What is the Nipah Virus and its Recent Outbreak in Kerala

Overview

In recent years, the world has faced growing concerns over zoonotic diseases—those that spread from animals to humans. Sloth fever, Mpox, and the recent Nipah virus has emerged as a significant threat, especially in regions like South and Southeast Asia. This deadly virus, primarily transmitted by fruit bats, poses a severe risk due to its high fatality rate and ability to spread from person to person. As outbreaks continue to surface, most recently in Kerala, India, understanding the Nipah virus and its mode of transmission is important for preventing further infections. Early detection, containment and quick preventive measures are essential to controlling its spread and protecting public health.

This year, on September 16, a 24-year-old student in Kerala’s Malappuram district died of Nipah virus infection while undergoing treatment. This is the second death this year, last July a 14-year-old boy from Vandoor, Malappuram succumbed to the Nipah virus infection.

History of Nipah virus

The Nipah virus is a zoonotic RNA virus (transmitted from animals to humans). Fruit bats or flying foxes belonging to the Pteropodidae family are a reservoir for the virus. It can spread to humans from animals such as bats and pigs and through contaminated foods. The virus can also be transmitted from human to human.^(1.2)

The outbreak was first reported in 1999 in Malaysia where the disease was transmitted from infected pigs to pig farmers. ^(1,2) The outbreaks were also identified in Bangladesh, Singapore, India, and the Philippines.

India reported its first outbreak in 2001 in Siliguri, West Bengal; another outbreak was reported in 2007 in West Bengal’s Nadia district. ⁽²⁾ Kerala witnessed outbreaks of the Nipah virus in Kozhikode, Ernakulam, and Malappuram districts in 2018, 2019, 2021, and 2023.

According to the experts, various factors such as environmental degradation, habitat loss, contact with infected animals, and contaminated fruits are responsible for the virus outbreaks.

Mode of transmission

The first reported outbreak in Malaysia among pig farmers. It was due to close contact with infected pigs and no human-to-human transmission was recorded. During the Indo-Bangladesh outbreaks, the transmission mode was consumption of raw date palm juice contaminated by infected fruit bats’ urine or saliva.^(3,4,5)

The transmission of the virus from human to human was also reported in the outbreaks in India and Bangladesh. In the 2001 outbreak in Siliguri, West Bengal the virus transmission was identified within a healthcare facility.⁽³⁾

The exposure risks of the Nipah virus are higher among the families and caregivers of the infected people, healthcare providers of the patients, and people who made direct contact with the infected animals and their bodily fluids.⁽⁵⁾

The estimated death rate of the Nipah virus infection ranges between 40-70%, and the range may heighten up to 100% depending on the disease surveillance and medical facilities.^(1,2)

Symptoms

The symptoms may range from mild to severe. The symptoms include

• Fever
• Dizziness
• Headache
• Muscle pain
• Sore throat
• Vomiting
• Severe neurological issues
• Altered consciousness
• Breathing difficulties
• Seizures and coma in severe cases

Diagnosis

The early diagnosis of the Nipah virus infection is difficult due to its non-specific signs and symptoms in the initial stages. The virus can be diagnosed during the acute and convalescent phases of the infection.

The major tests involved in the diagnosis are:^(2,6)

1. Reverse transcriptase polymerase chain reaction assay (RT-PCR) – from bodily fluids such as blood, urine, nasal and throat swabs
2. Enzyme-linked immunosorbent assay (ELISA) – antibody detection from cerebrospinal fluid or serum
3. Advanced diffusion-weighted magnetic resonance imaging (MRI) of the brain – for diagnosis of encephalitis

Treatment

There are no vaccines or medications to treat the Nipah virus infection. Supportive care to treat severe neurological and respiratory issues of the patients is the treatment option available.

Prevention and Control

• Follow proper hand hygiene before and after direct contact with the patient.
• Standard infection control precautions should be applied while handling the Nipah suspected or infected patients.
• Restrict the movement of infected animals to other places
• Wear gloves and protective equipment while handling sick animals
• Healthcare settings should apply droplet, airborne, and contact precautions to prevent the infection from spreading
• Proper washing of fruits before consumption
• Avoid direct contact with infected pigs
• Healthcare staff should follow standard infection control precautions while treating and handling suspected Nipah patients and their samples

How Kerala tackled the Nipah virus

Kerala witnessed outbreaks of the Nipah virus since 2018 and this is the second outbreak in 2024. During the outbreak in 2018, the Nipah virus infected 29 people and claimed the lives of 22. However, the Kerala government and central government successfully managed the outbreak.

