[An etiological and serological study on Dengue epidemic in Guangdong Province]

In 1978-1995, Dengue fever epidemics(serotype 1-4) occurred in Guangdong Province. Among 9 species of mosquitoes found in the epidemic areas, the positive rate of virus isolation in Aedes albopictus was 20.69%, in Aedes aegypti 18.95%, in Culex quinquefasciatus 10.29%, Dengue viruses were not isolated in other 6 species of mosquitoes. The positive rate of virus isolation in the three species showed no significant differences (chi 2 = 2.77 P > 0.05). Aedes aegypti was the main transmitting vector in Hainan Island and Zhanjiang District, whereas Aedes albopictus was in the other epidemic areas. The positive rate of virus isolation within 3 days of disease onset was between 73.58% and 82.05%, but the virus could still be isolated on the 8th day of disease onset. The highest antibody positive rate from the patients' paired-sera was 93.89% and the lowest was 33.71%. IgM antibody could be detected 5 days after the disease onset in some cases, even on the 33rd day of disease onset. These results suggest that virus isolation by collecting patient's blood within 1-4 days of disease onset, or IgM antibody detection after 5 days of disease onset can be used as method for early and rapid diagnosis of the disease.