The fabric of life: what if mosquito nets were durable and widely available but insecticide-free?

BACKGROUND: Bed nets are the commonest malaria prevention tool and arguably the most cost-effective. Their efficacy is because they prevent mosquito bites (a function of physical durability and integrity), and kill mosquitoes (a function of chemical content and mosquito susceptibility). This essay follows the story of bed nets, insecticides and malaria control, and asks whether the nets must always have insecticides. METHODS: Key attributes of untreated or pyrethroid-treated nets are examined alongside observations of their entomological and epidemiological impacts. Arguments for and against adding insecticides to nets are analysed in contexts of pyrethroid resistance, personal-versus-communal protection, outdoor-biting, need for local production and global health policies. FINDINGS: Widespread resistance in African malaria vectors has greatly weakened the historical mass mosquitocidal effects of insecticide-treated nets (ITNs), which previously contributed communal benefits to users and non-users. Yet ITNs still achieve substantial epidemiological impact, suggesting that physical integrity, consistent use and population-level coverage are increasingly more important than mosquitocidal properties. Pyrethroid-treatment remains desirable where vectors are sufficiently susceptible, but is no longer universally necessary and should be re-examined alongside other attributes, e.g. durability, coverage, acceptability and access. New ITNs with multiple actives or synergists could provide temporary relief in some settings, but their performance, higher costs, and drawn-out innovation timelines do not justify singular emphasis on insecticides. Similarly, sub-lethal insecticides may remain marginally-impactful by reducing survival of older mosquitoes and disrupting parasite development inside the mosquitoes, but such effects vanish under strong resistance. CONCLUSIONS: The public health value of nets is increasingly driven by bite prevention, and decreasingly by lethality to mosquitoes. For context-appropriate solutions, it is necessary to acknowledge and evaluate the potential and cost-effectiveness of durable untreated nets across different settings. Though ~ 90% of malaria burden occurs in Africa, most World Health Organization-prequalified nets are manufactured outside Africa, since many local manufacturers lack capacity to produce the recommended insecticidal nets at competitive scale and pricing. By relaxing conditions for insecticides on nets, it is conceivable that non-insecticidal but durable, and possibly bio-degradable nets, could be readily manufactured locally. This essay aims not to discredit ITNs, but to illustrate how singular focus on insecticides can hinder innovation and sustainability.

Mosquito feeding behavior and how it influences residual malaria transmission across Africa.

The antimalarial efficacy of the most important vector control interventions-long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS)-primarily protect against mosquitoes' biting people when they are in bed and indoors. Mosquito bites taken outside of these times contribute to residual transmission which determines the maximum effectiveness of current malaria prevention. The likelihood mosquitoes feed outside the time of day when LLINs and IRS can protect people is poorly understood, and the proportion of bites received outdoors may be higher after prolonged vector control. A systematic review of mosquito and human behavior is used to quantify and estimate the public health impact of outdoor biting across Africa. On average 79% of bites by the major malaria vectors occur during the time when people are in bed. This estimate is substantially lower than previous predictions, with results suggesting a nearly 10% lower proportion of bites taken at the time when people are beneath LLINs since the year 2000. Across Africa, this higher outdoor transmission is predicted to result in an estimated 10.6 million additional malaria cases annually if universal LLIN and IRS coverage was achieved. Higher outdoor biting diminishes the cases of malaria averted by vector control. This reduction in LLIN effectiveness appears to be exacerbated in areas where mosquito populations are resistant to insecticides used in bed nets, but no association was found between physiological resistance and outdoor biting. Substantial spatial heterogeneity in mosquito biting behavior between communities could contribute to differences in effectiveness of malaria control across Africa.

Evaluating Response Time in Zanzibar's Malaria Elimination Case-Based Surveillance-Response System.

