There is increasing talk of the Nipah virus after an outbreak occurred in West Bengal, India, and countries in Asia began taking measures to prevent the spread. The virus scares because the mortality rate is very high, similar to that of Ebola, but the contagiousness is much lower than in the case of other infectious diseases, says epidemiologist Emilian Popovici. He explained to “Adevărul” what is important to know when it comes to Nipah virus infection.
What is Nipah virus and how is it transmitted
“The Nipah virus was discovered relatively recently, more precisely in 1998, in Malaysia. And since then there have been a number of outbreaks located exclusively in South Asia, Southeast Asia. (…) The disease is a zoonosis, i.e. a disease transmitted from animals to humans, through the consumption of contaminated food, through animal fluids that end up in one form or another being consumed by humans”. explains Prof. Dr. Emilian Popovici, vice-president of the Romanian Society of Epidemiology.
The main “reservoir” animal for the virus is the fruit bat, which also harbors other viruses, such as the coronavirus. Pigs can also be a source of infection.
However, the virus is also transmitted from person to person. The epidemiologist says:
“Transmission occurs via the oro-nasal route. It means mouth and nose. The virus is concentrated in the respiratory tract, so there is a respiratory component, but it is not highly effective respiratory transmission as it is in the case of influenza or COVID”.
How contagious the virus is
The R₀ (basal reproduction number), which shows how contagious an infectious disease is, is very low in Nipah virus.
,,This basal reproduction number is between 0.2 and 0.7, which means that, being below 1, the infection is practically self-limiting in human communities, because an infected person infects, in turn, less than one person in a receptive community. Thus, the outbreak spontaneously extinguishes,” explains Dr. Emilian Popoivici.
By comparison, says the doctor, in the case of COVID, the basal reproduction number exceeds 2 and even reaches 7 (for some variants). To talk about a growing epidemic, R₀ must exceed 1.
“This is the positive aspect: the fact that we will not face, at least based on the current data, a pandemic generated by Nipah virus infection, or even a large-scale epidemic. There will remain epidemic outbreaks that will manifest as they have so far, in the respective areas, where, unfortunately, there is this contact with the animals that represent the reservoir of the virus”emphasizes the epidemiologist.
Mortality rate
What is worrying about the virus is the very high mortality rate.
“Mortality is somewhere between 40% and 70%-75%. And 20% of those who escape, let’s say, remain with neurological sequelae, with personality changes. So it is a serious disease at the moment it manifests itself”.
But there is one more aspect that we have to take into account, says the doctor:
“It is valid for any infectious disease. The moment a death rate is reported in Vietnam, in South or Southeast Asia, we have to have a backup; that mortality rate will certainly not be recorded in Europe or any other developed area of the world, where medical assistance and intensive care are done at a much better level. Certainly, in a Western European intensive care unit, the mortality rate will be significantly lower. But there is definitely an increased mortality rate, because we don’t have a specific treatment, like we don’t even have a vaccination”.
Symptoms given by Nipah virus infection
Regarding the symptoms, Dr. Emilian Popovici says:
“The problem of symptoms is complex, because this infection can start with fever, headaches, dizziness and vomiting. And these symptoms are followed by rapidly progressive encephalitis, leading to drowsiness, disorientation, confusion and coma. There is also a symptomatology that is related to the central nervous system and, therefore, a decrease in the level of consciousness, a dysfunction of the brain stem can be observed; the lack of reflexes, hypotonia can be observed.
And also, the disease can present a fulminant form, in which multiorgan dysfunction occurs. (….)So it is a disease with a very serious effect on the body and with a very severe evolution.”
Preventive measures
So far, five cases have been identified in the Indian state of West Bengal, which borders Bangladesh.
“Basically, when an area is affected by a disease of such severity, the most effective measure is to avoid contact with that area. If you really have to make that journey or you have already arrived, follow the measures that are also recommended for the population there.“emphasizes the doctor.
Recommended measures include:
- avoiding contact with animals that transmit the disease
- increased attention to food consumption (where we eat, under what conditions the food is consumed, where it comes from)
- protective equipment when handling sick animals
- boiling the freshly collected date juice
- washing date fruits before consumption
When it comes to human-to-human transmission, avoiding contact with people showing signs of illness and rigorous hand hygiene are most important.
