CSU 46/2010: TWO ON SUSTAINING MALARIA CONTROL IN AFRICA

Wednesday, 21st of April 2010 Print

1) Bill Jobin blogs on www.malariaworld.org. Are ACT and LLINs less than enough?

 

Cross posted with thanks.

 

2)  EFFECT OF TWO DIFFERENT HOUSE SCREENING INTERVENTIONS: AN RCT (Abstract only)

 

Good reading.

 

BD

 

 

1) SUSTAINING MALARIA CONTROL IN AFRICA

 

 

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The current enthusiasm for malaria control in Africa will bring us much closer to our goal if we build on the successes of the past, and avoid repeating the mistakes. The major mistake in the global Malaria Eradication Program of 1955 was to embark on an unsustainable strategy, which collapsed within a decade. We need to ensure that current strategies do not repeat this mistake.

 

There is a serious need to understand our history right now, because of the growing unease among donors as they start to appreciate the costs of measures being employed in the current strategies in Africa. The current strategies are based on temporary measures which have to be continued indefinitely: drugs, chemically treated bednets, and spraying of insecticides.

 

Unfortunately those of us riding the new wave of optimism are missing two important historical points which we must correct, if we want to succeed. The first important point ignored by current planners, is that the sustainability and endurance of successful malaria control during the first half of the Twentieth Century in the USA, Puerto Rico, Europe, parts of Indonesia, and some other tropical islands, was because the strategies were based primarily on permanent environmental control measures. These included improvements in housing and installation of window and door screens. Also larval habitat control included filling and drainage of water-retaining depressions, and water management in large irrigation and hydropower systems.

 

The second important point being missed by current planners is that the new control methods being implemented in Africa by Roll Back Malaria, the Global Fund, and the US Presidential Malaria Initiative are based solely on the repeated use of drugs and insecticides, very similar to the Malaria Eradication Program of 1955. Given historic evidence for the implacable development of resistance by mosquitoes to any kind of insecticide, and the track record of the malaria parasite to eventually overcome any widely employed drug, our enthusiastic programs are again going to founder in the swamp of biological resistance. Resistance to the new artemisin-based drugs and to the permethrin chemicals used in bednets and indoor spraying is already showing in Asia and Africa.

 

A correction to our current strategies against malaria is needed to overcome the errors in thinking which have led us to the current programs. The correction required is fairly simple. We have to add permanent control measures to the temporary measures now being used.

 

As a first step, in addition to using treated bednets which have to be replaced or retreated every few years, we should invest some of that money in permanently blocking mosquito entry to houses through closing off the eaves and holes in the walls, and by putting metal screens on carefully built windows and doors. This is work which can be done by local carpenters. Even the home-owners can help. Covering ceilings with papyrus-paper has been recently employed successfully in Africa.

 

Secondly, in addition to spraying of houses, and treatment of larval habitats with chemical or biological agents which have to be applied repeatedly, we should enlist the skills of local farmers and laborers to drain or fill the habitats. Local people can be organized to dig ditches that rapidly drain away accumulated rainwater. On a larger scale, improved irrigation and agricultural drainage systems can permanently reduce malaria mosquito production.

 

Now is an ideal time to harness the enthusiasm for malaria control, especially in Africa. But to do so successfullly, we must read history properly. We will then see that adding permanent control measures to the currently unsustainable efforts in Africa is the only way we can continue the successes that we enjoyed in the first half of the Twentieth Century.

 

Bill, hoping for sustainability

 

2)  EFFECT OF TWO DIFFERENT HOUSE SCREENING INTERVENTIONS ON EXPOSURE TO MALARIA VECTORS AND ON ANAEMIA IN CHILDREN IN THE GAMBIA: A RANDOMISED CONTROLLED TRIAL.

 

Lancet. 2009 Sep 19;374(9694):998-1009. Epub 2009 Sep 3. 

 

Kirby MJ, Ameh D, Bottomley C, Green C, Jawara M, Milligan PJ, Snell PC, Conway DJ, Lindsay SW.

Science Laboratories, Durham University, Durham, UK.

Abstract

 

BACKGROUND: House screening should protect people against malaria. We assessed whether two types of house screening--full screening of windows, doors, and closing eaves, or installation of screened ceilings--could reduce house entry of malaria vectors and frequency of anaemia in children in an area of seasonal malaria transmission.

 

METHODS: During 2006 and 2007, 500 occupied houses in and near Farafenni town in The Gambia, an area with low use of insecticide-treated bednets, were randomly assigned to receive full screening, screened ceilings, or no screening (control). Randomisation was done by computer-generated list, in permuted blocks of five houses in the ratio 2:2:1. Screening was not treated with insecticide. Exposure to mosquitoes indoors was assessed by fortnightly light trap collections during the transmission season. Primary endpoints included the number of female Anopheles gambiae sensu lato mosquitoes collected per trap per night. Secondary endpoints included frequency of anaemia (haemoglobin concentration <80 g/L) and parasitaemia at the end of the transmission season in children (aged 6 months to 10 years) who were living in the study houses. Analysis was by modified intention to treat (ITT), including all randomised houses for which there were some outcome data and all children from those houses who were sampled for haemoglobin and parasitaemia. This study is registered as an International Standard Randomised Controlled Trial, number ISRCTN51184253.

 

FINDINGS: 462 houses were included in the modified ITT analysis (full screening, n=188; screened ceilings, n=178; control, n=96). The mean number of A gambiae caught in houses without screening was 37.5 per trap per night (95% CI 31.6-43.3), compared with 15.2 (12.9-17.4) in houses with full screening (ratio of means 0.41, 95% CI 0.31-0.54; p<0.0001) and 19.1 (16.1-22.1) in houses with screened ceilings (ratio 0.53, 0.40-0.70; p<0.0001). 755 children completed the study, of whom 731 had complete clinical and covariate data and were used in the analysis of clinical outcomes. 30 (19%) of 158 children from control houses had anaemia, compared with 38 (12%) of 309 from houses with full screening (adjusted odds ratio [OR] 0.53, 95% CI 0.29-0.97; p=0.04), and 31 (12%) of 264 from houses with screened ceilings (OR 0.51, 0.27-0.96; p=0.04). Frequency of parasitaemia did not differ between intervention and control groups.

 

INTERPRETATION: House screening substantially reduced the number of mosquitoes inside houses and could contribute to prevention of anaemia in children.

 

FUNDING: Medical Research Council.

 

 



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