The Brazilian Ministry of Health has reported 746,000 registered cases of Dengue fever and 229 confirmed deaths since January 2015 [1,3]. This marks a 234% increase in Dengue cases and a 45% increase in Dengue deaths since the previous year . Although nine states are currently experiencing an outbreak of Dengue, more than half of these cases occurred in São Paulo, which also happens to be Brazil’s most populous state . To date, São Paulo has had three times as many Dengue cases as there were reported in 2014 .
Dengue fever is a viral disease transmitted to humans through the bite of an infected female mosquito [1-5]. Dengue can be found in tropical and sub-tropical climates across the globe, primarily in urban and semi-urban areas . This places about half of the world’s population at risk . The incubation period for Dengue fever is 4 to 10 days . Symptoms last about 2 to 7 days and include: high fever, severe headache, pain behind the eyes, muscle and joint pain, nausea, vomiting, and swollen glands [1-5]. Dengue Hemorrhagic Fever (DHF) is a potentially deadly complication that can arise from a Dengue infection . Symptoms of DHF, also known as Severe Dengue, include severe abdominal pain, rapid breathing, persistent vomiting, and bleeding gums .
Since there is currently no specific treatment or vaccine against Dengue, vector control is the most effective prevention method . The primary Dengue vector in South America is the Aedes aegypti mosquito [2,5]. The Aedes aegypti mosquito is also capable of transmitting Yellow Fever and Chikungunya . These mosquitoes are daytime feeders that prefer urban habitats, bite multiple humans during each feeding period, and breed primarily in man-made containers such as water tanks, plastic bottles, discarded tires, and flower pots [1-2,5]. An infected mosquito is capable of transmitting the virus for the remainder of its life .
Outbreak in Brazil
Dengue has been endemic in Brazil since its re-emergence in 1981 . Cases typically increase during the peak of the rainy season, which lasts from January to May [2,4]. However, this year’s rainy season in Brazil has been particularly dry, resulting in severe drought throughout much of the country . São Paulo, for example, has been facing the worst drought in decades . As a result of the drought, people have been storing water in large, open containers. These containers are an ideal breeding ground for the Aedes aegypti mosquito, resulting in a proliferation of mosquito populations . This increase in Dengue vectors results in increased transmission of the virus to humans. The increased prevalence of the disease among humans will also increase transmission. As a result of the drought, São Paulo has reduced the flow of water in several of the major water pipes throughout the city . This has resulted in a decrease in access to running water for thousands of people and an increase in the use of home water tanks .
What is Being Done?
Hospitals in São Paulo have been overburdened with the large number of Dengue cases. Therefore, “Dengue tents” have been set up to treat patients in high-risk areas within the city . Additionally, 2,500 health officials have been tasked to go door-to-door and educate residents on preventive measures, such as filling potted plants with sand, keeping containers dry and swimming pools covered, as well as placing mosquito nets over open water tanks [2,4]. This mass educational campaign has had limited success because individuals are wary about opening their doors to strangers . As a result, the mayor of São Paulo has recruited soldiers who have been trained to go door-to-door and provide education on proper mosquito control, water storage, and effective repellant and insecticide use . The hope is that the public will be more trusting and receptive toward the army, resulting in greater cooperative with the health officials and their educational messages .
Brazilian health authorities announced on May 5th, that they believe the outbreak has reached its peak. The weather is beginning to change and becoming less favorable for the mosquitoes . Additionally, Brazil is currently testing three Dengue vaccines and hopes to have an effective vaccine available to the public by 2016 .