Metagenomic Next-generation Sequencing Aids Diagnosis of Leishmania donovani-associated Hemophagocytic Lymphohistiocytosis in Infants: Case Report and Systematic Review

Diagnosing hemophagocytic lymphohistiocytosis (HLH) triggers in infants is challenging. In a 9-month-old boy with unresponsive fever and pancytopenia, conventional tests were negative. Metagenomic next-generation sequencing detected Leishmania donovani , confirming Leishmania donovani -associated HLH. Targeted antiparasitic therapy replaced empiric immunosuppression, leading to rapid recovery. This case demonstrates that metagenomic next-generation sequencing is crucial for rapid pathogen identification in critically ill infants with HLH of unknown cause.