Long-term follow-up of schistosomiasis serology post-treatment in Australian Travelers and Immigrants

Background. We undertook an observational follow-up study of schistosomiasis serology in both travelers and immigrants in a nonendemic country to determine the natural history of schistosomiasis antibody titer post-adequate treatment in those who have not been reexposed. Methods. Longitudinal study of all adult travelers and immigrants presenting to the Royal Melbourne Hospital, Australia with positive schistosomiasis serology (titer >1: 64) between July 1995 and December 2005. All patients were treated with praziquantel and followed up clinically and serologically for a period up to 30 months. Results. A total of 58 patients were included in the study including 26 travelers and 32 immigrants. Antibody titers often increased in the first 6 to 12 months post-treatment, especially in immigrants. After 30 months of post-treatment, 68% of travelers and 35% of immigrants (p < 0.01) achieved a fourfold antibody decline. Conclusions. Schistosomiasis antibody titers varied after adequate treatment. Therefore an increase in titer in the first 6 to 12 months or a failure to reduce after 3 years should not automatically justify re-treatment. © 2010 International Society of Travel Medicine.