Since 2019, the Institute of Epidemiology, Disease Control and Research (IEDCR), Bangladesh, has been conducting a nationwide surveillance of leptospirosis across eight sentinel sites by detection of IgM antibodies and confirmatory PCR testing (https://iedcr.portal.gov.bd/site/page/4dd56857-84df-4269-b341-04e9e8a55725, accessed on 14 March 2025). The gene discussed is CD40LG; the disease is leptospirosis.