As countries transition toward malaria elimination, malaria programs rely on surveillance-response systems, which are often supported by web- and mobile phone-based reporting tools. Such surveillance-response systems are interventions for elimination, making it important to determine if they are operating optimally. A metric to measure this by is timeliness. This study used a mixed-methods approach to investigate the response time of Zanzibar's malaria elimination surveillance-response system, Malaria Case Notification (MCN). MCN conducts both passive and reactive case detection, supported by a mobile phone-based reporting tool called Coconut Surveillance. Using data obtained from RTI International and the Zanzibar Malaria Elimination Program (ZAMEP), analysis of summary statistics was conducted to investigate the association of response time with geography, and time series techniques were used to investigate trends in response time and its association with the number of reported cases. Results indicated that response time varied by the district in Zanzibar (0.6-6.05 days) and that it was not associated with calendar time or the number of reported cases. Survey responses and focus groups with a cadre of health workers, district malaria surveillance officers, shed light on operational challenges faced during case investigation, such as incomplete health records and transportation issues, which stem from deficiencies in aspects of ZAMEP's program management. These findings illustrate that timely response for malaria elimination depends on effective program management, despite the automation of web-based or mobile phone-based tools. For surveillance-response systems to work optimally, malaria programs should ensure that optimal management practices are in place.

New Prototype Screened Doors and Windows for Excluding Mosquitoes from Houses: A Pilot Study in Rural Gambia.

Despite compelling evidence that modern housing protects against malaria, houses in endemic areas are still commonly porous to mosquitoes. The protective efficacy of four prototype screened doors and two windows designs against mosquito house entry, their impact on indoor climate, as well as their use, durability and acceptability was assessed in a Gambian village. A baseline survey collected data on all the houses and discrete household units, each consisting of a front and back room, were selected and randomly allocated to the study arms. Each prototype self-closing screened door and window was installed in six and 12 units, respectively, with six unaltered units serving as controls. All prototype doors reduced the number of house-entering mosquitoes by 59-77% in comparison with the control houses. The indoor climate of houses with screened doors was similar to control houses. Seventy-nine percentage of door openings at night occurred from dusk to midnight, when malaria vectors begin entering houses. Ten weeks after installation the doors and windows were in good condition, although 38% of doors did not fully self-close and latch (snap shut). The new doors and windows were popular with residents. The prototype door with perforated concertinaed screening was the best performing door because it reduced mosquito entry, remained fully functional, and was preferred by the villagers. Screened doors and windows may be useful tools for reducing vector exposure and keeping areas malaria-free after elimination, when investment in routine vector control becomes difficult to maintain.

Assessment on the ownership and use of mosquito nets in Mozambique.

OBJECTIVE: To assess the ownership and use of mosquito nets in 2014, in Mozambique. METHODS: This observational and cross-sectional study assessed, in February and March 2015, 69 districts (nine of 11 provinces of Mozambique) that have benefited from the mass distribution of mosquito nets. The Lot Quality Assurance Sampling methodology was used. Each locality was denominated supervision area. The Lot Quality Assurance Sampling opts for a minimum of 19 households (in this case, we decided for a minimum of 100 households per district) from each supervision area to assess an indicator (in this case, two indicators were assessed: ownership and use of mosquito nets). Two questions guided the research: a) received a mosquito net; b) used a mosquito net the night before. RESULTS: A total of 6,725 households were assessed. Eighty three percent of them had received mosquito nets in the campaign. Of the 6,232 respondents, 82.0% said they used mosquito nets the night before. The districts of the provinces with low coverage of ownership and use were Tete (69.5% and 60.0%, respectively), Zambezia (79.0% and 60.0%, respectively), and Gaza (81.6% and 70.7%, respectively). The largest coverage of ownership and use were observed in the districts of Nampula (96.7% and 93.8%, respectively) and Niassa (86.0% and 85.4% respectively). CONCLUSIONS: In the districts assessed, the progression of ownership and use of mosquito nets is satisfactory. Nampula and Niassa are the only provinces where ownership and use are at desired levels. OBJECTIVO: Avaliar a posse e o uso das redes mosquiteiras no ano de 2014 em Moçambique. MÉTODOS: Este estudo observacional transversal avaliou, em fevereiro e março de 2015, 68 distritos (nove das 11 províncias de Moçambique) que se beneficiaram da distribuição de redes em massa. Usou-se a metodologia Lot Quality Assurance Sampling. Cada localidade foi designada de área de supervisão. O Lot Quality Assurance Sampling opta por um mínimo de 19 agregados familiares (neste caso decidiu-se um mínimo de 100 agregados familiares por distrito) de cada área de supervisão, a fim de avaliar um indicador (neste caso dois indicadores foram avaliados: posse e uso de redes mosquiteiras). Duas perguntas nortearam a pesquisa: a) recebeu rede; b) usou rede na noite anterior. RESULTADOS: Foram avaliados 6.725 agregados familiares . Desses, 83,0% tinham recebido redes na campanha. Dos 6.232 inqueridos, 82,0% disseram que usaram na noite anterior. As províncias com distritos com menores coberturas de posse e uso foram Tete (69,5% e 60,0%, respectivamente), Zambézia (79,0% e 60,0%, respectivamente) e Gaza (81,6% e 70,7%, respectivamente). As maiores coberturas de posse e uso foram observadas nos distritos de Nampula (96,7% e 93,8%, respectivamente) e Niassa (86,0% e 85,4%, respectivamente). CONCLUSÕES: Nos distritos avaliados, a progressão para a posse e uso de redes mosquiteiras é satisfatória. Nampula e Niassa são as únicas províncias onde a posse e o uso estão em níveis desejados.

