The southern Indian state of Kerala has had to close several schools and agencies this week as local authorities race to contain the deadly Nipah virus following two recent fatalities.
According to Reuters, scientists first identified the Nipah virus in 1998 during an outbreak among pig farmers in Malaysia and Singapore. This outbreak had significant economic impacts, as over a million pigs were culled to control the disease.
While there have been no further outbreaks of the Nipah virus in Malaysia and Singapore since 1999, cases have been reported almost annually in certain regions of Asia, primarily Bangladesh and India.
As of now, there is no vaccine or cure for Nipah virus infection. The disease has a mortality rate of approximately 70%. Standard treatment involves supportive care and symptom management.
The World Health Organization (WHO) states that early symptoms of the disease include fever, respiratory distress, headaches, and vomiting. In severe cases, encephalitis and seizures may occur, leading to coma within 24 to 48 hours.
WHO has classified the Nipah virus as a priority pathogen for research and development of vaccines.
Healthcare workers bury the body of a patient who died from the Nipah virus in Kozhikode, Kerala, southern India. (Photo: AP).
Authorities have intensified contact tracing efforts, identifying, isolating, and testing individuals who may have come into contact with the young boy. Veena George, head of the Kerala Health Department, reported that as of September 6, 188 contacts of the boy had been identified, including 20 high-risk individuals, mostly family members. All have been strictly quarantined or hospitalized.
On September 6, two healthcare workers who had contact with the patient developed symptoms of Nipah virus infection. They have been hospitalized and their blood samples have been taken for testing.
Officials have cordoned off an area within a 3 km radius of the boy’s home and are screening symptomatic individuals in all neighboring districts of Kerala. The nearby state of Tamil Nadu is also on high alert for any suspected cases of fever.
This is the second outbreak of the Nipah virus reported in Kerala in three years, where there is also a high rate of COVID-19 cases. Approximately 68% of the 40,000 new COVID-19 cases reported daily in India are in Kerala.
What is the Nipah Virus?
Nipah is a zoonotic virus transmitted from animals to humans. Transmission typically occurs when humans come into direct contact with infected animals or consume contaminated food. However, numerous human-to-human transmission cases of the Nipah virus have also been documented.
Fruit bats of the Pteropodidae family, commonly referred to as flying foxes, are the natural hosts of the Nipah virus. They can transmit the virus to other animal species, including pigs, dogs, cats, goats, horses, and sheep.
Individuals infected with the Nipah virus often experience symptoms such as fever and headache for a period ranging from 3 days to 2 weeks. Subsequently, patients may develop cough, sore throat, and respiratory issues. Rapid disease progression can result in encephalopathy, leading to drowsiness, confusion, and potential coma and death.
Currently, there is no treatment or vaccine for the Nipah virus, and patients receive only supportive medical care.
According to the WHO, up to 75% of Nipah virus infections can be fatal. In contrast, the mortality rate for SARS-CoV-2 is about 2% of all cases. Approximately 20% of survivors may experience long-term neurological symptoms such as seizures and personality changes.
A researcher captures bats to collect samples for Nipah virus research in the Shuvarampur area of Faridpur, Bangladesh. (Photo: Reuters).
Is the Nipah Virus a New Threat?
The Nipah virus was first discovered in Malaysia in 1999 during an outbreak among pig farmers. Since then, there have been several outbreaks in South Asia and Southeast Asia, resulting in over 260 deaths.
A 2004 outbreak in Bangladesh was linked to individuals consuming date palm sap contaminated with the Nipah virus from infected fruit bats. The most recent outbreak in India occurred in 2018 in Kerala, resulting in the deaths of 17 out of 18 infected individuals. The cases were all linked to dead fruit bats found in a family’s water well.
The Nipah virus is considered to have a lower transmission rate than SARS-CoV-2, but its mortality rate is significantly higher. The incubation period can also be longer, up to 45 days, and its ability to infect multiple animal species raises considerable concerns for epidemiologists attempting to predict and prevent the next pandemic.
Veasna Duong, a virologist at the Pasteur Institute in Phnom Penh, Cambodia, has studied human-bat interactions in the region and stated that the close proximity of humans and bats in markets and other crowded places throughout Asia poses a serious risk of infection.
Veasna Duong told the BBC that, in some cases, the Nipah virus could mutate and pose a risk of causing future pandemics.
“We have observed fruit bats in Cambodia and Thailand, in markets, religious sites, schools, and tourist destinations like Angkor Wat. There are many bats there. Every year, Angkor Wat welcomes around 2.6 million tourists. That’s 2.6 million opportunities for the Nipah virus to transmit from bats to humans annually at just one location,” said expert Veasna Duong.
Scientists warn that climate change and human destruction of the natural habitats of animals like fruit bats in Asia will create opportunities for zoonotic viruses to emerge.
In a note about the Nipah virus, WHO warns of the “risk of the virus spreading to other countries through fruit or fruit products like date sap contaminated with the urine or saliva from infected fruit bats.” WHO also recommends preventing virus transmission by thoroughly washing and peeling fruit before consumption and discarding any fruit showing signs of bat bites.
