Abstract
One of the major routes of transmission of rickettsial and ehrlichial diseases is via ticks that infest numerous host species, including humans. Besides mammals, reptiles and amphibians also carry ticks that may harbor Rickettsia and Ehrlichia strains that are pathogenic to humans. Furthermore, reptiles and amphibians are exempt from quarantine in Japan, thus facilitating the entry of parasites and pathogens to the country through import. Accordingly, in the current study, we examined the presence of Rickettsia and Ehrlichia spp. genes in ticks associated with reptiles and amphibians originating from outside Japan. Ninety-three ticks representing nine tick species (genera Amblyomma and Hyalomma) were isolated from at least 28 animals spanning 10 species and originating from 12 countries (Ghana, Jordan, Madagascar, Panama, Russia, Sri Lanka, Sudan, Suriname, Tanzania, Togo, Uzbekistan, and Zambia). None of the nine tick species are indigenous in Japan. The genes encoding the common rickettsial 17-kDa antigen, citrate synthase (gltA), and outer membrane protein A (ompA) were positively detected in 45.2% (42/93), 40.9% (38/93), and 23.7% (22/93) of the ticks, respectively, by polymerase chain reaction (PCR). The genes encoding ehrlichial heat shock protein (groEL) and major outer membrane protein (omp-1) were PCR-positive in 7.5% (7/93) and 2.2% (2/93) of the ticks, respectively. The p44 gene, which encodes the Anaplasma outer membrane protein, was not detected. Phylogenetic analysis showed that several of the rickettsial and ehrlichial sequences isolated in this study were highly similar to human pathogen genes, including agents not previously detected in Japan. These data demonstrate the global transportation of pathogenic Rickettsia and Ehrlichia through reptile- and amphibian-associated ticks. These imported animals have potential to transfer pathogens into human life. These results highlight the need to control the international transportation of known and potential pathogens carried by ticks in reptiles, amphibians, and other animals, in order to improve national and international public health.
Highlights
Members of the genera Rickettsia and Ehrlichia are obligate intracellular bacteria belonging to the order Rickettsiales, in the Rickettsiaceae and Anaplasmataceae families, respectively
This study revealed that rickettsial and ehrlichial organisms are transported into Japan from abroad through imported exotic animals
The rickettsial genes were detected at comparatively high rates in reptile- and amphibianassociated ticks; by contrast, the Ehrlichia-specific genes were detected at low rates, and the Anaplasma-specific gene was not detected at all in this study
Summary
Members of the genera Rickettsia and Ehrlichia are obligate intracellular bacteria belonging to the order Rickettsiales, in the Rickettsiaceae and Anaplasmataceae families, respectively. Ticks carrying pathogens can infest a variety of hosts, including domestic animals as well as humans [2]; tick-borne disease is an important concern in both human and veterinary medicine. Rickettsia-carrying reptile-associated ticks can be pathogenic to humans [3,4,5,6]. Ixodes ricinus has a broad host range and can be found on certain lizards (Lacerta viridis); these ticks reportedly carry Anaplasma, Borrelia, and Rickettsia in central European populations [4]. Anaplasma phagocytophilum, which causes the potentially fatal tick-borne disease human granulocytic anaplasmosis, was isolated from multiple species of snakes and lizards in the United States [6]. There have been several global reports of reptile-associated ticks carrying members of the pathogenic Rickettsiaceae and Anaplasmataceae families, there has been no such information reported for Japan. Amphibians have potential to carry or transfer pathogenic Rickettsiaceae and Anaplasmataceae
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
