Dengue in south-east asia

Abstract

Epidemics of dengue-like disease have been recorded for more than 200 years and haemorrhagic manifestations were occasionally described in patients during the epidemics that occurred 75-100 years ago. Dengue haemorrhagic fever (DHF), as presently seen, is associated with an increased incidence of severe haemorrhages, hypovolaemia and, sometimes, shock. It appeared as a new disease in the Philippines in 1953, then spread to other countries in South-East Asia during the following decade, to become endemic in these countries. Within the past 20 years epidemics have also occurred outside South-East Asia. When DHF first appeared, epidemics occurred in cycles of 2-5 years. Now the cycles are irregular and infection has spread from the large cities to towns and villages in rural areas. Dengue is now the most important arboviral infection in the world. Both dengue fever and DHF have been caused by all four types of the virus, but a close association between type 2 infection and the dengue.shock syndrome (DSS) has been found in Thailand, and between type 3 and DSS in Indonesia and Malaysia. Aedes aegypti, a domestic breeder, is the most important vector, followed by Aedes albopictus. In Singapore, comprehensive vector control measures during the 1970s reduced not only the incidence of infection, but also the herd immunity of the population. As a result, outbreaks of increasing size and severity occurred from 1986 onwards, culminating in the largest recorded epidemic in 1991, when 2179 notified cases with 6 deaths occurred. Dengue type 2 virus was the predominant type associated with this epidemic. A similar resurgence of infection is also occurring in other countries in the region, a situation highlighting the problems associated with vector control methods for the eradication of this infection. Epidemics of dengue-like disease have been recorded for more than 200 years and haemorrhagic manifestations were occasionally described in patients during the epidemics that occurred 75-100 years ago. Dengue haemorrhagic fever (DHF), as presently seen, is associated with an increased incidence of severe haemorrhages, hypovolaemia and, sometimes, shock. It appeared as a new disease in the Philippines in 1953, then spread to other countries in South-East Asia during the following decade, to become endemic in these countries. Within the past 20 years epidemics have also occurred outside South-East Asia. When DHF first appeared, epidemics occurred in cycles of 2-5 years. Now the cycles are irregular and infection has spread from the large cities to towns and villages in rural areas. Dengue is now the most important arboviral infection in the world. Both dengue fever and DHF have been caused by all four types of the virus, but a close association between type 2 infection and the dengue.shock syndrome (DSS) has been found in Thailand, and between type 3 and DSS in Indonesia and Malaysia. Aedes aegypti, a domestic breeder, is the most important vector, followed by Aedes albopictus. In Singapore, comprehensive vector control measures during the 1970s reduced not only the incidence of infection, but also the herd immunity of the population. As a result, outbreaks of increasing size and severity occurred from 1986 onwards, culminating in the largest recorded epidemic in 1991, when 2179 notified cases with 6 deaths occurred. Dengue type 2 virus was the predominant type associated with this epidemic. A similar resurgence of infection is also occurring in other countries in the region, a situation highlighting the problems associated with vector control methods for the eradication of this infection.