LSTM Home > LSTM Research > LSTM Online Archive

Insecticide-treated bednets to control dengue vectors: preliminary evidence from a controlled trial in Haiti

Lenhart, Audrey, Orelus, N., Maskill, R., Alexander, N., Streit, T. and McCall, Philip ORCID: https://orcid.org/0000-0002-0007-3985 (2008) 'Insecticide-treated bednets to control dengue vectors: preliminary evidence from a controlled trial in Haiti'. Tropical Medicine & International Health, Vol 13, Issue 1, pp. 56-67.

Full text not available from this repository.

Abstract

OBJECTIVES Insecticide-treated bednets (ITNs) are effective in preventing nocturnally transmitted vector-borne diseases, but their effect on diurnally active dengue vectors has never been studied. We investigated the efficacy of ITNs in reducing Aedes aegypti populations and dengue transmission.
METHODS A cluster-randomized trial was carried out in Leogane, Haiti between July 2003 and July 2004. The study area (1017 houses) was divided into 18 sectors (clusters): nine received ITNs (Olyset (R) long-lasting insecticidal bednets) and nine were untreated controls. Entomological surveys [measuring Breteau (BI), house (HI), container (CI) and pupae per person (PPI) indices and oviposition activity] were undertaken at baseline and at 1 and 5 months post-intervention. All houses were georeferenced to enable spatial analysis. Control sectors received ITNs at 6 months, and a final entomological and attitudinal survey was undertaken at 12 months after baseline. Anti-dengue IgM seropositivity rates were measured at baseline and after 12 months. Efficacy of ITNs was assessed by WHO cone bioassays.
RESULTS At 1-month post-intervention, entomological indices fell in all sectors, with HI and E-I in the bednet sectors reduced by 6.7 (95% CI -10.6, -2.7; P < 0.01) and 8.4 (95% CI -14.1, -2.6; P < 0.01) respectively. Moreover at 1 month, ovitraps in control sectors were significantly more likely to be positive than in bednet sectors (P < 0.01). By 5 months, all indices remained low and HI, CI and BI were also significantly lower than that of baseline in the control arm. Curiously, at 5 months, HI, CI and BI were lower in the control arm than that in the bednet arm. A final survey, 12 months after the initial baseline study (5 months after bednets had been given to all households) indicated that all indices were significantly lower than that at baseline (P < 0.001). Control houses located within 50 In of a bednet house had significantly lower CI (Z = -2.67, P = 0.008) and PPI (Z = -2.19, P = 0.028) at 1 month, an effect that extended to 100 m by 5 months (Z = -2.03, P = 0.042 and Z = -2.37, P = 0.018 respectively), suggesting a spill-over effect of the bednets. An IgM serosurvey showed a 15.3% decrease (95% CI 5.0-25.5%, P < 0.01) in the number of IgM-positive individuals from baseline to 12 months later.
CONCLUSIONS Insecticide-treated bednets had an immediate effect on dengue vector populations after their introduction, and over the next 5-12 months, the presence of ITNs may have continued to affect vector populations and dengue transmission.

Item Type: Article
Uncontrolled Keywords: dengue insecticide-treated bednets cluster-randomized trial community-based control vector control aedes mosquito haiti deltamethrin-impregnated bednets united-nations mission ultra-low volume aedes-aegypti anopheles-gambiae randomized-trials virus-infection chagas-disease household use cote-divoire Aedes/drug effects* Aedes/growth & development Bedding and Linens* Culex/drug effects* Culex/growth & development Dengue/epidemiology Dengue/prevention & control* Dengue Virus/immunology Haiti/epidemiology Humans Immunoglobulin M/blood Insect Vectors/drug effects Insecticides/pharmacology* Mosquito Control/methods* Patient Acceptance of Health Care Permethrin/pharmacology* Treatment Outcome
Subjects: WA Public Health > Preventive Medicine > WA 108 Preventive health services. Preventive medicine. Travel Medicine.
WA Public Health > WA 30 Socioeconomic factors in public health (General)
WC Communicable Diseases > Tropical and Parasitic Diseases > WC 755.1 General coverage
QV Pharmacology > QV 55 Pharmaceutical preparations (General)
WA Public Health > WA 100 General works
QX Parasitology > Insects. Other Parasites > QX 600 Insect control. Tick control
WA Public Health > WA 105 Epidemiology
QX Parasitology > Insects. Other Parasites > QX 530 Culex
WC Communicable Diseases > Tropical and Parasitic Diseases > WC 770 Therapy
WC Communicable Diseases > Tropical and Parasitic Diseases > WC 755 Epidemiology
WC Communicable Diseases > Tropical and Parasitic Diseases > WC 705 Trypanosomiasis
QX Parasitology > Insects. Other Parasites > QX 650 Insect vectors
QX Parasitology > Insects. Other Parasites > QX 515 Anopheles
WA Public Health > Preventive Medicine > WA 110 Prevention and control of communicable diseases. Transmission of infectious diseases
WC Communicable Diseases > Tropical and Parasitic Diseases > WC 765 Prevention and control
WC Communicable Diseases > Virus Diseases > Infectious Mononucleosis. Arbovirus Infections > WC 528 Dengue
QX Parasitology > Insects. Other Parasites > QX 510 Mosquitoes
QX Parasitology > Insects. Other Parasites > QX 525 Aedes
Faculty: Department: Groups (2002 - 2012) > Vector Group
Digital Object Identifer (DOI): https://doi.org/10.1111/j.1365-3156.2007.01966.x
Depositing User: Users 183 not found.
Date Deposited: 04 Aug 2010 12:01
Last Modified: 06 Feb 2018 13:00
URI: http://archive.lstmed.ac.uk/id/eprint/840

Statistics

View details

Actions (login required)

Edit Item Edit Item