Immunodiagnosis of giardiasis by ELISA and studies on cross-reactivity between the anti-Giardia lamblia antibodies and some heterologous parasitic antigens and fractions.

Specific antibodies against Giardia lamblia in 92 sera from asymptomatic carriers were investigated by ELISA. Using cyst antigen, antibodies were detected in 91 of the sera, by means of alkaline phosphatase-labelled antispecies immunoglobulin. The E/405nm values of the positive sera ranged between 0.350 and 1.700, whereas in the 78 control sera they were 0.270 +/- 0.220. Cross-reactivity between the anti-G. lamblia antibodies and 18 heterologous parasitic antigens and fractions was also studied. Cross-reactions were observed with antigens of Toxoplasma gondii, Sarcocystis spp., Leishmania donovani, Fasciola hepatica Y, F. hepatica I, Echinococcus granulosus AM, Cysticercus tenuicollis, Taenia saginata, Dipylidium caninum Y, D. caninum I, Trichuris suis Y, T. suis I, Trichinella spiralis and Litomosoides carinii. No cross-reactions were observed with the antigens and fractions of Entamoeba histolytica, Dicrocoelium dendriticum, Schistosoma mansoni and Echinococcus granulosus Y. The results show that the ELISA could be easily and very successfully applied for routine diagnosis of giardiasis.