Screening of ectoparasites from domesticated dogs for bacterial pathogens in Vientiane, Lao PDR

Arthropod-borne diseases are widespread worldwide and are a complex interaction between animals, humans and ectoparasites. The understanding of the diversity and epidemiology of organisms transmitted by arthropod vectors, and the role of hosts and vectors in transmission of infections remain limited in Lao PDR. What knowledge does exist is primarily focused on more rural regions of the country. This study screened ectoparasites from domestic dogs in Vientiane city for the presence of bacterial pathogens of zoonotic importance. A total of 3,511 arthropod vectors were collected from 112 dogs. Vectors collected wereRhipicephalus sanguineusticks,Ctenocephalides felis felis and Ctenocephalides felis orientisfleas andHeterodoxus spinigerlice. A sub-sample of vectors from each dog was analysed by PCR to identify the potential bacteria. From 129 vector pools,Rickettsiaspp. was detected in 6.7% (7/105) pools of ticks, 86.4% (19/22) pools of fleas and both pools of lice. Sequencing analysis confirmedRickettsia felisin 13 flea pools and one louse pool andRickettsia asembonensisin six flea pools. Anaplasmataceae was identified in 14.3% (15/105) tick pools and 100% (22/22) flea pools. Sequencing revealed the presence ofAnaplasma platysin ticks andWolbachia pipientisin fleas.Leptospiraspp. was detected in one tick and one louse pool, andBrucellaspp. was detected in 12.4% (13/105) tick pools. All samples were negative forBartonellaspp.,Coxiella burnetiiandBorrelia burgdorferi. This is the first study providing evidence ofR. asembonensisin fleas in Laos. Results from this study show arthropods are potential vectors to transmit zoonotic infection in Vientiane city, suggesting humans are at risk of zoonotic infections in the city.