About a month back, a small town in Kerala, called Perambra was pushed into the limelight due to a series of very mysterious deaths. The patients showed strange and unusual symptoms and doctors could not fathom what caused these symptoms and by extension, how to save these patients. The story begins with Mr. Mohammed Salih, who was rushed to Baby Memorial Hospital, Kozhikode. He was severely ill and the doctors reported encephalitis, which means his brain tissue was heavily inflamed. While the doctors performed routine differential analysis to eliminate possible causes, the critical care physician Dr. A.S Anoop Kumar suspected something bigger than the usual. Mohammed Salih’s samples were then dispatched to Manipal Centre for Virus Research (MCVR) in Karnataka, wherein the cause of the encephalitis was zeroed down to the exotic and extremely dangerous Nipah virus. Over the course of just a few weeks, Nipah virus has claimed the lives of 17 people in Kerala and the state remains to be on high alert.
What is Nipah Virus and how did it reach Kerala? It is now common knowledge that the Nipah virus resides in the Pteropus genus of bats. Then how did it reach humans? Let’s go back to 1998, in Malaysia, where the first case of Nipah virus was documented. In this case, Nipah virus jumped from bats to pigs and then ultimately to humans through meat. A few years later, in 2000, the next outbreak of Nipah virus was documented. This time, in Bangladesh. The virus infected humans through raw palm sap contaminated by bat urine.
Diseases, such as Nipah fever are known as zoonotic diseases, they are transmitted from animals to humans and India frequently falls victim to such diseases due to poor sanitation control, large population and lack of awareness. The disease was also found to spread among the human population through body fluids.
A general scheme for transmission of Nipah virus
The virus responsible for the Nipah fever is an RNA virus of the genus Henipavirus. Symptomatically, Nipah fever presents encephalitis, fever, headache and progressively, drowsiness, disorientation, and mental confusion. If left unattended, these symptoms can worsen and lead to coma and death. Clinical diagnosis of Nipah virus can be made only during some specific stages of the disorder. And more importantly, multiple tests must be run to confirm infection. Commonly, the RNA of the virus is isolated from patient body fluids, such as CSF, blood or urine, and then a test called Real-time PCR is performed to detect the presence of the viral particles. It is important that the collection of body fluids be done at the early stages of the disease. Following this, another test called ELISA (Enzyme-Linked Immunosorbent Assay) is performed to confirm the presence of the Nipah Virus.
Now, we must remember that while these tests seem quite simple, they are extremely specific. The efforts of the diagnosticians in India are commendable as this was the first Nipah outbreak in India and they had no idea what they were looking at. Once, the disease and the pathogen were successfully identified, the very obvious next step was to cure it and at the same time, make sure it did not spread and infect more people. While the hospitals immediately quarantined people who lived in close proximity with infected people, the bigger challenge was to prevent any fresh infections.
Since Nipah spreads mostly through bats and at times, through pigs, it is advised to not venture into areas with bat dwellings and introduce physical barriers where pigs are being reared. Fruits and vegetables must not be consumed raw and palm sap, in particular, must be avoided. Also, physical contact with an infected individual must be avoided at all costs.
Since Nipah is a new virus and not much research studies have been performed on it, there is no particular cure or vaccination that exists. Currently, the treatment being used is the administration of ribavirin. Ribavirin is an antiviral drug and while it seems quite effective in in-vitro studies, scientists are not quite sure of its usefulness in the case of humans. As far as immunization goes, scientists are looking into passive immunizations using an antibody against a Nipah antigen and these experiments are still in the animal-model stage.
The containment of the Nipah virus infection at such an early stage is due to the tremendous effort on behalf of the Kerala government and the medical personnel. Doctors tracked up to 2000 contact cases, quarantined them using strategies similar to the ones followed during the Ebola outbreak. Currently, since there is no cure for Nipah virus, WHO has listed it under its category of priority diseases. Accelerated research into the diagnostics and treatment of the disease are currently in progress.