Explained: What is the rare, brain-damaging virus that is spreading in Kerala?

20 September,2023 12:21 PM IST |  Mumbai  |  Ainie Rizvi

The Nipah virus spreads to human bodies primarily through direct contact with infected animals or consumption of food products exposed to saliva or urine from infected bats

Nipah virus outbreak grows to six cases in Kerala. Image Courtesy: iStock

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Kerala, the southernmost Indian state, has become the epicentre of an alarming development. A rare virus with the ability to cause brain damage has been identified in the blood samples of the affected patients. With high fatality rates ranging from 40 to 75 percent, the outbreak is raising concerns among experts who view it as a potential epidemic risk.

The virus is naturally harboured within fruit bats found in South and Southeast Asia. Experts have discovered that its transmission to humans is occurring through contact with the animal's bodily fluids. Upon acquiring the virus, patients experience inflammation of the brain, confusion, dizziness seizures - leading to coma. The World Health Organisation (WHO) lists Nipah as one of its priority pathogens capable of turning into a plague.

Unfortunately, there is neither a vaccine nor a cure available for this infection. Its first outbreak was recorded in Malaysia and Singapore in 1988, informs Dr Mala Kaneria - a consultant with Jaslok Hospital and Research Centre, Mumbai. The virus gets its name from the village where it was first discovered - Nipah in Malaysia.

Tracing the spread of Nipah Virus

It is believed that the genesis of this virus can be traced to the fruit bats of the Pteropodidae family. The bat's saliva and urine contain viruses, which can easily contaminate food or water sources when they feed or roost near them. Apart from bats, the virus also spreads through other animals like pigs, horses and dogs; and is also being considered a bioterrorism threat by WHO.

The Nipah virus spreads to human bodies primarily through direct contact with infected animals or consumption of food products exposed to saliva or urine from infected bats. Human-to-human transmission is also possible through respiratory secretions which is why infected people have to be kept isolated, adds Dr P Venkata Krishnan, Sr. Consultant, Internal Medicine, Artemis Hospital Gurugram. Close contact with other Nipah-infected patients in hospitals without protective equipment is also a leading cause.

According to research conducted by the National Institute of Virology, the Nipah virus is spreading among bat populations in nine Indian states and one union territory. States like Kerala, Tamil Nadu, Karnataka, Goa, Maharashtra, Bihar, West Bengal, Assam, Meghalaya, and Pondicherry all had antibodies to the Nipah virus, shares Dr Shridhar Deshmukh - an intensivist with Ruby Hall Clinic, Mumbai.

Kerala Health Minister Veena George said that The Indian Council of Medical Research and WHO had conducted studies on the issue to verify the presence of the virus in those nine Indian states. She further adds, "The virus we found in Kerala is identified as Indian Genotype or I Genotype which is similar to the strain found in Bangladesh. We have two strains of Nipah Virus one is Malaysian and the other from Bangladesh."

Since May 2018, when Kerala encountered its inaugural Nipah outbreak within Kozhikode district, there have been three more Nipah outbreaks, including the most recent in late August 2023. It is noteworthy that, for reasons still undiscovered, three out of the four Nipah outbreaks in Kerala in 2018, 2021, and 2023 have exclusively affected Kozhikode district, whereas the 2019 outbreak was confined to Ernakulam district.

Why does the Nipah virus keep returning to India?

Deshmukh attributes the recurring presence of the Nipah virus in India to several factors. First, the virus is naturally hosted by fruit bats, which are widespread in India, leading to ongoing opportunities for transmission to other animals and humans through contaminated fruit or direct contact.

Second, India's diverse population and extensive livestock farming can facilitate human-animal interactions, increasing the risk of viral spillover. Additionally, challenges in surveillance, healthcare infrastructure, and public awareness can hinder early detection and containment efforts. Climate change and deforestation might also be driving bats into closer contact with humans.

Signs of infection

An emerging zoonotic disease, it turns conspicuous through ailments like high-grade fever, headache and altered cognitive abilities. Patients often undergo a range of neurological symptoms including seizures, hallucinations and altered consciousness.

