Comparative efficacy of two poeciliid fish in indoor cement tanks against chikungunya vector Aedes aegypti in villages in Karnataka, India

<p>Abstract</p> <p>Background</p> <p>In 2006, severe outbreaks of <it>Aedes aegypti</it>-transmitted chikungunya occurred in villages in Karnataka, South India. We evaluated the effectiveness of combined information, education and communication (IEC) campaigns using two potential poeciliid larvivorous fish guppy (<it>Poecilia reticulata</it>) and mosquitofish (<it>Gambusia affinis</it>), in indoor cement tanks for <it>Aedes </it>larval control.</p> <p>Methods</p> <p>Trials were conducted in two villages (Domatmari and Srinivaspura) in Tumkur District from March to May 2006 for <it>Poecilia </it>and one village (Balmanda) in Kolar District from July to October 2006 for <it>Gambusia</it>. A survey on knowledge, attitude and practice (KAP) on chikungunya was initially conducted and IEC campaigns were performed before and after fish release in Domatmari (IEC alone, followed by IEC + <it>Poecilia</it>) and Balmanda (IEC + <it>Gambusia</it>). In Srinivaspura, IEC was not conducted. Larval surveys were conducted at the baseline followed by one-week and one-month post-intervention periods. The impact of fish on <it>Aedes </it>larvae and disease was assessed based on baseline and post-intervention observations.</p> <p>Results</p> <p>Only 18% of respondents knew of the role of mosquitoes in fever outbreaks, while almost all (<it>n </it>= 50 each) gained new knowledge from the IEC campaigns. In Domatmari, IEC alone was not effective (OR 0.54; <it>p </it>= 0.067). Indoor cement tanks were the most preferred <it>Ae. aegypti </it>breeding habitat (86.9%), and had a significant impact on <it>Aedes </it>breeding (Breteau Index) in all villages in the one-week period (<it>p </it>< 0.001). In the one-month period, the impact was most sustained in Domatmari (OR 1.58, <it>p </it>< 0.001) then Srinivaspura (OR 0.45, <it>p </it>= 0.063) and Balmanda (OR 0.51, <it>p </it>= 0.067). After fish introductions, chikungunya cases were reduced by 99.87% in Domatmari, 65.48% in Srinivaspura and 68.51% in Balmanda.</p> <p>Conclusions</p> <p><it>Poecilia </it>exhibited greater survival rates than <it>Gambusia </it>(86.04 <it>vs</it>.16.03%) in cement tanks. Neither IEC nor <it>Poecilia </it>alone was effective against <it>Aedes </it>(<it>p </it>> 0.05). We conclude that <it>Poecilia </it>+ IEC is an effective intervention strategy. The operational cost was 0.50 (US$0.011, 1 US$= 47) per capita per application. Proper water storage practices, focused IEC with <it>Poecilia </it>introductions and vector sanitation involving the local administration and community, is suggested as the best strategy for <it>Aedes </it>control.</p

Changing Domesticity of Aedes aegypti in Northern Peninsular Malaysia: Reproductive Consequences and Potential Epidemiological Implications

BACKGROUND: The domestic dengue vector Aedes aegypti mosquitoes breed in indoor containers. However, in northern peninsular Malaysia, they show equal preference for breeding in both indoor and outdoor habitats. To evaluate the epidemiological implications of this peridomestic adaptation, we examined whether Ae. aegypti exhibits decreased survival, gonotrophic activity, and fecundity due to lack of host availability and the changing breeding behavior. METHODOLOGY/PRINCIPAL FINDINGS: This yearlong field surveillance identified Ae. aegypti breeding in outdoor containers on an enormous scale. Through a sequence of experiments incorporating outdoors and indoors adapting as well as adapted populations, we observed that indoors provided better environment for the survival of Ae. aegypti and the observed death patterns could be explained on the basis of a difference in body size. The duration of gonotrophic period was much shorter in large-bodied females. Fecundity tended to be greater in indoor acclimated females. We also found increased tendency to multiple feeding in outdoors adapted females, which were smaller in size compared to their outdoors breeding counterparts. CONCLUSION/SIGNIFICANCE: The data presented here suggest that acclimatization of Ae. aegypti to the outdoor environment may not decrease its lifespan or gonotrophic activity but rather increase breeding opportunities (increased number of discarded containers outdoors), the rate of larval development, but small body sizes at emergence. Size is likely to be correlated with disease transmission. In general, small size in Aedes females will favor increased blood-feeding frequency resulting in higher population sizes and disease occurrence

Variation in Aedes aegypti (Linnaeus) (Diptera, Culicidae) infestation in artificial containers in Caxias, state of Maranhão, Brazil

INTRODUCTION: Dengue is a serious public health problem worldwide, with cases reported annually in tropical and subtropical regions. Aedes aegypti (Linnaeus, 1762), the main vector of dengue, is a domiciliary species with high dispersal and survival capacities and can use various artificial containers as breeding sites. We assessed potential container breeding sites of A. aegypti in the municipality of Caxias, Maranhão, Brazil. METHODS: In the initial phase, we analyzed 900 properties in 3 neighborhoods during the dry and rainy seasons (August-October 2005 and February-April 2006, respectively). During the second sampling period, September 2006-August 2007, we used 5 assessment cycles for 300 properties in a single neighborhood. RESULTS: During the dry and rainy seasons, water-storage containers comprised 55.7% (n = 1,970) and 48.5% (n = 1,836) of the total containers inspected, and showed the highest productivity of immature A. aegypti; we found 23.7 and 106.1 individuals/container, respectively, in peridomicile sites. In intradomicile sites, water-storage containers were also the most important breeding sites with 86.4% (n = 973) and 85.6% (n = 900) of all containers and a mean of 7.9 and 108.3 individuals/container in the dry and rainy seaso-October 2006 (1,342). The highest number of positives (70) was recorded in May, mostly (94%) in storage containers. CONCLUSIONS: Storage containers are the principal and most productive A. aegypti breeding sites and are a major contributing factor to the maintenance of this vector in Caxias