Prevalence and Molecular Characterization of Rickettsia spp. from Wild Small Mammals in Public Parks and Urban Areas of Bangkok Metropolitan, Thailand.

Artharee Rungrojn,Peeraya Ekchariyawat,Jiraphan Junjhon,Yossapong Paladsing,Stuart D Blacksell,Serge Morand,Kittipong Chaisiri

doi:10.3390/tropicalmed6040199

Abstract

Rural areas usually show a higher prevalence of rickettsial infection than urban areas. However, information on the rickettsial infection status in urban settings (e.g., built-up areas and city parks) is still limited, particularly in the Bangkok metropolitan area. In this study, we performed a molecular rickettsial survey of spleen samples of small mammals caught in public parks and built-up areas of Bangkok. Out of 198 samples, the Rattus rattus complex was found to be most prevalent. The amplification of rickettsial gltA fragment gene (338 bp) by nested PCR assay revealed positive results in four samples, yielding a low prevalence of infection of 2.02%. DNA sequencing results confirmed that three samples were matched with Rickettsia typhi, and one was identified as R. felis. It is noteworthy that this is the first report of the occurrence of R. felis DNA in rodents in Southeast Asia.

Highlights

Accepted: 4 November 2021Rickettsia are small, Gram-negative, obligate intracellular bacteria [1,2]
This study aimed to investigate the prevalence and characterize rickettsiae isolated from small mammals in Bangkok metropolitan area, from green areas, such as public parks
Between September and December 2018, small mammals were trapped at 7 public parks located in the Bangkok metropolitan area—Suan Luang Rama IX, Suan Lumpini, Suan Serithai, Suan Taweevanarom, Suan Thonburirom, Suan Vareepirom, and Suan Wachirabenjatas

Summary

Introduction

Rickettsia (order Rickettsiales; family Rickettsiaceae) are small, Gram-negative, obligate intracellular bacteria [1,2]. Rickettsia spp. are best known as vector-borne pathogens and include blood-sucking arthropod vectors, such as lice, ticks, fleas, and mites [1]. These pathogens infect a wide range of vertebrate hosts, such as small mammals and humans. The genus Rickettsia can be classified into four groups—a spotted fever group (SFG), typhus group (TG), transitional group, and non-pathogenic ancestral group [3]. A flea-borne acute febrile illness caused by the bacteria R. typhi of TG rickettsiae, has been reported worldwide. The mortality rate of murine typhus is low

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