The World Health Organization categorized the Nipah virus as a priority pathogen due to its high possibility of causing an epidemic. The state was on high alert with the recent occurrence, it declared five wards in two panchayats in Malappuram districts as containment zones and instructed the wearing of masks compulsory in public places.

Conclusion

The Nipah virus is emerging as a new health concern. With its periodic outbreaks and non-specific initial signs and symptoms, it is quite challenging to take immediate action to prevent the infection rate. The recent outbreaks underline the importance of further research, education, proper surveillance, early diagnosis, and preventive measures to reduce the transmission rate of the Nipah.   

FAQs

1. What is the Nipah virus?

The Nipah virus is zoonotic, meaning it spreads from animals to humans. Transmission is by fruit bats, pigs, or through contaminated food, and can also spread from human to human.

2. What are the symptoms of the Nipah virus?

Symptoms range from mild to severe and include fever, dizziness, headache, muscle pain, sore throat, vomiting, neurological issues, and in severe cases, seizures, coma, and difficulty breathing.

3. Is there a treatment or vaccine for the Nipah virus?

Currently, there are no specific treatments or vaccines for Nipah virus infection. Treatment focuses on supportive care to manage symptoms.

4. How can I prevent Nipah virus infection?

Preventive measures include practicing good hand hygiene, avoiding direct contact with infected animals, consuming properly washed and cooked food, and following standard infection control protocols in healthcare settings.

5. What are the risk factors for Nipah virus infection?

People at higher risk include those in close contact with infected animals or individuals, healthcare workers treating Nipah patients, and those consuming contaminated food.

6. Has India experienced Nipah virus outbreaks before?

Yes, India has witnessed several outbreaks of Nipah virus, particularly in the state of Kerala. The first outbreak in India was reported in 2001 in West Bengal.

7. Why is the Nipah virus a concern?

Nipah virus has a high fatality rate, ranging from 40% to 70%, and can cause severe neurological and respiratory symptoms.

8. How is the Nipah virus diagnosed?

Diagnosis: Tests like RT-PCR to detect viral genetic material and ELISA for detecting antibodies. In severe cases, MRI.

9. What is Kerala’s approach to managing Nipah outbreaks?

Kerala has successfully managed several Nipah virus outbreaks through strict containment measures, contact tracing, isolation of high-risk individuals, and enforcing health protocols like wearing masks and restricting movement in affected areas.

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References:

1. Nipah virus [Internet]. [cited 2024 Oct 18]. Available from: https://www.who.int/news-room/fact-sheets/detail/nipah-virus.
2. Banerjee S, Gupta N, Kodan P, Mittal A, Ray Y, Nischal N, et al. Nipah virus disease: A rare and intractable disease. IRDR [Internet]. 2019 [cited 2024 Oct 18]; 8(1):1–8. Available from: https://www.jstage.jst.go.jp/article/irdr/8/1/8_2018.01130/_article.
3. Islam MS, Sazzad HMS, Satter SM, Sultana S, Hossain MJ, Hasan M, et al. Nipah Virus Transmission from Bats to Humans Associated with Drinking Traditional Liquor Made from Date Palm Sap, Bangladesh, 2011–2014. Emerg Infect Dis [Internet]. 2016 [cited 2024 Oct 18]; 22(4):664–70. Available from: http://wwwnc.cdc.gov/eid/article/22/4/15-1747_article.htm
4. Luby SP, Rahman M, Hossain MJ, Blum LS, Husain MM, Gurley E, et al. Foodborne transmission of Nipah virus, Bangladesh. Emerg Infect Dis. 2006; 12(12):1888–94.
5. CDC. Nipah virus: Facts for Clinicians. Nipah Virus [Internet]. 2024 [cited 2024 Oct 18]. Available from: https://www.cdc.gov/nipah-virus/hcp/clinical-overview/index.html.
6. Lim CT. MR imaging in Nipah virus infection. Neurology Asia. 2009 Jun 1;14(1):49-52.             

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