Pakistan has become the latest country to order enhanced screening of incoming travellers for signs of the deadly Nipah virus.
Thailand, Singapore Malaysia, Indonesia and Vietnam have already tightened airport screening. Authorities in Hong Kong have bolstered operations to help curb the spread of the virus.
It comes after India confirmed two cases of the virus, which can cause fever and brain inflammation, but also be asymptomatic.
No vaccine exists for the virus, which has a fatality rate of between 40 per cent and 75 per cent. It spreads from infected animals, mainly fruit bats, to humans.
Although it can spread from person to person, transmission is not easy and typically requires prolonged contact with someone who has been infected.
“It has become imperative to strengthen preventative and surveillance measures at Pakistan's borders,” said the Border Health Services department. “All travellers shall undergo thermal screening and clinical assessment at the point of entry.”
Passengers will be required to provide transit history for the previous 21 days to check whether they had travelled through Nipah-affected regions, it said.
The two people infected in the eastern Indian state of West Bengal in late December were health workers and are both being treated at a local hospital, a district health officer told Reuters.
Authorities have identified 196 contacts linked to the two cases with none showing symptoms and all testing negative for the virus, the Indian Health Ministry said.
“Speculative and incorrect figures regarding Nipah virus disease cases are being circulated,” it said. “Enhanced surveillance, laboratory testing and field investigations were undertaken … which ensured timely containment of the cases.”
Reports of the infections put authorities on alert in South-East Asian nations, as well as Nepal and Hong Kong. “While vigilance is warranted, there is no evidence to suggest a broader public health threat at this stage,” said Efstathios Giotis, lecturer in molecular virology at the UK's University of Essex.
There are no direct flights between Pakistan and India and travel between the two countries is extremely limited, particularly since their worst fighting in decades in May last year.
In Vietnamese capital Hanoi, the health department ordered the screening of incoming passengers at Noi Bai airport, particularly those arriving from India. Passengers will be checked with body temperature scanners to detect suspected cases.
The virus was first identified about 25 years ago during an outbreak among pig farmers in Malaysia and Singapore, although scientists believe it has circulated in fruit bats for thousands of years.
The WHO classifies Nipah as a priority pathogen. India regularly reports sporadic infections, particularly in the southern state of Kerala, regarded as one of the highest-risk regions in the world for the virus.
