Dengue haemorrhagic fever in Burma.
Although sporadic from 1965 to 1969, a major outbreak of dengue haemorrhagic fever (DHF) occurred for the first time in Rangoon in 1970. Since then the disease has occurred every year in Rangoon and is now observed to be expanding to other urban areas in the country. The clinical diagnosis of DHF was confused by concurrent outbreaks of influenza A in 1971 and influenza A and B in 1972. A laboratory study of 3,447 clinically diagnosed haemorrhagic fever cases showed that 1643 cases (47.8%) were due to dengue and chikungunya, 296 (8.6%) to influenza A, 85(2.5%) to influenza B, 12(0.3%) to measles and 1411(40.8%) were of unknown aetiology during the 5 year period 1970-1974. Ae. aegypti mosquitoes are widely distributed in the country up to and including 900 meters above sea level but breeding is not found above that altitude. The absolute larval population which is highest in July as well as landing rate correlated with the peak incidence of DHF cases.