Anaplasmosis in farmers and domestic animals in Anhui province, China

Objective: To investigate the epidemiological status of anaplasmosis among farmers and domestic animals in Guangde County where the unusual nosocomial human to human transmission of human granulocytic anaplasmosis occurred in Anhui province and the index patient in this event lived, as well as Huaiyuan County and Mingguang City in Anhui province. Methods: From April to May in 2009, 596 farmers, 132 goats, 12 dogs and 6 cows was collected from Guangde, Mingguang and Huaiyuan counties and the IgG antibodies against A. phagocytophilum in farmers, goats, dogs and cattle was determined using an immunofluorescence assay (IFA). The A. phagocytophilum 16S rRNA gene was amplified from blood samples from domestic animals using nested PCR, and the genetic diversity of the 16S rRNA gene was analysed. Results: The percentage of farmers with IgG antibodies against A. phagocytophilum in the 3 survey counties was 33.7%, and the individual percentages for Guangde, Mingguang and Huaiyuan counties were 76.5%, 59.2% and 10.4%, respectively. The total seroprevalence in dogs, goats and cattle was 33.3%, 0.8% and 0%, respectively. The percentage of samples positive for amplification of the 16S rRNA gene of A. phagocytophilum in goats, dogs and cattle was 33.3%, 25.0% and 0%, respectively. Analysis of the genetic diversity of the 16S rRNA gene showed that there were two genotypes of A. phagocytophilum. Group A was endemic in Guangde County, which is located in the southeast of Anhui province, where the nosocomial human granulocytic outbreak of anaplasmosis in 2006 occurred. Group B was located north of Huaiyuan County. Conclusions: We concluded the prevalence of A. phagocytophilum among farmers and domestic animals in Anhui province was demonstrated, and diagnosis and differential diagnosis of zoonotic "rickettsial" infections should be emphasized in clinical practice. A systemic ecological survey should be conducted to reduce the public health threat to humans and animals. © 2012 Asian Pacific Tropical Medicine Press.