Strongyloidiasis is an infection caused by the intestinal nematode Strongyloides stercoralis. Infected healthy individuals are usually asymptomatic, however it is potentially fatal in immunocompromised hosts due to its capacity to cause an overwhelming hyperinfection. Strongyloidiasis could be missed during routine screening because of low and intermittent larval output in stool and variable manifestations of the symptoms. We present two cases of strongyloidiasis occurring in children with solid organ malignancies suspected to have the infection based on their clinical conditions and treatment history for cancer. Both patients were diagnosed by molecular and serological tests and were successfully treated. Thus, strongyloidiasis in patients undergoing intensive treatment for malignancies should be suspected, properly investigated and treated accordingly.
Strongyloides stercoralis infection can persist in the host for several decades, and patients with cancer and other clinical conditions who are exposed to immunosuppressive therapy are at risk of developing hyperinfection.
Enzyme-linked immunosorbent assays (ELISAs) were developed for the detection of IgG, IgG4 and IgE antibodies against Strongyloides stercoralis. A commercial ELISA (IVD Research, USA) was also used, and the sensitivities and specificities of the four assays were determined. Serum samples from 26 patients with S. stercoralis infection and 55 patients with other infections or no infection were analysed. Sensitivities of the IgG4 , IgG, IgE and IgG (IVD) assays were 76.9%, 84.6%, 7.7% and 84.6%, respectively, while the specificities were 92.7%, 81.8%, 100% and 83.6%, respectively. If filariasis samples were excluded, the specificities of the IgG4 -ELISA and both IgG-ELISAs increased to 100% and 98%, respectively. A significant positive correlation was observed between IgG- and IgG4 -ELISAs (r = 0.4828; P = 0.0125). IgG- and IgG- (IVD) ELISAs (r = 0.309) were positively correlated, but was not significant (P = 0.124). Meanwhile there was no correlation between IgG4 - and IgG- (IVD) ELISAs (r = 0.0042; P = 0.8294). Sera from brugian filariasis patients showed weak, positive correlation between the titres of antifilarial IgG4 and the optical densities of anti-Strongyloides IgG4 -ELISA (r = 0.4544, P = 0.0294). In conclusion, the detection of both anti-Strongyloides IgG4 and IgG antibodies could improve the serodiagnosis of human strongyloidiasis. Furthermore, patients from lymphatic filariasis endemic areas who are serologically diagnosed with strongyloidiasis should also be tested for filariasis.