Brazil’s minister of Health, José Gomes Temporão, says there is a possibility that dengue type 4 will spread and become a problem next summer. Three cases have been confirmed in Roraima (a state in the far north of the country).
“We have to be prepared,” said the minister. “It is not certain that dengue type 4 will spread. The behavior of the virus is unknown. However, there are direct flights from Roraima to São Paulo and other locations. So, we have to be ready next summer to aggressively reduce the disease vector. Dengue is presently at a level we expected. It can become an epidemic only when there are many mosquitoes, so we must reduce them.”
Temporão explains that the dengue type 4 is dangerous because it has not appeared in Brazil for 28 years. As a result, there is a large part of the population that is not immune to it. The cases in Roraima are believed to have come from Venezuela.
“As we cannot stop people from crossing the border and we don’t have a vaccine, we have to attack the mosquito that transmits the disease,” says the minister.
The symptoms of dengue type 4 are the same as other forms of dengue: headache, severe pain in the body and especially the joints (sometimes in English it is called breakbone fever), diarrhea, vomiting and fever.
The state Secretary of Health in Roraima has confirmed three cases of dengue type 4, and says there is another suspected case. All of them occurred in the capital, Boa Vista, where preliminary exams took place. Later, samples were sent to the Evandro Chagas Institute in Belém, Pará state, for further analysis.
The secretariat has mobilized an emergency team in an effort to isolate the disease vector and halt its spread to other parts of Brazil. Health agents are engaged in what is called “active search,” which includes spraying insecticide in areas where the mosquito can thrive.
At the same time, the ministry of Health announced it had spent $1 billion reais (US$ 569 million) on dengue this year (training professionals to control the disease and treating patients with it) and was now concentrating on the quality of control activities. “This is an effort that has no end,” said the minister.
Dengue type 4 was last seen in Brazil in 1982. Since then it has been present in ten South American nations, including Venezuela, which borders Roraima.
Edmilson Migowiski, an infectologist at the Federal University of Rio de Janeiro, explains that an epidemic of dengue type 4 is possible exactly because it has been so long since it was present in Brazil and so few people are immune to it.
Another problem is that people who have had dengue types 1, 2 or 3, can get type 4 and if they do it can easily evolve into a fatal form of dengue. “This is an extremely worrisome situation. You have a population that has already had dengue but is vulnerable to a new dengue virus. The death rate can be much higher with dengue type 4,” says Migowiski.
Meanwhile, the coordinator of the National Dengue Control Program, Giovanni Coelho, who is in Boa Vista, admits that there is a risk of rapid spread if the virus disperses. “The possibility of dengue transmission is very high if this sorotype circulates in urban centers,” he declares.
Between January and July this year, there have been 788,809 cases of dengue in Brazil, an increase of 159% over the same period a year ago.
Dengue type 1 has been detected in Rio de Janeiro after being inactive in the region for 20 years. That is bad news as it increases the risk of an epidemic in a population with low immunological resistance to this particular strain of dengue.
According to Rafael Freitas, entomologist and researcher at the Oswaldo Cruz Foundation, there are a lot of mosquitoes in Rio at this time of year and it is hard to tell which ones, if any, are transmitting dengue.
Now, he says, if there are Aedes aegypti mosquitoes, then the possibility of an epidemic increases. Up to the beginning of August, there had been 22,600 cases of dengue registered in the state of Rio with 31 deaths.
That is double the amount of dengue cases for the whole of 2009 (the total was 11,411 with 12 deaths). The state secretariat of Health says the numbers are still not cause for concern and that it is doing everything possible to control the spread. “The numbers are not good news. But they are within expectations,” he declared.