Dengue mosquito: is the epidemic also leading to an increase in cases of zika and chikungunya?

Brazil reached the mark of more than two million probable cases of dengue registered this year, with 682 deaths due to the disease. A higher number than that recorded last year, when 1.6 million probable cases of the disease were recorded.

As dengue cases increase, reports of chikungunya and zika infections are also growing in the country. Both diseases are transmitted by the Aedes aegypti mosquito, the same one that transmits dengue fever.

Data from the Ministry of Health indicate that in 2024 the country has already recorded 1,318 cases of Zika virus, 16% more than what was recorded in the same period last year, when 1,134 cases were recorded in the same period.

No person has died this year in the country due to the disease. In 2023, there were two deaths recorded throughout the year.

The increase in Zika cases raises an alarm, as the disease is responsible for causing microcephaly in babies — causing congenital malformations, meaning that the brain does not develop properly.

In general, these children presented grade 5 cerebral palsy, the highest according to the Gross Motor Function Classification System, cognitive, motor and neurological delay.

Between 2015 and 2016, the country faced an outbreak of Zika virus infection with 265,156 registered cases, with the highest concentration of occurrence in the northeast region.

The birth of 12,716 babies with suspected microcephaly resulting from virus infection caused the country to declare a state of Public Health Emergency of National Importance (ESPIN).

Experts interviewed by BBC News Brasil are unanimous in stating that the country is susceptible to a new outbreak of the disease, if the vector, that is, the mosquito, is not controlled. Aedes aegypti.

“The country has the potential to face new outbreaks, since there are regions that have the potential for an epidemic because people have not contracted the disease in the past, not creating antibodies, and there is a lot of circulation of the transmitting mosquito”, says Edimilson Migowski, infectious disease specialist and pediatrician, director of the Institute of Pediatrics at the Federal University of Rio de Janeiro (UFRJ).

Contrary to what happened in the past, this year the majority of cases of the disease are concentrated in the southeast region of the country, with Espírito Santo being the state with the highest number of records, with just over 1,300 cases.

The infection concentrated in the State has two explanations: the greater circulation of the virus in the area due to the population’s lack of antibodies and the intense circulation of mosquitoes that transmit the disease.

The State is third in the number of dengue cases, which shows that there is a large circulation of mosquitoes in the area.

“If a person was infected in another region and is in an area where there are large numbers of mosquitoes, it is very likely that the place will experience an outbreak of the disease. Because when a ‘healthy’ mosquito bites that patient, it starts transmitting the virus to other people and it becomes a cascade effect”, explains Dorival Duarte, infectious disease specialist and deputy clinical director at Hospital Adventista de São Paulo.

Unlike dengue, which has four different serotypes (DENV-1, DENV-2, DENV-3 and DENV-4) which allows a person to be infected more than once, zika has only one serotype, which makes so that a person who has already had the disease does not become infected again.

For Zika to be reinfected, the virus must undergo a mutation, which has not yet been recorded in the country.

The biggest concern is with the infection of pregnant women, as they can transmit the virus to their fetuses during pregnancy, causing various congenital anomalies to the baby such as microcephaly, changes in the central nervous system and other neurological complications that, together, constitute the Congenital Zika Virus Syndrome (CZS).

Children with SCZ may have a variety of irreversible intellectual, physical, and sensory disabilities.

“Pregnant women need to be extra careful, such as using repellents that are appropriate and authorized by Anvisa, wearing long clothes covering most of the body and also placing screens on the windows of the house”, details Álvaro Furtado da Costa, director of Sociedade Paulista of Infectious Diseases (SPI).

Also transmitted by mosquitoes Aedes aegyptichikungunya follows the same increasing trend.

This year, 97,508 cases have already been registered, an increase of just over 65% compared to the same period last year, when 58,586 cases were registered in the same period.

To date, in the country, 36 people have died from chikungunya compared to 106 in the entire year 2023.

Minas Gerais has the highest number of records, with 62 thousand cases.

The infection concentrated in this area is also related to the greater circulation of the virus in the locality due to the lack of antibodies in the local population combined with the high number of circulating mosquitoes.

As with Zika infection, a person who contracts chikungunya tends to produce antibodies against the virus, only experiencing symptoms of infection once.

Although the symptoms of chikungunya are milder when compared to dengue and the disease causes fewer deaths, experts say that some consequences can last for months.

“The disease causes very intense and almost disabling joint pain to the patient. This pain can take four, five or even six months to improve. There are studies that show that they can last for years”, adds Costa.

There is no specific medication for the treatment of chikungunya, what is done is to treat the symptoms of the disease with analgesics.

It is necessary for the patient to intensify hydration and the medication is recommended by a professional.

• Fever and body pain;
• Pain behind the eyes;
• Red spots on the skin;
• Intense and continuous abdominal pain;
• Vomiting;
• Lethargy or irritability;
• Mucosal bleeding.

• Fever;
• Joint pain;
• Conjunctivitis;
• Back pain;
• Muscle aches;
• Red spots on the body;
• Itchy skin – especially on the palms of the hands and soles of the feet;
• Headache and pain behind the eyes;
• Nausea and vomiting;
• Sore throat;
• Chills;
• Diarrhea or abdominal pain.

• Low fever (less than 38.5º C);
• Headache, arthralgia, asthenia and myalgia;
• Periarticular edema, lymph node enlargement.