Dengue: A burgeoning problem in the new millennium

The resurgence of dengue fever, and the emergence of dengue haemorrhagic fever (DHF) as major public health problems, are rooted in the demographic trends and socio-economic policies of the 20^th Century. The population of the world has doubled in the last 27 years, accelerating most rapidly in the developing countries of the tropics and sub-tropics where this viral disease is spread by mosquitoes. Population growth, rural-urban migration, inadequacy of basic urban infrastructure and exponential growth of consumerism, have combined to produce epidemiological conditions that are highly favourable for viral transmission by the main mosquito vector, Aedes aegypti. This species thrives in intimate association with humans and is also the vector of epidemic yellow fever, a vaccine-preventable disease.

World Urbanization Trends, 1950-2030

Source: United Nations. World Urbanization Prospects (The 1996 Revision).

THE GENERAL DISTRIBUTION DENGUE AND/OR DENGUE HAEMORRHAGIC FEVER, 1975-1999

Rapid increase in dengue haemorrhagic fever

Forty percent of the world’s population is now at risk from dengue but only a small proportion of cases are officially reported to WHO. Nevertheless, 1998 witnessed unprecedented levels of reporting, with approximately 1.2 million cases from 56 countries. However, an estimated 50 million infections occur annually, including 500,000 cases of DHF and dengue shock syndrome, with 24,000 deaths, mostly in children.

Before 1970 only nine countries had experienced DHF epidemics, a number which has since increased more than four-fold. Today, in several Asian countries DHF is a leading cause of paediatric hospitalisation and death. There is no specific cure and a vaccine is not available. However, the adoption of appropriate, standardized clinical management practices can effectively reduce DHF case fatality rates.

Recent calculations of the global burden of disease indicate that the combined losses attributable to dengue and DHF are much greater than previously indicated. For example, the economic impact of dengue and DHF per million population in Puerto Rico is estimated to be similar to that of all of Latin American and the Caribbean for malaria, for hepatitis and for meningitis. The magnitude of the public health problem will continue to grow unless more effective measures are taken to reduce transmission. Currently the only available control measures are aimed at reduction of the mosquito vector population.