Coxiella burnetii detected in Rhipicephalus sanguineus ticks collected in Portuguese autochthonous livestock.

Overview

• This research examined the presence of the bacterium Coxiella burnetii in ticks collected from native Portuguese livestock breeds, specifically investigating if ticks contribute to the transmission of this pathogen.

Background

• Coxiella burnetii is a bacterium responsible for coxiellosis in animals and Q fever in humans.
• The primary reservoirs for C. burnetii are ruminants (such as sheep, goats, and cattle).
• The role of ticks as vectors or reservoirs in spreading C. burnetii is not well understood and remains controversial.
• This study focused on two indigenous Portuguese livestock breeds: Churra Galega Mirandesa sheep and Garrano horses.

Study Design and Methods

• A total of 555 ticks were collected from the two livestock breeds.
• The ticks belonged to two species:
  • Rhipicephalus sanguineus sensu stricto (s.s.): 100 ticks collected from sheep.
  • Rhipicephalus bursa: 455 ticks collected from horses.
• The study tested all ticks for the presence of Coxiella burnetii DNA, likely using molecular detection methods (e.g., PCR, though the abstract does not specify).
• Positive detections underwent phylogenetic analysis to confirm the identity and relationship of the bacterial strains.

Key Findings

• Coxiella burnetii DNA was detected in 7% of the Rhipicephalus sanguineus s.s. ticks collected from sheep.
• No C. burnetii was detected in the Rhipicephalus bursa ticks collected from horses.
• Phylogenetic analyses confirmed that the detected strains were indeed C. burnetii and allowed researchers to relate them to known strains.
• Detection in R. sanguineus s.s. suggests these ticks may have a role in maintaining or transmitting C. burnetii within livestock populations, specifically sheep in Portugal.

Implications and Conclusions

• The study adds evidence that Rhipicephalus sanguineus s.s., a common tick species, could be involved in the ecology of C. burnetii among Portuguese livestock.
• Since Rhipicephalus bursa ticks from horses tested negative, the role of this species in transmission appears limited or absent in this context.
• The findings emphasize the need for further research to define the epidemiological role of ticks in C. burnetii transmission cycles, especially under local Portuguese conditions.
• Understanding the role of ticks can influence strategies for controlling coxiellosis in animals and Q fever risk in humans.