The headlines regarding the Zika outbreak in the Americas have been many and frankly scary; reading about an “Imminent Zika disaster” or “Zika crisis spreading” surely makes the outbreak seem alarmingly severe. But how dangerous is Zika? Should you be scared of traveling to Brazil? Let’s get the facts straight.

What is Zika?

Zika fever is an illness caused by the Zika virus, which is a mosquito-borne flavivirus closely related to dengue virus. The fever and virus are named after the Ugandan forest where the virus was first isolated in 1947.

Transmission occurs via the bite of Aedes aegypti and Aedes albopictus mosquitoes, the same mosquitoes that transmit dengue, chikungunya and yellow fever. Zika can also be sexually transferred. The virus can remain in those infected for a long time, and it is recommended that those who have visited a country with Zika do not attempt pregnancy or engage in unprotected sex for up to six months.

During the cooler winter months (May – September), the mosquito population is expected to decrease which will likely reduce the risk of infection.

The response from the Brazilian government to combat Zika-carrying mosquitoes has been strong. Army, navy and air force personnel have been called into action, as well as roughly 300 000 public officials. Several measures are being taken to tackle the issue such as large scale use of insecticides. Still, there is no indication that the outbreak is slowing down. However during the cooler winter months (May – September), the mosquito population is expected to decrease which will likely reduce the risk of infection.

What are the symptoms?

Symptoms are similar to Dengue fever, but are milder in form and usually last four to seven days. Common symptoms include a maculopapular skin rash that starts on the face or upper body, before moving to the rest of the body. Conjunctivitis, joint pain (mainly in the smaller joints of the hands and feet), low-grade fevers and headache are also common. The symptoms of Zika are thus rather mild and not very dangerous. In fact, roughly 80 % of all infected don’t even experience any symptoms. 

While the symptoms of Zika are mild, there are some potential complication from the infection such as Microcephaly or Guillain–Barré syndrome. These complications are often what gives people cause for concern.


Microcephaly is a condition where babies are born with a much smaller head than normal, or where the head stops growing after birth. The condition is rare but there is scientific consensus that it can be linked to the Zika virus. Over 1500 cases of microcephaly have been recored in Brazil since the Zika outbreak, which is a significantly higher number than normal.

Babies with microcephaly experience poor brain growth and can have developmental disabilities. Those suffering from microcephaly can also develop epilepsy, cerebral palsy, learning disabilities, hearing loss and vision problems. In some cases however, the children have an entirely normal development.

If you are pregnant, or planning on becoming pregnant in the near future, it is recommended that you postpone any travel to Zika infected areas.

Guillain–Barré syndrome

A number of countries, including Brazil, have recorded an unusual increase of Guillain–Barré syndrome in connection to the Zika outbreak. The link between the two diseases is being investigated, and right now there is scientific consensus that the Zika virus is a cause Guillain–Barré syndrome. The cause of Guillain–Barré is often hard to determine, but can be triggered by an infection such as dengue, HIV and influenza.   

Guillain–Barré is a rare condition of an autoimmune nature which can affect people of all ages and genders. It is however most commonly found among adult males. The disease affects a person’s immune system and attacks their peripheral nerves, which control muscle movement and feeling of temperature, pain and touch. This can result in muscle weakness and loss of feeling in the limbs, as well as paralysis. Many also experience difficulty breathing due to weakening in the breathing muscles. The first symptoms are usually weakness and tingling sensations.

Most patients recover fully, even from very severe cases. However 3-5 % of those infected die from complications. Patients are usually hospitalized in order to monitor their health. There is no cure, but different treatments exist to improve the patient’s condition and shorten the duration of the disease.

What is the risk in Rio?

As most probably have have heard, a large zika outbreak has been ongoing in the Americas and the Caribbean since 2014, affecting dozens of countries including Brazil. The epidemic in Brazil started in the northeast, but has since spread to other regions as well.  

While the presence of the disease is clear, the outbreak has proven difficult to track: The symptoms are very similar to dengue and chikungunya, the disease can only be confirmed via laboratory testing, and as mentioned before, roughly 80 % of those infected are believed to not experience any symptoms. There might therefore be a large number of people infected who have not been recorded. The number of those affected is, however, likely to be very high. In some regions in northeastern Brazil, it is believed that around 80 % of the population have been infected, but still the risk of contracting the disease is difficult to evaluate. Nevertheless, since the mosquitoes that transfer the disease are present in virtually all of Brazil, there is a risk of infection in all regions and cities including Rio de Janeiro.

The mosquitoes that carry the Zika virus can bite during the day and night, both indoors and outdoors, and often live around buildings in urban areas. The Aedes mosquito is however rarely found at altitudes above 2000 m. In Brazil, the risk of contracting mosquito borne diseases is the highest between January-May due to favorable climate conditions for the mosquitoes. During Brazil’s winter months (May – September) the risk is somewhat lower but still a factor.

How can I avoid Zika fever?

Prevention depends on control of- and protection from the bites of the mosquito that transmits it. People can prevent mosquito bites by wearing clothing that fully covers the skin, using mosquito netting while resting, and/or the application of insect repellent (DEET being the most effective).

It is also recommended to avoid unprotected sex with anyone who can potentially carry the virus.

Vaccine and treatment

Zika fever is generally mild and requires no special treatment. If you are sick, get plenty of rest and drink enough fluids. There is no vaccine to prevent Zika or medicine to treat it.

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