Assessment on the ownership and use of mosquito nets in Mozambique / Avaliação sobre a posse e uso de redes mosquiteiras em Moçambique

ABSTRACT OBJECTIVE To assess the ownership and use of mosquito nets in 2014, in Mozambique. METHODS This observational and cross-sectional study assessed, in February and March 2015, 69 districts (nine of 11 provinces of Mozambique) that have benefited from the mass distribution of mosquito nets. The Lot Quality Assurance Sampling methodology was used. Each locality was denominated supervision area. The Lot Quality Assurance Sampling opts for a minimum of 19 households (in this case, we decided for a minimum of 100 households per district) from each supervision area to assess an indicator (in this case, two indicators were assessed: ownership and use of mosquito nets). Two questions guided the research: a) received a mosquito net; b) used a mosquito net the night before. RESULTS A total of 6,725 households were assessed. Eighty three percent of them had received mosquito nets in the campaign. Of the 6,232 respondents, 82.0% said they used mosquito nets the night before. The districts of the provinces with low coverage of ownership and use were Tete (69.5% and 60.0%, respectively), Zambezia (79.0% and 60.0%, respectively), and Gaza (81.6% and 70.7%, respectively). The largest coverage of ownership and use were observed in the districts of Nampula (96.7% and 93.8%, respectively) and Niassa (86.0% and 85.4% respectively). CONCLUSIONS In the districts assessed, the progression of ownership and use of mosquito nets is satisfactory. Nampula and Niassa are the only provinces where ownership and use are at desired levels.

RESUMO OBJECTIVO Avaliar a posse e o uso das redes mosquiteiras no ano de 2014 em Moçambique. MÉTODOS Este estudo observacional transversal avaliou, em fevereiro e março de 2015, 68 distritos (nove das 11 províncias de Moçambique) que se beneficiaram da distribuição de redes em massa. Usou-se a metodologia Lot Quality Assurance Sampling. Cada localidade foi designada de área de supervisão. O Lot Quality Assurance Sampling opta por um mínimo de 19 agregados familiares (neste caso decidiu-se um mínimo de 100 agregados familiares por distrito) de cada área de supervisão, a fim de avaliar um indicador (neste caso dois indicadores foram avaliados: posse e uso de redes mosquiteiras). Duas perguntas nortearam a pesquisa: a) recebeu rede; b) usou rede na noite anterior. RESULTADOS Foram avaliados 6.725 agregados familiares . Desses, 83,0% tinham recebido redes na campanha. Dos 6.232 inqueridos, 82,0% disseram que usaram na noite anterior. As províncias com distritos com menores coberturas de posse e uso foram Tete (69,5% e 60,0%, respectivamente), Zambézia (79,0% e 60,0%, respectivamente) e Gaza (81,6% e 70,7%, respectivamente). As maiores coberturas de posse e uso foram observadas nos distritos de Nampula (96,7% e 93,8%, respectivamente) e Niassa (86,0% e 85,4%, respectivamente). CONCLUSÕES Nos distritos avaliados, a progressão para a posse e uso de redes mosquiteiras é satisfatória. Nampula e Niassa são as únicas províncias onde a posse e o uso estão em níveis desejados.

