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Field issues related to effectiveness of insecticide-treated nets in Tanzania

Erlanger, T. E., Enayati, Ahmad Ali, Hemingway, Janet ORCID:, Mshinda, H., Tami, A. and Lengeler, C. (2004) 'Field issues related to effectiveness of insecticide-treated nets in Tanzania'. Medical and Veterinary Entomology, Vol 18, Issue 2, pp. 153-160.

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Insecticide-treated nets (ITNs) impregnated with pyrethroid insecticides have become one of the most promising interventions to prevent malaria in highly endemic areas. Despite the large body of experience documenting their health impact and the best way to distribute them, some key practical issues remain unresolved. For example, the duration of effective life of a net under field conditions is unknown. The most important factor affecting net effectiveness is the issue of regular re-treatment with insecticide. Washing is also an important determinant of insecticide longevity in the field. Trials were undertaken to provide some essential field information on ITNs within the site of an extended ITN programme in the Morogoro region of Tanzania. It was found that 45% of all nets were in bad condition (defined as more than seven large holes). It is concluded that an effective 'life' for polyester nets is 2-3 years. Further, two-thirds of the 20% of nets that were reported as having been re-treated within the last 12 months had less than 5 mg/m(2) of insecticide. According to the World Health Organization this is insufficient to be effective. People reported that they washed their nets four to seven times per year, usually with soap. Observations showed that such washing does not harm the nets and that the wash-water was unlikely to have an impact on the environment. Finally, bioassays were carried out with Anopheles gambiae on polyester netting with 0.5, 2, 5, 10 and 30 mg/m(2) of deltamethrin, alphacypermethrin and lambdacyhalothrin to assess the effectiveness of pyrethroids. The results confirmed that even with low insecticide concentrations, nets can still provide partial protection.

Item Type: Article
Uncontrolled Keywords: anopheles insecticide insecticide re-treatment insecticide-treated nets malaria malaria prevention pyrethroid wash resistance tanzania malaria control mosquito nets bednets impregnation retreatment pyrethroids morbidity district impact trial
Subjects: QW Microbiology and Immunology > QW 45 Microbial drug resistance. General or not elsewhere classified.
QW Microbiology and Immunology > Immune Responses > QW 700 Infection. Mechanisms of infection and resistance.
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
WA Public Health > Preventive Medicine > WA 240 Disinfection. Disinfestation. Pesticides (including diseases caused by)
WB Practice of Medicine > Medical Climatology > WB 710 Diseases of geographic areas
Faculty: Department: Groups (2002 - 2012) > Vector Group
Digital Object Identifer (DOI):
Depositing User: Sarah Lewis-Newton
Date Deposited: 10 Jan 2012 11:57
Last Modified: 06 Feb 2018 13:03


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