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Ecohealth interventions limit triatomine reinfestation following insecticide spraying in La Brea, Guatemala.

ABSTRACT: In this study, we evaluate the effect of participatory Ecohealth interventions on domestic reinfestation of the Chagas disease vector Triatoma dimidiata after village-wide suppression of the vector population using a residual insecticide. The study was conducted in the rural community of La Brea, Guatemala between 2002 and 2009 where vector infestation was analyzed within a spatial data framework based on entomological and socio-economic surveys of homesteads within the village. Participatory interventions focused on community awareness and low-cost home improvements using local materials to limit areas of refuge and alternative blood meals for the vector within the home, and potential shelter for the vector outside the home. As a result, domestic infestation was maintained at ? 3% and peridomestic infestation at ? 2% for 5 years beyond the last insecticide spraying, in sharp contrast to the rapid reinfestation experienced in earlier insecticide only interventions.

SUBMITTER: Lucero DE

PROVIDER: S-EPMC3617845 | biostudies-other | 2013 Apr

REPOSITORIES: biostudies-other

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Ecohealth interventions limit triatomine reinfestation following insecticide spraying in La Brea, Guatemala.

Lucero David E DE Morrissey Leslie A LA Rizzo Donna M DM Rodas Antonieta A Garnica Roberto R Stevens Lori L Bustamante Dulce M DM Monroy Maria Carlota MC

The American journal of tropical medicine and hygiene 20130204 4

In this study, we evaluate the effect of participatory Ecohealth interventions on domestic reinfestation of the Chagas disease vector Triatoma dimidiata after village-wide suppression of the vector population using a residual insecticide. The study was conducted in the rural community of La Brea, Guatemala between 2002 and 2009 where vector infestation was analyzed within a spatial data framework based on entomological and socio-economic surveys of homesteads within the village. Participatory in ...[more]

PMID: 23382173

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Project description:BACKGROUND:Indoor residual spraying of insecticide (IRS) is a key intervention for reducing the burden of malaria in Africa. However, data on the impact of IRS on malaria in pregnancy and birth outcomes is limited. METHODS:An observational study was conducted within a trial of intermittent preventive therapy during pregnancy in Tororo, Uganda. Women were enrolled at 12-20 weeks of gestation between June and October 2014, provided with insecticide-treated bed nets, and followed through delivery. From December 2014 to February 2015, carbamate-containing IRS was implemented in Tororo district for the first time. Exact spray dates were collected for each household. The exposure of interest was the proportion of time during a woman's pregnancy under protection of IRS, with three categories of protection defined: no IRS protection, >0-20 % IRS protection, and 20-43 % IRS protection. Outcomes assessed included malaria incidence and parasite prevalence during pregnancy, placental malaria, low birth weight (LBW), pre-term delivery, and fetal/neonatal deaths. RESULTS:Of 289 women followed, 134 had no IRS protection during pregnancy, 90 had >0-20 % IRS protection, and 65 had >20-43 % protection. During pregnancy, malaria incidence (0.49 vs 0.10 episodes ppy, P = 0.02) and parasite prevalence (20.0 vs 8.9 %, P < 0.001) were both significantly lower after IRS. At the time of delivery, the prevalence of placental parasitaemia was significantly higher in women with no IRS protection (16.8 %) compared to women with 0-20 % (1.1 %, P = 0.001) or >20-43 % IRS protection (1.6 %, P = 0.006). Compared to women with no IRS protection, those with >20-43 % IRS protection had a lower risk of LBW (20.9 vs 3.1 %, P = 0.002), pre-term birth (17.2 vs 1.5 %, P = 0.006), and fetal/neonatal deaths (7.5 vs 0 %, P = 0.03). CONCLUSION:In this setting, IRS was temporally associated with lower malaria parasite prevalence during pregnancy and at delivery, and improved birth outcomes. IRS may represent an important tool for combating malaria in pregnancy and for improving birth outcomes in malaria-endemic settings. Trial Registration Current Controlled Trials Identifier NCT02163447.

Project description:BACKGROUND:Triatomine insects are vectors of Trypanosoma cruzi, a protozoan parasite that is the causative agent of Chagas' disease. This is a neglected disease affecting approximately 8 million people in Latin America. The existence of diverse pyrethroid resistant populations of at least two species demonstrates the potential of triatomines to develop high levels of insecticide resistance. Therefore, the incorporation of strategies for resistance management is a main concern for vector control programs. Three enzymatic superfamilies are thought to mediate xenobiotic detoxification and resistance: Glutathione Transferases (GSTs), Cytochromes P450 (CYPs) and Carboxyl/Cholinesterases (CCEs). Improving our knowledge of key triatomine detoxification enzymes will strengthen our understanding of insecticide resistance processes in vectors of Chagas' disease. METHODS AND FINDINGS:The discovery and description of detoxification gene superfamilies in normalized transcriptomes of three triatomine species: Triatoma dimidiata, Triatoma infestans and Triatoma pallidipennis is presented. Furthermore, a comparative analysis of these superfamilies among the triatomine transcriptomes and the genome of Rhodnius prolixus, also a triatomine vector of Chagas' disease, and other well-studied insect genomes was performed. The expression pattern of detoxification genes in R. prolixus transcriptomes from key organs was analyzed. The comparisons reveal gene expansions in Sigma class GSTs, CYP3 in CYP superfamily and clade E in CCE superfamily. Moreover, several CYP families identified in these triatomines have not yet been described in other insects. Conversely, several groups of insecticide resistance related enzymes within each enzyme superfamily are reduced or lacking in triatomines. Furthermore, our qRT-PCR results showed an increase in the expression of a CYP4 gene in a T. infestans population resistant to pyrethroids. These results could point to an involvement of metabolic detoxification mechanisms on the high levels of pyrethroid resistance detected in triatomines from the Gran Chaco ecoregion. CONCLUSIONS AND SIGNIFICANCE:Our results help to elucidate the potential insecticide resistance mechanisms in vectors of Chagas' disease and provide new relevant information for this field. This study shows that metabolic resistance might be a contributing cause of the high pyrethroid resistance observed in wild T. infestans populations from the Gran Chaco ecoregion, area in which although subjected to intense pyrethroid treatments, vector control has failed. This study opens new avenues for further functional studies on triatomine detoxification mechanisms.

