BartonellaSpecies and Trombiculid Mites of Rats from the Mekong Delta of Vietnam

Abstract

A survey of Bartonella spp. from 275 rats purchased in food markets (n=150) and trapped in different ecosystems (rice field, forest, and animal farms) (n=125) was carried out during October, 2012–March, 2013, in the Mekong Delta of Vietnam. The overall Bartonella spp. prevalence detected by culture and PCR in blood was 14.9% (10.7–19.1%), the highest corresponding to Rattus tanezumi (49.2%), followed by Rattus norvegicus (20.7%). Trapped rats were also investigated for the presence and type of chiggers (larvae of trombiculid mites), and Bartonella spp. were investigated on chigger pools collected from each rat by RT-PCR. A total of five Bartonella spp. were identified in rats, three of which (B. elizabethae, B. rattimassiliensis, and B. tribocorum) are known zoonotic pathogens. Among trapped rats, factors independently associated with increased prevalence of Bartonella spp. included: (1) Rat species (R. tanezumi); (2) the number of Trombiculini–Blankaartia and Schoengastiini–Ascoschoengastia mites found on rats; and (3) the habitat of the rat (i.e., forest/fields vs. animal farms). The prevalence of Bartonella infection among chiggers from Bartonella spp.–positive R. tanezumi rats was 5/25 (25%), compared with 1/27 (3.7%) among Bartonella spp.–negative R. tanezumi rats (relative risk [RR]=5.4, 95% confidence interval [CI] 0.68–43.09). The finding of Bartonella spp.–positive chiggers on Bartonella spp.–negative rats is strongly suggestive of a transovarial transmission cycle. Rats are ubiquitous in areas of human activity and farms in the Mekong Delta; in addition, trapping and trading of rats for food is common. To correctly assess the human risks due to rat trapping, marketing, and carcass dressing, further studies are needed to establish the routes of transmission and cycle of infection. The widespread presence of these zoonotic pathogens in rats and the abundance of human—rat interactions suggest that surveillance efforts should be enhanced to detect any human cases of Bartonella infection that may arise.

Bartonella Bacteria in Urban Rats: A Movement From the Jungles of Southeast Asia to Metropoles Around the Globe

“…The species isolated from these rats were B. rattimassiliensis, B. tribocorum, B. elisabethae, B. coopersplainensis, and B. queenslandensis (corresponding to 43.8, 21.9, 18.8, 9.4, and 6.3% of 32 Bartonella-infected rats. Two species (B. rattimassiliensis and B. coopersplainensis) were identified in R. tanezumi only, while all other species of Bartonella were detected at least in two rat species (Loan et al, 2015). The prevalence of Bartonella species in rats from rural parts of Vietnam (Mekong Delta) was significantly lower than in Saigon Port, but the diversity of the species was evidently higher.…”

“…Bartonella sequences obtained from rats of several Rattus species from Southeast Asia represented over 40 different genetic variants and clustered into nine lineages (Jiyipong et al, 2012). All described rat-adapted Bartonella species were identified in rats (R. argentiventer, R. tanezumi, R. norvegicus, and Bandicota indica) from the Mekong Delta in Vietnam (Loan et al, 2015). The prevalence of Bartonella infection among rats trapped in farms, filed, and forest was 22.4%, much higher than the infection prevalence in rats that were purchased in city markets (8.7%).…”

“…The patient had no history of exposure to cats or other pets or intravenous drug use. A source of the infection remained mysterious until Ellis et al (1999) found relatively similar bacteria in rats from the U.S. Ying et al (2002) reported a variety of similar bacteria in rats in Southern China and, finally, an identical bacterium was found to be prevalent in rats from Vietnam (Loan et al, 2015). Later, an identical bacterium was identified in a febrile patient in Bangladesh (Faruque et al, 2017).…”

Occurrence rates of wild rodent hosts and chigger mites and the infection rate ofOrientia tsutsugamushiin the central region of South Korea from 2015 to 2018

“…The most common hosts are rodents, but chigger mites are also known to parasitize birds, amphibians, reptiles, invertebrates, and arthropods (Traub & Wisseman ; Loan et al . ). After 2–3 days of feeding on animal tissue fluid, the chigger mites return to the ground.…”

“…mostly live underground, but, during their development into adults, these species' larvae consume tissue fluid from wild animals, whom they temporarily parasitize (Lipovsky 1954;Lerdthusnee et al 2002). The most common hosts are rodents, but chigger mites are also known to parasitize birds, amphibians, reptiles, invertebrates, and arthropods (Traub & Wisseman 1974;Loan et al 2015). After 2-3 days of feeding on animal tissue fluid, the chigger mites return to the ground.…”