Low entomological impact of new water supply infrastructure in southern Vietnam, with reference to dengue vectors.

We did a prospective study in southern Vietnam where new water infrastructure was added. New 1,200-L tanks may present potential breeding grounds for Aedes aegypti, particularly when sealed lids were not always supplied. Some householders in these communes received a piped water supply, however there was no reduction in water storage practices. The prevalence of Aedes aegypti immatures in tank and tap households reached 73%, but were non-significantly different from each other and from control households that received no infrastructure. In all three communes, standard jars comprised from 48% to 71% of containers but were associated with > 90% of III-IV instars and pupae on occasions. In contrast, project tanks contributed from 0-21% of the total population. Non-functional or no lids were apparent 4 months after installation in 45-76% of new tanks, but there was no difference between communes with lids and without lids.