What is Nipah Virus (NiV)?
Nipah virus is a zoonotic virus that belongs to the family of viruses called Paramyxoviridae and the genus Henipavirus. It is capable of spreading from an infected animal to a person and is mainly transmitted from fruit bats which are also known as flying foxes. These Nipah viruses are transmissible to pigs and human beings and can cause infection in them. It causes mild to severe illness, encephalitis(a rare acute inflammation of the brain), and may sometimes be fatal. Avoiding contact with fruit bats and pigs, drinking raw date palm sap, and consuming fruits infected with fruit bats help in preventing the Nipah virus infection.
What Is the Origin and What Are the Nipah Outbreaks Reported So Far?
An infection due to the Nipah virus was first reported in a village called Sungai Nipah in Malaysia in September 1998. Hence, it got its name from the location. It was seen among the farmers working in the pig farming industry. Later, in December 1998 the second and third outbreaks occurred in Malaysia which then spread to Singapore in February 1999. In India, outbreaks were seen in January 2001 and 2007 in West Bengal and during May 2018 and 2019 in Kerala. Sporadic outbreaks of the virus were also seen in Bangladesh in April 2001. The recent outbreak of the Nipah virus has been reported in Kerala in September 2021.
How Does the Virus Spreads?
Hosts of Nipah Virus:
- It is a newly emerging zoonosis, meaning, it spreads from animals to humans. The hosts are fruit bats (Pteropus genus), birds, and domestic animals such as horses, goats, dogs, cats, and pigs.
Modes of Transmission
Transmission of the Nipah virus from animals to humans is possible through the following routes:
- Direct contact with the body fluids like blood, urine, or saliva of an infected animal.
- Consuming fruits that have been infected by the fruit bats or pigs.
In addition to the above, human-to-human transmission can also occur through close contact with the infected person or the body fluids of an infected person like urine, blood, or respiratory air droplets.
How Long Does Nipah Virus Survive?
The virus is fragile and does not survive too long outside the host body, it may survive just a few hours or a few days in the air. The virus is relatively stable and may survive up to three days in fruits or fruit juices kept at room temperature. The virus is found to have a half-life of 18 hours in fruit bats’ urine.
What Are the Symptoms?
Symptoms start to appear after 4 to 14 days of exposure to the virus. Although the symptoms resemble that of flu, it also produces serious symptoms which include respiratory illnesses, encephalitis, and death in a few cases. The symptoms range from mild to severe. It may even present as a subclinical (no symptoms present) infection to acute respiratory infection.
The common symptoms are:
- Muscle pain.
- Breathing difficulty.
The serious symptoms include:
These symptoms can eventually lead to a coma in about one to two days and death. The virus can cause death anywhere between two to seven days after the onset of symptoms and the mortality rate is approximately 75 percent. In a few cases, death occurs months or years after exposure to the virus and this is called dormant or latent infection. In severe cases, encephalitis and seizures occur and progress to coma in one to two days. Long-term neurological complications like seizure disorder and personality changes have been reported in those who recover from acute encephalitis.
Nipah Virus in Domestic Animals:
Pigs are the vulnerable animal hosts of the Nipah virus which are infectious between 4 to 14 days (incubation period). The symptoms include fever, labored breathing, and nervous system problems like muscle spasms, twitching, and trembling. In dogs, the Nipah virus has an increased mortality rate and causes distemper-like syndrome (clinical signs that are similar to canine distemper which is a fatal condition).
How Is the Condition Diagnosed?
The initial symptoms are non-specific which hinders accurate diagnosis and creates challenges during an outbreak. Furthermore, the accuracy of lab results depends on a number of factors like quality, quantity, and timing of sample collection.
Diagnosis of the Nipah virus can be done either during the illness or after recovery. During active infection, it is diagnosed by real time-polymerase chain reaction (RT-PCR) test taken from nasal swabs, throat swabs, blood, urine, and cerebrospinal fluid. After recovery, antibody testing like enzyme-linked immunosorbent assay (ELISA) helps in its diagnosis.
Symptomatic diagnosis of the infection is hard as the symptoms are not specific. It is important to look for constant symptoms in an area where Nipah virus infection is common because early diagnosis helps in increasing the rate of survival, preventing the spread of the virus, and taking efforts to stop community spread.
What Are the Treatment Options?
There is no vaccine found yet for this disease, nor is there any known treatment as of now although research is ongoing. Only supportive care like rest, hydration, etc., is provided to give relief from the symptoms. This makes taking precautionary measures of paramount importance.
What Are the Preventive Measures?
Animal-To-Human transmission can be prevented by taking the following steps:
- Drinking raw date palm sap is to be avoided in endemic areas.
- Avoid eating fruits that are half-bitten or possibly contaminated by the urine or saliva of bats.
- People working in close contact with susceptible animal hosts should take adequate preventive measures like wearing gloves, and masks and washing their hands properly.
- Doctors, nurses, and veterinary doctors are highly susceptible to getting this virus from exposure to infected cases and are advised to be alert.
- Practicing regular handwashing with soap and water in susceptible areas is recommended.
Human-To-Human transmission can be prevented by taking the following steps:
- Healthcare professionals are advised to wear protective masks and gloves when caring for patients.
- Persons suspected to be carrying the Nipah virus are to be isolated in special wards in hospitals.
- Avoid making contact with the patient.
- The blood samples collected from suspected persons are to be tested in specially designated accredited laboratories to prevent their spread in the community through improper handling of specimens.
Since the Nipah virus has the potential for a major outbreak, and treatment protocols are still being formulated, the general public is cautioned to be alert and take all preventive measures to reduce the risk of infection. The risk of global transmission through fruit or fruit products that are contaminated with the body fluid of infected bats can be prevented by taking proper preventive measures.