Detection of Rickettsia spp. in Rhipicephalus sanguineus (sensu lato) collected from free-roaming dogs in Coahuila state, northern Mexico

Erika Nava-Reyna,Consuelo Almazán,Alejandro Cabezas-Cruz,Verónica Ávila-Rodríguez,Vicente H González-Álvarez,Quetzaly K Siller-Rodríguez,Filipe Dantas-Torres,Antonio Castillo-Martínez,Aldo I Ortega-Morales

doi:10.1186/s13071-019-3377-z

Abstract

BackgroundThe aim of this study was to detect and molecularly identify Rickettsia spp. in Rhipicephalus sanguineus (sensu lato) collected from free-roaming dogs in 30 communities from five municipalities in the south of Coahuila State, northern Mexico, where Rocky Mountain spotted fever is endemic.MethodsIn total, 60 dogs from each municipality were examined for engorged ticks. DNA was isolated from tick pools and conventional PCR assays targeting the 23S-5S ribosomal RNA intergenic spacer and outer membrane protein (ompA) gene of Rickettsia spp. were performed.ResultsAll ticks (n = 1238) were morphologically identified as R. sanguineus (s.l.). Six pools (each with six engorged females) from four municipalities were positive to Rickettsia spp. DNA sequencing and phylogenetic analyses confirmed the presence of R. rickettsii and R. rhipicephali in R. sanguineus (s.l.) in these ticks.ConclusionsThis study confirms the presence of R. rickettsii and R. rhipicephali in R. sanguineus (s.l.) from stray dogs in the south of Coahuila. This suggests that stray dogs may play a role in the inter-municipal dissemination of infected ticks in this region. Further research is required to assess whether ticks from stray dogs could serve as good indicators for the molecular xenomonitoring of R. rickettsii in this region. Considering that R. sanguineus (s.l.) is a proven vector of R. rickettsii in Mexico, increased awareness regarding permanent tick control in dogs is warranted.

Highlights

The aim of this study was to detect and molecularly identify Rickettsia spp. in Rhipicephalus sanguineus collected from free-roaming dogs in 30 communities from five municipalities in the south of Coahuila State, northern Mexico, where Rocky Mountain spotted fever is endemic
Rickettsia rickettsii is the causative agent of Rocky Mountain spotted fever (RMSF), a tick-borne disease with increasing incidence rate in North, Central and South American countries, including Mexico [1,2,3]
Two sequences from San Pedro and one from Torreon showed 99% identity to Rickettsia rhipicephali from south-eastern Brazil (GenBank: KT340606), New Mexico (USA) (GenBank: CP013133) and North Carolina (USA) (GenBank: CP003342)

Summary

Introduction

The aim of this study was to detect and molecularly identify Rickettsia spp. in Rhipicephalus sanguineus (sensu lato) collected from free-roaming dogs in 30 communities from five municipalities in the south of Coahuila State, northern Mexico, where Rocky Mountain spotted fever is endemic. Recent epidemics of RMSF in south-western USA and northern Mexico have been associated to massive environmental infestations by brown dog ticks, Rhipicephalus. Brown dog ticks are recognized as important vectors of several pathogenic organisms in south-western USA and northern Mexico, including R. rickettsii [1, 3, 6, 7], and are the most frequent ectoparasites of dogs [1, 3, 6,7,8]. Free-roaming dogs are common in northern Mexico and could play a role in disseminating R. rickettsii-infected brown dog ticks between communities and even between municipalities

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