Nipah virus cases in India: Several Asia countries step up border health measures

Several countries in Asia have heightened border health control measures following confirmed cases of Nipah virus infection in West Bengal, India. 

Last Sunday (Jan 25), Thailand started screening passengers arriving from the region at three airports: Suvarnabhumi, Don Mueang, and Phuket. 

Nepal started doing the same at Kathmandu airport as well as other cross-border checkpoints with India, BBC reported.

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Malaysia's health ministry said on Tuesday that it is assessing the situation and reassured the public that border health control measures are always maintained.

Meanwhile, Taiwan authorities said on Wednesday they will officially list Nipah virus infection as a category five notifiable infectious disease in March, Taipei Times reported.

These measures come after two confirmed cases of the deadly virus in West Bengal since December. 

On Tuesday, India's Ministry of Health and Family Welfare said that a total of 196 contacts linked to the two cases have been identified, traced, monitored and tested. 

All of them were asymptomatic and tested negative for the Nipah virus.

"The situation is under constant monitoring, and all necessary public health measures are in place," it added.

Bangkok Post reported on Tuesday that health officials at Suvarnabhumi Airport have not found any passengers showing symptoms of the virus following the enhanced screening measures. 

Last year, Bangladesh reported four deaths from Nipah virus infection between Jan 1 and Aug 29. 

What is Nipah?

The Nipah virus is a zoonotic virus, which means it can be spread from animals to humans. 

According to Singapore's Ministry of Health (MOH) and the National Centre for Infectious Diseases (NCID), the virus originates from fruit bats, and possibly other species of bats. Pigs may also serve as intermediate amplifying hosts for outbreaks in humans. 

Transmission can occur from animal to human through direct contact with infected animals or consumption of date palm sap or fruits contaminated by infected bats. Limited human-to-human transmission through close contact has also been documented. 

The incubation period of the Nipah virus in humans is between 4 and 45 days, with 90 per cent of symptoms developing between four to 14 days after exposure. 

While the duration of the infectious period is unknown, it likely begins during the incubation period and continues until the patient stops shedding the virus.

Symptoms of Nipah virus infection

According to the US Centres for Disease Control and Prevention, Nipah virus infection can cause mild to severe disease, including encephalitis (inflammation of the brain) and potentially death. 

Some symptoms include fever, headache, cough, sore throat, and difficulty breathing. 

As the infection progresses, the patient's condition may deteriorate and develop encephalitis, which may then progress to coma within 24 to 48 hours. 

Death occurs in 40 to 75 per cent of cases, according to the World Health Organisation. 

There are currently no licensed treatments and vaccines available for the Nipah virus. 

According to NCID, there have been no new cases of the virus reported in Singapore since 1999. 

It noted that further outbreaks mainly occurred in western Bangladesh and West Bengal.

Singapore steps up vigilance

The Communicable Diseases Agency (CDA) said on Wednesday that it is closely monitoring the Nipah virus outbreak in West Bengal, India.

While the Nipha virus is mainly transmitted by exposure to bats and consumption of date palm sap or fruits contaminated by bats, human-to-human transmission is rare but can occur.

"The outbreak in West Bengal is reportedly between humans, with two cases so far," CDA noted.

The agency added that the ongoing bio-surveillance programmes monitoring Singapore's bat populations since 2011 have not detected the Nipah virus.

Singapore has also stepped up vigilance in several ways, including:

• requiring medical practitioners and laboratories to immediately notify CDA of confirmed and suspected cases
• alerting hospitals and emergency departments to be vigilant for Nipah virus infections
• setting up temperature screening at the airport for flights arriving from affected areas
• disseminating health advisories to travellers entering and leaving Singapore
• stepping up surveillance of newly arrived migrant workers from South Asia, and engaging Ministry of Manpower's primary care providers to increase vigilance
• reaching out to counterparts in South Asia to better understand the situation and work together to report genome sequencing of detected cases

CDA said it may introduce additional public health measures in Singapore, should new information indicate an increased public health risk.

To reduce the risk of exposure to the Nipah virus, those travelling to affected areas are advised to:

• avoid food and drinks potentially contaminated by bats, such as raw date palm sap, and fruit found on the ground
• avoid direct contact with unwell persons
• avoid direct contact with animals (especially bats and pigs) and bat roosting areas
• consume fully cooked food and fruits that can be washed and peeled
• maintain good personal hygiene

"Travellers who develop symptoms during or after travel should seek prompt medical attention and inform their doctors of their recent travel and any potential exposure to raw date palm sap, bats or unwell persons," CDA said.

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carol.ong@asiaone.com