Dengue fever: Millions at risk as a new outbreak of dengue fever sweeps Latin America
Apr 19, 2007 – There is no vaccine. There is also no good way to treat it – just fluids and the hope that the fever will break. At first it seems like a case of severe flu, but then the fever rises, accompanied by headaches, excruciating joint pain, nausea and rashes. In its most serious form, known as dengue hemorrhagic fever (DHF), it involves internal and external bleeding and can result in death. Fuelled by climate change, dengue fever is on the rise again throughout the developing world, particularly in Latin America.
According to the World Health Organization, dengue is now endemic in more than 100 tropical and sub-tropical countries around the world, affecting some 50 million people a year, mostly in urban or semi-urban areas. A further 2.5 billion, two-fifths of the world’s population, are considered “at risk”. About 500,000 people, many of them children, are believed each year to develop a form of DHF serious enough to require treatment in hospital. Worldwide, 2.5% of DHF cases die; without proper care, the proportion can exceed 20%.
Anyone who survives an infection by one of the four viruses that cause the disease gains lifelong immunity from that virus. But subsequent infection by another variant increases the risk of developing DHF, which is becoming much more common in Latin America. In Mexico, for example, just one in 50 cases was hemorrhagic six years ago, says José Ángel Córdoba Villalobos, Mexico’s secretary of health. Now one in five is.
Last year just over 500,000 cases of dengue were reported in Latin America, including more than 14,000 hemorrhagic cases, 187 of which resulted in death. This year nearly 200,000 dengue cases have already been reported, including 2,693 cases of DHF. At least 37 people have died, including 11 in Paraguay and 17 in Brazil.
The dengue viruses are transmitted to humans through the bite of a female Aedes mosquito, which acquires the viruses while feeding, normally on the blood of an infected person. Given that there is no known preventive treatment or anti-viral cure, the only practical way to prevent the viruses’ spread is to eliminate the Aedes mosquitoes by preventing them from breeding.
In Mexico, the house-to-house programme mounted by the government to get people during the rainy season to remove rubbish and standing water where mosquitoes breed has been extended year-round – with some success. The number of dengue cases reported this year is well down on last year, but the rainy season – the main breeding time for the mosquitoes – has yet to come.