00000000In 1975, which was expected to be a year of low incidence, the number of cases increased and remained high until 1976 - 1977(12). Between 1976 and 1978, the attack rate was highest in the 4 - 8 year age group and the case fatality rate was high in the 0 to 4 year age group(5). An analysis of sero-confirmed cases showed that among the age groups of 1 - 4, 5 - 9, 10 - 14, and 15 + years, 1.8, 41.3, 49 and 7.7 per cent respectively of cases had occurred, indicating that the age groups of 5 - 9 and 10 - 14 years are the vulnerable age-groups(11). There was no difference in sex distribution.

00000000During the first outbreak in 1970, the epidemic began in June and reached peak incidence in October(3). In the dry cool months i.e., November to February, 8.5 per cent of the annual cases were reported while the corresponding figure for the dry season, i.e., March to June, was 15 per cent. During the rainy season (July to October), 76.7 per cent of cases were reported. August was the peak month(11).

00000000No virus isolation studies were carried out before 1976. The results of virus isolation studies in 1976 are shown in Table 3(13). Similar results were obtained in the virus isolation studies of 1977. Dengue viruses type 2 and type 3 were most commonly isolated from both shock and non-shock cases.

Table 3. Viruses isolated from acute cases of
dengue haemorrhagic fever and fever of unknown origin
(FUO) 1976, at the Children's Hospital, Yangon*

*Dengue 3 (DEN-3) viruses were isolated from acute sera and autopsy material (liver) in two cases.