Strongyloides and COVID-19: Challenges and Opportunities for Future Research

Strongyloides stercoralis hyperinfection presenting pneumatosis intestinalis and acute respiratory distress syndrome after treatment for COVID-19

A 91-year-old man was admitted with vomiting and abdominal pain. He had had COVID-19 pneumonia a month before and the treatment had consisted of remdesivir, dexamethasone and baricitinib. CT scans showed pneumatosis intestinalis. His respiratory condition rapidly deteriorated and chest CT scans showed ground-glass opacity and Strongyloides stercoralis was identified in the sputum, making a diagnosis of hyperinfection syndrome associated acute respiratory distress syndrome. Treatment of ivermectin was not achieved in time and he died of multiple organ failure. S. stercoralis is a soil-transmitted helminth endemic to tropical and subtropical areas. Immunosuppressive conditions can cause hyperinfection syndrome and life-threatening conditions. Our case highlights the importance of assessing for untreated chronic strongyloidiasis in COVID-19 patients requiring steroid treatment in endemic areas.

Strongyloidiasis

Strongyloidiasis is a neglected tropical disease caused primarily by the roundworm Strongyloides stercoralis. Strongyloidiasis is most prevalent in Southeast Asia and the Western Pacific. Although cases have been documented worldwide, global prevalence is largely unknown due to limited surveillance. Infection of the definitive human host occurs via direct skin penetration of the infective filariform larvae. Parasitic females reside in the small intestine and reproduce via parthenogenesis, where eggs hatch inside the host before rhabditiform larvae are excreted in faeces to begin the single generation free-living life cycle. Rhabditiform larvae can also develop directly into infectious filariform larvae in the gut and cause autoinfection. Although many are asymptomatic, infected individuals may report a range of non-specific gastrointestinal, respiratory or skin symptoms. Autoinfection may cause hyperinfection and disseminated strongyloidiasis in immunocompromised individuals, which is often fatal. Diagnosis requires direct examination of larvae in clinical specimens, positive serology or nucleic acid detection. However, there is a lack of standardization of techniques for all diagnostic types. Ivermectin is the treatment of choice. Control and elimination of strongyloidiasis will require a multifaceted, integrated approach, including highly sensitive and standardized diagnostics, active surveillance, health information, education and communication strategies, improved water, sanitation and hygiene, access to efficacious treatment, vaccine development and better integration and acknowledgement in current helminth control programmes.