Dr. G Arunkumar, who heads the Manipal Centre for Virus Research under MAHE, was the first person to identify the cause of a recent encephalitis outbreak in Kerala as Nipah virus. In a candid conversation with the MTTN team, he tells us about the events that lead to the detection of the virus and the various factors which helped in curbing the outbreak.
Could you tell us a little about Nipah Virus? Why is it so deadly?
Nipah Virus is a paramyxovirus and is quite similar to the measles virus. Primarily the virus is a respiratory pathogen and most patients die due to the severe lung damage caused by it. It also causes myocarditis (inflammation of the heart muscle) and encephalitis (inflammation of the brain). Unlike most pathogens which affect individuals with a compromised immunity, Nipah virus has the ability to cause the disease in even a perfectly healthy person. When the symptoms appear after a brief latent period, they rapidly progress and can cause death as fast as within two days. Since it is a recently emerged virus, it has not yet adapted to the human host and the immune response generated by the body is vigorous. That’s the main reason for its lethality.
Fruit bats are the natural reservoir of the virus. It is to be noted that not all fruit bats may carry this virus; in a colony of thousand bats perhaps only four or five bats may carry it. The virus is shed in the bat’s saliva, urine and other body secretions, especially when the animal is in stress. The virus has to be present in sufficiently large number to be shed by the animal.
It is spread mainly by three different ways – bat to human, bat to pig to human, and human to human. Direct bat to human transmission is a rare event, where a person comes in contact with an infected bat. This seems to be the most likely cause in the recent outbreak in Kerala. Another way, particularly common in Bangladesh is by consuming raw date palm sap contaminated by bat saliva and urine. The first ever outbreak seen in Malaysia in 1998 was due to the handling of infected pigs which had caught the virus from fruit bats.
Then, there is human to human transmission through respiratory droplets. Compared to the Malaysian outbreak, where a majority of the cases were caused due to pig to human transmission, in India and Bangladesh, human to human transmission was the major cause. This can be explained by the fact that a larger percentage of the infected patients developed respiratory symptoms.
Could you tell us about the events that lead to the detection of Nipah virus outbreak in Kerala?
On the 17th of May, I was approached by the clinician about a patient with encephalitis, in a rapidly deteriorating condition. The patient’s brother had died twelve days back and had shown similar symptoms. Moreover, his father and his aunt were also admitted to the hospital and were showing symptoms of early stages of the same disease.
This put us in a scenario, where there was a clustering of encephalitis cases. Now the commonest cause of encephalitis in India is the Herpes Simplex virus. Given the sporadic nature of this type of encephalitis, four members of the same family developing it at the same time was highly unlikely.
The next major cause is Japanese encephalitis, which is a mosquito-borne disease. Statistically, only one in three hundred of the infected people develops encephalitis. Again, four cases from the same house weren’t possible. In this manner, we eliminated toxic encephalopathy, Chandipura virus, and various other causes and ultimately narrowed it down to Nipah Virus. And Nipah is notorious for causing clusters of encephalitis cases in the community.
Our laboratory is one of the two labs in the country equipped to test for Nipah. Within the same day, we got the test result, and it was positive for Nipah virus.
Thankfully, the outbreak has now been contained. What role did different factors play in bringing this about?
Our job mainly was detecting the virus. Since Nipah virus infection is a disease of international concern, it had to be officially reported and there were several other rules to be followed before we could make a public announcement. The samples were sent to the National Institute of Virology, Pune for a reconfirmation. So even though the virus was detected within the same day, I couldn’t outright give the name of the virus to the clinicians. I just informed them that it was a deadly and contagious virus.
This is where the Kerala state government did a commendable job. Without losing time by waiting for the official announcement, they promptly started isolating the cases and took other public health measures. It was a key decision which helped in blocking further transmission. After reconfirmation by the lab in Pune, the official announcement by the Government of India came forty-eight hours later and by that time, the state government already had all bases covered.
We have overcome several viral epidemics along the years, but Nipah virus outbreak particularly managed to cause widespread panic among the general public as well as the health workers. This may be attributed to its rapid progression and a mortality above ninety percent. Hearing the news about the death of a nurse, some doctors even went as far as drafting a will at the time of the outbreak. This required the government to constantly communicate with the public and spread awareness about the disease.
There were also several unexpected issues which the state was not prepared to deal with. Since it was told that fruit-eating bats transmit the virus, people stopped buying fruits and the fruit market collapsed. People simply did not understand that the fruit bats don’t lick each and every fruit. False messages on social media platforms warning people about catching the virus from chicken caused the meat market to collapse within a day and a loss of crores of rupees. The Kerala tourism got affected. The outbreak ended up causing a massive economic loss for the state. So the outbreak was no longer just the health ministry’s concern; several other sectors also got dragged into it.
Apart from the basic information that has been circulated among the general public, is there anything else that you would like the public to know about the virus?
There were many misconceptions among the public regarding the transmission of the virus. Several people thought that it was an aerosol transmission. Though it is true that human to human transmission occurs through droplets, you have to be present within one meter from the sick person to get infected. There were also speculations that the virus was brought by immigrants from the Nipah prone areas like Bangladesh, the North-eastern states or Malaysia. It is highly unlikely, given the fact that the virus can be transmitted only when the person is very sick and not during the asymptomatic period.
What is an average day at work like for a virologist? Could you tell us a little about the research that the department is involved in?
In our lab, the main area of expertise is in providing diagnoses. Next, there is disease surveillance, where we look for trends and patterns in diseases. Then we have translational research, where we try to develop new vaccines and tests, and research other basic virological and immunological aspects of viral diseases.
The major project our department is currently involved in is a surveillance project aimed to find the etiology of febrile illnesses which require hospital admission. In this program, we test samples from patients admitted to the hospital with a fever. There are around thirty-three hospitals from ten states across the country included under this survey. We have gained several important findings through this project. For instance, Kyasanur Forest disease, which was thought to be a disease exclusive to Karnataka, was found in four other states along the Western Ghats. We also found the fourth case of Zika virus in India.
Tripura and Assam are among the ten states included under the survey. Since these states are close to Bangladesh, we were expecting a spillover of Nipah virus there and were regularly testing for it as well. We received training in November 2017 from the Centre for Disease Control, Atlanta to test for Nipah virus. This came handy in detecting the virus during the recent outbreak.
Overall, every day is a challenging day as a virologist, dealing with new challenges and ending up with new findings. These timely findings help the society at large, if the right steps are taken, in containing contagious diseases, before they turn catastrophic.
Writer- Sindhuri Sriraman
Interviewer- Sarthak Bhardwaj
Photographer- Sanketh Mohanty