Secondary Human-to-human Transmission of Nipah Virus in an Ambulance, Northwestern Bangladesh, February 2019

Abstract

Nipah virus (NiV) infection is a zoonotic disease with epidemic potential due to its human-to-human transmission. In Bangladesh, where NiV infection is frequent, NiV spillover from fruit bats to humans usually occurs in winter. This study aimed to describe the magnitude and scope of a NiV outbreak in February 2019, identify the source of infection, and contain the spread of disease. We interviewed the cases’ family members, conducted verbal autopsies, and collected samples for laboratory tests. Five family members reported died from, at the time, an unknown disease. All had fever, altered mental status, vomiting and diarrhea. Reverse transcription polymerase chain reaction confirmed NiV in one person. We suspected secondary transmission occurred when the family traveled with the primary case from their house to the hospital by ambulance. The trip took 8.5 hours and no one wore a face mask or gloves. The secondary attack rate among ambulance travelers was 67%. In this outbreak, NiV was transmitted human-to-human among riders in the ambulance. We recommend that everyone should use protective measures while traveling with suspected NiV infected patients to reduce the risk of transmission. Strengthening the existing Nipah virus surveillance system may generate earlier notification and response to contain further transmission.