Key containers of Aedes species, vectors to transmit dengue viruses in Nam Dinh province, 2007

ABSTRACT

Background: Dengue Fever/Dengue Hemorrhagic Fever (DF/DHF) has emerged as one of the most important public health concerns in Viet Nam in recent years. Key breeding containers plays an important role in driving dengue vector control in the public. Objectives: The research was conducted to discover the dengue situation, its vectors and key containers to make relevant recommendations in reducing effectively the vector population. Subjects and methods: Two hundred households in two communes of Nam Dinh province (100 in each studied commune) were selected randomly. Vectors collected from the field were identified using mosquito key. The number of dengue larvae and mosquitoes were directly counted or adjustment methods were used to estimate the true number in each type of water storage facility. Results: In Minh Thuan commune, Ae. albopictus larvae were mainly concentrated in jars (49%) and discards (59%), most of Ae. aegypti was found in cement tanks with a volume more than 500L (72%). In Trung Dong commune, larvae of Ae. albopictus concentrated in jars (40%) and discards (25%) and aquariums (15%), while most of the Ae. aegypti larvae was discovered in cement tanks with volumes more than 500L (86%). Mosquito density index of Ae. albopictus in Trung Dong and Minh Thuan communes was 0.56 and 0.38, respectively. The Aedes larvae, houses for larvae and Breteau index were nearly at the threshold of dengue epidemic occurrence for Ae. aegypti and over a certain threshold for Ae. albopictus. Some recommendations were provided to help reduce the dengue vectors. Conclusion: Investigation of key mosquito larvae in water containers was useful in driving the effective dengue vector control. Further studies are required to evaluate the impact and methods to manage water containers in the local area.