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CAREC Surveillance Report

ISSN 0376-8951
Vol. 21 No. 1
Jan-Feb 1999

Editorial

 The health situation in the Caribbean today is complex, both in terms of the emergence of new health problems, diseases and risks, and the hurricane of change in the health sector, consequent upon health sector reforms, the latter posing both a threat and an opportunity for public health.

New mortality analyses, 1980-1995, show that since 1990, after decades of decline, mortality rates from communicable disease have been on the rise, with AIDS now being the major cause of death in males and females aged 15-44 years. On the other hand, mortality from diabetes, violence and injuries also increased over the same period. These changing mortality trends will be featured in future issues of the CSR.

Emerging/re-emerging disease problems have also increased with significant human and economic impact, particularly given the tourism dependent nature of Caribbean economies, e.g., tuberculosis, and food and water borne diseases. In this issue, we feature two vectors borne disease challenges, dengue fever and malaria. The former has been increasing in frequency and severity in recent years, while constant vigilance is needed to prevent resumption of malaria transmission as nearly all member countries have competent vectors.

Economically, the Caribbean's dependence on tourism continues to grow, while in the past year there was continued degradation of the physical environment, with growing concern over global climate trends, and two very damaging hurricanes and an ongoing volcanic eruption reminded all of the turbulent nature of the Caribbean.

Regionally, a more inclusive Caribbean Cooperation in Health phase 2 (CCH-2) has begun, recognising the primacy of the health promotion approach. Under CCH-2, the Center has particular responsibility for disease prevention and control, and the building of epidemiologic capacity and surveillance systems responsive to the health situation. In future issues we will feature some of our Caribbean surveillance (CARISURV) initiatives, such as a physician sentinel surveillance system and a laboratory surveillance network.

C. James Hospedales, MB BS, MSc, FFPHM
Editor-in-Chief

WHAT WILL CONTROL EPIDEMIC DENGUE?

ABSTRACT

During an outbreak of dengue fever, which occurred in Jamaica from October to December 1995, a study was carried out to determine the impact of aerial Ultra Low Volume (ULV) Malathion treatment on adult Aedes aegypti. This was done by monitoring oviposition rates of the vector in three urban communities in Kingston and by exposing caged mosquitoes both directly and indirectly to the aerial Malathion treatment. The insecticide was delivered at a rate of 219 ml/ha between 07:10 and 08:45 hrs. The results of the study clearly showed that the insecticidal application was ineffective in interfering with Aedes aegypti oviposition activity, based on the proportion of houses with positive ovitraps and on the mean number of eggs oviposited per house per day before and after intervention. Figure 1 shows that the number of mosquitoes did not drop after aerial sprays in three sections of Kingston. Caged adult mosquitoes held inside dwellings were largely unaffected by the aerial application. Consequently, this type of intervention seemed unlikely to have had any significant impact in arresting or abating dengue transmission.

COMMENT

There is an inclination for Caribbean people to believe that the ultimate weapon for use against dengue and its vector Aedes aegypti is adulticide sprays in the form of

This research report and others generated in locations such as Puerto Rico and Caracas, Venezuela indicate that the adulticide tool on its own is at best unreliable for the following reasons:

At worse, large-scale adulticide treatments may have a negative impact on the population: the temptation to leave intervention for dengue on the public health authorities. This may be a very significant cost since the only real reliable tool for dengue vector control is the mobilization of the population to eliminate breeding habitats-source reduction. Thus, mixed messages may be confusing to the general population.

Integration of all the possible available tools is the ideal way to go when faced with an epidemic of dengue: -