Risk Factors for the Presence of Aedes aegypti and Aedes albopictus in Domestic Water-Holding Containers in Areas Impacted by the Nam Theun 2 Hydroelectric Project, Laos

Hiscox, Alexandra; Kaye, Angela; Vongphayloth, Khamsing; Banks, Ian J.; Piffer, Michele; Khammanithong, Phasouk; Sananikhom, Pany; Kaul, S. M.; Hill, Nigel; Lindsay, Steve W.; Brey, Paul T.

doi:10.4269/ajtmh.12-0623

Cited by 50 publications

(58 citation statements)

References 34 publications

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“…use of lids) and hygiene. This finding was contrary to those made in other studies where jars were considered a high-risk factor for mosquito breeding in Laos [37] and in Thailand [22], but again the combined purpose and handling practices will play a major role.…”

Section: Discussioncontrasting

confidence: 99%

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Effects of socio-demographic characteristics and household water management on Aedes aegypti production in suburban and rural villages in Laos and Thailand

et al. 2017

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BackgroundDengue fever is a mosquito-borne disease accounting for 50–100 million annual cases globally. Laos and Thailand are countries in south-east Asia where the disease is endemic in both urban and rural areas. Household water storage containers, which are favourable breeding sites for dengue mosquitoes, are common in these areas, due to intermittent or limited access to water supply. This study assessed the effect of household water management and socio-demographic risk factors on Aedes aegypti infestation of water storage containers.MethodsA cross-sectional survey of 239 households in Laos (124 suburban and 115 rural), and 248 households in Thailand (127 suburban and 121 rural) was conducted. Entomological surveys alongside semi-structured interviews and observations were conducted to obtain information on Ae. aegypti infestation, socio-demographic factors and water management. Zero-inflated negative binomial regression models were used to assess risk factors associated with Ae. aegypti pupal infestation.ResultsHousehold water management rather than socio-demographic factors were more likely to be associated with the infestation of water containers with Ae. aegypti pupae. Factors that was significantly associated with Ae. aegypti infestation were tanks, less frequent cleaning of containers, containers without lids, and containers located outdoors or in toilets/bathrooms.ConclusionsAssociations between Ae. aegypti pupae infestation, household water management, and socio-demographic factors were found, with risk factors for Ae. aegypti infestation being specific to each study setting. Most of the containers did not have lids, larvicides, such as temephos was seldom used, and containers were not cleaned regularly; factors are facilitating dengue vector proliferation. It is recommended that, in Lao villages, health messages should promote proper use and maintenance of tightly fitted lids, and temephos in tanks, which were the most infested containers. Recommendations for Thailand are that small water containers should be cleaned weekly. Furthermore, in addition to health messages on dengue control provided to communities, attention should be paid to larval control for indoor containers in rural villages. Temephos or other immature control measures such as the use of pyriproxyfen, antilarval bacteria, or larvivorous fish should be used where temephos resistance is prevalent. Dengue control is not possible without additional adult mosquito control and community participation.

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Section: Discussioncontrasting

confidence: 99%

“…This has also been shown in many other studies where containers without lids or partly covered produced more Ae. aegypti than those with lids [16, 31, 37, 42]. Container lids are not an absolute barrier and must be tightly fitted to prevent gravid females to enter for oviposition [43, 44].…”

Section: Discussionmentioning

confidence: 99%

Effects of socio-demographic characteristics and household water management on Aedes aegypti production in suburban and rural villages in Laos and Thailand

et al. 2017

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“…Aedes aegypti is known to breed mainly in domestic water containers in and around human dwellings [2–4]. These containers are ecosystem microcosms supporting food webs that are dependent on bacteria [5].…”

Section: Introductionmentioning

confidence: 99%

Comparative assessment of the bacterial communities associated with Aedes aegypti larvae and water from domestic water storage containers

