title: Novel Rickettsia and emergent tick-borne pathogens: A molecular survey of ticks and tick-borne pathogens in Shimba Hills National Reserve, Kenya.
abstract: Ticks are important vectors of emerging and re-emerging zoonoses, the majority of which originate from wildlife. In recent times, this has become a global public health concern that necessitates surveillance of both known and unknown tick-borne pathogens likely to be future disease threats, as well as their tick vectors. We carried out a survey of the diversity of ticks and tick-borne pathogens in Kenya's Shimba Hills National Reserve (SHNR), an area with intensified human-livestock-wildlife interactions, where we collected 4297 questing ticks (209 adult ticks, 586 nymphs and 3502 larvae). We identified four tick species of two genera (Amblyomma eburneum, Amblyomma tholloni, Rhipicephalus maculatus and a novel Rhipicephalus sp.) based on both morphological characteristics and molecular analysis of 16S rRNA, internal transcribed spacer 2 (ITS 2) and cytochrome oxidase subunit 1 (CO1) genes. We pooled the ticks (3-8 adults, 8-15 nymphs or 30 larvae) depending on species and life-cycle stages, and screened for bacterial, arboviral and protozoal pathogens using PCR with high-resolution melting analysis and sequencing of unique melt profiles. We report the first molecular detection of Anaplasma phagocytophilum, a novel Rickettsia-like and Ehrlichia-like species, in Rh. maculatus ticks. We also detected Ehrlichia chaffeensis, Coxiella sp., Rickettsia africae and Theileria velifera in Am. eburneum ticks for the first time. Our findings demonstrate previously unidentified tick-pathogen relationships and a unique tick diversity in the SHNR that may contribute to livestock, and possibly human, morbidity in the region. This study highlights the importance of routine surveillance in similar areas to elucidate disease transmission dynamics, as a critical component to inform the development of better tick-borne disease diagnosis, prevention and control measures.
authors.affiliation: International Centre of Insect Physiology and Ecology (icipe), P.O. Box 30772-00100, Nairobi, Kenya; School of Biological Sciences, University of Nairobi, P.O. Box 30197-00100, Nairobi, Kenya. Electronic address: mwananje@gmail.com.
authors.forename: Micky M
authors.initials: MM
authors.lastname: Mwamuye
authors.affiliation: Department of Veterinary and Capture Services, Kenya Wildlife Service, P.O. Box 40241-00100, Nairobi, Kenya. Electronic address: ekariuki@kws.org.
authors.forename: Edward
authors.initials: E
authors.lastname: Kariuki
authors.affiliation: International Centre of Insect Physiology and Ecology (icipe), P.O. Box 30772-00100, Nairobi, Kenya; Molecular Biology and Virology Laboratory, Department of Medical Biosciences, University of Western Cape, Private Bag X17, Bellville, 7535, South Africa; Biochemistry and Molecular Biology Department, Egerton University, P.O. Box 536, Egerton, 20115, Kenya. Electronic address: omondiouma08@gmail.com.
authors.forename: David
authors.initials: D
authors.lastname: Omondi
authors.affiliation: International Centre of Insect Physiology and Ecology (icipe), P.O. Box 30772-00100, Nairobi, Kenya. Electronic address: jkabii@icipe.org.
authors.forename: James
authors.initials: J
authors.lastname: Kabii
authors.affiliation: School of Biological Sciences, University of Nairobi, P.O. Box 30197-00100, Nairobi, Kenya. Electronic address: david.odongo@uonbi.ac.ke.
authors.forename: David
authors.initials: D
authors.lastname: Odongo
authors.affiliation: International Centre of Insect Physiology and Ecology (icipe), P.O. Box 30772-00100, Nairobi, Kenya. Electronic address: dmasiga@icipe.org.
authors.forename: Daniel
authors.initials: D
authors.lastname: Masiga
authors.affiliation: International Centre of Insect Physiology and Ecology (icipe), P.O. Box 30772-00100, Nairobi, Kenya. Electronic address: jandouwe@icipe.org.
authors.forename: Jandouwe
authors.initials: J
authors.lastname: Villinger
mesh_terms: D000818:Animals; D000835:Animals, Wild / Q000469:parasitology; D021821:Communicable Diseases, Emerging / Q000453:epidemiology / Q000382:microbiology*; D004269:DNA, Bacterial / Q000235:genetics; D007630:Kenya / Q000453:epidemiology; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012281:Rickettsia / Q000302:isolation & purification*; D013984:Tick Infestations / Q000453:epidemiology / Q000662:veterinary; D017282:Tick-Borne Diseases / Q000453:epidemiology / Q000382:microbiology*; D013987:Ticks / Q000235:genetics / Q000382:microbiology*
chemical_list: D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S
keywords: Anaplasma; Coxiella; Ehrlichia; Rickettsia; Theileria; Tick diversity