The following is a summary of the situation of dengue/DHF in the region:

• Mexico. To week 48, a total of 18,053 cases were reported of which 252 were confirmed cases of DHF (an additional 354 cases are being investigated) with 13 deaths. Most DHF cases were reported by the states of Vera Cruz, Tolima and Taumalipas. All four dengue serotypes have been detected in the country.

• Central America. Countries of this subregion have reported 10,648 cases of which 72 were DHF cases, but no deaths (reports range from 30 weeks to 47 weeks). All four dengue virus serotypes continue to circulate in Central America.

• Caribbean. A total of 4,720 cases were reported by English and Latin Caribbean countries of which 34 were DHF cases; the DHF cases were notified exclusively by the Dominican Republic and Puerto Rico, including two deaths. An outbreak of dengue fever associated with dengue-1 affected Trinidad in the second half of the year; up to week 36, 1,587 cases were reported in the island.

• Venezuela. So far the 1996 outbreak has been much less severe than that observed in 1995: up to week 42 of 1996, 7,527 cases of which 1,333 (11 deaths) were DHF cases, whereas in 1995 there were 32,280 reports with 5,380 DHF cases and 43 fatalities. Only serotypes 2 and 4 have been detected in the country.

• Colombia, Ecuador and Peru. Ecuador and Peru reported 3,933 (week 30) and 5,774 (week 36) cases of dengue (no DHF) respectively with circulation of serotypes 1, 2 and 4. To date Colombia has reported 7,787 cases of which 1,606 cases were of DHF.

• Brazil. Up to week 38 this country reported 132,049 cases of dengue, only two of which were cases of DHF. Cases were reported by 23 of the 26 Brazilian states. The majority of reports, however, originated from the northeast region, mainly from the state of Bahia (48,260 cases). Only serotypes 1 and 2 were detected in the country.

Multiple causes are contributing for the spread and increased activity of dengue and DHF in the Americas. Among these are population growth and the increased urbanization and poor sanitation-- insufficiency of adequate and reliable water supply and waste management; the exponential increase of number of plastic containers in modern societies, often discarded in the environment can become important breeding sites for Aedes aegypti. On the other hand the increase in frequency of travel facilitates the dissemination of the vector and the dengue viruses. Other important factors include the lack of adequate knowledge by the population of the importance of the dengue problem and of domestic sanitation to control breeding sites; sometimes the communities become aware of the problem but no change in behavior is observed. These factors combined with the lack of well structured programs to control Aedes aegypti in most countries explain the deterioration of the dengue/DHF problem in the Americas. Unfortunately in most countries there are insufficient well trained personnel, the funds are inadequate and there is a lack of political will to implement effective programs with adequate methodology.

PAHO activities in support of National programs in 1996

Seminar on integrated dengue control. A seminar was held in Nicaragua for all Central American countries, which focused in the situation of dengue/DHF in the subregion and in control measures, including community participation.

Support to the network of dengue laboratories. This support includes the following:

• Provision of kits for MAC-ELISA, prepared and distributed by the Pedro Kouri Institute (IPK) in Cuba funded by PAHO free of charge to countries.

• Proficiency testing of serology for national dengue laboratories, is being undertaken by the IPK and CDC, Puerto Rico.

• Training of two virologists at the San Juan Laboratory of the Centers for Disease Prevention and Control of the United States of America. In addition virologists from this laboratory visited Bolivia and Paraguay to conduct local training in a project funded by PAHO.

• Workshop on the use of PCR for detection of dengue viruses was organized by the CDC. This workshop was held at Oswaldo Cruz Foundation (FIOCRUZ), in Rio de Janeiro, Brazil. Each of the 11 participants from 7 countries received a PCR kit for testing more than 50 samples, paid for with PAHO funds. Participants received a panel of coded specimens for proficiency testing in their own laboratories.

Technical Meetings. Two technical meetings were organized in 1996, the first one being held in Paraguay for the countries of the Southern Cone to discuss effective measures to combat dengue. The second one took place in Rio de Janeiro and was a Task-Force meeting convened to study the feasibility, timeliness and appropriateness of eradicating Aedes aegypti from the Americas.

Collection and dissemination of information. Beginning in the second semester of 1995, special efforts are being made to obtain and disseminate current information on dengue in the Americas. In this context, a table with the reported number of cases of dengue/DHF and deaths, and virus serotypes, is continually updated and regularly circulated among Member countries. This approach has been rewarding as most countries are improving their reporting systems and updating the information on dengue/DHF.

Consultantships to national programs. Technical cooperation was provided on matters related to dengue/DHF prevention and control to Bolivia, Brazil and Venezuela.

Source: Division of Disease Prevention and Control, Communicable Diseases Program, HCP/HCT, PAHO.