Nipah Virus is back? Here’s what we know about it so far

The death of a 12-year-old to Nipah Virus infection in Kerala’s Kozhikode on Sunday has led to increased worry about the infectious disease.

The samples of the boy were sent for examination to the National Institute of Virology, Pune, where it was confirmed that the boy did in fact die of Nipah Virus.

The Centre rushed a team of National Centre for Diseases Control to the state to provide technical support to the state.

State Health Minister Veena George confirmed that the boy passed away at 5 am and that his condition was critical the night before.

Three samples of the boy were reportedly found infected – plasma, CSF and serum. The child was admitted to the hospital with high fever four days ago but his condition gradually worsened.

All those who came in contact with the boy have been traced and proper steps are being taken to isolate his primary contacts.

Also Read: 12yr-old dies of Nipah, local authorities gear up to check transmission

About the Virus:

Here are some key facts about this highly infectious virus, as reported by the World Health Organisation (WHO).

1. Nipah virus infection in humans causes a range of clinical presentations, from asymptomatic infection (subclinical) to acute respiratory infection and fatal encephalitis.
2. The case fatality rate is estimated at 40% to 75%. This rate can vary by outbreak depending on local capabilities for epidemiological surveillance and clinical management.
3. Nipah virus can be transmitted to humans from animals (such as bats or pigs), or contaminated foods and can also be transmitted directly from human-to-human.
4. Fruit bats of the Pteropodidae family (particularly species belonging to the Pteropus genus) are the natural host of this virus. Evidence of Henipavirus infection in Pteropus bats have been found in Australia, Bangladesh, Cambodia, China, India, Indonesia, Madagascar, Malaysia, Papua New Guinea, Thailand and Timor-Leste.
5. There is no treatment or vaccine available for either people or animals. The primary treatment for humans is supportive care.

Although Nipah virus has caused few known outbreaks in Asia, it infects a wide range of animals and causes severe disease and death in people, making it a public health concern.

The 2018 annual review of the WHO Research & Development (R&D) Blueprint list of priority diseases indicates that there is an urgent need for accelerated research and development for the Nipah virus.

Symptoms

According to the World Health Organisation, the following symptoms may be seen in a person effected by Nipah Virus:

1. Human infections may range from asymptomatic to acute respiratory infection (mild, severe), and fatal encephalitis.
2. Infected people initially develop symptoms including 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.
3. Some people may also experience atypical pneumonia and severe respiratory problems, including acute respiratory distress.
4. Encephalitis and seizures occur in severe cases, progressing to coma within 24 to 48 hours. 
5. The incubation period (interval from infection to the onset of symptoms) is believed to range from 4 to 14 days. However, an incubation period as long as 45 days has been reported.
6. Most people who survive acute encephalitis make a full recovery, but long term neurologic conditions have been reported in survivors. 
7. Approximately 20% of patients are left with residual neurological consequences such as seizure disorder and personality changes.
8. A small number of people who recover subsequently relapse or develop delayed onset encephalitis.
9. The case fatality rate is estimated at 40% to 75%. This rate can vary by outbreak depending on local capabilities for epidemiological surveillance and clinical management.

Diagnosis

1. Initial signs and symptoms of Nipah virus infection are nonspecific, and the diagnosis is often not suspected at the time of presentation.  This can hinder accurate diagnosis and creates challenges in outbreak detection, effective and timely infection control measures, and outbreak response activities. 
2. In addition, the quality, quantity, type, timing of clinical sample collection and the time needed to transfer samples to the laboratory can affect the accuracy of laboratory results.
3. Nipah virus infection can be diagnosed with clinical history during the acute and convalescent phase of the disease. The main tests used are real time polymerase chain reaction (RT-PCR) from bodily fluids and antibody detection via enzyme-linked immunosorbent assay (ELISA). 
4. Other tests used include polymerase chain reaction (PCR) assay, and virus isolation by cell culture.

Nipah Virus in Pigs

Outbreaks of the Nipah virus in pigs and other domestic animals such as horses, goats, sheep, cats and dogs were first reported during the initial Malaysian outbreak in 1999. The virus is highly contagious in pigs. Pigs are infectious during the incubation period, which lasts from 4 to 14 days.

An infected pig can exhibit no symptoms, but some develop acute feverish illness, labored breathing, and neurological symptoms such as trembling, twitching and muscle spasms. These symptoms are not dramatically different from other respiratory and neurological illnesses of pigs.

Nipah virus should be suspected if pigs also have an unusual barking cough or if human cases of encephalitis are present. Mortality is generally low in pigs, except in young piglets.

Prevention and cure

Currently, there are no vaccines available against Nipah virus. Based on the experience gained during the outbreak of Nipah involving pig farms in 1999, routine and thorough cleaning and disinfection of pig farms with appropriate detergents may be effective in preventing infection.

Health-care workers looking after patients with suspected or confirmed infection, or handling specimens from them, must take standard precautionary measures at all times.

As human-to-human transmission has been reported, in particular in health-care settings, contact and droplet precautions should be used in addition to standard precautions.

Airborne precautions may be required in certain circumstances.