Tackling Aedes aegypti mosquito for Zika, Dengue fever and Chikungunya in Rio de Janeiro

Dengue fever has always been a problem for locals, who have lived with the disease since last century’s 8th decade. Now that the same mosquito is reported to be responsible for the transmission of two other diseases, the problem has grown exponentially, scaring locals, who hope the authorities will take quick and effective action in tackling the problem.

Writing about these diseases is difficult for those who live in Rio, since the amount of people affected is always high, and there are many stories passed around by cariocas about people they know. However, we consider it our duty to inform the visitor that these diseases represent a real risk to their health. The purpose of this article is not to alarm or scare tourists away, but to offer real information and the experience of those who unfortunately have had to learn to live with these diseases. We want to show you the basic forms of protection, and what to do if something goes wrong.

Please understand that although locals have learned to live with these circumstances, the situation of women who are planning to conceive and those already pregnant is still considered very worrying in the city. Consequently, due to the real risk of microcephaly for babies, we strongly recommend pregnant women avoid coming to Rio de Janeiro and other Brazilian cities known to be affected by these diseases. The advice from locals also goes for women intending to become pregnant soon.

The numbers of notifications of cases of the three diseases are not reliable, due to the fact that many people simply don’t go to the doctors when they get infected; there is also the low quality of notifications, a direct consequence of the poor medical care available within the public health system.

However, even with an admittedly low number of notifications, the number of cases of the three diseases remained very high during last summer in Rio. Summer is the most favorable season for the mosquito Aedes aegypti, the carrier of the diseases. The expectation is that by direct influence of the cold weather during winter, the population of mosquitoes will decrease dramatically, significantly reducing the numbers of cases and the risks to locals and visitors.

However, we believe that being better informed about viruses will help tourists know how to prevent contamination and, in the event of infection, how to identify the problem and get the best treatment. The importance of information applies not only to Zika, Dengue fever and Chikungunya, but also to the mosquito Aedes aegypti, archenemy of the population for many decades.

Characteristics of the mosquito Aedes aegypti

The first scientific record of the mosquito Aedes aegypti dates back to 1762. Aedes, in Latin, means unwanted, and aegypti refers to Egypt, the insect’s place of origin. It arrived in Brazil in the lower level of slave ships and was identified for the first time in the country in 1898. Campaigns against yellow fever (also transmitted by the same carrier) dramatically reduced the occurrence of mosquitoes in the 1950s, but human displacement and the relaxation of prevention policies in the following decade made the presence of Aedes grow again in Brazil.

The adult mosquito measures between five and seven millimeters and is a dark color with white stripes on the body and legs. Only the female bites, and it does so preferably early in the morning and late in the afternoon. Their most common targets are the legs and feet. The mosquito only carries the viruses, becoming their host after biting a contaminated person and unintentionally transmitting the disease as it feeds on the blood. One mosquito can infect up to five people a day.

Aedes breeds in standing water and with temperatures of approximately 30°C. The fight against the transmission of these diseases by the mosquito is now focused on actions to prevent the formation of habitats for reproduction, such as the proper disposal of items that, when scattered outdoors, can turn into breeding grounds by accumulating rainwater, as well as the use of larvicide.

Differences between Aedes aegypti and the Stilt mosquito

It’s also important to understand the differences between Aedes aegypti and the Stilt mosquito, generally called Culex. According to researcher José Bento Ribeiro, from Fiocruz, a Brazilian institution of excellence for biological research and related issues, many people are scared when they find common mosquitoes, thinking that they are Aedes aegypti. He says that Aedes has daytime habits, but as far as being an opportunist, the female can bite at night if it gets the chance. In addition, it flies below 1.2 meters, preferring therefore to bite feet, legs and knees. This mosquito has a painless bite. The Stilt, on the other hand, besides flying high and making a buzzing sound, comes out to feed at night, applying a more painful and uncomfortable bite. See the differences in the table below.


The disease was named after the Zika forest, in Uganda, due to the incidences of the condition there, first recorded in 1947. The virus arrived in Brazil in April 2015. There have been controversial reports of its transmission in the country through breastfeeding, vaccines, sex, and contact with urine and saliva. Around 80% of people infected with the Zika virus don’t show symptoms of the disease, which begin to be felt between three and seven days after the patient has been bitten by the mosquito.

