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

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.

Molecular Detection of Tick-Borne Pathogens in American Bison (Bison bison) at El Uno Ecological Reserve, Janos, Chihuahua, Mexico

“…In fact, reference sequences from GeneBank show a genetic distance below 1% with R. rickettsii, whereas genetic distance from our samples with R. parkeri is above 3%, suggesting that DNA samples in this study might belong to R. rickettsii [61,62]. Similarly, Ortega-Morales [63] compared R. rickettsii with other rickettsias and reports based on the OmpA gene. Further studies detecting different genes such as ribosomal RNA and citrate synthase genes might be necessary to corroborate this finding.…”

“…RAP-1 gene were inferred using Molecular Evolutionary Genetics Analysis (MEGA) software, X v version [93]. Reference sequences of Rickettsia (using ompA) and Babesia (using RAP-1) species or strains, from diverse hosts were collected in GenBank to build the NJ tree [63]. The sequences were aligned using MUSCLE algorithms configured applying the cluster method of NJ with 1000 interactions.…”

Rocky Mountain Spotted Fever in a Large Metropolitan Center, Mexico–United States Border, 2009–2019

“…The ecology of RMSF in Mexicali, as in other regions of the southwestern North America with hyperendemic or epidemic levels of disease, is linked inextricably to an overabundance of tick-infested free-ranging and stray dogs in affected communities (3,4,(10)(11)(12)(13)19,39). Results of a citywide canine serosurvey conducted in Mexicali in 2017 identified antibodies reactive to R. rick-ettsii in 65% of 213 owned dogs, and 55% of all examined animals were infested with brown dog ticks (10).…”

“…Results of a citywide canine serosurvey conducted in Mexicali in 2017 identified antibodies reactive to R. rickettsii in 65% of 213 owned dogs, and 55% of all examined animals were infested with brown dog ticks ( 10 ). Levels of tick infestation and exposure to R. rickettsii are likely even greater among stray dogs ( 30 , 39 ). Movement of free-ranging, tick-infested canines within and among neighborhoods could contribute to multifocal recurrences of RMSF identified in Mexicali during the 11-year study period.…”

Is Rocky Mountain spotted fever the only disease of the spotted fever group rickettsioses found in Mexico?

“…Although their pathogenicity is still unknown, they can generate cross-reactivity with R. rickettsii: Rickettsia amblyommatys in Amblyomma mixtum and Rickettsia rhipicephali in R. sanguineus s.l. 12,13 .…”