Transmission and symptoms of Nipah virus

For several weeks, a virus has worried the authorities in India. It is a virus called Nipah which is transmitted from animals to humans. What’s this ? What are its symptoms? Treatments? Its death rate? Should we fear an epidemic? Transmission and knowledge to date.

For several weeks, a particularly dangerous virus has worried health authorities in India. This virus called “Nipah” is not new since it was detected for the first time in 1999 in Malaysia, among pig farmers, then it was identified sporadically in Asia for twenty years. However, according to the WHO, this infectious agent is emerging, transmitted mostly by infected bats, may pose a risk of epidemic in the near future if its transmission capacity were to change. What are its symptoms? His transmission risks ? Mortality? His treatments? Is there a vaccine? What we know.

the Nipah virus (NiV) is a virus said “zoonotique”, in other words, who is transmitted from animal to human and vice versa. In an infected person, it causes illness that can range fromasymptomatic infection To acute respiratory infection (mild or severe) which may progress to fatal encephalitis (inflammation of the brain). Symptoms usually appear in 4 to 14 days that follow exposure to the virus.

The risk of transmission of the Nipah virus depends on the characteristics of the patient, such as age and the presence of respiratory symptoms.“, indicates thePastor Institute. The Nipah virus can be transmitted in several ways:

  • from animal to man (and vice versa), particularly pork (Nipah virus is very contagious in pigs) or the infected bat, more rarely domestic animals such as horses, goats, sheep, dogs and cats,
  • directly between two men, by close contact with the secretions or excretions of infected people,
  • by contaminated food.

In the first outbreaks (Malaysia, Singapore), infections resulted from direct contact with sick pigs or with their contaminated tissue. “Transmission is believed to have occurred through contact with secretions from pigs or tissue from a sick animal“, reports theWHO. In subsequent outbreaks (Bangladesh, India), the most likely source of transmission was the consumption of fruits or derived products (date or palm juice) contaminated with urine or saliva from infected bats. It’s about bats frugivores of the species Pteropus, that is, they feed on fruit. A case of human-to-human transmission has also been reported among families and caregivers of infected patients.

Transmission and symptoms of the Nipah virus ©  artitcom – 123RF

Nipah virus can cause asymptomatic illness or acute respiratory infection, which can lead to fatal encephalitis.

>> First of all:

  • Fever
  • Headache (headache)
  • Muscle pain (myalgia)
  • Vomiting
  • Sore throat

>> Secondly:

  • Dizziness
  • Somnolence
  • Altered state of consciousness (disorientation, mental confusion …)

>> In severe cases:

  • Atypical pneumonia
  • Severe breathing problems including acute respiratory failure
  • Neurological signs typical of acute encephalitis (swelling of the brain)
  • Seizures that can progress to a coma in 24 to 48 hours.

About 20% of cured patients have neurological sequelae

Researchers know the dangerousness and contagiousness of the Nipah virus. It is capable of infecting a large number of animal species, including pigs, and causing serious illness and death in humans, says the World Health Organization. The case fatality rate (proportion of deaths in relation to the total number of cases affected by the disease) is between 40 and 75%. “Most patients who survive acute encephalitis recover completely, but long-term neurological conditions have been reported among survivors. About 20% of cured patients have neurological sequelae, such as seizures and personality changes. In a small number of cases, those who have recovered subsequently suffer from relapse orlate-onset encephalitisThe WHO says. The 2018 review of the WHO list of priority diseases indicated that there was an urgent need to include Nipah virus infection.

WHO estimates that the incubation period (time from infection to onset of symptoms) varies from 4 to 14 days. However, longer incubation periods, which can reach 45 days, have already been observed.

As the symptoms are not disease specific, it is difficult to diagnose a Nipah virus infection during a consultation. Infection can be diagnosed at the same time as examining the clinical history during the acute phase and the convalescent phase of the disease. The main tests that are used include the test of RT-PCR (real-time polymerase chain reaction) from body fluids, as well as the detection of antibodies throughan ELISA test. This method is mainly used to detect the presence of an antibody or an antigen in a blood sample.

No Nipah virus infection has been detected in Europe.

The Nipah virus is present throughout South and Southeast Asia. Signs of infection have been demonstrated:

  • In India: a 12-year-old child died on September 5, 2021. Since then, the state of Kerala is “on alert”, the news agency said Associated Press.
  • In Malaysia
  • In Bangladesh
  • In singapore
  • In Cambodia
  • In Ghana
  • In indonesia
  • A Madagascar
  • In the Phillippines
  • In Thailand

For the moment, no Nipah virus infection has been detected in Europe and therefore in France.

To date, there is no medicine to treat a Nipah virus infection. Alone intensive supportive care can treat severe respiratory and neurological complications.

There is no vaccine capable of treating or preventing Nipah virus infection, either in humans or in animals.

Without a vaccine, the only way to reduce the number of human infections is to educate people about the risk factors and tell them what to do to reduce their exposure to the Nipah virus:

  • Boil, wash and peel harvested fruit in risk areas (listed above) before consumption.
  • Discard the fruit partly eaten by the bats.
  • Wear gloves and other protective clothing when handling sick animals or their tissues, as well as during slaughter.
  • Take into account the presence of fruit bats and protect pigsties and animal food from bats.
  • Avoid close unprotected physical contact with people infected with the Nipah virus and wash your hands regularly after providing care or visiting sick people.

Sources: Nipah virus, WHO file, May 30, 2018 / Signs and symptoms of the Nipah virus, Centers for Disease Control and Prevention, October 6, 2020 / Institut Pasteur press release of May 9, 2019.

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