US officials have advised pregnant women to delay travel to 11 South-East Asian countries because of the “uncertain risk of Zika virus infection.” As Southeast Asia looks to grow its very important tourism sector this is seen as a potentially damaging development.

The countries include Brunei, Myanmar, Cambodia, Indonesia, Laos, Malaysia, Maldives, Philippines, Thailand, East Timor and Vietnam.

The advisory issued by the Centers for Disease Control and Prevention (CDC) noted that the Zika virus has been present in parts of South-East Asia for several years, is endemic in some countries and that many in the region are likely immune to it.

However, US travellers would possibly not be immune to Zika and a number of those who have visited the region have been infected.

Zika is mainly spread through mosquitoes and those infected suffer flu-like symptoms. While most Zika patients recover quickly, the virus can cause brain malformations in unborn children, as well as other neurological disorders.