Washington, DC, February 21, 2002 (PAHO) - If there is one disease that proves the importance of continuous surveillance

"The eradication program did not fail. But, after a successful eradication of the vector by the participating countries, there was a relaxation of surveillance resulting in reinfestation by the mosquito. Then, the introduction of various serotypes of the virus aggravated the situation", said Dr. Jorge R. Arias, regional advisor in Communicable Diseases for the Pan American Health Organization (PAHO).

The rapid expansion of dengue to new areas, especially in its most severe form, dengue hemorrhagic fever, makes it likely that in coming years the countries of the region will witness the highest levels ever seen of the disease. Increased air travel, unplanned urbanization, difficulties in the water supply and deterioration in vector control programs are some of the factors related to the dissemination of Aedes aegypti and to an increase in circulation of the four serotypes of the virus, according to Dr. Arias.

"The return of dengue to the Americas is due to many reasons, including reinfestation of Aedes aegypti, lack of good, inexpensive insecticides, lack of financial resources, deterioration in prevention and control programs, disorganized growth of large cities and lack of health education," says Dr. Arias.

There are few countries in the region free of the disease, which causes acute fever, severe pain, and even hemorrhage. To contain the growing dengue trend, PAHO is promoting community participation for behavior change, using social communication to teach people to reduce mosquito-breeding sites in their homes, explains Dr. Arias.

An effective and accessible vaccine is not yet available, and until that occurs dengue control and prevention will be based on measures to control the mosquito and its breeding sites, along with rapid early detection of cases.

"If people eliminate breeding sites for mosquitoes, such as water containers, old tires, urns, and other water recipients, the incidence of the disease will be reduced. Schoolchildren and adolescents can help carry out these sustainable actions," said Dr. Stephen Corber, director of the Division of Communicable Diseases of PAHO. "With little or no expenditure, the members of every family can easily eliminate breeding sites of mosquitoes without using chemical products," by emptying containers, cleaning sites where trash is piled up, and maintaining covers on water containers, he added.

Epidemics in various countries have promoted urgent campaigns to control dengue, which is transmitted by the Aedes aegypti mosquito, that lives in the vicinity of houses and lays its eggs in water containers. Dengue is basically a problem of domestic sanitation and its incidence can be reduced substantially through domestic clean-up campaigns, say experts of PAHO.

Dengue is a growing public health problem that affects more than 100 countries in the world, with more than 50 million reported cases every year, including 500,000 hospitalizations and around 20,000 deaths. Four types of dengue, or serotypes are circulating in the Americas, where cases explode from 66,000 in 1980 to more than 717,000 in 1998. Last year, PAHO figures showed 609,152 cases of dengue reported in the Americas, including 15,000 cases of dengue hemorrhagic fever and 115 deaths.

"The difficulty in eliminating dengue resides in the broad distribution of its vector. It is highly improbable that the vector is going to be eradicated with the instruments that we have today. Furthermore, uncontrolled expansion of large cities creates ideal conditions for the mosquito to multiply," Dr. Arias said.

Furthermore, control and prevention programs lack integration among sectors, Dr. Arias said. "The principal problem is how to administer integrated control that includes: water supply, sewerage, solid wastes, environmental education, chemical and biological control, policies on used tires, standards for export and import of tires, entomological and epidemiological surveillance especially in ports and airports, and related topics. "

PAHO, which also serves as the Regional Office for the Americas of the World Health Organization, was established officially in 1902 and is the oldest health organization in the world. It works with all the countries of the Americas to improve health and raise living standards.

Related Information:
PAHO BOOK: Dengue and Dengue Hemorrhagic Fever in the Americas: Guidelines for Prevention and Control