Seroprevalence of babesiosis in immunocompetent and immunocompromised individuals

Interest in Babesia species is gaining an increasing attention as an emerging tick-borne pathogen. Infection is primarily transmitted through Ixodes ticks, and alternatively by blood transfusions from asymptomatic donors.

The aim of the study was detection of Babesia seroprevalence in different groups of population with the usage of experimental B. divergens whole-cell slide antigen and commercial B. microti immunofluorescence assay substrate slide.

Indirect immunofluorescence assay trial was performed by testing of 145 blood samples of different origins: healthy individuals (60 - blood donors), risk groups (30 - HIV-infected individuals, 30 - Lyme disease patients) and false-positive IFA controls (10 - seropositive rheumatoid arthritis patients, 15 - patients with toxoplasmosis).

The study revealed Babesia antibodies to B. divergens (6.9%) and B. microti (3.4%) that were detected with higher (p <0.05) frequency in HIV-infected individuals (26.7%) and in Lyme disease patients (16.7%) than at blood donors (1.7%). Diagnostically significant IgG titres were detected at 23.3% HIV-infected individuals, 13.3% Lyme disease patients and by 1.7% of blood donors and patients with seropositive latent toxoplasmosis. Specific IgM were detected at 20.0% HIV-infected individuals and 13.3% Lyme disease patients. 57.1% of diagnostically significant titres in HIV-infected and Lyme disease patients were represented by IgG and IgM.

Immunofluorescence assay has a limited use in babesiosis: in acute form with negative microscopy or PCR; in chronic, asymptomatic and subclinical form with low level of parasitemia; and in retrospective and epidemiological studies of the population immune structure. Clinicians need to have increased awareness of babesiosis, and further studies are needed to clarify the optimal management of this infection in risk groups (including HIV-infected patients and blood donors).