How Nipah got its name & more

Since 1999, there have been occasional outbreaks across a wide region but the current outbreak in Kerala has garnered the most attention

Zoonotic diseases are perhaps, the most striking argument in favour of evolution. These are diseases that can leapfrog from animals to human beings. The most notorious examples would include Ebola, HIV, mad cow disease, and rabies. Nipah was added to the list in 1998-99 when there was an outbreak of a mysterious illness in the Malaysian kampung (village) of Sungai Nipah.  

The disease was identified as being caused by an hitherto-unknown virus, and named Nipah after the village. It had infected local pigs and then been transmitted to human beings. It was discovered that the virus, which caused the disease was commonly found in various species of fruit bats, which are considered “natural reservoirs” and carriers for the disease. There is no apparent disease even in bats which carry the virus. Apart from pigs, versions of Nipah have infected animals such as horses, goats, sheep, dogs, cats. 

Since 1999, there have been occasional outbreaks of Nipah across a wide region including Australia, Bangladesh, India, Philippines, Indonesia, Vietnam, Cambodia, China, Thailand etc, In theory, given the wide geographic dispersion of the bat species, Pteropodidae, which can carry the disease, it could strike across most of Africa, infect people across most of Africa, Iran, Madagascar. 

Although there have been at least two outbreaks in eastern India earlier, and there have been multiple outbreaks in Bangladesh, the current outbreaks in Kerala have garnered the most attention. There have been quite a few deaths in Kerala, around 10 at the time of writing, including at least one nurse. There are unconfirmed reports that the disease has also been noted in Himachal Pradesh. 

Nipah is an RNA (ribonucleic acid) virus that is part of the Paramyxoviridae family and of the genus, Henipavirus. It can cause a wide range of effects among those it infects, ranging from zero (asymptomatic infection) to flu-like symptoms, to severe fever, breathing issues and encephalitis (inflammation of the brain). One huge problem is diagnosis since the disease can only be positively identified by sophisticated lab studies and it has symptoms that fit several other diseases. 

The disease is contracted by direct contact, which could occur by touching food contaminated by infected animals. It can also be contracted by direct contact with an infected human being which is what happened with the unfortunate nurse. Apparently it can also be contracted from drinking raw palm juice, probably due to contamination by fruit bats.  

Nipah is fatal in a large number of cases, though not as deadly as Ebola or HIV. There is no specific treatment beyond supportive care, treating symptoms and keeping the patient hydrated. There is also no specific vaccine. 

The WHO says that the case fatality rate is somewhere between 40-75 per cent depending on local medicare facilities. Another paper, “A treatment for and vaccine against the deadly Hendra and Nipah viruses" states that it was fatal in 54 per cent (315 deaths) of 582 cases  studied in Bangladesh.

There have been long-term complications noted even among patients who contract the severe version with encephalitis and make long-term recovery. Some patients have neurological disorders or relapse long after making an apparent recovery. 

Nipah is classified as a “priority” disease on the WHO’s Blueprint due to the high fatality rate. In the absence of vaccines, quarantine and avoidance of potentially contaminated sites and food is recommended. The WHO says that raw date palm sap should be boiled after collection and the sap collection equipment should be cleaned and disinfected since this is probably the main cause of bat-human infections. Face-masks are also useful since mucus from infected persons can be dangerous. Kerala has tried the isolation method by locking down the village, Panthirikkara Sooppikkada, in Kozhikode district, where the disease was first located in this outbreak.

The WHO has put out a document which outlines the “target product profile” for developing a Nipah vaccine.  (https://bit.ly/2GKfG3X) . This describes the preferred and minimally acceptable profiles for a human vaccine for reactive or emergency use to prevent NiV. 

Such a vaccine could be administered to populations experiencing an outbreak, or geographically close to an outbreak, and therefore, at high risk. Medical and paramedic personnel would also be protected if such a vaccine is developed. One possible approach would be passive immunisation. This would take antibodies from a Nipah patient who had recovered, to create a vaccine. This method was tested using ferrets, and it seems to give good results. Australia has also licensed a couple of vaccines for use in cats, monkeys and horses. However, it’s a long way from there, to a vaccine that meets the WHO standards for safety and efficacy.