Indirect immunofluorescence test for human Babesia microti infection: antigenic specificity

Area of Science:

• Medical Parasitology
• Immunology
• Infectious Diseases

Background:

• Babesia microti is an important tick-borne parasite causing human babesiosis.
• Accurate serological diagnosis of B. microti infections is crucial for public health.
• Cross-reactivity in serological tests can complicate accurate diagnosis.

Purpose of the Study:

• To investigate the specificity of indirect immunofluorescence (IIF) tests for Babesia microti antibodies.
• To assess cross-reactivity with other parasitic organisms and tick-borne diseases.
• To identify potential geographic foci of B. microti infection.

Main Methods:

• Indirect immunofluorescence (IIF) assay performed on human sera.
• Testing for cross-reactivity against various Babesia species, other blood/tissue parasites, and tick-borne organisms.
• Analysis of sera from patients with suspected Rocky Mountain spotted fever and from a North Carolina population.

Main Results:

• B. microti antisera exhibited cross-reactivity with other Babesia species, particularly during the acute phase.
• Cross-reactions with malaria, Colorado tick fever, and other parasitic diseases were infrequent.
• Four patients with Rocky Mountain spotted fever showed elevated B. microti titers.
• Six of 185 children in North Carolina had high B. microti IIF titers (≥1:256).

Conclusions:

• The IIF test for B. microti shows some cross-reactivity with related species, necessitating careful interpretation.
• Potential diagnostic confusion exists with other tick-borne illnesses like Rocky Mountain spotted fever.
• Evidence suggests a possible endemic focus of B. microti infection in humans in North Carolina.