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Now people are worried about Nipah Virus (NiV) that is killing people in Southern India. And they are asking several worried questions. So here we go again to educate people, even though not much information is available, and protect them...

Nipah Virus was first identified during an outbreak of disease that took place in Kampung Sungai Nipah, Malaysia in 1998. Then, pigs were the intermediate hosts. Later in subsequent NiV outbreaks, there were no intermediate hosts. In Bangladesh in 2004, humans became infected with NiV as a result of consuming date palm sap that had been contaminated by infected fruit bats. Human-to-human transmission has also been documented in India since then. 

 Nipah virus (NiV) infection is a zoonosis (a disease which can be transmitted to humans from animals)

that causes severe disease in both animals and humans and has a very high fatality rate. The natural host of the virus are fruit bats of the Pteropodidae Family, Pteropus genus. However, some biologists dispute this. As it is a newly emerging infection, confusion still persists about details and there are neither  vaccines, nor cure for this disease. 

Nipah Virus is an airborne transmission infection and can affect those who come in direct contact with contaminated patients and dead bodies.

The symptoms start to appear within 3–14 days after exposure. Initial symptoms are fever, headache, drowsiness followed by disorientation and mental confusion. These symptoms can progress into coma as fast as in 24–48 hours. Encephalitis is the dreaded complication of nipah virus infection. Respiratory illness can also be present during the early part of the illness. Nipah-case patients who had breathing difficulty are more likely than those without respiratory illness to transmit the virus.

Nipah and its viral cousin Hendra latch onto a proteins called ephrin-B2 and ephrin-B3  on the surface of nerve cells and the endothelial cells lining blood and lymph vessels, researchers have found. Nipah can also invade lung and kidney cells.

Virologists who have studied Nipah’s behavior in animals think that in humans, it initially targets the respiratory system before spreading to the nervous system and brain. Most patients who die succumb to an inflammation of blood vessels and a swelling of the brain that occurs in the later stages of the disease. 

The two known Nipah strains currently circulating aren’t all that easy to transmit.

While the mortality rate for those infected can be high, infection is not all that common. Before this latest outbreak, about 300 deaths had been linked to Nipah, most of which occurred in Southeast Asia and Bangladesh. But the actual number could be higher with some cases going untested or unreported. Because the symptoms of Nipah infection are similar to those for other diseases, including encephalitis and the flu, cases may be misdiagnosed. India has only two main diagnostic laboratories, both in the central city of Pune, equipped to confirm Nipah infection. 

“In order for a disease to spread globally, each person has to infect at least more than one person,” according to experts. But a person with Nipah tends to infect either zero or one other person, according to a 2009 study published online by the U.S. Centers for Disease Control and Prevention. By comparison, a person with measles can infect on average 10 others who aren’t vaccinated. And people who caught Ebola during the 2014 outbreak in West Africa tended to pass it on to between one and three others, PLOS Current Outbreaks reported in 2014.

Prevention of Nipah virus infection is important since there is no effective treatment for the disease.

People should stop eating 'damaged or bird or bat-bitten fruits'. Stop drinking toddy sap. Stop visiting places where the disease is highly prevalent. 

The only way to treat this virus is through intensive supportive care. The infection can be prevented by avoiding exposure to bats in endemic areas and sick pigs. Drinking of raw palm toddy contaminated by bat excrete, eating of fruits partially consumed by bats and using water from wells infested by bats  should be avoided. Bats are known to drink toddy that is collected in open containers, and occasionally urinate in it, which makes it contaminated with the virus. If you suspect something dangerous, go for immediate testing. 

 Surveillance and awareness are important for preventing outbreaks. The association of this disease within reproductive cycle of bats is not well studied. Standard infection control practices should be enforced to prevent infections of the respiratory track. A subunit vaccine using the Hendra G protein was found to produce cross-protective antibodies against henipavirus and nipavirus has been used in monkeys to protect against Hendra virus, although its potential for use in humans has not been studied.

The risk of exposure is high for hospital workers and caretakers of those infected with the virus. In Malaysia and Singapore, Nipah virus infection occurred in those with close contact to infected pigs. In Bangladesh and India, the disease has been linked to consumption of raw date palm sap (toddy) and contact with bats (1).

Citations:

1.  Luby, Stephen P.; Gurley, Emily S.; Hossain, M. Jahangir (2012). TRANSMISSION OF HUMAN INFECTION WITH NIPAH VIRUS. National Academies Press (US). Archivedfrom the original on 22 May 2018. Retrieved 21 May 2018.

