Epidemiology and Molecular Detection of Tick-Borne Rickettsiae in Hyalomma and Rhipicephalus Ticks Infesting Dogs and Sheep in Pakistan.

Background: Tick-borne rickettsiae present significant health risks to both humans and animals globally. However, the epidemiology of rickettsial pathogens in Pakistan remains largely unexplored.

Objective: This study aimed to investigate the epidemiology and molecular detection of tick-borne Rickettsia in Hyalomma and Rhipicephalus ticks infesting dogs and sheep in Pakistan.

Methods: A total of 810 ticks were collected from six geographical locations in Khyber Pakhtunkhwa. Morphological and molecular identification classified the ticks as Rhipicephalus linnaei, Hyalomma dromedarii, Hyalomma scupense and Hyalomma isaaci, with Rh. linnaei being the most prevalent species (34.81%).

Results: Molecular analysis indicated that 43.58% of the ticks tested positive for rickettsiae. The prevalence of specific rickettsial species was as follows: Rickettsia massiliae (16.79%), Rickettsia sp. (11.48%), R. slovaca (8.77%), Ca. R. kotlanii (5.31%) and R. japonica (1.23%). Notably, approximately 13.95% of the ticks harboured at least one tick-borne Rickettsia, with double and triple co-infections found in 5.06% and 1.23%, respectively. Phylogenetic analysis revealed that isolates of Candidatus Rickettsia kotlanii and Rickettsia sp. from Pakistan shared close genetic similarities with isolates from Japan and South Africa.

Conclusion: These findings underscore the urgent need for enhanced surveillance and monitoring of Pakistani tick populations and rickettsial pathogens. Understanding the dynamics of rickettsial transmission is crucial for mitigating the risks of tick-borne diseases in humans and animals and informing public health strategies.