Background: Human strongyloidiasis has been included as a target for control and elimination in the NTD roadmap 2021–2030 by the WHO. Persons with primary or secondary immunodeficiency are at the highest risk of hyperinfection or disseminated strongyloidiasis. The NTD roadmap lays emphasis on planned surveillance and quantification of precise burden of strongyloidiasis. Though there are many case reports from India, there is a paucity of systematic surveillance for this helminth. In this study, we screened immunocompromised patients to quantify the burden of infection in this high-risk population.
Methods: Patients with immunosuppressive conditions and/or on steroids/cytotoxic medications from various specialties of our tertiary care hospital in North India were enrolled from December 2020 to March 2022. Their stool samples were subjected to microscopy, Agar plate, Baermann’s funnel and Harada Mori culture techniques, and 18S rRNA gene PCR. Serum samples were subjected to anti-Strongyloides IgG antibody ELISA (Bordier Affinity Products).
Results: A total of 166 serum samples were obtained, 27 (16.3%) of which were positive for IgG antibodies; 121 stool samples were obtained, 09 (7.4%) of which were positive by 18S rRNA PCR (LOD: 2.6 pg/µL); 02 of the PCR positive patients were seronegative. Of these 09 stool samples, only 03 (2.5%) were positive by microscopy and helminth culture. The infected patients were from various clinical specialties, belonged to both rural and urban localities, and were distributed across 07 states of India.
Conclusion: The screening of this cohort of immunocompromised patients from varied clinical specialties and geographical locations clearly show that Strongyloides infection is widely endemic in North India. Microscopy had a poor sensitivity and is liable to miss a large proportion of cases. IgG ELISA is a sensitive screening test but may not always indicate current infection and may need a confirmation by PCR in high-risk individuals. Well planned studies are required for mapping the hotspots and true prevalence of Strongyloides infection to meet the NTD roadmap 2021-2030 targets.