São Paulo has 8 times more cases of chikungunya this year; inner city is on alert

Chikungunya cases increased eight times at the beginning of this year, compared to last year, in the State of São Paulo. From the 1st to the 27th of January, a period equivalent to 4 epidemiological weeks, 249 cases were confirmed across the State, while in the same period in 2023 there had been 30, according to the State Department of Health.

In both periods there were no deaths from the disease, but this year there are two deaths under investigation. Throughout 2023, 2,299 cases and 12 deaths from chikungunya were confirmed in São Paulo.

Chikungunya is transmitted by Aedes aegypti, a mosquito that also transmits dengue, zika and urban yellow fever. The state department reported that the mosquito is present in all municipalities in the state and has supported city halls in actions to control the transmitter.

The city of São José do Rio Preto, in the interior of São Paulo, registered 115 confirmed cases of chikungunya in January and went on alert for an epidemic of the disease. The number in a single month is equivalent to the total number of cases registered in the city throughout the year 2023. It also corresponds to 46% of January records throughout the State.

According to the Rio Preto Health Department, the city has a high rate of infestation by Aedes aegypti. Of 10,000 properties inspected in the first half of January by health agents, 300 had larvae. The 3% rate puts the city on high alert for arboviruses, according to the Ministry of Health, as the ideal is for it to be below 1%. In December, building infestation was 2.1%. This year, in Parque da Cidadania, mosquito breeding sites were found in 9.5% of properties.

According to the Health Surveillance coordinator, Andreia Negri, although dengue is endemic in the city, pointing to an epidemic, in the case of chikungunya the numbers can already be considered epidemic. In addition to the confirmed cases of chikungunya, another 73 are under investigation. “We need people to check their homes weekly to prevent mosquitoes from spreading,” she said.

Among the patients who sought the health system with symptoms of the disease, many had high fever and intense joint pain, more serious conditions. The number of dengue cases is also high in the city, which increases the demand for health services.

There were 149 positive records in January and another 996 cases are under investigation. “We are in the period of seasonality of the disease, where there is an increase in cases,” said Andreia Negri, referring to the period of heat and high humidity.

According to the health department, measures to combat mosquitoes are being intensified, with actions to remove breeding sites, nebulization, blockades in risk areas, inspections and house-to-house guidance. “The fight against chikungunya involves the same measures as dengue, since the vector is the same”, recalled Andreia.

The Epidemiological Surveillance Center (CVE) of the State of São Paulo reported that it monitors the epidemiological scenario of reported and confirmed cases and also the serotypes circulating in the State, in addition to assisting actions to combat mosquitoes that transmit arboviruses by providing technical support to municipalities, who are responsible for field work to prevent the disease.

“All actions are detailed in the State Contingency Plan for Urban Arboviruses, prepared in partnership with the other management levels of the Unified Health System (SUS) in the State. Arboviruses, such as dengue, chikungunya and zika, are seasonal diseases in which epidemic and inter-epidemic cycles can occur from one year to the next,” he said in a note.

In Brazil, in the first four weeks of January 2024, 14,958 probable cases of chikungunya were reported. The geographic regions where the highest incidences are concentrated are the Southeast, Central West and North. Among the States, Minas Gerais, Mato Grosso do Sul, Goiás and Espírito Santo have the highest incidence rates. There were three confirmed deaths, all in the Northeast region.

Symptoms

Chikungunya is a febrile illness caused by a virus, with a set of symptoms similar to those of dengue. The virus is transmitted by mosquito bites Aedes aegypti and symptoms appear over a period of two to ten days. Symptoms begin with fever, headache, malaise, body aches and a lot of pain in joints, such as knees, elbows and ankles, which may also present red spots on the body.

The acute condition lasts up to 15 days, but can be prolonged if it includes severe arthralgia (inflammation in the joints) becoming a chronic and disabling post-acute condition. There are no licensed vaccines for chikungunya, but, in December 2023, the Butantan Institute asked the National Health Surveillance Agency (Anvisa) for definitive registration of a vaccine developed in partnership with the French-Austrian Valneva.

Generally, the symptoms of chikungunya are cured spontaneously. Antiviral medications help prevent and treat the infection. The diagnosis of chikungunya is clinical and made by a doctor. All exams are available on the Unified Health System (SUS). The disease must be notified to the ministry.