A new outbreak of the deadly Nipah virus in India, which has left scores dead, has forced Asian countries to step up screening and put health systems on high alert. The pathogen has a mortality rate of up to 75%, which is especially worrying because of serious neurological complications, but experts say the risk of a global pandemic like Covid-19 is low.
Asia is once again on high alert due to the outbreak of the rare but extremely dangerous Nipah virus in the Indian state of West Bengal. Reports of several deaths have prompted countries such as Thailand, Malaysia and Singapore to introduce additional screening and testing measures for arrivals. This virus belongs to the henipavirus family and is considered a zoonotic disease, meaning it can be transmitted from animals to humans. Its natural “reservoir” is fruit bats, and the mortality rate among infected people, according to WHO, can be as high as 40–75%.
Nipah virus was first identified in a large outbreak in Malaysia in 1998, when pigs were exposed to infected bats. There are three main routes of transmission. The first is direct contact with the biological fluids of infected bats (saliva, urine, feces) or with other sick animals. Second, and most common in some regions, is the consumption of food contaminated with these secretions, especially raw date sap, collected at night, just when fruit bats are active. A third route is person-to-person transmission through close contact, such as during patient care or through infected secretions in a hospital setting, although this mechanism is considered less effective.
The incubation period of the disease can last from 4 days to 3 weeks, after which the infection develops rapidly.
The disease begins with flu-like symptoms: high fever, headache, muscle weakness. However, the main danger is neurological complications. The virus can cause severe encephalitis – inflammation of the brain, leading to confusion, disorientation, seizures, coma and, in some cases, sudden personality changes or acute psychosis. It is the damage to the central nervous system that causes such a high mortality rate. Of particular concern are the long-term consequences: some survivors may experience a recurrence of encephalitis years or even decades later.
There are currently no specific treatments or approved vaccines for Nipah virus, making each outbreak particularly difficult to control. Major efforts focus on maintenance therapy. However, there is a glimmer of hope: a monoclonal antibody called m102.4 is being developed in Australia. Results from the phase 1 study showed that the drug was well tolerated in healthy volunteers. Theoretically, it could be used for both treatment and post-exposure prophylaxis, but widespread clinical use is still a long way off.
Despite its scary characteristics, experts agree that the risk of Nipah becoming a global pandemic like Covid-19 is extremely low. The main reason is that the efficiency of person-to-person transmission is limited. According to experts, this virus is not highly infectious and its outbreaks are often localized, closely linked to specific food operations or occupational contact with animals.
“For residents of countries that do not border areas of infection, the risk is considered minimal. Even for travelers returning from endemic areas with fever, doctors will first consider more common infections such as malaria or typhoid fever,” the experts concluded.
