Rural Residents in China Are at Increased Risk of Exposure to Tick-Borne PathogensAnaplasma phagocytophilumandEhrlichia chaffeensis

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.

Occurrence of Anaplasma phagocytophilum in goats and sheep in Hebei Province, China

“…In these studies, the infection rates at different sampling sites varied from 0 to 78.1%, which implies an extensive distribution of this pathogen in China (22). The prevalence of A. phagocytophilum infection in sheep and goats in the regions surveyed in the current study was lower than in sheep and goats from Gansu Province (40.0%, 56/140) and central and Southeastern China (25.2%, 106/421), but higher than in goats from Henan (13.0%, 6/46), Jilin (5.7%, 8/35), and Hubei (14.5%, 10/69) (23). This may have been due to the sampling sites chosen, temporal effects on samples, the sampling method used, the distribution of the vectors, the different diagnostic methods used, or any other factor related to the ecological environment.…”

Analysis on epidemiological characteristics of 4 species natural-focal diseases in Shandong Province, China in 2009-2017: a descriptive analysis

“…First, with the advancement of China’s urbanization process and the expansion of enrollment in higher education institutions, a large number of middle-aged men and young people from rural areas have entered the city to work or study, and the elderly become the main force of agricultural production[34]. Therefore, elder people who had more opportunity to expose to insect vector when undertaking farm work than young people who work or study in cities except Spring Festival[35]. Second, the immune function of the elderly may be lower than young people.…”

The Seroprevalence of Anaplasma phagocytophilum in global human populations: a systematic review and meta‐analysis

“…In China, 46 confirmed and 16 probable cases were diagnosed from 2009 to 2010 with an 8.1% fatality rate (Zhang et al, 2013). However, seroprevalence studies suggest that the number of reported cases in China is underestimated (Zhang et al, 2014).…”