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Abstract. This study aimed to evaluate the effects of existing practices of residents in reducing pre-adult Aedes aegypti (L.) infestation and to assess the effect of dengue-related knowledge on the practices. A house-to-house survey was conducted in two areas with different socioeconomic status in Ho Chi Minh City between October and November 2007. Some residents in both the areas used covers on the productive containers such as the jars and plastic buckets (i.e., 58% and 81% in the two study areas), and it was effective in reducing Ae. aegypti infestation: odds ratio (OR) of 4.0 and 4.9 (95% confidence interval [CI]: 1.49-10.76 and 1.2-19.57, respectively) for the containers with inappropriate covers compared with those with appropriate covers in the two areas, respectively. Appropriate cover use was an effective practice; however, no beneficial role of the knowledge related to dengue in promoting the practice was identified.

Abstract. Monitoring antimalarial drug resistance is a useful epidemiologic tool and provides early detection of resistance foci. Using DNA extracted from the head/thorax of wild mosquitoes collected from Bagamoyo Coastal Tanzania, samples infected by Plasmodium falciparum (N ‫ס‬ 89, in 2002 and N ‫ס‬ 249 in 2004) were screened by nested polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) assay for mutations at Pfcrt76 and Pfmdr1-86 associated with chloroquine (CQ) resistance. The majority of isolates were of single infection (71%), and the prevalence of mutant alleles of Pfcrt76 decreased from 64.5% in 2002 to 16% in 2004; likewise, mutant Pfmdr1-86 alleles decreased from 46.6% to 2.7%. Overall, there was a decline of mutant isolates by a factor of 17 and 4 for Pfmdr1 and Pfcrt, respectively. In contrast, isolates with wild-type alleles increased significantly from < 20% in 2002 to 67.6% for Pfcrt76 and 83.5% for Pfmdr1-86 in 2004. This observation suggest a biologic trend of decrease of CQ mutants and a subsequent increase of CQ susceptible parasites in circulation after the discontinued use of CQ in 2001 as a first-line drug in Tanzania. High prevalence of susceptible P. falciparum found in circulation not only supports other reports of a decline of mutant parasites after a reduction of drug selection pressure but suggests that the fitness cost is high in mutant parasites. Typing parasite isolates from infected mosquitoes, an alternative means of data collection, has the potential to increase the spatial and temporal coverage, and this approach is practical in highly endemic regions of Africa.

ABSTRACT. The fecundity and survival of 6 copepod species were assessed under laboratory conditions in order to choose the best candidates to control the aquatic stages of dengue mosquitoes in the field. Females of all the 6 species (Mesocyclops aspericornis, Mesocyclops pehpeiensis, Mesocyclops woutersi, Mesocyclops thermocyclopoides, Mesocyclops ogunnus, and Megacyclops viridis) mated more than once. Multiple mating resulted in increased egg production. The reproductive ability and longevity varied among the species, and M. aspericornis had the highest values. The lowest values were observed in M. thermocyclopoides. Multiple mating of males of M. aspericornis was also observed. The paternal fecundity decreased with each additional mating. There was no difference in the paternal fecundity between the males that mated at low and high female frequencies. The sperm stored in the M. aspericornis females remained viable for 30 days after storage under moist conditions at 25uC or 15uC. This feature in M. aspericornis represents an additional positive factor indicating that this species is a good biological agent for controlling mosquito larvae, especially in domestic water containers that may dry intermittently.