Discovery of Nipah virus
The deadly virus discovered in a village known as Kampung Sungai Nipah in Malaysia about twenty years ago is called Nipah virus (1).
Later on Singapore, Bangladesh and India also witnessed the outbreak of Nipah virus. More recently the virus has spread in Kerala, a southern most part of India where about a dozen people have died in spite of medical intervention.
What is Nipah virus?
A virus is an infectious agent. It is composed of either DNA or RNA only. The virus which is a microorganism, invades the host organism in the animal or human body. The virus invades the host but does not involve in the metabolism.
Nipah virus can spread from birds to animal and from animal to animal. It can also spread from bird or animal to human and from human to human. This is a zoonotic virus that is transmitted from animals (or birds) to humans.
It has been established that the virus basically spread from bats of which fruit bats is the major contributor of the virus. Pigs are also another source of the virus. The virus is known to infect the pigs and then transmitted from the pigs to humans. Fruit bats of Pteropus genus from the Pteropodidae family are the natural host of the virus.
Outbreak of the virus is caused by the human contact of the bats or the pigs infected. But consumption of fruit or raw date palm sap which are possibly contaminated by the excretion of the bats could also infect humans. Transmission of the virus (2) from within the family members of a person affected is considered a distinct possibility of the infection.
During the initial years of discovery, pigs were also known to spread the virus (3) by contacting the same from the fruit bats. Presently it is fruit bats that are considered to be the major cause for spreading the virus. The virus spread by contact from person to person or by consumption of food contaminated by the virus. Precisely due to this reason we hear recently after the outbreak of the virus in Kerala, that some of the fruits are shunned by consumers fearing infection due to fruit bat bites in the said fruits(4).
Research studies have confirmed that fruit bats which live on fruit trees are the stores of the virus. One of the studies have indicated that due to human interference into their living space has made them starve for fruits and consequently the virus accumulate in their stomach in large quantities. When they become so large they spill outside in their saliva and excretions. Likewise fruits bitten by the bats also contact the virus which in turn affect the humans or animals consuming the affected fruits or their products.
So far there is no treatment available to cure the disease caused by the virus but patients affected are put on intensive support care only. Once contacted the virus cause inflammation in the brain and becomes fatal within about two to three days. Efforts by various health care organizations world over, including WHO have not produced any positive result until now. However, WHO endeavors to encourage appropriate research and inventions leading to formulation of a vaccine both as a preventive and also as a curative measure.
Why is there no vaccine for Nipah infection?
One of the reasons for non-discovery of any vaccine to treat the virus is that the medical fraternity has not thoroughly understood the complexities of Nipah virus. It may be also because the virus is confined to South Asian countries which has not forced the western world into aggressive research in the field.
Nipah virus cause asymptomatic infections, respiratory disorders and also fatal encephalitis. Fatal encephalitis is known as inflammation of the brain caused by infection leading to death. Presently no vaccine to cure the viral infection is available.
The cause of the virus is infection transmitted from fruit bats and the symptoms may or may not surface initially. Acute respiratory disorder and fever are observed as noticeable symptoms.
Diagnosis of the disease is through various clinical tests and observations of the symptoms noticed in the patients. Since members of the family of the affected person are vulnerable to the contact of the disease. Since they are the persons who initially attend to the needs of the patient, all the family members are isolated as a precautionary measure and put on close observation preferably with intensive support care.
It must be known that experiments to trace the first source of the virus have not established the source. It is also not certain whether there are any other carriers of the virus other than fruit bats.
Symptoms of the disease
Those affected by the infection initially suffer from headaches, muscle pain followed by fever with symptoms like influenza. As the infection advances, the person experiences drowsiness, dizziness, disorders of consciousness and then neurological disorders. All these indicate that the patient is affected by encephalitis and also seizures in extreme cases which may lead to coma stage within about two to three days.
Illness caused by the virus may prolong for about two weeks’ time before eventually causing encephalitis. The incubation period of the virus is generally between five to fourteen days.
Treatment for Nipah virus infection – is there any?
But the treatment is more complex. In fact presently there is no treatment available and the only way to treat the patients is by providing them intensive support care. But certain precautions must be taken while treating those patients. Since the infection gets transmitted from person to person, the foremost thing is to separate the affected person by putting in an intensive support system and monitoring the escalation of the infection in the body.
In the absence of specific vaccine to treat Nipah virus, symptoms of neurological disorders and fever alone are treated. As the virus affects the central nervous system in the advanced stages, treatment given is directed towards addressing neurological disorders.
The fatality rate is very high in the outbreak of this virus infection. However capabilities of the local medical team in strict epidemiological supervision and management through clinical processes can reduce the fatality to some extent.
Since the outbreak of the virus is confined to South Asian countries, barring reports and notes of caution from WHO there are no worthwhile information emanating from other parts of the world.
Ways to prevent Nipah virus infection
In the absence of specific treatment to protect from the infection, it is the preventive measures that need to be given more attention. Preventive measures include:
- Educating people about the peculiarity and seriousness of the virus in addition to raising their awareness among masses.
- Reduction of the risk of infection from bat to human: This is done by using protective body covers while collecting fruits from the bat habitant trees. By scrutinizing the surface of the fruits for possible bat bite cracks and completely washing the fruits and peeling off the fruits before consumption and by boiling the collected palm saps before consumption (5).
- Reduction of the risk of infection from animal to human-by avoiding contacts with infected pigs, using hand gloves while attending to animals in the virus prone regions, by not constructing sheds for pigs near the fruit bat habitat and ensuring providing non-bat infected feed to the pigs.
- Reduction of the risk of infection from human to human- by avoiding direct contact with persons infected, by using appropriate protective gloves if the infected patients are taken care of after isolation.
- The virus is found to be inactivated with soaps and detergents. Hence cleanliness and hygiene are of paramount importance in containing the spread of the disease.
Nipah in India – How the virus spreads
Stains of Malaysia and Bangladesh Nipah virus are known to affect India. The recent outbreak in Kerala is identified as similar to Bangladesh stain. Both are considered to be with high level of fatality. The classification is made in order to attempt to treat and take precautionary measures based on the experiences of the respective countries. For example, in Bangladesh consumption of palm sap infected by the bat urine or saliva is found to be the reason for contact of the virus by humans.
Biosecurity is the most important factor in preventing the outbreak of the disease.
The way the virus reached Kerala is still a mystery. The first few people affected by the virus belonged to the same family who had consumed water from a dug well in which bats were hanging (6). Though originally it was presumed to be the reason later on further experiments have proved that to be untrue. From reports published from medical departments of the region experts have ruled out the possibility of the virus infection through fruit bats. But the particular source of the virus is still to be identified.
How does the virus survive?
Nipah virus can survive for a longer period in sugar concentrated medium like palm fruits or dates. Since various varieties of dates are procured from Bangladesh into India there is a possibility that the virus has been transmitted through dates. However no confirmation is available so far.
Causalities due to the outbreak of the virus is not alarming when compared to many other infectious diseases even after taking into account the total period of two decades since the first outbreak in Malaysia. Although it is not essential to panic, complacency in finding out the source and discovery of a vaccine must be avoided.