Seroplrevalence of Anaplasma phagocytophilum and Ehrlichia sp. among people affected by tick bites

   Background. In spring and summer, the population of the Baikal region regularly comes into contact with the pathogens transmitted through the bites of ixodid ticks. In the Center for Diagnosis and Prevention of Tick-Borne Infections (Irkutsk, Russian Federation), we annually detect anaplasmas of the Anaplasma phagocytophilum species, as well as Ehrlichia chaffeensis/E. muris in both ixodid ticks and blood samples from people who have been bitten by ticks. At the same time, there are no data in open sources on the incidence of human granulocytic anaplasmosis and human monocytic ehrlichiosis in the Baikal region. Currently, there is very little information on the studies of intensity of the immune response to anaplasmas and ehrlichia in people living in the surveyed area, although this information is critical for assessing the frequency of contacts and the risk of infection of people in a territory endemic for tick-borne infections.   The aim. To update information on the presence and prevalence of specific immunoglobulins M and G to A. phagocytophilum and Ehrlichia sp. among the population of the Irkutsk Region affected by tick bites.   Materials and methods. In total, 204 samples of blood serum from the residents of the Irkutsk Region who were registered to be bitten by ticks were analyzed for the presence of IgM and IgG to human monocytic ehrlichiosis and human granulocytic anaplasmosis agents.   Results. IgG to A. phagocytophilum were found in 9 samples, IgG to E. chaffeensis/E. muris – in 1 sample; no IgM to both pathogens were found in any sample.   Conclusions. The results obtained indicate regular infection of the population with anaplasmas and ehrlichia which is a testifies to the existence of active natural foci of human monocytic ehrlichiosis and human granulocytic anaplasmosis in the Baikal region. To clarify the real epidemic role of these infections, a detailed study of the immune status is required both among healthy individuals and among patients with symptoms of an infectious disease.