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What is Nipah virus?

Nipah virus (NiV) was initially isolated in 1999 upon examining samples from an outbreak of encephalitis and respiratory illness among adult men in Malaysia and Singapore. Its name originated from Sungai Nipah, a village in the Malaysian Peninsula where pig farmers became ill with encephalitis.

Nipah virus, along with Hendra virus comprises a new genus designated Henipavirus in the subfamily Paramyxovirinae.

Pteropus giganteus Image/Video Screen Shot

Pteropus giganteus
Image/Video Screen Shot

Fruit bats of the genus Pteropus have been identified as natural reservoirs of NiV.

According to the World Health Organization-Regional Office of South-East Asia, infected bats shed virus in their excretion and secretion such as saliva, urine, semen and excreta but they are symptomless carriers. The NiV is highly contagious among pigs, spread by coughing. Direct contact with infected pigs was identified as the predominant mode of transmission in humans when it was first recognized in a large outbreak in Malaysia in 1999. Ninety percent of the infected people in the 1998-1999 outbreaks were pig farmers or had contact with pigs.

Luby, et al reported in 2009, the primary pathways of transmission from bats to people in Bangladesh are through contamination of raw date palm sap by bats with subsequent consumption by humans and through infection of domestic animals (cattle, pigs, and goats), presumably from consumption of food contaminated with bat saliva or urine with subsequent transmission to people. Approximately one-half of recognized Nipah case patients in Bangladesh developed their disease following person-to-person transmission of the virus.

From the paper, Transmission of Human Infection with Nipah Virus, the authors write:

The most frequently implicated route is ingestion of fresh date palm sap. Date palm sap is harvested from December through March, particularly in west central Bangladesh. A tap is cut into the tree trunk and sap flows slowly overnight into an open clay pot. Infrared camera studies confirm that P. giganteus bats frequently visit date palm sap trees and lick the sap during collection . NiV can survive for days on sugar-rich solutions such as fruit pulp. Most date palm sap is processed at high temperature to make molasses, but some is enjoyed as a fresh juice, drunk raw within a few hours of collection. In the 2005 Nipah outbreak in Tangail District, Bangladesh, the only exposure significantly associated with illness was drinking raw date palm sap

The Institute of Epidemiology, Disease Control and Research (IEDCR) in Dhaka says the median incubation period of the secondary cases who had a single exposure to Nipah case was nine days (range 6–11 days) but exposure to onset of illness varies from 6-16 days. The median incubation period following single intake of raw date palm sap to onset of illness is 7 days (range: 2-12 days) in Bangladesh. 

The US CDC Special Pathogens Branch says patients present early with flu-like symptoms, i.e. fever and headache. This is followed by drowsiness and disorientation characterized by mental confusion. These signs and symptoms can progress to coma within 24-48 hours. Some patients have had a respiratory illness during the early part of their infections.

This transmission electron micrograph (TEM) revealed some cytoarchitectural changes in an unknown human-derived tissue sample associated with a Nipah virus infection./CDC

This transmission electron micrograph (TEM) revealed some cytoarchitectural changes in an unknown human-derived tissue sample associated with a Nipah virus infection./CDC

The WHO says concerning laboratory diagnosis– Procedures for the laboratory diagnosis of NiV include serology, histopathology, PCR and virus isolation. Serum Neutralization Test, ELISA, RT-PCR are used for laboratory confirmation.

Most countries in the South-East Asia Region do not have adequate facilities for diagnosing the virus or on ways of controlling it. Bangladesh, India and Thailand have developed laboratory capacity for diagnostic and research purposes.

Nipah virus is classified internationally as a biosecurity level (BSL) 4 agent.

In the initial recognized outbreak in Malaysia/Singapore in 1998-1999, there were 276 cases and 106 deaths. Approximately a 40 percent case-fatality rate (CFR).

The Dhaka Tribune reported last month that in Bangladesh from 2001-2013, there was 189 cases of NiV resulting in 148 deaths (CFR of 78 percent).

In addition to being a human pathogen,  it is also a serious pathogen for pigs and a wide range of animals which has resulted in serious economic loss.

The WHO says that prevention messages should focus on the following:

  • Reducing the risk of bat-to-human transmission. Efforts to prevent transmission should first focus on decreasing bat access to date palm sap. Freshly collected date palm juice should also be boiled and fruits should be thoroughly washed and peeled before consumption.
  • Reducing the risk of human-to-human transmission. Close physical contact with Nipah virus-infected people should be avoided. Gloves and protective equipment should be worn when taking care of ill people. Regular hand washing should be carried out after caring for or visiting sick people.
  • Reducing the risk of animal-to-human transmission. Gloves and other protective clothing should be worn while handling sick animals or their tissues, and during slaughtering and culling procedures.

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About the Author

- Writer, Co-Founder and Executive Editor of The Global Dispatch. Robert has been covering news in the areas of health, world news and politics for a variety of online news sources. He is also the Editor-in-Chief of the website, Outbreak News Today and hosts the podcast, Outbreak News Interviews on iTunes, Stitcher and Spotify Robert is politically Independent and a born again Christian Follow @bactiman63

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  1. Truthstream: The Officially Ignored Link Between Lyme Disease and Plum Island | Thought Crime Radio says:

    […] disease (FMD) and will focus its BSL-4 research on such deadly pathogens as the Hendra and Nipah viruses, which are zoonotic pathogens that can be transmitted from animals to humans and for which no […]

  2. Bangladesh reports nine Nipah virus cases to date in 2015 | Outbreak News Today says:

    […] Related: What is Nipah virus? […]

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