Dengue, Zika, chikungunya: Risk of contracting diseases during the Olympics is small

by Otávio Clark | Jun 23, 2016

Dengue, Zika, chikungunya. Just one mosquito can transmit all three diseases – and cause a lot of trouble for authorities, health professionals and the general population. With the approach of the Olympic and Paralympic Games, which will be held in Rio de Janeiro in August and September this year, outbreaks in Brazil have been gaining international attention.

However, the risk of contracting these diseases during the games is low. The World Health Organization (WHO) stated that during the games it will be winter in Brazil, when the rates of diseases transmitted by the mosquito Aedes aegypti are declining. WHO also affirmed that the risk of international spread of these diseases as a result of the Olympic and Paralympic Games is very low. It is important to note that these diseases are self-limited, usually causing mild symptoms, and in most cases they don’t present major problems besides fever and pain.

Alarming rates

Much of the concern, however, comes from the alarming rates that these diseases have been presenting in Brazil. The most recent data from Brazil’s Ministry of Health show that from February to April this year, 91,300 probable cases of Zika, 802,000 of dengue and 39,000 of chikungunya were reported in the country. However, the problem is not restricted to Brazil: according to WHO data, transmission of Zika and chikungunya has been documented in more than 60 countries in Africa, Asia, the Americas and Europe. Moreover, dengue is considered endemic in more than 100 countries. The fear that these diseases, especially Zika, will spread worldwide is unfounded, especially because they are already widespread in many countries.

Despite the worrisome figures, these diseases are usually mild or moderate. In many cases, symptoms are confused with those of a common cold: dengue is characterized by pain in the body, chikungunya is marked by pain and swelling in the joints, and Zika presents as a lower fever (or absence of fever), many spots on the skin and itching.

However, some cases may be serious, with worrying consequences. Classic dengue rarely has serious consequences, but hemorrhagic dengue can lead to death. Severe cases are very rare, and the mortality rate is relatively low – about 40 deaths per 100,000 cases recorded (0.04%).

The main risk of Zika is the infection of pregnant women, which may cause microcephaly and other complications in babies. Furthermore, the Zika virus is also associated with Guillain-Barré syndrome (a rare disease in which the immune system attacks peripheral nerves cells, causing muscle weakness and loss of sensation).

The mosquito and the Olympics Games

These diseases also affect quality of life, productivity and tourism. In the year that Brazil will host the Olympic and Paralympic Games, this impact can become overwhelming.

A study conducted by Evidências – Kantar Health pointed out that, in 2008, an outbreak of dengue in Rio de Janeiro decreased the number of tourists visiting the city by 15% to 30%. Other cities were also significantly affected, and several canceled Carnival to prioritize the use of resources for the disease control program. The study also showed that dengue outbreak generated an economic impact of about US$ 603 million in 2013.

There is still a great lack of research and international data on these diseases. We need more studies on the impact that they cause on quality of life, productivity, tourism and other areas. We also need more data on their consequences and other forms of transmission. Recently it was found that Zika virus can be transmitted sexually, so we need to generate more knowledge to be able to combat and prevent these diseases.

The vaccine

A vaccine for dengue already exists. A French group produced the first vaccine against the disease, which was registered with Brazil’s National Health Surveillance Agency (ANVISA) since December 2015. Authorities are now discussing the costs and benefits of including the vaccine, which protects against the four types of dengue virus, in the national immunization schedule and campaigns of mass vaccination. The same group that produced the vaccine aims to develop a vaccine against Zika within three years.

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