Nipah Virus Infection

Introduction

Nipah Virus is a kind of virus that can be transmitted from animals to humans through contaminated food or even directly from person to person. This virus outbreak was discovered first in Malaysia in 1999 amongst a group of pig farmers. This virus causes several illnesses starting from asymptomatic (subclinical) infection to fatal encephalitis. There have been quite a few outbreaks of this virus, especially in the Indian sub-continent infecting both animals and humans resulting in major public health concerns.

Epidemiology

Nipah Virus (NiV) is a zoonotic virus coming from the family of Paramyxoviridae. The fruit bat, also known as the flying fox, is the animal host reservoir for this virus. These infected bats transmit the disease from animals to animals and people. When someone comes in contact with an infected person or animal or their body fluids the virus is transmitted.

Fruit bats are flying foxes that feed on the nectar of flowers and fruits found in orchards and farms of the tropical and subtropical regions of Africa, Asia and Australia. Some of the oceanic islands in these areas have also proven to be associated with Nipah virus outbreaks. These bats carry the virus in their urine, semen, saliva and excreta. The bat populations in Thailand, Cambodia, Madagascar, and Ghana are found carrying NiV-neutralizing antibodies during the serological studies.

Outbreaks

Since its discovery in the year 1999, the Nipah virus outbreaks have been reported in India, Bangladesh, Malaysia and Singapore. The first outbreak of the Nipah virus in Malaysia reported more than 265 human cases of encephalitis with 105 deaths. Again after a few years in 2001, there were two outbreaks of the Nipah virus, one in India and the other one in Bangladesh. Siliguri witnessed the outbreak of the Nipah virus with 66 cases and a 74% mortality rate. All the infected patients were either hospital staff or someone who came to visit other patients, which indicated person to person transmission of the virus.

In mid-2001, Bangladesh witnessed the virus outbreak with 13 cases and a 69% mortality rate. Later, in 2003, 2004 and 2005, there were several outbreaks of this virus in Bangladesh having a total of 67 cases and 31 deaths. In 2007, there were 50 suspected cases of the Nipah virus in Nadia, India and 8 cases in Bangladesh. In 2008, 2010 and 2011, there were fewer cases in Bangladesh of 37 fatalities in total. There was a good gap after 2011. But in 2018, there was another outbreak of the Nipah virus in Kerala, which killed 21 people. The latest victim of the Nipah virus is a 12-year-old boy from Kerala, who succumbed to the virus in September 2021.

Symptoms

Nipah virus infection can be mild or severe, depending on case to case. In fatal cases, it includes swelling of the brain leading to death.

Once exposed to the virus, symptoms start appearing from 4 to 14 days. It starts with 3 to 14 days of fever and headache along with cough, sore throat, and difficulty in breathing. Later it might lead to brain swelling (encephalitis) that includes disorientation, drowsiness, mental confusion, and coma. Long-term survivors of Nipah have complained of sudden convulsions and personality changes.

Sometimes Nipah virus infections may be dormant or latent leading to symptoms or even death months or even years after exposure.

Diagnosis and Treatment

The primary hindrance in the diagnosis and treatment in most cases of this virus is that the initial symptoms are not specific before it starts spreading in very little time. This creates a lot of challenges in effective and timely control measures and response activities. Further, the timing of the clinical sample collection, the quality and the quantity also affect the accuracy of the laboratory results.

The best time to identify the disease is when it is in the acute and convalescent-phase. The primary tests for this disease include the real-time polymerase chain reaction (RT-PCR) test for the body fluids and the enzyme-linked immunosorbent assay (ELISA) test. The other tests are the polymerase chain reaction (PCR) test and cell culture for virus isolation.

Presently, there are no vaccines or drugs or any existing treatment specially made for this infection. In cases of severe neurological or respiratory complications, intensive care is highly recommended. However, the World Health Organization (WHO) identified this virus infection as a priority disease for WHO Research and Development Blueprint.

A phase I clinical trial for the Nipah virus vaccine started in February and is expected to be completed by September 2021. The Coalition for Epidemic Preparedness Innovations (CEPI) has invested 25 million USD to conduct a safety study. The test will be conducted at the Cincinnati Children’s Hospital Medical Center in Cincinnati, USA. Once the vaccine is ready, it will be tested in healthy adults aged 18 to 49 years to observe the immune response.

Prevention

Since the disease is transmitted easily from infected people to others, prevention of disease is essential. Some of the preventive measures that people should follow are:

• Regular hand wash with soap and water;
• Avoid contact with sick animals such as pigs and bats;
• Avoid such places where bats are roasted;
• Avoid eating raw date palm sap;
• Avoid fruits contaminated by animals like bats;
• Avoid contact with the body fluids of any Nipah virus-infected person.

The Nipah virus infection spreads from person to person, so standard infection control must be practised and nursing techniques followed should prevent hospital-acquired infections, especially where there are confirmed patients with NiV infection.

Some of the geographic locations hugely infected by the flying foxes are Cambodia, Indonesia, Madagascar, the Philippines, and Thailand. Inhabitants of these locations should take extra precautions as these places might be at greater risk of contracting the virus.

Additionally, to further lower the risk of this infection, communities, scientists, and researchers need to continue their research to prevent any more outbreaks in future.

Some of the other prevention methods to lessen the infection in the future include:

• Improving the research on the fruit bats to understand their living conditions and their spread to other people and animals;
• Improving the observation and surveillance of people and animals that have chances of being infected by the virus;
• Evaluating newer technologies to lessen the spread of the virus of the flying bats;
• Enhancing the tools for early virus detection in the livestock and communities;
• Strengthening the healthcare protocols for better infection control and prevention of person to person transmission
• Raising awareness about this infection, its signs and symptoms amongst people who are at higher risk due to:

• their geographic location;
• higher chances of contamination from fruit bats;
• higher chances of contact with pigs and animals
• higher chances of contamination for healthcare workers and caregivers of people infected with NiV

Preventive Measures in Healthcare setting

It is extremely essential to take better preventive measures in the healthcare areas as it is expected that people working in this area would be more exposed to the infection since they would be carrying specimens or taking care of infected people. Due to the presence of human to human transmission, primarily through blood or body fluids, special airborne precautions are required in these cases. People carrying samples of suspected NiV patients should be well-trained and well-equipped with safety kits.

How to avoid a NiV pandemic?

Nipah virus infection is a deadly disease with a fatality rate of 75%. It is assumed that if the future spread is not prevented, the Nipah virus could emerge as the next big pandemic after Covid. Moreover, reasons such as globalization, international trade, and climate change are causing the bats to seek new habitats.

Therefore, all kinds of possible preventive measures must be taken to prevent the spread of the disease. Better diagnostics, better surveillance, vaccines and therapeutics are essential to identify and verify cases faster and accurately. Additionally, investigating spill-overs and contact tracing and understanding the science behind the spread of this virus is important.

Local people should also be involved in increasing awareness, preventing infection and reducing risky behaviour to avoid unnecessary transmission of the disease. Better utilization of natural resources like pastures and forests would further help in avoiding a pandemic.

Indian Scenario

India has witnessed quite a few outbreaks of the Nipah virus in the past decades. Even though lately there has been only one death from the Nipah virus in September 2021, the Ministry of Health and Family Welfare is monitoring the situation closely. Advisory has been set up for healthcare personnel, treatment guidelines, case definitions, biosafety manuals, and hospital prevention guidelines have also been created to address the issue immediately.