Detection of Rickettsia species in rodents collected in the Northern provinces of Vietnam, 2020–2022

Rickettsiae, which are obligate intracellular bacterial parasites, have a life cycle commonly associated with arthropod vectors and animal hosts. Rodents are recognized as their natural reservoir hosts and play a role in transmitting the bacteria to humans through arthropod vectors. The true extent of rickettsial infections in Vietnam remains underestimated due to a limited understanding of the disease’s epidemiology, resulting in a significant public health burden.

The aim of this investigation was to assess the prevalence of Rickettsia in wild-living rodents in Dien Bien, Son La, and Phu Tho provinces of Northern Vietnam between 2020 and 2022.

Materials and methods. A total of 396 wild-living rodents were collected from the Northern provinces of Vietnam during 2020–2022. Real-time polymerase chain reaction (PCR) was employed to detect the percentage of Rickettsia-positive specimens. Subsequently, the ompB and 17kDa genes were extracted, amplified, and sequenced from the Rickettsia-positive rodents.

Results and discussion. Among the 396 rodents examined, the majority were Rattus norvegicus (56.1%), followed by R. tanezumi (37.4%), R. nitidus (2.5%), and R. germaini (1.8%). R. korodentsensis and R. argentiverter constituted the remaining rodents, accounting for 2.2% of the total. The real-time PCR analysis revealed that 27 blood samples out of the 396 rodent samples collected, tested positive for Rickettsia (6.81%). R. germaini was shown to have the highest positive rate 1/8 (12.5%), followed by R. nitidus 1/10 (10.0%), R. tanezumi 14/149 (9.5%), and R. norvegicus 11/222 (4.9%). No other tick-borne pathogens were detected in any of the provinces. Sequencing of the positive samples as regards the ompB and 17kDa genes revealed the closest relation to R. felis. These findings highlight the potentially high risk of R. felis infection in humans and animals within the studied areas.

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