Impact of health education intervention on insecticide treated nets uptake among nursing mothers in rural communities in Nigeria.

BACKGROUND: ITN use is generally poor in Nigeria among all categories of people. Although use of ITNs has been shown to reduce malarial morbidity and mortality, this measure needs to be supported by an adequate healthcare system providing ITN possibly at the household level. This study was therefore designed to determine the effect of health education on the uptake of ITN among nursing mothers in rural communities in Nigeria. METHODS: The study design was a quasi-experimental study carried out in Ijebu North Local Government Area of Ogun State. A multistage random sampling technique was used in choosing the required samples for this study and a semi- structured questionnaire was used to collect relevant information. The intervention consisted of a structured educational programme based on a course content adapted from the national malaria control programme. A total of 400 respondents were recruited into the study with 200 each in both the experimental and control groups and were followed up for a period of 3 months when the knowledge and uptake of ITN was reassessed. RESULT: There was no significant difference (P >0.05) observed between the experimental and control groups in terms of socio-dermographic characteristics such as age, marital status, religion, and income. The ITN ever users in experimental group were 59 [29.5%] and 138 [72.6%] in pre and post intervention period, respectively (p value =0.0001). These proportions of ITN ever users were 55 [27.5%] and 57 [31.6%] in control group, during the pre and post intervention periods (p = 0.37). Post health education intervention, degree of change in knowledge of ITN re-treatment [37.0%] and mounting [33.5%], readiness to use if given free [30.5%] and belief in efficacy [36.9%] improved significantly in the experimental group while there was no significant change in the control group [p = 0.84, 0.51, 0.68 & 0.69 respectively]. Majority [89%] of the respondents were willing to buy ITN for between US$ 1.5 to US$ 3.0. There was no statistically significant change (P >0.05) despite intervention in the amount the respondents were willing to pay to own an ITN in both the experimental and control groups. CONCLUSION: The study concludes that the use of ITN in the study population was significantly increase by health education and that the free distribution of ITN may not guarantee its use. Uptake of ITN can be significantly improved in rural areas if the nets are made available and backed up with appropriate health education intervention.

Lay perceptions of kala-azar, mosquitoes and bed nets in Bihar, India.

OBJECTIVE: To describe the lay perception of kala-azar (KA) in an endemic area of Muzaffarpur District, Bihar, India: local names, symptoms, affected persons, perceived severity and modes of transmission, as well as perceived mosquito nuisance, modes of protection and use of bed nets. METHODS: We held 16 focus group discussions (FGD) in eight remote villages with altogether 157 participants in March 2008. Separate FGDs were held according to gender, socio-economic status (SES) and with key informants. RESULTS: Kala-azar is most commonly named pilahi. Poor people were said to be the most affected. Knowledge about symptoms was satisfactory. Fever and prolonged fever were the most stated symptoms. KA was perceived as a life-threatening disease with a heavy economic burden. Mosquito bites were perceived as the main mode of transmission but in lower socio-economic groups, non-vector-related explanations were also provided. The main modes of protection from mosquitoes mentioned were the use of fumes and bed nets. Season was the strongest factor influencing the use of bed nets and non-affordability for not owning them. CONCLUSIONS: Although the sand fly is not recognised as the vector, the relatively good awareness of disease transmission by mosquitoes and the nuisance caused by their high density might be an entry point for adopting preventive measures to protect from mosquito bite and thereby indirectly preventing from KA. Educational campaigns targeted to the poorer segments of society are needed to enhance knowledge about KA, its mode of transmission, risks of getting infected and to increase bed net use.

Assessing bed net use and non-use after long-lasting insecticidal net distribution: a simple framework to guide programmatic strategies.

