Data collected by the Brazilian Ministry of Health over the last 20 years indicates that there is no history of outbreaks of illnesses caused by the aedes aegypti mosquito – which transmits dengue and zika – during winter in the country. Rio de Janeiro will host athletes from more than 200 countries for the Olympic and Paralympic Games in August and September, which are winter months in Brazil.

However, Rio 2016’s chief medical officer João Grangeiro stressed on Tuesday (2 February) the importance of following the advice of the World Health Organisation (WHO), which has classed the link between zika and a birth defect called microcephaly as a Public Health Emergency of International Concern.

While the WHO called for a coordinated international response to the zika problem, it also said “the committee found no public health justification for restrictions on travel or trade to prevent the spread of zika virus”.

Speaking after a press conference at the Rio 2016 headquarters, alongside state under-secretary of health Alexandre Chieppe and Rio de Janeiro municipal health secretary Daniel Soranz, Grangeiro said: “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.” 

Responsible for the well-being of athletes and spectators during the Games, Grangeiro also spoke about the importance of intensifying preventive measures against the proliferation of the mosquito that transmits zika – in partnership with the state and city governments – in the coming months, 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.”

Prevention in Olympic venues

The highest number of illnesses caused by the aedes aegypti mosquito happen during the Brazilian summer (December-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. However, Rio 2016 is working with the International Olympic Committee (IOC) and governmental bodies to ensure preventive measures are taken in competition venues, for example by eliminating any stagnant water, which can be a breeding ground for mosquitos.

“There is a large proliferation of the mosquito during summer, particularly when it rains a lot. 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 a outbreak of illness caused by aedes aegypti"

João Grangeiro, Rio 2016 chief medical officer

Grangeiro said it was important to avoid panic. The general symptons of the illness – which affect only 20 per cent – are milder than dengue and include headaches, fever and rash, which tend to disappear after about one week. The more serious concern is in relation to pregnant women, as the virus is linked with microcephaly in babies.

The IOC has also provided athletes and National Olympic Committees with guidance about prevention and symptoms. “We are in close contact with the World Health Organisation as well as with the Games organising committee and the Brazilian authorities,” said IOC President Thomas Bach last week during a press conference in Athens. “We will do everything to ensure the health of the athletes and all the visitors.”