Epidemiology and Diversity of Rickettsiales Bacteria in Humans and Animals in Jiangsu and Jiangxi provinces, China

Abstract

Diseases caused by Rickettsiales bacteria are a global public health problem. To better understand the diversity and origins of Rickettsiales infection in humans and animals, we sampled 134 febrile patients, 173 rodents and 43 shrews, as well as 358 ticks, from two cities in Jiangsu and Jiangxi provinces, China. Our data revealed a relatively high prevalence of scrub typhus cases in both localities. In addition, both serological tests and genetic analysis identified three patients infected with Anaplasma bovis, Rickettsia monacensis, and Orientia tsutsugamushi bacteria. Molecular epidemiological investigation revealed the co-circulation of multiple species of Rickettsiales bacteria in small mammals and ticks in both provinces, potentially including novel bacterial species. In sum, these data demonstrate the ongoing importance of Rickettsiales infection in China and highlight the need for the regular surveillance of local arthropods, mammals and humans.

Figure 1

Annual number of cases of scrub typhus in Yancheng and Ganzhou cities, China, 2008–2017.

Figure 2

Map showing the location of sample collection sites in Yancheng city (Jiangsu province) and Ganzhou city (Jiangxi province), China.

Figure 3

Phylogenetic trees based on the partial rrs gene sequences of Rickettsia (A), Anaplasma (B), Ehrlichia (C), and the TSA56 gene sequences of Orientia tsutsugamushi (D). All trees were mid-point rooted for clarity only. Bootstrap values (>70%) are shown for appropriate nodes. The scale bar represents number of nucleotide substitutions per site. The sequences from patient samples are marked in red, those from rodents and shrews are marked in blue, and sequences from ticks are marked in orange.

Figure 4

Phylogenetic tree based on partial groEL gene sequences of the Anaplasmataceae. The tree was mid-point rooted for clarity only. Bootstrap values (>70%) are shown for appropriate nodes. The scale bar represents number of nucleotide substitutions per site. Taxa shown in blue were obtained from rodents and shrews.