Acute Schistosomiasis With a Schistosoma mattheei x Schistosoma haematobium Hybrid Species in a Cluster of 34 Travelers Infected in South Africa

Background. Diagnosis of schistosomiasis remains elusive soon after infection. We evaluated several diagnostic methods in a cluster of travelers with simultaneous freshwater exposure in South Africa. Methods. Eosinophil count, schistosome antibody tests, stool and urine microscopy, and serum Dral PCR assays were performed at weeks 4-5 (early symptomatic phase), 7-8 (praziquantel treatment), and 13-14 (after treatment). Sequencing was done on serum samples from 3 patients to identify the species. Results. Of the 34 travelers (16 adults and 18 children), 32 developed symptoms 2-6 weeks after exposure. A raised eosinophil count (>750/mu L) was seen in 12 of 33 at weeks 4-5, and in 22 of 34 at weeks 7-8. Schistosoma antibodies were detected in 3 of 33 at weeks 4-5 and in 12 of 34 at weeks 7-8 and weeks 13-14. The Dral PCR result was positive in 24 of 33 travelers at weeks 4-5, in 31 of 34 at weeks 7-8, in 25 of 34 at weeks 13-14, and at least once in all. Ova were absent in all urine and stool samples obtained. Sequencing identified Schistosoma mattheei nuclear and Schistosoma haematobium mitochondrial DNA, indicative of a hybrid species. Conclusions. The Dral PCR confirmed the diagnosis in all exposed travelers at a much earlier stage than conventional tests. The causative species is probably an S. mattheei x S. haematobium hybrid.

Automated summary

The diagnosis of schistosomiasis in a group of travelers with freshwater exposure in South Africa was evaluated using various diagnostic methods. Results showed that eosinophil count, Schistosoma antibody tests, and PCR assays were effective in confirming the diagnosis, with sequencing identifying a hybrid species. These findings suggest that Dral PCR can confirm the diagnosis at an earlier stage than traditional tests and may be useful in identifying hybrid species.