An Immunofluorescence Test to Detect Serum Antibodies to Giardia lamblia

doi:10.1059/0003-4819-93-6-802

An Immunofluorescence Test to Detect Serum Antibodies to Giardia lamblia

Atlanta, Georgia; and Denver, Colorado

Abstract

We used an indirect immunofluorescence test with Giardia lamblia trophozoites as antigen to detect anti-G. lamblia antibodies in serum. Seventy-one patients and control subjects were studied in a blinded protocol. Titers in 29 of 30 patients with symptomatic giardiasis (1:16 to 1:1024) did not overlap titers in 19 healthy control subjects (1:2 to 1:4); titers in 15 patients with hookworm, Entamoeba histolytica, or intestinal bacterial overgrowth were 1:16 or less. Absorption of giardiasis patients' sera with G. lamblia trophozoites but not with E. histolytica, Trichomonas vaginalis, or Escherichia coli reduced the titers to, or nearly to, control values. Titers in individual sera were 93.9% reproducible within a fourfold or less dilution. Our results indicate that G. lamblia, an intestinal parasite often regarded as noninvasive, induces a systemic antibody response. The indirect immunofluorescence test for anti-G. lamblia antibodies is specific and reproducible; it may be useful in epidemiologic and immunologic studies of giardiasis.

Article and Author Information

▸From the General Parasitology Branch, Parasitology Division, Bureau of Laboratories, Center for Disease Control, U.S. Public Health Service, Atlanta, Georgia; and the Division of Gastroenterology, Department of Medicine, University of Colorado Health Sciences Center and the Veterans Administration Medical Center, Denver, Colorado.
Grant support: in part by the Medical Research Services of the Veterans Administration. Dr. Smith was supported by Career Development Grant No. 8007-01, CC 108, FCP 101 from the Veterans Administration.
The use of trade names is for identification only and does not constitute endorsement by the Public Health Service or by the U.S. Department of Health, Education, and Welfare.
▸Requests for reprints should be addressed to Phillip D. Smith, M.D.; Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Building 5, Room 118; Bethesda, MD 20205.