The main symptoms of contamination by Zika are itching, headache, a low fever and redness of the skin and eyes. Other less common effects of the viral disease are sore throat, body swelling, coughing and vomiting. The first case of death caused by the disease was recorded in Brazil in November 2015.

The Federal Government has confirmed on 28 November 2015 the link between cases of the Zika virus in pregnant women and a microcephaly outbreak in newborns in the Northeastern region of the country. Microcephaly is a congenital malformation in which the brain doesn’t develop properly. All babies born with a head circumference equal to or less than 32 cm after 37 weeks of gestation are considered to suffer from the condition.

Approximately 90% of the victims of microcephaly have an intellectual disability of different types and levels. According to information gathered by the government, the problem seems to be more common in children of mothers who had Zika in the first three months of pregnancy. Another rare consequence of Zika is Guillain-Barré syndrome, characterized by weakness and paralysis of the muscles, which can be fatal without medical intervention.

Dengue fever

Dengue means whining or sluggishness in Spanish. The name of the disease is a reference to the state of prostration characteristic of those infected by the virus. The first case in Brazil was registered in 1986. Summer is the main contamination period, due to the increase in the mosquito population. The monitoring carried out by the Municipal Department of Health of Rio de Janeiro recorded 1,405 cases of Dengue fever in the city through last February 11th. Recreio, Realengo, Complexo do Alemão, Barra da Tijuca and Bangu are the neighborhoods with the highest occurrence of the disease, which has a lower occurrence in regions such as Botafogo, Copacabana, Ipanema and Leblon.

Dengue fever symptoms are felt between three and 14 days after the mosquito bite. High fever, nausea, vomiting and headache and pain in the eyes, muscles and joints are some of them. The discomfort usually lasts up to seven days. The worsening of the situation can lead to Dengue hemorrhagic fever, which affects the amount of blood platelets in the body and is characterized by persistent vomiting, difficulty breathing, bleeding from the nose, mouth and gums, excessive thirst, dry mouth, drowsiness, agitation and clouded mind. The condition can be fatal, and one should seek medical help immediately. There’s no vaccine or specific treatment for Dengue fever. The World Health Organization recommends rest and fluid intake for patients affected by the disease, as well as medical care for the most serious cases.


Chikungunya means “those who bend down” in Swahili. The term is a reference to the stooped appearance of patients with the disease, which was first identified in Tanzania in 1952. The virus arrived in Brazil in 2014. The Ministry of Health recorded 12 cases in Rio in 2015. One possible explanation for the small amount of Chikungunya notifications in the State is the fact that 30% of patients don’t show symptoms.

Symptoms of Chikungunya are severe pain in the joints of the feet, hands, fingers, ankles and wrists. In addition, the infection causes red patches on the skin, high fever, headaches and muscular pain. There’s no vaccine or specific treatment for the disease. The World Health Organization suggests that patients get plenty of rest, keep the fever under control by taking Paracetamol, and drink water, juices, homemade saline solutions or coconut water.

Preventing Zika, Dengue fever and Chikungunya

The basic prevention for Zika, Dengue fever and Chikungunya is very similar to that of the bites by Aedes aegypti: wearing clothes that protect legs, ankles and feet, as well as using insect repellent and insecticides according to the manufacturers’ instructions. It’s also important to tackle the mosquito breeding spots, that is, any object that serves as a container for water accumulation outdoors. Therefore, please pay attention to your rubbish bins and don’t leave cans, bottles and packaging scattered around, but always place them in the bin. You can report sources of contamination by phone, on 1746, for which we thank you in advance. If you prefer, you can fill out this short form , through which we will notify the authorities on your behalf.

Given that the information is still conflicted regarding spreading Zika through unprotected sexual contact, besides sexually transmitted diseases, always use protection. It’s also undecided if Zika can be spread through contact with the urine of infected people. Therefore, we strongly advise you to always wear closed shoes, especially in locations near crowds (carnival, festivals, squares etc.), where poorly educated individuals may choose to urinate on the streets (yes, unfortunately that happens in Rio). And, more recently, scientific research points to the possibility of contagion through unhealed wounds.

