The impact of charging for insecticide on the Gambian National Impregnated Bednet Programme

Culminating anti-malaria efforts at long lasting insecticidal net?

BACKGROUND

Long-lasting insecticidal nets (LLINs) are a primary method in malaria control efforts. However, a decline in the biological efficacy and physical integrity over a period of comparatively lesser time than claimed, waning of naturally acquired immunity among regular users and misuse of LLINs are serious concerns.

SEARCH AND SELECTION OF LITERATURE

The literature for the current review was searched in PubMed, SCOPUS Database and Google using combined search strings of related key-words. Literature with sufficient data and information on the current subject was selected to reach a valid conclusion.

FINDINGS

The World Health Organization (WHO) has emphasized that LLINs should be considered a public good for people inhabiting malaria endemic settings. LLINs exhibited a cumulative effect on the vector density and may force anthropophilic mosquito vectors to find alternative animal hosts for blood meal. However, the physical integrity and biological activity of LLINs declines faster than the anticipated time due to different operational conditions and the spread of insecticide resistance. LLINs have been successful in reducing malaria incidences by either reducing or not allowing human exposure to the vector mosquitoes, but at the same time, LLINs debilitate the natural protective immunity against malaria parasite. Misuse of LLINs for deviant purposes is common and is a serious environmental concern, as people believe that traditional methods of prevention against malaria that have enabled them to survive through a long time are effective and sufficient. Moreover, people are often ill-informed regarding the toxic effects of LLINs.

CONCLUSIONS

Specific criteria for determining the serviceable life and guidelines on the safe washing and disposal of LLINs need to be developed, kept well-informed and closely monitored. Malaria case management, environment management and community awareness to reduce the misuse of LLINs are crucial. Focused research on developing effective anti-malarial drugs, vaccines and new insecticides to reduce resistance is imperative to tackle malaria in the future.

Socially marketed insecticide-treated nets effectively reduce Plasmodium infection and anaemia among children in urban Malawi

BACKGROUND

Use of insecticide-treated nets (ITNs) has become a central focus for the Roll Back Malaria campaign, and many countries in Africa have now embarked on large-scale public health programmes aimed at making ITNs available to those at greatest risk. However, the effectiveness of these programmes has rarely been evaluated.

METHOD

We conducted a cross-sectional survey to assess the impact of an ITN social marketing programme on Plasmodium falciparum infection and anaemia among children in urban Malawi.

RESULTS

Knowledge of ITNs was high; however, only 42% of the children surveyed reported to have used an ITN the previous night. Nevertheless, 17% (295/1721) of children had a positive P. falciparum smear at enrolment. Use of ITNs was associated with 52% protective efficacy against Plasmodium parasitemia. More than two-thirds of children were anaemic, yet the mean haemoglobin concentration was significantly higher in children using ITNs than in those not using nets. ITN use was associated with wealth, as poorer households were 60% less likely to use treated nets.

CONCLUSION

Although ITN social marketing programmes have the potential of improving malaria control and prevention, additional efforts are required to reach those for whom even subsidized nets are still too expensive.

Use of insecticide-treated nets (ITNs) following a malaria education intervention in Piron, Mali: a control trial with systematic allocation of households

BACKGROUND

Insecticide-treated nets (ITNs) reduce malaria morbidity and mortality, but use is limited. A barrier to ITN use may be lack of knowledge regarding malaria transmission and prevention. This study is a controlled trial comparing ITN use and malaria knowledge levels between households in Piron, Mali, undertaken in 2003.

METHODS

Households received net impregnation services either with or without antecedent education. The main outcome measure was ITN use, defined as impregnation of at least one of the household's existing bednets with insecticide during the study. Knowledge about malaria and prevention practices was assessed pre- and post- educational intervention. Results were analysed by household and by individual.

RESULTS

Forty-nine percent (34/70) of households who received the educational component impregnated their nets in comparison to 35% (22/62) of households who did not (OR = 1.6 CI = 0.8-3.3, P = 0.19). In individual analysis, ITN use was significantly greater in participants who had received the educational intervention (48%) vs. individuals who did not (33%, OR = 1.9, P = 0.012). Knowledge levels about malaria significantly increased for each individual pre- versus post- educational intervention (average change score = 2.13, standard deviation = 1.97, t = -17.78, P < 0.001), although there was no difference found between educational (change score = 2.14) and control groups (change score = 2.12).

