Molecular Identification ofRickettsiaSpecies inHaemaphysalisTicks Collected from Southwest China

Abstract

Rickettsia species are obligate intracellular Gram-negative bacteria that can infect a wide range of vertebrate hosts, including humans, through arthropod vectors such as Ixodid ticks. These ticks are a threat to humans and animals because they are the primary vectors or reservoirs for rickettsiae, which is of public health importance. In this study, we report the identification and percent of positive of Rickettsia spp. in ticks collected from Cangxi County, Southwest China. Haemaphysalis longicornis comprised 48.4% of the 188 ticks collected followed by Haemaphysalis flava (29.3%), H. doenitzi (12.2%), and Haemaphysalis hystricis (10.1%). A total of 63 (33.5%) ticks were positive with Rickettsia spp., with 48 (57%) of those being H. longicornis and 15 (27.3%) being H. flava. The other two tick species, however, did not have any ticks positive for rickettsial DNA. In addition, two different Rickettsia spp. were identified using gltA and ompA as molecular markers. The sequence of Rickettsia sp. infecting H. longicornis ticks was found to be identical to the Rickettsia sequences from Northeastern China and Japan (KF728367, AB516964). Phylogenetic analyses using these molecular markers support the notion that Rickettsia species from H. flava is the most close to a member of the Candidatus Rickettsia gannanii subgroup. The high percentage of Rickettsia positive in this Southwest China region suggests potential public health threat in the future and warrants to be monitored.

Case report: A case of sepsis caused by rickettsial infection-induced hemophagocytic syndrome

“…Proper fluid management is crucial for resuscitation, as positive water balance is linked to more extensive organ failure and mortality (13). Our investigation revealed that the sepsis was caused by rickettsial infection, an intracellular, specialized gram-negative bacterium that can infect humans through arthropods such as ticks (14). A study by P. Aarthi et al utilizing PCR-based DNA sequencing found that rickettsial infection could lead to neonatal sepsis (15).…”

Growth Characteristics of <i>Rickettsia</i> Species LON Strains Closely Related to <i>Rickettsia</i> <i>japonica</i> Isolated from <i>Haemaphysalis longicornis</i> Ticks in Mouse Derived L929 and Human-Derived THP-1 Host Cell Lines

“…Recently, the detection of rickettsial DNAs from H. longicornis ticks has been reported in Korea and China (17)(18)(19)(20). Some were likely to be identical, or similar, to gltA of LON-13 (AB516964) and the nomenclature was proposed as Candidatus Rickettsia longicornii, despite no live rickettsia isolated.…”