Introduction: Diagnosis of acute schistosomiasis in the early stage of infection is elusive. A cluster of concomitantly exposed patients offers an excellent opportunity to compare different diagnostic tools. Aim: To compare the performance of standard diagnostic tests and molecular tools for the diagnosis of acute phase Schistosoma infection in a cluster of travellers exposed to infested freshwater in an endemic region. Methods: Patients were subjected to eosinophil count, schistosome antibody tests (ELISA and IHA assay), ova detection in feces and urine by microscopy and PCR assays targeting the Dra1 sequence of the S. haematobium complex and the Sm1-7 sequence of the S. mansoni complex in serum samples from the early phase (week 4-5) and during week 7-8. Results: Nineteen to 41 days after freshwater exposure in South-Africa, 32/34 (94%) travellers developed symptoms. Of the 33 patients evaluated at week 4-5, the eosinophil count was increased (>750/µL) in 12 (36%) and Schistosoma antibodies were detected in 3 (9%) by IHA but in none by ELISA. Ova were absent in all 33 urine and all 31 feces samples. The Dra1 PCR was positive in 24 (73%) travellers. The Sm1-7 PCR in serum was positive in only one, which was also positive with the Dra1 PCR. Sequencing is ongoing to identify the (hybrid) species. At week 7-8, all 34 travellers were tested, of which 22 (65%) demonstrated an increased eosinophil count and 12 (35%) seroconverted with ELISA. The IHA test was negative in 14 and invalid in 20 travellers. Eggs were still absent in all 34 urine and 32 examined fecal samples. By week 7-8, the Dra1 PCR was positive in the patient not initially tested, and turned positive in an additional 6, giving a total diagnostic yield for this test of 31/34 (91%) patients. Conclusion: In this cluster of exposed travellers, the schistosome infection rate was extremely high. PCR was able to diagnose infection at an earlier stage than any of the standard diagnostic tests. Whether the 3 patients with negative test results were not infected remains to be evaluated by follow-up.