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

Abstract

Background Diagnosis of schistosomiasis remains elusive soon after infection. We evaluated several diagnostic methods in a cluster of travelers simultaneously exposed to freshwater in South Africa. Methods Eosinophil count, schistosome antibody tests, stool and urine microscopy, and serum Dra1 PCR assays were performed at week 4-5 (w4-5, early symptomatic phase), week 7-8 (w7-8, praziquantel treatment), and week 12-14 (w12-14, post-treatment). Sequencing was done on serum of 3 patients to identify the species. Results Of the 34 travelers (16 adults, 18 children), 32 developed symptoms 2 to 6 weeks after exposure. A raised eosinophil count (>750/µL) count was seen in 12/33 at w4-5, and in 22/34 at w7-8. Schistosoma antibodies were detected in 3/33 at w4-5, in 12/34 at w7-8 and w12-14. The Dra1 PCR was positive in 24/33 travelers at w4-5, in 31/34 at w7-8, in 25/34 at w12-14, and at least once in all. Ova were absent in all urine and fecal samples obtained. Sequencing identified S. mattheei nuclear and S. haematobium mitochondrial DNA, indicative of a hybrid species. Conclusion The Dra-1 PCR confirmed diagnosis in all exposed travelers at a much earlier stage than conventional tests. The causative species is probably a S. mattheei x S. haematobium hybrid.

New Insights on Acute and Chronic Schistosomiasis: Do We Need a Redefinition?

“…Recently, volunteers were exposed to male-only schistosome parasites and developed Katayama syndrome despite the absence of eggs [58] (Figure 2A). Similarly, a cluster of Katayama cases has been observed in exposed Belgian travelers returning from South Africa, where recent infection due to S. haematobium-Schistosoma mattheei hybrids was detected based on PCR only in the absence of detectable eggs [59]. Pulmonary nodules seem to be therefore unrelated to 'inflammatory' pulmonary symptoms, both in the early [6,60] and chronic [14] phase of infection.…”

Schistosomes in the Lung: Immunobiology and Opportunity

“…mattheei hybrid, shown to be infertile, symptoms of acute schistosomiasis developed 16-41 days post exposure, with fever, muscle ache and cough the most common symptoms (present in 50-69% of patients). Notably, schistosome eggs were not detected in stool or urine (via PCR or microscopy), although parasite infection was confirmed by PCR on serum (55). Katayama syndrome also occurred in a pioneering study of human experimental schistosome infection with male parasites alone (preventing egg production) (54), although only 1 out of 17 (6%) of the volunteers experienced pulmonary symptoms (cough) (56).…”

“…Nodular lesions have been shown to occur in response to clusters of schistosome eggs, with histological analysis of lung biopsies revealing eosinophilic granulomas surrounding these eggs (53). However, recent studies have supported the idea that egg deposition is not required for Katayama syndrome (54,55).…”

Future schistosome hybridizations: Will all Schistosoma haematobium hybrids please stand-up!

“…We should now be especially mindful of more distant species variants, particularly given ancestral genomic signatures [22] as well as more obvious recent ones, have been brought to light by detection of S. mansoni-haematobium hybrids in a migrant boy, even though the viability of their progeny was not determined [23]. Of recent note also is the report of an infection cluster of prepatent S. haematobium-mattheei hybrids, with evidence of S. mansoni infection, as detected in returned Belgium travellers from South Africa that were subjected to a more in-depth diagnostic investigation with molecular methods than usual routine practice [24].…”