Ticks infesting dogs in rural communities of Yucatan, Mexico and molecular diagnosis of rickettsial infection.

Abstract

Rickettsial infection in dog-associated ticks in three rural communities of Yucatan, Mexico was investigated using qPCR and nested PCR assays. A total of 319 dogs were studied and ticks samples were collected. A total of 170 dogs were infested with ticks (frequency of 53.4%). Overall, 1,380 ticks representing seven species were collected: Amblyomma mixtum, A.&#xa0;ovale, A.&#xa0;parvum, A. cf. oblongoguttatum, Ixodes affinis, Rhipicephalus microplus, and R.&#xa0;sanguineus sensu lato. The most abundant species was R.&#xa0;sanguineus s.l. with a mean intensity of 7.4 ticks/host. Dogs in the communities of Chan San Antonio and Yaxcheku were 2.84 and 2.41 times more likely to be infected with R.&#xa0;sanguineus compared with Sucopo (p&#xa0;<&#xa0;0.05). Adult pools of A. mixtum, A.&#xa0;parvum, I.&#xa0;affinis, R.&#xa0;microplus, and A. c.f. oblongoguttatum were negative to E.&#xa0;chaffeensis, E.&#xa0;ewingii, A.&#xa0;phagocytophilum, and R.&#xa0;rickettsii. However, pools of R.&#xa0;sanguineus s.l. adults and A.&#xa0;ovale adults, as well as nymphs of Amblyomma spp. were positive to E.&#xa0;canis. Sequencing analysis of the nested PCR products amplifying the 16S rRNA gene fragment of E.&#xa0;canis confirmed the results and revealed 100% identity with sequences of E.&#xa0;canis. This is the first report worldwide of E.&#xa0;canis infection in A.&#xa0;ovale by PCR. This finding does not necessarily indicate that A.&#xa0;ovale is a competent vector of E.&#xa0;canis because pathogen transmission of this specific tick to a na&#xef;ve dog remains to be documented. This study documented that different tick species parasitize dogs in Yucatan, Mexico, where R. sanguineus s.l., A.&#xa0;ovale, and nymphs of Amblyomma spp. were shown to be infected with E.&#xa0;canis. These findings highlight the need for control strategies against tick infestations in dogs to prevent the risk of tick-borne disease transmission among companion animal and probably human populations.