Molecular Characterization of Rickettsial Agents in Ticks (Acari: Ixodidae) from Sri Lanka

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  • 1 Rickettsial Zoonoses Branch, Centers for Disease Control and Prevention, Atlanta, Georgia;
  • | 2 Jiann-Ping Hsu College of Public Health, Georgia Southern University, Statesboro, Georgia;
  • | 3 University of Kelaniya, Ragama, Sri Lanka;
  • | 4 University of Peradeniya, Peradeniya, Sri Lanka

Because the majority of spotted fever group rickettsiae are transmitted to humans by tick bites, it is important to understand which ticks might play a role in transmission of rickettsial pathogens in Sri Lanka. The purpose of our study was to conduct molecular surveillance of 847 ticks collected in different locations in central Sri Lanka to determine which were infected with Rickettsia and Anaplasmataceae. Molecular methods were used to identify the ticks and the agents detected. Most ticks (Amblyomma, Haemaphysalis, and Rhipicephalus) were collected by flagging, and lower number was collected from dogs, cattle, pigs, a pangolin, and tortoises. Five spotted fever genotypes were identified: a Rickettsia africae-like agent in Amblyomma larvae, Rhipicephalus massiliae and a related genotype identified in association with the tropical type of Rhipicephalus sanguineus from dogs and Rhipicephalus haemaphysaloides from dogs and cattle, and Candidatus R. kellyi and another novel genotype (SL94) in R. haemaphysaloides. Twenty-three ticks were positive for Anaplasmataceae, including one Anaplasma and two Ehrlichia genotypes. Because the sequence database for both ticks and rickettsial agents from Sri Lanka and southern India is not extensive, additional molecular characterization of the tick species of Sri Lanka and their rickettsial agents is required to understand their pathogenic potential more completely. However, several of the agents we identified in this survey may well be pathogenic for humans and domestic animals, and should be considered as a part of epidemiological surveillance and patient management.

Author Notes

Address correspondence to Gregory A. Dasch, XXXXX. E-mail: cougar78901@aol.com

These authors contributed equally to this work.

Disclaimer: The findings and conclusions in this article are those of the authors and do not necessarily represent the official position of the CDC (G. A. D. and M. L. Z.).

Authors’ addresses: Gregory A. Dasch and Maria L. Zambrano, Rickettsial Zoonoses Branch, Centers for Disease Control and Prevention, Atlanta, GA, E-mails: cougar78901@aol.com and daq6@cdc.gov. Marina E. Eremeeva, Jiann-Ping Hsu College of Public Health, Georgia Southern University, Statesboro, GA, E-mail: meremeeva@georgiasouthern.edu. Ranjan Premaratna, University of Kelaniya, Ragama, Sri Lanka, E-mail: ranjanp64@kln.ac.lk. S. A. M. Kularatne and R. P. V. Jayanthe Rajapakse, University of Peradeniya, Peradeniya, Sri Lanka, E-mails: tbn1917@gmail.com and jayanthar@pdn.ac.lk.

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