Abstract
BackgroundAnaplasma and Ehrlichia species are tick-borne pathogens of both veterinary and public health importance. The current status of these pathogens, including emerging species such as Ehrlichia minasensis and Anaplasma platys, infecting cattle in Kenya, remain unclear, mainly because of limitation in the diagnostic techniques. Therefore, we investigated the Anaplasma and Ehrlichia species infecting dairy cattle in Nairobi, Kenya using molecular methods.ResultsA total of 306 whole blood samples were collected from apparently healthy dairy cattle. Whole blood DNA was extracted and tested for presence of Anaplasma and Ehrlichia DNA through amplification and sequencing of the 16S rDNA gene. Sequence identity was confirmed using BLASTn analysis while phylogenetic reconstruction was performed to determine the genetic relationship between the Kenyan isolates and other annotated genotypes available in GenBank. Anaplasma and Ehrlichia species were detected in 19.9 and 3.3% of all the samples analyzed, respectively. BLASTn analysis of the sequences against non-redundant GenBank nucleotide database revealed infections with A. platys (44.8%), A. marginale (31%) and A. bovis (13.8%). All four sequenced Ehrlichia spp. were similar to Ehrlichia minasensis. Nucleotide polymorphism was observed for A. platys, A. bovis and E. minasensis. The Anaplasma species clustered in four distinct phylogenetic clades including A. marginale, A. platys, A. bovis and some unidentified Anaplasma spp. The Kenyan Ehrlichia minasensis clustered in the same clade with isolates from America and Australia but distant from E. ruminantium.ConclusionThis study provides the first report of infection of dairy cattle in Kenya with A. platys and E. minasensis, which are emerging pathogens. We conclude that cattle in peri-urban Nairobi are infected with various species of Anaplasma and E. minasensis. To understand the extent of these infections in other parts of the country, large-scale screening studies as well as vector identification is necessary to inform strategic control.
Highlights
Anaplasma and Ehrlichia species are tick-borne pathogens of both veterinary and public health importance
The Anaplasma species yielded a specific band corresponding to 424 bp (Fig. 1a) while primers targeting the 16S rDNA gene of Ehrlichia species produced a specific band corresponding to the expected size of 838 bp (Fig. 1b)
Basic Local Alignment Search Tooln (BLASTn) analysis revealed that majority, 13(44.8%) of the Anaplasma 16S rDNA sequences were similar to A. platys with sequence identity of between 98.72 and 100% to annotated sequences in Genbank
Summary
Anaplasma and Ehrlichia species are tick-borne pathogens of both veterinary and public health importance. The current status of these pathogens, including emerging species such as Ehrlichia minasensis and Anaplasma platys, infecting cattle in Kenya, remain unclear, mainly because of limitation in the diagnostic techniques. Anaplasma and Ehrlichia species of the family Anaplasmataceae are tick-borne pathogens of livestock with some species known to infect humans and are of both veterinary and public health importance [1]. Anaplasma species documented to infect domestic ruminants including cattle are Anaplasma marginale (A. maginale), A. centrale, A. ovis, A. bovis, A. phagocytophilum and more recently A. platys [2, 3]. 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]. Infections of cattle with E. ruminantium and E. minasensis are mainly characterized by severe fever, anemia, thrombocytopenia and enlarged lymph nodes [14]
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