Nipah Virus | Symptoms,Diagnosis, Tretment & Prevention
What Is Nipah Virus
As per the World Health Organisation (WHO), Nipah Virus is a newly emerging zoonosis that causes a severe disease in both animals and humans. This virus was first identified in Malaysia and Singapore in 1998. At that time, it was primarily caused in pigs and through them got transferred to humans. Nipah Virus infected as many as 265 people then, out of which 40 per cent were taken under intensive care due to the infection having spread severely. As quoted by the WHO, the natural host of the virus are fruit bats of the Pteropodidae Family, Pteropus genus.
The virus can be transferred through infected bats, pigs or humans who have been infected. In 2004, humans who consumed the date palm sap infected by fruit bats, caught the virus as well. Humans who were infected by other humans were reported in Bangladesh and India.
Signs and symptoms
Human infections range from asymptomatic infection, acute respiratory infection (mild, severe), and fatal encephalitis. Infected people initially develop influenza-like symptoms of fever, headaches, myalgia (muscle pain), vomiting and sore throat. This can be followed by dizziness, drowsiness, altered consciousness, and neurological signs that indicate acute encephalitis. Some people can also experience atypical pneumonia and severe respiratory problems, including acute respiratory distress. Encephalitis and seizures occur in severe cases, progressing to coma within 24 to 48 hours.
The incubation period (interval from infection to the onset of symptoms) is believed to range between from 4-14 days. However an incubation period as long as 45 days has been reported.
Most people who survive acute encephalitis make a full recovery, but long term neurologic conditions have been reported in survivors. Approximately 20% of patients are left with residual neurological consequences such as seizure disorder and personality changes. A small number of people who recover subsequently relapse or develop delayed onset encephalitis.
The case fatality rate is estimated at 40% to 75%; however, this rate can vary by outbreak depending on local capabilities for epidemiological surveillance and clinical management.
Fruit Bats And Nipah Virus
Having been around for millions of years, bats have probably carried infectious diseases for nearly as long, Gurley says. Several bat species can carry viruses that are deadly to humans, including Ebola, Marburg, SARS and Nipah, without getting sick themselves .
But scientists say that villainizing bats is not the answer. “They’re a crucial part of their ecosystems,” Gurley says. “They are also really important pollinators.”
Several factors have increased the chance of bat-borne viruses being passed humans, including development that has encroached on the bats’ natural habitats. “It used to be that these bats stayed far away from human populations,” Wang says.
Initial signs and symptoms of NiV infection are non-specific and the diagnosis is often not suspected at the time of presentation. This can hinder accurate diagnosis and creates challenges in outbreak detection and institution of effective and timely infection control measures and outbreak response activities.
In addition, clinical sample quality, quantity, type, timing of collection and the time necessary to transfer samples from patients to the laboratory can affect the accuracy of laboratory results.
NiV infection can be diagnosed together with clinical history during the acute and convalescent phase of the disease. Main tests including real time polymerase chain reaction (RT-PCR) from bodily fluids as well as antibody detection via ELISA. Different tests include:
-enzyme-linked immunosorbent assay (ELISA)
-polymerase chain reaction (PCR) assay
-virus isolation by cell culture.
There are currently no drugs or vaccines specific for NiV infection although this is a priority disease on the WHO R&D Blueprint. Intensive supportive care is recommended to treat severe respiratory and neurologic complications.
Nipah virus infection can be prevented by avoiding exposure to sick pigs and bats in endemic areas and not drinking raw date palm sap.
Additional efforts focused on surveillance and awareness will help prevent future outbreaks. Research is needed to better understand the ecology of bats and Nipah virus, investigating questions such as the seasonality of disease within reproductive cycles of bats. Surveillance tools should include reliable laboratory assays for early detection of disease in communities and livestock, and raising awareness of transmission and symptoms is important in reinforcing standard infection control practices to avoid human-to-human infections in hospital settings (nosocomial infection).
A subunit vaccine, using the Hendra G protein, produces cross-protective antibodies against HENV and NIPV has been recently used in Australia to protect horses against Hendra virus. This vaccine offers great potential for henipavirus protection in humans as well.