Hantavirus hemorrhagic fever with renal syndrome (HFRS) is an emerging zoonotic disease in Europe and Asia, which is clinically indistinguishable from leptospirosis. A total of 1,032 patients with clinical suspicion of HFRS-like illness were included in the analysis from March 2013 to March 2021. Of these, 168 were positive for hantavirus immunoglobulin M (IgM) antibodies. Thirty-one of 35 patients had a 4-fold increase in IgG antibody titer with paired serum, confirming acute hantavirus infections. The detected antibodies showed a diverse pattern, strongly cross-reacting with the Seoul, Hantaan, and Puumala virus antigens. All the IgM-positive patients had no serological evidence of acute dengue or leptospirosis and had classical features of HFRS, including fever, thrombocytopenia, and renal involvement. More than 90% of patients had a history of rodent exposure 2-3 weeks prior to the onset of the fever. The highest number of positive cases was diagnosed in the Western and North Central Provinces of Sri Lanka during the paddy harvesting seasons. A significant number of patients develop severe complications with high mortality rates. Therefore, hantavirus infection should be considered as a differential diagnosis for leptospirosis-like illnesses in Sri Lanka.
Keywords: HFRS; Hantavirus; Sri Lanka.