Control of dengue fever with active surveillance and the use of insecticidal aerosol cans.

An interventional study was conducted in southern Vietnam to evaluate the feasibility and effectiveness of a new approach to control dengue fever. The approach consisted of active surveillance of dengue patients and the use of insecticidal aerosol cans. Febrile patients were tested serologically at local health centers and insecticidal aerosol cans were given to the family and employed in the neighborhood of dengue patients instead of ultra low volume (ULV) fogging with insecticide. The number of dengue IgM antibody positive cases among febrile patients, the number of reported dengue hemorrhagic fever patients and the total cost were compared in the 2 approaches (prompt focal ULV fogging and the use of insecticidal aerosol cans) in 1997. The aerosol cans were employed 5 times (in June, July, August, September and October) in the study area. ULV fogging in the control area was performed 5 times (in March, May, July, August and September). Twenty-two serologically positive cases were found in the study area which was about half that found in the control area (43 cases). A total of 16 dengue hemorrhagic fever patients was reported in the study area and 43 in the control area. Compared with the reported numbers of the previous year, the reduction rate in the number of dengue hemorrhagic fever cases was 71.4% in the study area and 51.7% in the control area. There were statistically significant differences in the morbidity of dengue fever and the reduction rate of dengue hemorrhagic fever. The cost of the insecticidal aerosol cans was US$393 which was lower than the cost of US$553 for ULV fogging. The findings suggest that insecticidal aerosol cans were effective and feasible for dengue fever control.