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Dengue in Brazil: Situation-2001 and trends

Abstract:

Successive epidemics of dengue have been occuring in Brazil since 1986 and almost three million cases of dengue fever (DF) and 2,229 cases of dengue haemorrhagic fever (DHF) had already been recorded till 15 September 2002. The introduction of the three serotypes in circulation (DEN-1, DEN-2 and DEN-3) has always started in Rio de Janeiro. Approximately 47, 370 and 89, 394 cases of dengue due to DEN-1 were recorded in 1986 and 1987 respectively, corresponding to a risk rate of 34.5 and 64.63 per 100,000 inhabitants. The two following years were characterized by a low occurence of DF. The introduction of DEN-2 in 1990 was also followed by an epidemic reaching close to the magnitude of the previous epidemic (27.29 and 71.1 per 100,000 inhabitants in 1991 and 1992 respectively). From 1994 onwards, the transmission rapidly progressed to many Brazilian cities and this wave of epidemics remained constant for four consecutive years, reaching a peak in 1998 (326.4 cases per 100,000 inhabitants). However, it is very clear that the decline of this latest epidemic did not attain the inter-epidemic levels of the two previous waves, when the risk varied from 1.13 cases per 100,000 inhabitants in 1988 to 4.87 cases per 100,000 inhabitants in 1993, as the rate always remained greater than 127 cases per 100,000 inhabitants. The fourth wave began in 2001, shortly after the DEN-3 was detected, and was characterized by increased rates of both DF and DHF (2,669), considerably higher than the total accumulated over the entire previous decade (896).