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Nipah virus outbreak in India – what you need to know

There has been an outbreak of the deadly Nipah virus in Kerala, India. Five people have caught the virus, two of whom have died.

The authorities in the Kozhikode district, where the outbreak occurred, have instituted “containment zones” in the area and schools have been closed. Seventy-six people who came into contact with the infected are being closely monitored for signs of the disease.

This is the fourth Nipah virus outbreak in Kerala. The most deadly was in 2018, with 18 laboratory-confirmed cases and five suspected cases, 17 of whom died.

Nipah virus is an RNA virus of the Paramyxoviridae family. The first detected human outbreak occurred in Malaysia in 1998 and caused 265 cases and 105 deaths. Since then, one or two outbreaks occur each year. More than half the people who are infected die.

Outbreaks have most commonly been reported from Bangladesh, but also India, Malaysia, Singapore and the Philippines.

The proportion of Nipah virus infections that are asymptomatic varies from one outbreak to another and ranges from 17% to 45%. When the virus does cause disease, the main effect is encephalitis (brain swelling). Patients develop a fever and complain of an intense headache, and many will experience disorientation, drowsiness and confusion. Some patients also develop a chest infection.

There are no specific drugs to treat Nipah virus, so medical care is merely “supportive”, that is, treating individual symptoms and keeping the patient comfortable until they hopefully recover.

Some treatments look as though they have potential, at least in animal studies, but few studies have been conducted in humans. One small trial of a drug called ribavirin suggested it could reduce deaths, but more studies need to be done.

A targeted therapy called monoclonal antibodies have been shown to be effective at reducing death in green monkeys if given early enough in the course of a Nipah virus infection. But no studies have yet shown how effective these drugs are in humans with Nipah virus.

Nevertheless, the Indian authorities are buying monoclonal antibodies from Australia to use in the current outbreak.

There are no vaccines against Nipah virus although an mRNA vaccine against the virus is being tested in humans.

How do people get infected?

In the original outbreak in Malaysia, the main risk factor was contact with pigs or being a pig farmer, but there was no evidence of person-to-person transmission. At the time it was not clear why pigs had started transmitting the infection.

Since the initial outbreak, we have learned more about the virus and the risk factors associated with transmission to humans. It is now accepted that the primary host for Nipah virus is fruit bats, specifically the Indian flying fox. Nipah virus has been previously detected in bats in Kerala.


Flying foxes are a natural reservoir of Nipah virus. Nick Greaves/Alamy Stock Photo

Most infections are thought to come from contact with an infected animal, either the fruit bats themselves or from intermediate animals such as pigs, as in the first detected outbreak in Malaysia. But there are interesting differences between outbreaks. In Bangladesh, there is an association with drinking date palm sap, either raw or fermented.

In one Bangladeshi study, the researchers used motion-sensor-infrared cameras to show that fruit bats often visited those date palms where villages collected date palm sap for consumption.

Initially, it was thought that person-to-person transmission did not occur for Nipah virus as no healthcare workers were infected during the large outbreak in Malaysia. Since then, healthcare workers have been reported as having caught the infection, as in this most recent outbreak, where one of the deaths was in a healthcare worker who treated a person infected with the virus.

Deadly, but doesn’t transmit easily

A study of some 248 Nipah virus infections in Bangladesh conducted over several years concluded that about a third had been caught from another human. The researchers estimated that the R value – the number of people an infected person is likely to pass the disease to – is about 0.33, meaning the infection would be unlikely to spread far from its animal source.

Although the Nipah virus causes a deadly infection there is no evidence that it is likely to spread widely outside of areas where people or their livestock come into contact with infected bats. However, outbreaks of Nipah virus may be another indication that habitat loss as a result of human incursion forces greater contact between humans and animals increasing the risk of animal-to-human transmission.

Even though the R value is low, should infected animals be transported into large cities the increased population density would increase the risk of person-to-person transmission that could enable the evolution of the virus to become more human transmissible and trigger a new pandemic.

Correction: The original article incorrectly stated that the first detected human outbreak of Nipah occurred in Malaysia in 1978. The year was actually 1998.

By 

Professor of Medicine, University of East Anglia

https://theconversation.com/nipah-virus-outbreak-in-india-what-you-...

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