Rural residents in China are at increased risk of exposure to tick-borne pathogens Anaplasma phagocytophilum and Ehrlichia chaffeensis.

Lijuan Zhang,Shijun Lao,Weihong Li,Yong Wang,Fang Huang,Yonggen Zhang,Hong Liu,Weiming Li,Jieying Yin,Yuming Jin,Manli Bao,Qiyi Xu,Liang Li,Xiaoyan Tang,Qiang Yu,Xueqin Cheng,Litao Chang,Xiuchun Zhang,Zhilun Zhang,Bin Wu,Qunying Lu,Shiwen Wang,Desheng Fan,Lina Tian,Juan Li,Ying Zhang,Zhiyong Guan ,Mingfeng Cao ,Haowen Yang ,Bingying Xu ,Yuanli Shi

doi:10.1155/2014/313867

Abstract

As emerging tick born rickettsial diseases caused by A. phagocytophilum and E. chaffeensis, anaplasmosis and ehrlichiosis have become a serious threat to human and animal health throughout the world. In particular, in China, an unusual transmission of nosocomial cases of human granulocytic anaplasmosis occurred in Anhui Province in 2006 and more recent coinfection case of A. phagocytophilum and E. chaffeensis was documented in Shandong Province. Although the seroprevalence of human granulocytic anaplasmosis (former human granulocytic ehrlichiosis, HGE) has been documented in several studies, these data existed on local investigations, and also little data was reported on the seroprevalence of human monocytic ehrlichiosis (HME) in China. In this cross-sectional epidemiological study, indirect immunofluorescence antibody assay (IFA) proposed by WHO was used to detect A. phagocytophilum and E. chaffeensis IgG antibodies for 7,322 serum samples from agrarian residents from 9 provinces/cities and 819 urban residents from 2 provinces. Our data showed that farmers were at substantially increased risk of exposure. However, even among urban residents, risk was considerable. Seroprevalence of HGA and HME occurred in diverse regions of the country and tended to be the highest in young adults. Many species of ticks were confirmed carrying A. phagocytophilum organisms in China while several kinds of domestic animals including dog, goats, sheep, cattle, horse, wild rabbit, and some small wild rodents were proposed to be the reservoir hosts of A. phagocytophilum. The broad distribution of vector and hosts of the A. phagocytophilum and E. chaffeensis, especially the relationship between the generalized susceptibility of vectors and reservoirs and the severity of the disease's clinical manifestations and the genetic variation of Chinese HGA isolates in China, is urgently needed to be further investigated.

Highlights

Anaplasmosis and ehrlichiosis are emerging tick-borne rickettsial diseases (TBRDs) caused by the obligate intracellular bacteria Anaplasma phagocytophilum and Ehrlichia chaffeensis, respectively [1,2,3]
A recent national investigation assessing the epidemiological status of A. phagocytophilum among domestic animals in 10 provinces/cities in China showed that some domestic animals including dogs, goats, and cattle might be important reservoirs hosts of A. phagocytophilum [5]
57% of residents were engaged in planting crops; 23% of residents were engaged in planting fruit; 4% of residents were engaged in feeding domestic animals; and 16% of investigated individuals were preschool children, students, or retired people

Summary

Introduction

Anaplasmosis and ehrlichiosis are emerging tick-borne rickettsial diseases (TBRDs) caused by the obligate intracellular bacteria Anaplasma phagocytophilum and Ehrlichia chaffeensis, respectively [1,2,3]. These two rickettsiae are both in the family Anaplasmataceae but are in different genera. A recent national investigation assessing the epidemiological status of A. phagocytophilum among domestic animals in 10 provinces/cities in China showed that some domestic animals including dogs, goats, and cattle might be important reservoirs hosts of A. phagocytophilum [5]. A recent investigation assessing the seroepidemiological status of E. chaffeensis among rural residents in Beijing indicated that the seroprevalence was 16.4% [13]

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