Call for greater research into Zika virus amid Latin America pregnancy concerns

More must be done to research an "unprecedented epidemic" which could be leading to thousands of babies being born with birth defects, experts have said.

Thousands of children born to mothers infected with the Zika virus in Brazil have been born with microcephaly - a condition where the child has an underdeveloped brain.

The call comes as the World Health Organisation said that the virus is likely to spread across nearly all of the Americas apart from Canada and Chile.

The virus - which causes symptoms including rash, fever, conjunctivitis and headache - has already been found in 21 countries.

Professor Laura Rodrigues, professor of infectious disease epidemiology at the London School of Hygiene and Tropical Medicine, said: "There is an unprecedented epidemic of microcephaly in Brazil. It has never happened before.

"It is probably caused by contracting the Zika virus - by pregnant women getting infected and the virus and transmission to the baby's brain and destroying some structures there."

Around 4,000 cases of microcephaly have been associated with the virus in Brazil.

There is no treatment or vaccine and many South American countries have called on women to consider implications of the infection before getting pregnant over fears about birth defects.

Prof Rodrigues added: "This is a new situation, no one was thinking about Zika until November. We don't have a good test, there is no vaccine, no treatment.

"In a lot of Latin America, there is no legal abortion and Aedes mosquito is difficult to control. People have been trying to control it to control dengue and it is a struggle."

The virus is transmitted by Aedes mosquitoes. Prof Rodrigues said that the implications to the UK are small because it is too cold for the mosquitoes carrying the disease to survive.

So far, three British travellers have been confirmed to have contracted the virus after visiting South and Central America.

Prof Rodrigues said the virus could potentially affect areas where dengue fever is widespread which could have implications for pregnant women travelling to tropical and sub-tropical climates.

"This has the potential to spread to wherever there is dengue," Prof Rodrigues said.

"The risk is really for pregnant women going to areas that are affected."

The National Travel Health Network and Centre has advises that pregnant women should reconsider travel to areas where the outbreak has been reported.