Ticks and Associated Rickettsiae from Domestic Animals in Bhutan

In Bhutan, information on rickettsiae is limited to a few epidemiological studies. There is no information on ticks and tick-associated rickettsiae. Ticks were collected opportunistically from domestic animals residing in eight districts where a seroprevalence study had been carried out previously. Morphological identification of the ticks was performed in the United States National Tick Collection and testing for rickettsiae was carried out in the Australian Rickettsial Reference Laboratory. Samples positive for rickettsiae by qPCR were subjected to conventional PCR followed by DNA sequencing and phylogenetic analysis. A total of 200 ticks were sampled from 155 domestic animals including cattle, dogs, goats, horses, yaks, sheep and cats. The ticks belonged to twelve different species, the commonest being Rhipicephalus microplus, followed by Rhipicephalus haemaphysaloides, Haemaphysalis sp. near ramachandrai, Haemaphysalis tibetensis, Haemaphysalis bispinosa, Haemaphysalis sp., Haemaphysalis sp. near davisi, Rhipicephalus sanguineus, Haemaphysalis shimoga, Haemaphysalis hystricis, Ixodes ovatus, and Amblyomma testudinarium. Rickettsial DNA sequence analysis showed that the rickettsiae infesting ticks in Bhutanese domestic animals aligned with R. gravesii, R. canadensis, R. honei, R. africae, R. felis, R. akari, R. australis, R. japonica, R. africae, R. heilongjiangensis, R. conorii, R. peacockii, R. honei, R. massiliae and R. rhipicephali. However, these may not be conclusive due to low bootstrap values in the phylogenetic tree. Bhutan will benefit from larger studies on ticks and tick-borne infections, burden and damage assessment to livestock and human health, public health interventions and clinical guidelines to reduce morbidity and mortality in human and animal health.