Studies on filariasis in Singapore: immunodiagnosis using indirect immunofluorescence

Filarial antibodies were detected by the indirect fluorescent antibody (IFA) technique using sonicated microfilariae of Brugia malayi as antigen. Of the 324 sera of patients with clinical symptoms suggestive of filarial infection, 90 (28%) had detectable antibodies with titres ranging from 1 : 4 to 1 : 4096. Forty-six percent of patients with eosinophilic lung were positive with titres ranging from 1 : 4 to 1 : 1024. Highest rates of positives were seen in Indians (48%) with lower rates in Malays (36%) and Chinese (15%).