Henipavirus zoonosis: outbreaks, animal hosts and potential new emergence

Abstract

Hendra virus (HeV) and Nipah virus (NiV) are biosafety level 4 zoonotic pathogens causing severe and often fatal neurological and respiratory disease. These agents have been recognized by the World Health Organization as top priority pathogens expected to result in severe future outbreaks. HeV has caused sporadic infections in horses and a small number of human cases in Australia since 1994. The NiV Malaysia genotype (NiV-M) was responsible for the 1998–1999 epizootic outbreak in pigs with spillover to humans in Malaysia and Singapore. Since 2001, the NiV Bangladesh genotype (NiV-B) has been the predominant strain leading to outbreaks almost every year in Bangladesh and India, with hundreds of infections in humans. The natural reservoir hosts of HeV and NiV are fruit bats, which carry the viruses without clinical manifestation. The transmission pathways of henipaviruses from bats to humans remain poorly understood. Transmissions are often bridged by an intermediate animal host, which amplifies and spreads the viruses to humans. Horses and pigs are known intermediate hosts for the HeV outbreaks in Australia and NiV-M epidemic in Malaysia and Singapore, respectively. During the NiV-B outbreaks in Bangladesh, following initial spillover thought to be through the consumption of date palm sap, the spread of infection was largely human-to-human transmission. Spillover of NiV-B in recent outbreaks in India is less understood, with the primary route of transmission from bat reservoir to the initial human infection case(s) unknown and no intermediate host established. This review aims to provide a concise update on the epidemiology of henipaviruses covering their previous and current outbreaks with emphasis on the known and potential role of livestock as intermediate hosts in disease transmission. Also included is an up-to-date summary of newly emerging henipa-like viruses and animal hosts. In these contexts we discuss knowledge gaps and new challenges in the field and propose potential future directions.

Updated Insights into the Phylogenetics, Phylodynamics, and Genetic Diversity of Nipah Virus (NiV)

“…Since 2001, NiV-B showed more extensive circulation [ 27 ], justifying the higher number of genomes in the public databases. Bangladesh reported cases almost annually between 2004 and 2015, a pattern described in previous studies [ 28 , 29 , 30 ], with most outbreaks occurring in winter months.…”

One health and bat-borne henipaviruses

“…This process occurs through the interaction of two glycoproteins on the viral surface: an attachment protein (H, G, or HN, based on the extent of neuraminidase and/or hemagglutinin activities) and a fusion protein (F) [ 21 ]. These viruses employ ephrin-B2 and ephrin-B3 receptors to enter host cells [ 1 ]. This allows them to infect a wide range of tissues, including respiratory epithelium and neural cells.…”

“…Henipaviruses are a group of viruses that have the capability to be transmitted amongst the bats as well as other animal species and humans through spillover events. The primary viral organisms within this group encompass the Nipah virus (NiV) and Hendra virus (HeV), both of which belong to the genus Henipavirus in the family Paramyxoviridae [ 1 , 2 ]. The family Paramyxoviridae consists of a diverse collection of enveloped RNA viruses with single-stranded negative-sense genome, which infect both animals and humans [ 3 ].…”

A comparative genomic approach to decipher the mutations associated with Nipah viral human isolates from southeast Asia

“…The reported outbreaks from 1998 onwards indicated the dominance of the NiV-B clade compared with NiV-M, with the prevalence of the former in humans ( 13 ). This demands a thorough study to elucidate the underlying factors contributing to the observed variations in symptoms and mortality rates among individuals infected with NiV originating from disparate geographical locations.…”