et al. 2014

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BackgroundDomestic water storage containers constitute major Aedes aegypti breeding sites. We present for the first time a comparative analysis of the bacterial communities associated with Ae. aegypti larvae and water from domestic water containers.MethodsThe 16S rRNA-temporal temperature gradient gel electrophoresis (TTGE) was used to identify and compare bacterial communities in fourth-instar Ae. aegypti larvae and water from larvae positive and negative domestic containers in a rural village in northeastern Thailand. Water samples were cultured for enteric bacteria in addition to TTGE. Sequences obtained from TTGE and bacterial cultures were clustered into operational taxonomic units (OTUs) for analyses.ResultsSignificantly lower OTU abundance was found in fourth-instar Ae. aegypti larvae compared to mosquito positive water samples. There was no significant difference in OTU abundance between larvae and mosquito negative water samples or between mosquito positive and negative water samples. Larval samples had significantly different OTU diversity compared to mosquito positive and negative water samples, with no significant difference between mosquito positive and negative water samples. The TTGE identified 24 bacterial taxa, belonging to the phyla Proteobacteria, Firmicutes, Actinobacteria, Bacteroidetes and TM7 (candidate phylum). Seven of these taxa were identified in larval samples, 16 in mosquito positive and 13 in mosquito negative water samples. Only two taxa, belonging to the phyla Firmicutes and Actinobacteria, were common to both larvae and water samples. Bacilli was the most abundant bacterial class identified from Ae. aegypti larvae, Gammaproteobacteria from mosquito positive water samples, and Flavobacteria from mosquito negative water samples. Enteric bacteria belonging to the class Gammaproteobacteria were sparsely represented in TTGE, but were isolated from both mosquito positive and negative water samples by selective culture.ConclusionsFew bacteria from water samples were identified in fourth-instar Ae. aegypti larvae, suggesting that established larval bacteria, most likely acquired at earlier stages of development, control the larval microbiota. Further studies at all larval stages are needed to fully understand the dynamics involved. Isolation of enteric bacteria from water samples supports earlier outcomes of E. coli contamination in Ae. aegypti infested domestic containers, suggesting the need to further explore the role of enteric bacteria in Ae. aegypti infestation.

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“…In addition to this, most of the indoor containers for water storage were often covered; this could have possibly contributed to many of them being unproductive. Water-holding containers that are in frequent use within the domestic environment were observed to be less likely to harbor mosquito immatures (85) conducted along the coastal region documented high indices (10,76). Mombasa was at a higher risk of arboviral infections due to the higher larval indices followed by Kilifi and the least was Malindi.…”

Section: Discussionmentioning

confidence: 99%

Urban ecology of arboviral mosquito vectors along the Kenyan coast

Karisa

Muriu

Omuoyo

et al. 2019

Preprint

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Background:The emergence and re-emergence of arboviral infections particularly Chikungunya, dengue hemorrhagic fever, rift valley fever, and yellow fever in humans around the world threatens global health and security. The purpose of this study was to determine the urban ecology of the common arboviral mosquito vectors in urban Coastal Kenya areas. Materials and Methods:The current study was conducted in urban settings of Kilifi and Mombasa counties in coastal Kenya in 2016 to 2017. Adult mosquitoes were collected both indoors and outdoors by CDC light traps and BG-Sentinel traps respectively. All blood fed mosquitoes were tested for blood meal sources by an Enzyme Linked Immunosorbent Assay (ELISA). Mosquito larvae were collected using standard dippers and pipettes. Egg survivorship in dry soil was evaluated by collecting of soil samples from dry potential breeding habitats, watering them for hatching and rearing of the eventual larvae to adults. Mosquitoes were screened for Flavivirus, Alphavirus, and Phlebovirus arboviruses using Reverse Transcriptase quantitative Polymerase Chain Reaction (RT qPCR).Results: A total of 3,264 adult mosquitoes belonging to ten species of Culex, Aedes and Anopheles were collected. Overall, the predominant species were Cx. quinquefasciatus 72.4% (n=2,364) andAe. aegypti, 25.7%, (n=838). A total of 415 breeding habitat types were identified indoors (n=317) and outdoors (n=98). The most productive habitat types in both indoors and outdoors were: assorted small containers, water tanks, drainages, drums and jericans. Overall, 62% (n=18) of the soil samples collected from the two sites (Kilifi and Malindi) were positive for larvae which were used as proxy to measure the presence of eggs. The mosquitoes had high preference for human blood (29.81%) and chicken (3.73%) but none had fed on either goat or bovine. Of 259 mosquitoes tested for viral infection, 11.6% were positive for flavivirus only.Conclusion: Domestic and peri-domestic containers were identified to be the key breeding areas of arboviral vectors. Therefore, efforts should be put in place targeting the productive habitat types.

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Risk Factors for the Presence of Aedes aegypti and Aedes albopictus in Domestic Water-Holding Containers in Areas Impacted by the Nam Theun 2 Hydroelectric Project, Laos

Cited by 50 publications

References 34 publications

Effects of socio-demographic characteristics and household water management on Aedes aegypti production in suburban and rural villages in Laos and Thailand

Effects of socio-demographic characteristics and household water management on Aedes aegypti production in suburban and rural villages in Laos and Thailand

Comparative assessment of the bacterial communities associated with Aedes aegypti larvae and water from domestic water storage containers

Urban ecology of arboviral mosquito vectors along the Kenyan coast

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