Molecular evidence confirms occurrence of Rhipicephalus (Boophilus) microplus in Kenya and suggests that an undifferentiated genotype is prevalent in the African continent

Abstract

Background The tick vector Rhipicephalus (Boophilus) microplus which transmits Babesia and rickettsial pathogens has not been reported in Kenya since 1998. More recently, the pathogenic Babesia bovis has been detected in cattle blood DNA. The status of R. microplus in Kenya remains unknown. This study employed morphological and molecular tools to characterize R. microplus originating from Kenya and assess the genetic relationships between Kenyan and other African R. microplus genotypes. Methods Morphological identification and differentiation of 35 Kenyan and 11 reference tick specimens was implemented by following standard tick reference keys and identification guides. Genetic and phylogenetic relationships between the Kenyan and other annotated R. microplus reference sequences was investigated by analysis of the cytochrome c oxidase subunit I (COI) gene. The complete mitochondrial (mt) genome of four tick specimens which included two R. microplus was assembled from whole genome data to further characterize the Kenyan ticks. A B. bovis specific Taqman probe qPCR assay was used to detect B. bovis in gDNA from R. microplus ticks. Results Of the 35 Kwale tick specimens analysed, 23 were confirmed to be R. microplus by both morphology and molecular characterizations. The Kenyan R. microplus COI sequences showed very high pairwise identities (>99%) and clustered very closely with reference African sequences. We also found a low differentiation and lack of geographical sub-structuring among the African COI sequences. The mitochondrial genome sequences of the two Kenyan R. microplus ticks also clustered closely with reference genome sequences from Brazil, USA, Cambodia and India. No B. bovis was detected in the Kwale R. microplus DNA. Conclusions These findings confirm the presence of R. microplus in Kenya and suggest that a common undifferentiated genotype is prevalent in cattle in Africa. These and other recent findings of widespread occurrence of R. microplus in Africa provide a strong justification for urgent surveillance to determine and monitor the spread of R. microplus and vector competence of Rhipicephalid ticks for B. bovis in Africa, with the ultimate goal of strategic control.

Prevalence of Ticks Infesting Dairy Cattle and the Pathogens They Harbour in Smallholder Farms in Peri-Urban Areas of Nairobi, Kenya

“…( boophilus ) microplus ) was also identified in the study cattle. This tick was first reported in the coastal areas of Kenya by Hoogstraal and Walker [ 41 ], and since then, no reports of this tick have been made until recently when Kanduma et al [ 12 ] characterized this tick in Kwale County using molecular markers. These tick species are highly invasive and have been reported to replace Rh.…”

“…There are limited studies in Kenya that have identified the tick species present and the pathogens they harbour. Such studies have mainly focused on pastoral areas [ 9 , 10 ] and livestock-wildlife interfaces [ 11 , 12 ] with hardly any focus on ticks present in unique production systems such as those in peri-urban areas of Nairobi.…”