The WHO declared that the virus constitutes a public health emergency earlier this week, increasing anxiety with thousands of athletes, officials and fans due in Rio de Janeiro for the Olympic and Paralympic Games in August and September.

Cases of the virus, which is caused by mosquitoes, have been rising in the country and the rest of the Americas ahead of Rio 2016.

A first case has been confirmed in the United States, which doctors said was sexually transmitted, and the WHO has warned it could spread in every European country if the Aedes mosquito gets a foothold on the continent.

Pregnant women have been advised not to travel to impacted areas due to a link between the virus and microcephaly - a condition which can lead to babies being born with small heads and under-developed brains.

Other symptoms include fevers, rashes, joint pain and conjunctivitis.

"Although the general symptons of the illness are mild and affect only 20 per cent of those infected, we have to be alert to the risks that the virus represents for pregnant women, who should speak with their doctors about preventative measures," said Grangeiro.

Grangeiro, who is responsible for the well-being of athletes and spectators during the Games, also spoke about the importance of intensifying preventive measures against the proliferation of the mosquito that transmits Zika in order to "guarantee a healthy and safe environment for athletes and visitors during the Games".

"The preventive measures are being intensified, with systematic inspections of not only the sporting facilities but also in potential mosquito breeding areas in Rio de Janeiro," he said.

"We have also offered guidance to athletes who come to compete in the test events about prevention, such as use of repellents."

Vanderson Berbat, manager of the Rio 2016 education programme, added: "We will use our programme to pass on more information about how to avoid the proliferation of the carrier mosquito and about the symptoms of Zika."

The highest number of illnesses caused by the Aedes mosquito happen during the Brazilian summer, from December to February, when the tropical climate is humid with lots of rain.

By the time winter arrives in Brazil, the proliferation of mosquitos tends to diminish substantially, leading to hopes that they will not be as prevalent come August.

"There is a large proliferation of the mosquito during summer, particularly when it rains a lot," said Grangeiro.

"From mid-April, the decline begins.

"Analysing the historical data, and the public health authorities do this with great care, in July there would not be the expectation of an outbreak of illness caused by Aedes aegypti."

Rio 2016 claims to be working with the International Olympic Committee and Governmental bodies to ensure preventive measures are taken in competition venues, such as eliminating any stagnant water, which can be a breeding ground for mosquitos.

Meanwhile, the Korean Olympic Committee (KOC) has published disease prevention guidelines for athletes set to compete at Rio 2016.

The KOC said its guidelines include information on how to prevent the Zika virus and yellow fever when athletes train or compete in Brazil ahead of the Olympics. 

They have been distributed to national sports bodies and the KOC says it will produce a more comprehensive collection of relevant information and preventive measures at a later date, after consulting with experts in infectious diseases.

It is also considering adding more doctors to the Olympic delegation.