The primary objective of this clinical investigation is to determine the percentage of travelers and migrants diagnosed with chronic schistosomiasis according to site-specific diagnostic practice who have active infection at the time of evaluation (as assessed and classified by composite reference standards that integrate clinical, laboratory, and diagnostic features, such as microscopy, PCR (where available), POC-CCA (where available), and serum CAA results).

All subjects with chronic schistosomiasis according to site-specific diagnostic practice will have a standardized baseline clinical and laboratory evaluation at the time of evaluation that will include blood sampling for hematology, schistosome serology available at each site, and schistosome PCR where available; urine sampling for microscopy, determination of hematuria as an indirect marker of morbidity for schistosomiasis, and Schistosome PCR (where available), and urine strip testing POC-CCA (where available); and stool sampling for microscopy and PCR, where available, and fecal occult blood as indirect markers of schistosomiasis morbidity.

Composite reference standards will be used to assess and classify the activity of the infection. Organ-specific ultrasound and other tests will be left to the physician's decision, but results will also be collected.

Serum (at least 1 ml remaining from routine diagnostics) will be sent to LUMC, the Netherlands, where CAA will be determined with the UCP-LF CAA test designed for routine use.

Participants will be asked to sign an additional consent form, which is optional and not precluding enrollment in the study, to allow the remaining serum to be stored at LUMC for 15 years, to allow secondary research.

Inclusion criteria

1. diagnosis of chronic schistosomiasis (>3 months after last potential exposure) according to site-specific diagnostic practice
2. signed informed consent (and assent for minors).

Exclusion criteria

1. age below 5 years;
2. exposure to praziquantel after the last potential exposure to schistosomes
3. acute infection, i.e. likely infection <3 months before presentation