CONCLUSION

It is possible to educate individuals about malaria and to implement net impregnation services with limited resources. Greater accessibility to net-impregnation services is necessary but not sufficient to increase ITN use.

How local community knowledge about malaria affects insecticide-treated net use in northern Ghana

Large-scale trials of insecticide-treated nets (ITNs) throughout Sub-Saharan Africa demonstrated that they reduce child mortality in malaria endemic communities. These encouraging results have generated interest in ITNs as a viable malaria control strategy in many malaria endemic countries. However, regular use of ITNs under routine or non-project conditions has been beset with several problems. This paper explores how local community knowledge about malaria acts as a barrier to the use of ITNs in three settings. We employed structured formal observation and a range of interviewing techniques which included informal interviews, focus group discussions, semi-structured in-depth interviews, and structured survey interviewing. People recognize the term 'malaria' but have limited biomedical knowledge of the disease, including its aetiology, the role of the vector, and host response. Convulsions and anaemia are rarely linked to malaria. The people acknowledged a role for ITNs in nuisance reduction, but not for malaria prevention.

The effects of untreated bednets on malaria infection and morbidity on the Kenyan coast

A study was conducted in order to determine whether children that slept under untreated bednets were protected against both malaria infection and clinical disease compared with children not sleeping under bednets. The study was conducted in Kilifi District, Kenya, during the malaria season (June-August, 2000) and involved 416 children aged < or = 10 years. Data collected from a cross-sectional survey showed evidence of protection against malaria infection among children sleeping under untreated bednets in good condition compared with those not using nets (adjusted odds ratio [AOR] = 0.4, 95% CI 0.22-0.72, P = 0.002). There was no evidence of a protective effect against infection when comparing those that used untreated bednets that were worn and those not using nets (AOR = 0.75, 95% CI 0.34-1.63, P = 0.47). When these same children were followed-up during the malaria season, there was evidence of a lower rate of clinical malaria among those that used untreated nets in good condition (adjusted incidence rate ratio = 0.65, 95% CI 0.45-0.94, P = 0.022), while the rate of clinical malaria among those that used untreated bednets that were worn was similar to that of those that did not use bednets. In the face of persistent failure of communities to take up net retreatment, there is hope that untreated nets will offer some protection against malaria infection and disease compared with not using nets at all.

Combined field and laboratory evaluation of a long-term impregnated bednet, PermaNet®

For how long does the insecticidal effect of long-lasting nets achieve high Anopheles mortality? Four PermaNets tested previously in Colombia for wash resistance were bioassayed again after 3 years of use and 23 washes. The tests were done both in Colombia and a reference laboratory in Indonesia. Additionally the residual concentration of deltamethrin on the nets was chemically analysed. The results showed high Anopheles mortality and a mean deltamethrin concentration of 9.6 mg/m2. Discrepancies with other studies are discussed.

Scaling-up coverage with insecticide-treated nets against malaria in Africa: who should pay?

Insecticide-treated nets (ITNs) have been shown to reduce the burden of malaria in African villages by providing personal protection and, if coverage of a community is comprehensive, by reducing the infective mosquito population. We do not accept the view that scaling-up this method should be by making villagers pay for nets and insecticide, with subsidies limited so as not to discourage the private sector. We consider that ITNs should be viewed as a public good, like vaccines, and should be provided via the public sector with generous assistance from donors. Our experience is that teams distributing free ITNs, replacing them after about 4 years when they are torn and retreating them annually, have high productivity and provide more comprehensive and equitable coverage than has been reported for marketing systems. Very few of the free nets are misused or sold. The estimated cost would be an annual expenditure of about US$295 million to provide for all of rural tropical Africa where most of the world's malaria exists. This expenditure is affordable by the world community as a whole, but not by its poorest members. Recently, funding of this order of magnitude has been committed by donor agencies for malaria control.