Project description:BackgroundThe coverage for reproductive care continuum is a growing concern for communities in low- income economies. Adolescents (15-19 years) are often at higher odds of maternal morbidity and mortality due to other underlying factors including biological immaturity, social, and economic differences. The aim of the study was to examine a) differences in care-seeking and continuum of care (4 antenatal care (ANC4+), skilled birth attendance (SBA) and postnatal care (PNC) within 24h) between adult (20-49 Years) and adolescents and b) the effect of multilevel community-oriented interventions on adolescent and adult reproductive care-seeking in Cambodia, Guatemala, Kenya, and Zambia using a quasi-experimental study design.MethodsIn each country, communities in two districts/sub-districts received timed community health worker (CHW) household health promotion and social accountability interventions with community scorecards. Two matched districts/sub-districts were selected for comparison and received routine healthcare services.ResultsResults from the final evaluation showed that there were no significant differences in the care continuum for adolescents and adults except for Kenya (26.1% vs 18.8%, p<0.05). SBA was significantly higher for adolescents compared to adult women for Guatemala (64% vs 55.5%, p<0.05). Adolescents in the intervention sites showed significantly higher ANC utilization for Kenya (95.3% vs 84.8%, p<0.01) and Zambia (87% vs 72.7%, p<0.05), ANC4 for Cambodia (83.7% vs 43.2%, p<0.001) and Kenya (65.9% vs 48.1%, p<0.05), SBA for Cambodia (100% vs 88.9%, p<0.05), early PNC for Cambodia (91.8% vs 72.8%, p<0.01) and Zambia (56.5% vs 16.9%, p<0.001) compared to the comparison sites. However, the findings from Guatemala illustrated significantly lower care continuum for intervention sites (aOR:0.34, 95% CI 0.28-0.42, p<0.001). The study provides some evidence on the potential of multilevel community-oriented interventions to improve adolescent healthcare seeking in rural contexts. The predictors of care continuum varied across countries, indicating the importance of contextual factors in designing interventions.

Project description:BackgroundThere is an increased need to mitigate the emergence of insecticide resistance and incorporate new formulations and modes of application to control the urban vector Aedes aegypti. Most research and development of insecticide formulations for the control of Ae. aegypti has focused on their peridomestic use as truck-mounted ULV-sprays or thermal fogs despite the widespread knowledge that most resting Ae. aegypti are found indoors. A recent modification of indoor residual spraying (IRS), termed targeted IRS (TIRS) works by restricting applications to 1.5 m down to the floor and on key Ae. aegypti resting sites (under furniture). TIRS also opens the possibility of evaluating novel residual insecticide formulations currently being developed for malaria IRS.MethodsWe evaluated the residual efficacy of chlorfenapyr, formulated as Sylando 240SC, for 12 months on free-flying field-derived pyrethroid-resistant Ae. aegypti using a novel experimental house design in Merida, Mexico. On a monthly basis, 600 female Ae. aegypti were released into the houses and left indoors with access to sugar solution for 24 hours. After the exposure period, dead and alive mosquitoes were counted in houses treated with chlorfenapyr as well as untreated control houses to calculate 24-h mortality. An evaluation for these exposed cohorts of surviving mosquitoes was extended up to seven days under laboratory conditions to quantify "delayed mortality".ResultsMean acute (24-h) mortality of pyrethroid-resistant Ae. aegypti ranged 80-97% over 5 months, dropping below 30% after 7 months post-TIRS. If delayed mortality was considered (quantifying mosquito mortality up to 7 days after exposure), residual efficacy was above 90% for up to 7 months post-TIRS application. Generalized Additive Mixed Models quantified a residual efficacy of chlorfenapyr of 225 days (ca. 7.5 months).ConclusionsChlorfenapyr represents a new option for TIRS control of Ae. aegypti in urban areas, providing a highly-effective time of protection against indoor Ae. aegypti females of up to 7 months.

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Ecohealth interventions limit triatomine reinfestation following insecticide spraying in La Brea, Guatemala.

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Ecohealth interventions limit triatomine reinfestation following insecticide spraying in La Brea, Guatemala.

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