Surveillance of Mosquito-Borne Viral Diseases in Thailand

A long term surveillance system is very necessary for planning and evaluation of hemorrhagic fever control. The method of dry blood collection and use of dengue 2 antigen has proven to be an efficient method to detect low and high levels of HI antibody and to prove dengue infection (Top 1975). Use of the hemagglutination inhibition test for dengue infection revealed 52% of the cases from the 72 provinces were from dengue viruses. The number of cases of dengue infection discovered by blood testing during the 3 year study period did not exceed 52%. Cases of dengue infection also occur during non-epidemic periods with the lowest incidence of disease appearing in January. The majority of dengue-proved cases occurs in children aged 6 years. Chikungunya infection has been studied in the metropolitan area of Bangkok and in the 72 provinces. Results of the study, clinically and in the laboratory, indicates that chikungunya has no significance in the surveillance program. This study provides definite information for use in planning and in evaluating methods to control hemorrhagic fever. (Author)