"The first symptoms can often mimic those of the common cold or flu, making it difficult to diagnose early on," observes Dr Samir Garde, from the Department of Pulmonology at Global Hospitals in Parel. However, as the infection progresses, patients tend to experience severe symptoms such as dizziness, vomiting, fatigue, cough, breathlessness and myalgia (pain in muscles).

Additionally, Nipah virus has a high mortality rate, with no specific antiviral treatment available, making early detection, isolation, and supportive care difficult for patient survival, informs Deshmukh. There's a market failure to protect people from this outbreak. It's not like treating baldness or breast cancer, where wealthy people will pay for the product. There's no big customer here, no incentive to find solutions until it escalates.

Initial symptoms could involve one or more of the following:

1. Fever
2. Headaches
3. Cough
4. Unwell throat
5. Trouble breathing
6. Vomiting

Severe signs and symptoms that reflect the presence of infection include:

1. Bewilderment, sleepiness or disorientation
2. Seizures
3. Coma Encephalitis-related brain swelling

How does it damage the brain?

One of the most devastating effects of the Nipah virus on the human body is its ability to cause encephalitis which is inflammation in the brain tissue resulting in coma or even death. When it reaches the human brain, the virus mainly targets the central nervous system, including certain vital regions of the brain.

Other regions that get affected include the cerebral cortex, thalamus, and brainstem. The virus invades a crucial structure - the brainstem, which is responsible for controlling essential functions like breathing, heart rate, and consciousness. This activity disrupts normal brain function, leading to neurological symptoms such as confusion, drowsiness and seizures.

This neurological damage is a hallmark of Nipah virus infection and contributes to the high morbidity and mortality associated with the disease. The virus can also affect other organs and systems in the body, but its most devastating impact is on the brain. Neurological complications may develop after more than 10 weeks from the initial exposure to the virus.

Beyond the neurological system, the virus attacks the respiratory system as well. Once inhaled, the virus directly invades lung cells and rapidly replicates, causing severe respiratory distress. This leads to coughing, difficulty breathing, and often pneumonia.

The Nipah virus targets multiple organs as it wreaks havoc on the human body. It can also affect the cardiovascular, gastrointestinal, and immune systems, potentially causing multi-organ dysfunction. It is presumed that a person may remain infectious from the day of onset of symptoms up to 21 days.

Who is at risk?

1. People in close contact with infected animals, especially those involved in the pig farming industry, are at higher risk

2. Healthcare workers caring for Nipah Virus-infected patients are also at risk due to potential nosocomial transmission

3. Communities living in regions with known Nipah Virus outbreaks face a higher risk

The Kerala bat population may have developed an endemic form of the Nipah virus, opines Deshmukh. The practice of drinking fresh toddy or sweet tree sap, which may become polluted by diseased bats, is another cultural factor cited as a contributing factor to Nipah outbreaks.

Preventive measures and treatment

There is no specific antiviral medication that exists for treating the Nipah virus, shares Garde. Patients with suspected or confirmed Nipah virus infection are usually provided with supportive care to manage their symptoms and complications. This may involve measures such as ensuring proper hydration, monitoring vital signs, providing respiratory support if needed, and managing any other issues that arise due to the infection.

Deshmukh shares how the healthcare industry can enhance preparedness against the Nipah virus:

Surveillance: Establishing robust surveillance systems for early detection
Training: Training healthcare workers in infection control and case management
Vaccine Development: Investing in research for vaccines and antiviral treatments
Public Awareness: Educating the public on preventive measures and the importance of reporting symptoms promptly
Isolation Facilities: Ensuring isolation facilities are available to contain outbreaks swiftly

Here are some guidelines to stay protected from the virus:

1. Practice hand washing regularly with soap and water
2. Avoid contact with sick bats or pigs
3. Avoid areas where bats are known to roost
4. Avoid eating or drinking products that could be contaminated by bats such as raw date palm sap, raw fruit, or fruit that is found on the ground
5. Avoid contact with the blood or body fluids of any person known to be infected with NiV

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