Too poor to pay: charging for insecticide-treated bednets in highland Kenya

WHO has proposed malaria control as a means to alleviate poverty. One of its targets includes a 30-fold increase in insecticide-treated nets (ITNs) in the next 5 years. How this service will be financed remains unclear. In July 2000, 390 homesteads in rural highland Kenya were interviewed on their willingness to pay for ITNs. The costs to a household of protecting themselves with ITNs were compared with current household expenditure. Homesteads expressed a willingness to pay for ITNs, but the amounts offered were not sufficient to cover the costs of providing this service without donor support to meet the difference. Furthermore, as most household expenditure was allocated to basic needs these interventions were 'unaffordable'. The cost of protecting a household with ITNs would be equivalent to sending three children to primary school for a year. The aspiration by poor rural homesteads to protect themselves with ITNs is not compatible with their ability to pay. One option to have an immediate equitable impact on ITN coverage and break the cycle between malaria and poverty is to provide this service free of charge.

The cost of not treating bednets

For centuries, bednets have been used as a physical barrier against biting insects. Recent epidemiological investigations into their protective effects against malaria were quickly overtaken by studies focusing on the benefits of impregnating bednets with insecticide. The operational problems encountered in re-treating bednets with insecticide are often cited as an impediment to wide-scale implementation. The evidence for a protective effect of untreated nets against malaria is presented here alongside an analysis of how well untreated nets would need to work in order to compete with treated nets within a cost-effectiveness framework.

Do untreated bednets protect against malaria?

Bednets are thought to offer little, if any, protection against malaria, unless treated with insecticide. There is also concern that the use of untreated nets will cause people sleeping without nets to receive more mosquito bites, and thus increase the malaria risk for other community members. Regular retreatment of nets is therefore viewed as critical for malaria control. However, despite good uptake of nets, many control programmes in Africa have reported low re-treatment rates. We investigated whether untreated bednets had any protective benefit (in October and November 1996) in The Gambia where nets, although widely used, are mostly untreated. Cross-sectional prevalence surveys were carried out in 48 villages and the risk of malaria parasitaemia was compared in young children sleeping with or without nets. Use of an untreated bednet in good condition was associated with a significantly lower prevalence of Plasmodium falciparum infection (51% protection [95% CI 34-64%], P < 0.001). This finding was only partly explained by differences in wealth between households, and children in the poorest households benefited most from sleeping under an untreated net (62% protection [14-83%], P = 0.018). There was no evidence that mosquitoes were diverted to feed on children sleeping without nets. These findings suggest that an untreated net, provided it is in relatively good condition, can protect against malaria. Control programmes should target the poorest households as they may have the most to gain from using nets.

Current status of malaria and potential for control

Malaria remains one of the world's worst health problems with 1.5 to 2.7 million deaths annually; these deaths are primarily among children under 5 years of age and pregnant women in sub-Saharan Africa. Of significance, more people are dying from malaria today than 30 years ago. This review considers the factors which have contributed to this gloomy picture, including those which relate to the vector, the female anopheline mosquito; to human activity such as creating new mosquito breeding sites, the impact of increased numbers of people, and how their migratory behavior can increase the incidence and spread of malaria; and the problems of drug resistance by the parasites to almost all currently available antimalarial drugs. In a selective manner, this review describes what is being done to ameliorate this situation both in terms of applying existing methods in a useful or even crucial role in control and prevention and in terms of new additions to the antimalarial armory that are being developed. Topics covered include biological control of mosquitoes, the use of insecticide-impregnated bed nets, transgenic mosquitoes manipulated for resistance to malaria parasites, old and new antimalarial drugs, drug resistance and how best to maintain the useful life of antimalarials, immunity to malaria and the search for antimalarial vaccines, and the malaria genome project and the potential benefits to accrue from it.

Comparison of bednets impregnated with different pyrethroids for their impact on mosquitoes and on re-infection with malaria after clearance of pre-existing infections with chlorproguanil-dapsone

Comparisons of bednets treated either with alphacypermethrin or lambdacyhalothrin showed similar effectiveness by various entomological criteria. Lambdacyhalothrin was associated with significantly more reports of nasal irritation than alphacypermethrin. The 2 net treatments were equally effective in reducing incidence of new malaria infections and the treated nets were much more effective than untreated nets. These measurements were made after clearing existing infections with chlorproguanil-dapsone. This drug combination was more than 99% effective in clearing infections 1 week after treatment and a study of children taken to an altitude with no malaria transmission showed that there were very few recrudescences.