiella burnetii were detected in both camels and associated ticks, and Ehrlichia chaffeensis, Rickettsia africae, Rickettsia aeschlimannii and Coxiella endosymbionts were detected in camel ticks. We also detected Ehrlichia ruminantium, which is responsible for heartwater disease in ruminants, in Amblyomma ticks infesting camels and sheep and in sheep blood, indicating its endemicity in Marsabit. Our findings also suggest that camels and/or the ticks infesting them are disease reservoirs of zoonotic Q fever (C. burnetii), ehrlichiosis (E. chaffeensis) and rickettsiosis (R. africae), which pose public health threats to pastoralist communities.

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“…evertsi evertsi sampled from livestock in both study locations, though we cannot rule out that this may have come from livestock blood meals. Amblyomma variegatum Fabricius 1794 is the most common and widely distributed Amblyomma tick species of livestock in SSA and is a very important vector of the E. ruminantium in cattle (65). Amblyomma gemma Dönitz 1909 sampled from livestock in both study areas was once thought to be less important as a disease vector, but has since been linked with the transmission of a number of pathogens (65, 66).…”

Section: Discussionmentioning

confidence: 99%

“…Pulchellus , and Am. gemma tick pools, all of which have been widely implicated in TBP transmission (65, 66, 83–85). Although all 28 pools of Ar.…”

Section: Discussionmentioning

confidence: 99%

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

et al. 2017

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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.

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Isolation of the causative agent of heartwater (Cowdria ruminantium) from three Amblyomma species in eight Districts of Kenya

Cited by 9 publications

References 9 publications

The epidemiology of tick-borne haemoparasites as determined by the reverse line blot hybridization assay in an intensively studied cohort of calves in western Kenya

The epidemiology of tick-borne haemoparasites as determined by the reverse line blot hybridization assay in an intensively studied cohort of calves in western Kenya

Ticks and Tick-Borne Pathogens Associated with Dromedary Camels (Camelus dromedarius) in Northern Kenya

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

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