India has ramped up the screening of travellers to keep the coronavirus at bay but a flurry of new cases has experts warning that it may be hard to contain a spread in densely populated South Asia with its generally poor medical infrastructure.

India, Pakistan and Bangladesh are home to some 1.7 billion people, or more than a fifth of the world’s population, but their over-stretched health systems could struggle to handle the type of intensive care required for coronavirus patients.

On top of that, a prevalence of existing health problems such as diabetes could spell trouble while the sort of sweeping restrictions China has imposed to stifle the virus would be hugely difficult in South Asia’s more unruly cities.

“The way Indian society is structured, the kind of lockdown that many countries including China and Japan have instituted, is pretty much impossible even under good circumstances,” said Vivekanand Jha, executive director of the George Institute for Public Health, in New Delhi.

India’s total confirmed coronavirus rose to 29 on Wednesday, from six early this week.

The coronavirus, which emerged in China late last year, has infected more than 95,000 people globally, and killed more than 3,200, most of them in China.

Some health experts fear that even with the recent spike in cases, India’s actual tally could be much bigger.

“There is a strong possibility that the number of cases in India is much higher than what has been detected,” Arunkumar G., director of the Manipal Institute of Virology, said, citing a virus incubation of up to two weeks.

Fears were fanned this week when India’s health minister disclosed that 16 foreign tourists who have tested positive had been touring since mid-February.

Last week, U.S. intelligence sources told Reuters that India’s available countermeasures and the potential for the virus to spread its dense population was a focus of serious concern.