Low genetic diversity of Ehrlichia canis associated with high co-infection rates in Rhipicephalus sanguineus (s.l.)

Abstract

BackgroundRhipicephalus sanguineus sensu lato (s.l.) is the most widely distributed ixodid tick and is a vector of major canine and human pathogens. High-throughput technologies have revealed that individual ticks carry a high diversity of pathogens, including bacteria, protozoa and viruses. Currently, it is accepted that co-infections (multiple pathogen species within an individual) are very common in ticks and influence pathogen acquisition and transmission as well as host infection risk. However, little is known on the impact of the genetic diversity of pathogens on the incidence of co-infections. Herein, we studied the frequency of co-infections in R. sanguineus (s.l.) and their association with the genetic diversity of Ehrlichia canis.MethodsRhipicephalus sanguineus (s.l.) female ticks (n = 235) were collected from healthy farm dogs in three districts of Pakistan. Microfluidic real-time PCR, a powerful nanotechnology for high-throughput molecular detection of pathogens, was used to test the presence of 25 bacterial and seven parasitic species in individual ticks. The genetic diversity of E. canis was evaluated by characterizing the trp36 gene.ResultsA total of 204 ticks were infected with at least one pathogen and 109 co-infected with two (80%) or three (20%) pathogens. Rickettsia massiliae (human pathogen) and E. canis (zoonotic dog pathogen) were the most common pathogens co-infecting (30.4%) ticks. Furthermore, all identified co-infections included R. massiliae and/or E. canis. Multiple correspondence analysis (MCA) revealed that single infections did not show clear regional association whereas some co-infections were restricted to certain geographical regions. The sequence analysis of trp36 in representative samples allowed the identification of three E. canis strains with low genetic diversity, and the strain found in Muzaffargarh district appeared to be more adapted to co-infection with R. massiliae.ConclusionsRhipicephalus sanguineus (s.l.) harbors multiple co-infections with human and dog pathogens of zoonotic potential. Findings of this study suggest that genetic diversity of E. canis may favor co-infections with different pathogens.

Balancing selection and high genetic diversity of Plasmodium vivax circumsporozoite central region in parasites from Brazilian Amazon and Rio de Janeiro Atlantic Forest

“…On the other hand, the allotype 3, considered a T-helper cell epitope, revealed an “excess” of nonsynonymous substitutions in the great majority of the samples. The low Sal-1 allotype 3 frequency has already been reported in China [ 63 ], Mexico [ 69 ], Sudan [ 61 ], and also in Brazil [ 27 , 28 , 71 ]. Thus, it is reasonable to speculate that such nonsynonymous polymorphisms are not essential for P .…”

“…A large number of VK210’s substitutions and length polymorphisms have been found worldwide [ 26 , 69 ]. However, its nonapeptide repeat structure remained conserved, probably by intragenic shuffling, as previously suggested for P .…”

Bovine ticks harbour a diverse array of microorganisms in Pakistan

“…4). Although studies from Pakistan have reported ehrlichiosis in dogs using blood smear examination [58] and molecular tools [38, 59], no information is available on the epidemiology of ehrlichiosis in bovines from Pakistan. Recently, one study investigated TBPs in bovine ticks from Punjab, Pakistan, and reported a high prevalence of Ehrlichia spp.…”

Seasonal Dynamics, Record of Ticks Infesting Humans, Wild and Domestic Animals and Molecular Phylogeny of Rhipicephalus microplus in Khyber Pakhtunkhwa Pakistan

“…The genus Dermacentor is of public and veterinary health concern as a vector reservoir for several pathogens with unknown potential risks in Pakistan. R. sanguineus , a vector of microorganisms of medical and veterinary health concern such as Hepatozoon canis and Ehrlichia canis (Dantas-Torres et al, 2018; Cabezas-Cruz et al, 2019) was collected for the first time from wild boars in the region.…”