Ticks and tick-borne zoonotic pathogens of domestic animals in Lesotho

MSc (Zoology), North-West University, Potchefstroom CampusTicks are vectors of diseases and transmit infectious pathogens of economic importance, some of these agents have a direct and indirect impact on the livestock industry globally. There is lack of published information on ticks and zoonotic pathogens in Lesotho. This study was therefore formulated to document information of tick species occurring in Lesotho and zoonotic pathogens that they are harbouring, with special focus on Anaplasma phagocytophilum, Coxiella burnetii and Rickettsia africae pathogens. A total of 2054 tick specimens were collected from various domestic animals including cattle, sheep, goats and dogs from five Lesotho districts namely, Butha-Buthe, Mafeteng, Maseru, Leribe and Qacha’s Nek. All tick species were identified morphologically under a stereo microscope and submitted to the ARC-Onderstepoort Veterinary Research Tick Museum where species identification was verified and voucher specimen was issued. Seven species were identified falling under four genera, of which three are from family Ixodidae and one from family Argasidae. Ticks collected and identified included Haemaphysalis elliptica 0.1% (n= 2), Hyalomma rufipes 3.6% (n= 73), H. truncatum 2% (n= 41), Otobius megnini 18.2% (n= 373), Rhipicephalus decoloratus 17% (n= 349), R. microplus 10.7% (n= 220), R. evertsi evertsi 46.4% (n= 953) and R. glabroscutatum 2.1% (n= 43). There was a significant difference at p= 0.005 (x2= 3.072, df= 3) in the overall species that were identified in five Lesotho districts. However, there was no significant difference at p= 0.06 (x2= 30.072, df= 3) for the abundance of species from each sampled district. The CO1 and 18S rRNA genes of the identified ticks were amplified by PCR, sequenced and aligned using MEGA 6 software whereby phylogenetic trees were constructed. The tick genera correctly clustered with their subsequent tick species further indicating that they were identified correctly. Out of the 247 pooled tick DNA samples screened by PCR for the presence of zoonotic pathogens; overall occurrence of A. phagocytophilum was 7% (18/247) for Butha-Buthe (n= 79), Mafeteng (n= 9), Maseru (n= 30) and Leribe (n= 2). PCR positive samples from H. truncatum DNA yielded highest number of A. phagocytophilum positive samples with 33% infection rate, followed by R. e. evertsi with 21% and the least was R. decoloratus with 13%. The R. microplus (n= 3) and O. megnini (n=2) tick specimens were negative for the presence of A. phagocytophilum infections. The overall occurrence of Coxiella burnetii a gram-negative pleomorphic etiological agent of Query fever (Q fever) was 7% (17/247) for Butha-Buthe (n= 49), Mafeteng (n= 7), Maseru (n= 23) and Leribe (n= 2). Overall infection from cattle, goats and sheep was 22% (17/79), highest infection rate was 33% from H. truncatum followed by, 13.2% from R. e. evertsi, then 13% from R. decoloratus and the least was 1% from O. megnini. The R. microplus DNA samples were negative for the presence of C. burnetii infections. The overall occurrence of Rickettsia africae which is the most prevalent tick-borne pathogen in sub-Saharan Africa causing African tick-bite fever (ATBF) was 1% (2/247) for Butha-Buthe (n= 7), Maseru (n= 30) and Leribe (n= 2). Overall infection from domestic animals including goats and cattle was 5% (2/37). From all PCR positive samples both R. e. evertsi and R. decoloratus had 2% infection rate. None of the O. megnini (n= 2), R. microplus (n= 3), H. truncatum (n= 15) tick specimens were PCR positive for the presence of R. africae. This current study has provided base line knowledge of the tick species and tick-borne bacterial pathogens (A. phagocytophilum, C. burnetii and R. africae) of economic and zoonotic importance in Lesotho districts. Further studies are needed to determine whether ticks are transmitting these pathogens to livestock and humans.Master