Global epidemiology and risk factors of nipah virus infection in human, 1998–2018

Objective To understand the epidemiology characteristics and risk factors of nipah virus infection in the world.

Methods According to the WHO case definition of nipah virus infection in 2004, we describe the spatial, temporal and population distributions of nipah virus infection in the world and analyze the risk factors by using the data from website of WHO and PubMed.

Results From September 1998 to June 2018, a total of 662 nipah virus infection cases, including 369 deaths, were reported in 5 countries, the case fatality rate was 55.7%. Before 2000, only Malaysia (283 cases) and Singapore (11 cases) reported nipah virus infection cases. During 2001–2010, 155 and 71 cases were reported by Bangladesh and India respectively. Since 2011, nipah virus infection cases have been reported by Bangladesh (106 cases), India (19 cases) and Philippines (17 cases). The case fatality rate increased from 38.5% in Malaysia and 9.1% in Singapore before 2000 to 62.6% in Bangladesh and 70.4% in India during 2001–2010 and to 81.1% in Bangladesh, 89.5% in India and 52.9% in Philippines after 2011. Among the reported cases, 623 (97.4%) occurred during January–May. The risk factors for nipah virus infection included close contact with sick pig in Malaysia and Singapore and human to human transmission and drinking of date palm sap contaminated by fruit bat in Bangladesh and India.

Conclusion Nipah virus infection had spread from Western Pacific Region to Southeast Asia and a rising trend was noted for the case fatality rate. Also, the cases were mainly reported in the harvested season of date palm sap in Western Pacific Region and Southeast Asia.