 |
|
|
War Declared on Dengue |
|
By Patricia Grogg*
This tropical disease, for which there is still no vaccine, is seeing an upsurge in Latin America this year. Experts link it to the effects of climate change.
HAVANA - Cuba has declared all-out war against the dengue-carrying Aedes aegypti mosquito because there has been a resurgence of the disease this year, hitting Venezuela, Brazil and several countries of Central America and the Caribbean particularly hard.
The campaign to block the mosquito vector intensified in mid-January in Havana, one of the cities under greatest threat from dengue, the hemorrhagic variant of which is fatal. Initial symptoms include sudden fever and headaches.
According to the Pan-American Health Organization (PAHO), dengue was considered a public health problem in Asia, but had largely been eradicated in Latin America - until 1981 when Cuba became the setting for the first serious epidemic in the region.
Cuban authorities at the time accused the United States Central Intelligence Agency (CIA) of intentionally introducing the disease on this socialist-run island. That outbreak affected 344,203 people, claiming the lives of 158, including 101 children.
In December 2001, after several months of rumors on the streets of the capital, President Fidel Castro acknowledged “a few” cases of dengue had been registered, though complete official information has not yet been made available.
Sources from the Public Health Ministry, however, said some 40 cases had been reported last November in the Havana area, home to 2.2 million people.
In urban areas, the Aedes aegypti can potentially be found in any open water container - where it lays its eggs -, particularly in shaded, damp areas of patios and gardens. Because Cuba’s climate is so favorable for this mosquito species, community cooperation is essential in the effort to control and eradicate it.
“In every house, neighborhood, education center and workplace, we must neutralize this hostile enemy,” said Liset Alvarez Ledesma, professor at a Havana school of social work.
More than 10,000 people are directly involved in the campaign’s clean-up and fumigation duties, as well as in health testing to detect those people infected with one of the four strains of the dengue virus, an ailment for which there is still not preventative treatment.
A person can be infected with each of the four strains only once, because with each infection specific antibodies are produced to fight the disease and remain in the person’s blood.
Epidemiologist Pedro Mas, with the Pedro Kouri Institute of Tropical Medicine (IPK) in Cuba, explained in a conversation with Tierramérica that a person infected with the first strain of dengue becomes immunized against that strain, but not against the other three.
With the second infection, there is a greater volume of the virus in the blood and increased risk of hemorrhagic fever and other complications, said Mas, adding that the combinations of the various strains cause an even more aggressive infection of the human organism.
Researchers from IPK, the Genetic Engineering and Biotechnology Center and from the Finlay Institute - all based in Cuba - are working together to develop a vaccine against dengue, an effort that has proven difficult because they have yet to find an immunogen with sufficient protection against the four viruses.
Experts consider Cuba a perfect habitat for the Aedes aegypti, due to the island’s geographic location and climate conditions. Last year, approximately 500,000 people were infected with dengue in 31 countries, 16 of which reported cases of hemorrhagic dengue.
Elia Rosa Lemus, who is in charge of the Cuban campaign to wipe out dengue, says that Latin America’s general epidemiological situation improved in the 1950s and 1960s, but dengue made a comeback in 2000-2001.
Current rates of infection are particularly high in Venezuela and Brazil, said Lemus, who pointed out that the virus is transmitted by the female mosquito, which feeds on blood and hates the cold.
Venezuela was the scene of a serious epidemic in 1990, and suffered an outbreak in 2001 with nearly 30,000 cases recorded, forcing the government to put 18 of the country’s 24 regions on “epidemiological alert”.
In Brazil, the government stepped up control measures in the second half of January after three people in Rio de Janeiro died from dengue hemorrhagic fever within 11 days.
The greenhouse effect, caused by the accumulation of carbon dioxide in the Earth’s atmosphere, contributes to the propagation of the virus because the mosquito prefers warm, damp climates, Lemus explained, agreeing with experts who see climate change as the cause of the increased presence of the vector in Latin America.
According to PAHO, the deterioration of anti-dengue programs, as well as changing climatic conditions have prolonged and intensified the effects of the disease in Central America.
* Patricia Grogg is an IPS correspondent.
|
