Following two deaths and several positive cases, India is stepping up efforts to contain an epidemic of the dreaded Nipah virus. What do we know about this virus? What real threat does it represent?
How is the Nipah virus transmitted?
The Nipah virus can be transmitted to humans by an animal (bats, pigs, etc.) or by contaminated food. This is a zoonotic virus. But it can also be transmitted from one person to another. Even if the outbreaks have not been significant or numerous so far, this virus is worrying in more than one way.
“It can infect a large number of animal species and causes serious illness and death in humans, making it a public health concern.“, already reported the World Health Organization (WHO) in its 2018 report. It had already included the Nipah virus in the priority diseases on which scientific and medical research should focus.
What are the symptoms ?
According to the WHO, the clinical picture of Nipah virus can be symptomatic or asymptomatic. The incubation time would be 4 to 14 days and in more serious cases 45 days. Most often, initially, infected people present the following symptoms:
- Fever ;
- Headaches;
- Muscle pain;
- Vomitings ;
- Sore throat.
Other signs may then appear:
- Dizziness ;
- Drowsiness;
- Alteration of the state of consciousness;
- Atypical pneumonia;
- Acute respiratory failure;
In the most serious cases, brain infection (encephalitis) and seizures which can lead to coma within 48 hours have been reported. The case fatality rate is between 40% and 75%.
“As always with these viral infections, the initial symptoms of infection are not specific and the disease is often not suspected during consultation.” says Dr. Gérald Kierzek, emergency doctor and medical director of TipsForWomens. “No test is therefore carried out and therefore the real cases are probably more numerous, distorting all the data and in particular the overestimated fatality rate.“.
Most patients who survive acute encephalitis recover completely, but long-term neurological conditions have been reported among survivors. Nearly one in five patients has neurological after-effects, such as convulsive disorders and personality changes. In a small number of cases, cured individuals subsequently suffer a relapse or late-onset encephalitis.
How is the Nipah virus transmitted?
The Nipah virus was first detected in 1999 in Malaysia among pig farmers, explains the WHO. There were no other cases after this cluster in the country. Several outbreaks have also occurred in Bangladesh since 2001, as well as in India.
Concerning the outbreaks in Malaysia and Singapore, the WHO specifies that “Most human infections have resulted from direct contact with sick pigs or their contaminated tissues. Transmission is believed to have occurred through contact with pig secretions or with tissues from a diseased animal“. Concerning those which occurred later in Bangladesh, the probable source of infection was the consumption of fruit or fruit juice contaminated with the urine or saliva of infected bats.
Since last month in India in the state of Kerala, 2 deaths and 4 positive cases were recorded. Local authorities are trying to contain the epidemic through a testing campaign, the closure of schools… This is only the 4th outbreak to affect the region in five years and the 17th in India since 2018.
Regarding contagion between humans, rare studies suggest close contact with the secretions or excretions of a patient positive for the virus.
According to the WHO: “Other regions could be at risk, as serological signs of infection have been demonstrated in the known natural reservoir of Nipah virus (Pteropus bats) and among several other bat species in many countries, including Cambodia, Ghana, Indonesia, Madagascar, Philippines and Thailand“.
What is the treatement ?
Currently there is no specific treatment or vaccine for Nipah virus. Management is limited to supportive care to treat respiratory and neurological complications.
Could the Nipah virus be the cause of a new pandemic?
The Asian origin of the virus may be reminiscent of Covid-19. However, there are several differences.
On the one hand, the Nipah virus has been known for more than 20 years and epidemics have remained very localized.
“The risk of international transmission could especially be linked to fruits or fruit-based products (raw date juice, etc.) potentially contaminated by the urine or saliva of infected bats. explains Dr. Kierzek. “But simple measures like washing or peeling fruit are effective. To date, there is therefore little risk of a new pandemic from this virus“.
We must of course monitor the situation in India but we can legitimately believe that this virus will not be the cause of a new pandemic. Until now, no case has ever been recorded in Europe.