Phylogenetic Variants of Rickettsia africae, and Incidental Identification of "Candidatus Rickettsia Moyalensis" in Kenya

Gathii, Kimita; Mutai, Beth; Nyanjom, Steven Ger; Wamunyokoli, Fred; Waitumbi, John N.

doi:10.1371/journal.pntd.0004788

Cited by 29 publications

(19 citation statements)

References 43 publications

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“…Analysis of tickborne zoonotic pathogens in this study corroborate findings of previous studies in Kenya, which have demonstrated circulation of zoonotic SFG Rickettsia in ticks from various ecologies [21,33,34). The presence of R. africae, which causes a potentially fatal, but as yet neglected febrile illness, was first reported in this ecosystem in 2003 [29].…”

Section: Discussionsupporting

confidence: 88%

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

Oundo

Villinger

Jeneby

et al. 2020

Preprint

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Background:The role of questing ticks in the epidemiology of tick-borne diseases in Kenya's Maasai Mara National Reserve (MMNR), an ecosystem with intensified human-wildlifelivestock interactions, remains poorly understood. Therefore, we carried out a survey of the diversity of questing ticks, their blood-meal hosts, and tick-borne pathogens to understand potential effects to human and livestock health.Methods: Questing ticks were collected by flagging and hand picks from vegetation in 25 localities and identified based on morphologic and molecular criteria. We used PCR with highresolution melting (HRM) analysis, and sequencing to identify Anaplasma, Babesia, Coxiella, Ehrlichia, Rickettsia, and Theileria pathogen diversities and blood meals in 231 tick pools. Results: A total of 1,465 host-seeking ticks were collected, including Rhipicephalus appendiculatus (n = 1,125), Rhipicephalus pulchellus (n = 6), Rhipicephalus evertsi (n = 5), Amblyomma cf. gemma (n = 178), Amblyomma gemma (n = 145), Amblyomma variegatum (n = 4), Amblyomma sp. (n = 1), and Haemaphysalis leachi (n = 1). Remnant blood-meals from humans, wildebeest, and African buffalo were detected in Rh. appendiculatus, goat in Rh. evertsi, sheep in Am. gemma, and cattle in Am. variegatum. Rickettsia africae was detected in Am. gemma (1/25 pools) that had blood-meal remnant from sheep and Am. variegatum (4/25 pools) that had fed on cattle. Rickettsia spp. were found in Am. gemma (4/25 pools) and Rh. evertsi (1/4 pools). Anaplasma ovis was detected in Rh. appendiculatus (1/172 pools) and Rh. evertsi (1/4 pools), while Anaplasma bovis was detected in Rh. appendiculatus (1/172 pools). Theileria parva was detected in Rh. appendiculatus (27/172 pools). Babesia, Ehrlichia and Coxiella pathogens were not found in any ticks. Unexpectedly, diverse Coxiella sp.endosymbionts were detected in all tick genera (174/231 pools). Conclusions:The data shows that ticks from the rapidly-changing MMNR are infected with zoonotic R.africae and unclassified Rickettsia spp, demonstrating the persistent risk of African tick-bite fever and other and Spotted Fever Group rickettsioses to local dwellers and visitors to the Maasai Mara ecosystem. Protozoan pathogens that may pose risk to livestock production were also identified. We also highlight possible existence of morphotypic variants of Amblyomma species, based on the observation of Ambyomma cf. gemma, which may be potential human parasites or emergent disease vectors. Our findings also demonstrate that questing ticks in this ecosystem have dynamic vertebrate blood sources including humans, wildlife and domestic animals, which may amplify transmission of tickborne zoonoses and livestock diseases. Further studies are needed to determine the role of Coxiella endosymbionts in tick physiology and vector competence.

