Is eosinophilia a reliable diagnostic clue for chronic strongyloidiasis? a case series from Khuzestan Province, Iran

Strongyloidiasis, a disease caused by Strongyloides stercoralis (S. stercoralis) nematode, can present in acute, chronic, hyperinfection, and disseminated forms. It is of particular important due to its high mortality rate, especially among immunocompromised patients, and the absence of a gold standard diagnostic method. Eosinophilia, as a key sign, can help in the diagnosis of the infection. This report presents five cases of strongyloidiasis who referred to the 17 Shahrivar Hospital, Abadan County, Iran, for various reasons, including cardiovascular diseases, elective surgeries, and routine health check-ups. Persistent eosinophilia and intermittent gastrointestinal and respiratory symptoms in their medical histories raised suspicion of an intestinal infection. S. stercoralis detection was performed by Enzyme Linked Immunosorbent Assay (ELISA), direct microscopy examination, and agar plate culture (APC). While all cases exhibited elevated IgG titers, S. stercoralis larvae were detected by direct microscopy examination in two cases (later confirmed by APC), and three additional cases, despite being microscopy-negative, tested positive through APC. Two patients were also infected with Giardia intestinalis, which one of them had Blastocystis hominis as well. Eosinophilia, can help identify parasitic infections, but its nonspecificity requires careful evaluation of the patient's medical history. In three of the cases, the final diagnosis was obtained using serial stool examination and APC. Thus, considering eosinophilia, the best strategy for optimal diagnosis of this infection involves combining serological and coprological methods along with identifying risk factors.