The Brazilian Federal Government has set up a good page with information on Zika, Dengue fever and Chikungunya, in case you need further details. The government also advises the public on the procedures below in case of contamination:

What to Do in Case of Suspected Contamination

There’s no specific treatment for Dengue fever. The treatment is to alleviate the symptoms. It’s important to seek health and medical advice, rest and drink plenty of fluids. It’s also important not to take medicine that hasn’t been prescribed by a doctor.

There’s no vaccine or specific treatment for Chikungunya either. The symptoms are treated with medication for fever (Paracetamol) and anti-inflammatory drugs for joint pain . It isn’t recommended to use acetylsalicylic acid, because of the risk of bleeding. It’s recommended to rest and drink plenty of fluids and certainly look for a health care service.

There’s no specific treatment for infection by the Zika virus. There’s no vaccine, either. The recommended treatment for symptomatic cases is based on the use of acetaminophen (Paracetamol) and Dipyrone to keep the fever under control and for pain management. In the event of an itchy rash, antihistamines may be considered. And it’s very important to seek health and medical care.

See the comparative table on the symptoms of Zika, Dengue fever and Chikungunya below, freely translated from the version prepared by Rio City Hall:

Differences in symptoms of Zika, Dengue fever and Chikungunya

It isn’t recommended to use acetylsalicylic acid and other anti-inflammatory drugs, due to the increased risk of bleeding complications observed in other flavivirus infections.

Suspected cases should be treated as Dengue fever, due to its increased frequency and higher severity.

If you have a domestic or international travel insurance or health plan, we have listed the main hospitals for assistance located in the main areas of tourist accommodation and traffic that are covered by main insurance policies (confirm if they accept your travel insurance): Copacabana Copa D’Or: +55 21 2545 3600, Rua Figueiredo de Magalhães, 875 – Copacabana, São Lucas: +55 21 2545 4000, Travessa Frederico Pamplona, nº 32 – Copacabana. Gávea São Vicente: +55 21 2529-4422, Rua João Borges, 204 – Gávea. Botafogo Samaritano: +55 21 3444-1000, Rua Bambina, 98 – Botafogo, Pró-Cardíaco: +55 21 2131 1400, Rua General Polidoro, 192 – Botafogo. Humaitá Casa de Saúde São José: +55 21 2538-7626, Rua Macedo Sobrinho, 21 – Humaitá.

If you don’t have travel insurance, the City Hall offers a service for location of health centers and public hospitals. The State Government also provides information on its Emergency Care Units network, which operate 24/7. We hope you never need it, but the emergency ambulance service phone in Rio de Janeiro is 192.

You Should Also Know

  • Sanitation issues and matters related to Dengue fever have always been political platforms in Rio de Janeiro . Unfortunately, definitive solutions to the problem have not yet been implemented, and the promises are repeated election after election. So it’s inexplicable how, after so many decades of problems, locals and many other Brazilians continue to suffer from this situation.
  • Although no one openly talks about it, the mosquito Aedes aegypti is also a carrier of many other diseases, Yellow fever being one of them. Perhaps only for lack of propitious conditions have the locals been kept from facing more serious difficulties.
  • The association between Zika and microcephaly is currently interfering in family planning for many local families, putting women in Rio de Janeiro in the difficult situation of having to choose between postponing the conception of their children, waiting for effective control of Zika or running the risk of being infected during pregnancy and exposing their unborn child to microcephaly. This situation is especially complicated for more mature women, who have less time left to be able to get pregnant and have a safe pregnancy.
  • Although it may seem exaggerated, our recommendation is that pregnant women or women who wish to become pregnant soon avoid coming to Rio de Janeiro and other cities that are known to suffer from Zika. For fear of risking the health of their children, local women who wish to become pregnant are opting for leaving the city, if they can do so.

Credits for the used images in this Zika, Dengue fever and Chikungunya article: Fotospublicas.com.br, Piktochart, Rio.rj.gov.br, Riocomsaude.rj.gov.br e Riocontradengue.com.br.