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Section: Discussionsupporting

confidence: 88%

“…Previous reports have demonstrated high diversity of Rickettsia spp. and their potential vectors in Kenya [21,33,43]. Given that these reports have showed existence of novel species and uncharacterized variants of unknown pathogenicity, it will be important to undertake further studies of the unclassified Rickettsia spp.…”

Section: Discussionmentioning

confidence: 99%

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

Oundo

Villinger

Jeneby

et al. 2020

Preprint

View full text Add to dashboard Cite

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“…Rickettsia africae was detected in ticks collected from domestic animals and wildlife in Kenya at the Maasai Mara and the Shimba hill reserves ( Macaluso et al 2003 , Mwamuye et al 2016 ) and R. africae variants detected in ticks from rural Western Kenya. In a recent study, the heterogeneity of R. africae was confirmed and a new Rickettsia species identified that had been collected from the northern part of Kenya where communities are mainly nomads ( Kimita et al 2016 ). Nomadic communities in Kenya live in arid and semiarid zones and practice pastoralism with herds predominantly consisting of sheep, goats, and camels.…”

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confidence: 93%

The Detection of Spotted Fever Group Rickettsia DNA in Tick Samples From Pastoral Communities in Kenya

et al. 2017

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In this study, ticks from pastoral communities in Kenya were tested for Rickettsia spp. infections in geographical regions where the presence of tick-borne arboviruses had previously been reported. Rickettsial and arbovirus infections have similar clinical features which makes differential diagnosis challenging when both diseases occur. The tick samples were tested for Rickettsia spp. by conventional PCR using three primer sets targeting the gltA, ompA, and ompB genes followed by amplicon sequencing. Of the tick pools screened, 25% (95/380) were positive for Rickettsia spp. DNA using the gltA primer set. Of the tick-positive pools, 60% were ticks collected from camels. Rickettsia aeschlimannii and R. africae were the main Rickettsia spp. detected in the tick pools sequenced. The findings of this study indicate that multiple Rickettsia species are circulating in ticks from pastoral communities in Kenya and could contribute to the etiology of febrile illness in these areas. Diagnosis and treatment of rickettsial infections should be a public health priority in these regions.

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“…A study conducted in Kenya by [63], reported that a partial fragment of ompB gene was found to be the most identical to Rickettsia rhipicephalus with 99.0% homology as against a required homology of 99.2% to qualify it as R. rhipicephalus, thus suggesting the probability of R. rhipicephalus circulating in African continent. Rhipicephalus spp.…”

Section: Discussionmentioning

confidence: 99%

Evidence of pathogenic zoonotic tick-borne Rickettsia and Borrelia spp. in some communal farms in the Eastern Cape Province, South Africa

Adelabu

Iweriebor

Okoh

et al. 2020

Preprint

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Abstract The abundance of tick populations in South Africa represents a probable risk for both animal and human health. Rickettsia spp. and Borrelia spp. are well-known significant agents of emerging human tick-borne infectious diseases throughout the world. Nevertheless, the epidemiology of their infections has been underreported in South Africa, therefore, the aim of this study was to profile for zoonotic Rickettsia and Borrelia species from ticks infesting domesticated animals in the Eastern Cape, South Africa. Morphological and molecular identification techniques were conducted on 1,200 tick samples collected from domestic animals before screening for the target bacterial pathogens. The molecular identification of the tick samples was based on the amplification of the 12S rRNA mitochondrial DNA while those of Rickettsia and Borrelia species were carried out by amplifying fragments of gltA, ompA and ompB genes for Rickettsia and flaB gene for Borrelia spp. Thereafter, the positive ticks, Borrelia and Rickettsia ompB amplicons were sequenced and further analysed. Eight species of ticks belonging to three genera; Rhipicephalus, Amblyomma, and Haemaphysalis were identified. A total of 320 (27%) samples were confirmed positive for Rickettsia out of which 74 (23%) were positive for both ompA and ompB genes. Phylogenetic analysis of ompB revealed a high homology to rickettsial reference strains from GenBank, while there was no positive result for Borrelia. The generated sequences showed 99.1 to 100% homology with R. africae-KX227790 (100 %), R. parkeri - KY113111 (99.8 %), R. peacock (99.3 %) and R. slovaca - KJ675445, JX683122 (99.1 %) representative sequences in GenBank. The findings from this study revealed that ticks collected from domesticated animals were parasitized by Rickettsia species with possible zoonotic potential, which is detrimental to human health if bitten by infected ticks.

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Phylogenetic Variants of Rickettsia africae, and Incidental Identification of "Candidatus Rickettsia Moyalensis" in Kenya

Cited by 29 publications

References 43 publications

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

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

The Detection of Spotted Fever Group Rickettsia DNA in Tick Samples From Pastoral Communities in Kenya

Evidence of pathogenic zoonotic tick-borne Rickettsia and Borrelia spp. in some communal farms in the Eastern Cape Province, South Africa

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