Nipah Virus
Nipah virus is an enveloped RNA virus that is a member of the family Paramyxoviridae, genus Henipavirus and is genetically related to Hendra virus. The name 'Nipah' comes from the Malaysian village, where the first outbreak was reported in 1998 and 1999.
Fruit bats, which are also called flying foxes (Pteropus species), are the natural animal reservoir for Nipah virus. Nipah virus infection is a bat-borne zoonotic disease transmitted to humans through contact with infected animals or ingesting contaminated food. It can also be transmitted directly from person to person through close contact with an infected person or body fluids.
Outbreaks occur almost annually in parts of Asia, primarily Bangladesh and India. They are seasonal and coincide with the harvesting of date palm sap which can be contaminated with infected bat droppings. During February 2023, Bangladesh has confirmed 11 cases, 8 of them fatal. Ten patients had consumed date palm sap, while the illness in a 15-day-old infant was considered to be a secondary case.
The incubation period usually ranges from 4 to 14 days, but an incubation period up to 45 days has been reported. Nipah virus infection in humans can range from asymptomatic infection to severe. Infected people initially develop symptoms including fever, headache, myalgia, vomiting, and sore throat. The prodrome can be followed by dizziness, drowsiness, altered consciousness, and neurological signs that indicate acute encephalitis. Some people can also develop atypical pneumonia and acute respiratory distress. Encephalitis can lead to seizures and coma within 24 to 48 hours. Most people who survive acute encephalitis make a full recovery, but long-term neurologic conditions have been reported. Approximately 20% of patients have residual neurological consequences such as seizure disorder and personality changes.
The overall global case fatality rate is estimated at 40% to 75% depending on local capabilities for epidemiological surveillance and clinical management. Currently, there are no licensed vaccines or therapeutics available for the prevention or treatment of Nipah virus infection.
Nipah virus infection can be confirmed during the acute and convalescent phases of the disease by a combination of Real Time Polymerase Chain Reaction (RT-PCR) using throat and nasal swabs and serum antibody detection via enzyme-linked immunosorbent assay (ELISA). RT-PCR can also detect virus in cerebrospinal fluid, urine, and blood.
References
World Health Organization, Nipah virus infection – Bangladesh, 17 February 2023, https://www.who.int/emergencies/disease-outbreak-news/item/2023-DON442
Centers for Disease Control and Prevention, Nipah Virus, October 19, 2022, https://www.cdc.gov/vhf/nipah/index.html
Banerjee S. et al. Nipah virus disease: A rare and intractable disease, Intractable Rare Dis Res. 2019 Feb;8(1):1-8. doi: 10.5582/irdr.2018.01130. PMID: 30881850; PMCID: PMC6409114.
