Molecular Detection and Phylogenetic Characterization of Spotted Fever Group Rickettsiae in Amblyomma javanense Ticks from Illegally Traded Malayan Pangolins

BACKGROUND: The Malayan pangolin (Manis javanica) is a critically endangered species that may harbor diverse zoonotic pathogens. This study aimed to characterize tick species parasitizing confiscated Malayan pangolins and determine the prevalence and genetic diversity of spotted fever group rickettsiae (SFGR) associated with these ticks. METHODS: We employed morphological and molecular approaches to identify ticks parasitizing pangolins confiscated in Guangdong Province between 2021 and 2024. A total of 435 adult ticks were collected from 32 pangolins and pooled into 87 groups (5 ticks per pool). Pooled tick samples were screened for SFGR by PCR targeting three rickettsial genes (gltA, ompA, and ompB), followed by Sanger sequencing and phylogenetic analysis. RESULTS: All collected ticks were identified as Amblyomma javanense. The pool positivity rate for SFGR was 41.4% (36/87), with a minimum infection rate of 8.3% (36/435; 95% CI: 5.8-11.2%). Molecular characterization identified the detected agent as Candidatus Rickettsia jingxinensis (Ca. Rickettsia jingxinensis), an agent recently confirmed to infect humans. CONCLUSION: These findings provide baseline data for tick-borne pathogen surveillance in the context of pangolin conservation and illegal wildlife trade control, highlighting the potential public health relevance of the pangolin-tick interface.