BACKGROUND: Insecticide-treated nets (ITNs) are becoming increasingly available to vulnerable populations at risk for malaria. Their appropriate and consistent use is essential to preventing malaria, but ITN use often lags behind ITN ownership. In order to increase ITN use, it is necessary to devise strategies that accurately identify, differentiate, and target the reasons and types of non-use. METHODS: A simple method based on the end-user as the denominator was employed to classify each individual into one of four ITN use categories: 1) living in households not owning an ITN; 2) living in households owning, but not hanging an ITN; 3) living in households owning and hanging an ITN, but who are not sleeping under one; and 4) sleeping under an ITN. This framework was applied to survey data designed to evaluate long-lasting insecticidal nets (LLINs) distributions following integrated campaigns in five countries: Togo, Sierra Leone, Madagascar, Kenya and Niger. RESULTS: The percentage of children <5 years of age sleeping under an ITN ranged from 51.5% in Kenya to 81.1% in Madagascar. Among the three categories of non-use, children living in households without an ITN make up largest group (range: 9.4%-30.0%), despite the efforts of the integrated child health campaigns. The percentage of children who live in households that own but do not hang an ITN ranged from 5.1% to 16.1%. The percentage of children living in households where an ITN was suspended, but who were not sleeping under it ranged from 4.3% to 16.4%. Use by all household members in Sierra Leone (39.9%) and Madagascar (60.4%) indicate that integrated campaigns reach beyond their desired target populations. CONCLUSIONS: The framework outlined in this paper provides a helpful tool to examine the deficiencies in ITN use. Monitoring and evaluation strategies designed to assess ITN ownership and use can easily incorporate this approach using existing data collection instruments that measure the standard indicators.

Comparative cost analysis of insecticide-treated net delivery strategies: sales supported by social marketing and free distribution through antenatal care.

Insecticide-treated nets (ITNs) are effective in substantially reducing malaria transmission. Still, ITN coverage in sub-Saharan Africa (SSA) remains extremely low. Policy makers are concerned with identifying the most suitable delivery mechanism to achieve rapid yet sustainable increases in ITN coverage. Little is known, however, on the comparative costs of alternative ITN distribution strategies. This paper aimed to fill this gap in knowledge by developing such a comparative cost analysis, looking at the cost per ITN distributed for two alternative interventions: subsidized sales supported by social marketing and free distribution to pregnant women through antenatal care (ANC). The study was conducted in rural Burkina Faso, where the two interventions were carried out alongside one another in 2006/07. Cost information was collected prospectively to derive both a financial analysis adopting a provider's perspective and an economic analysis adopting a societal perspective. The average financial cost per ITN distributed was US$8.08 and US$7.21 for sales supported by social marketing and free distribution through ANC, respectively. The average economic cost per ITN distributed was US$4.81 for both interventions. Contrary to common belief, costs did not differ substantially between the two interventions. Due to the district's ability to rely fully on the use of existing resources, financial costs associated with free ITN distribution through ANC were in fact even lower than those associated with the social marketing campaign. This represents an encouraging finding for SSA governments and points to the possibility to invest in programmes to favour free ITN distribution through existing health facilities. Given restricted budgets, however, free distribution programmes are unlikely to be feasible.

Determinants of bednet ownership and use in visceral leishmaniasis-endemic areas of the Indian subcontinent.

OBJECTIVE: To document ownership and use of bednets with its determinants in the visceral leishmaniasis (VL)-endemic region where mainly non-insecticide impregnated nets are available through commercial channels, and bednets are being considered as a leishmaniasis vector control measure. METHODS: In August-September 2006, semi-structured household (HH) questionnaires and observation guides were used in a random sample of 1330 HHs in VL-endemic districts of India and Nepal to collect data on VL knowledge, HH socio-economic status, bednet ownership and use patterns. An asset index was constructed to allow wealth ranking of the HH. A binary logistic response General Estimating Equations model was fitted to evaluate the determinants of bednet ownership and use. RESULTS: The proportion of HHs with at least one bednet purchased on the commercial market was 81.5% in India and 70.2% in Nepal. The bednets were used in all seasons by 50.6% and 54.1% of the Indian and Nepalese HH owning a bed net. There was striking inequity in bednet ownership: only 38.3% of the poorest quintile in Nepal owned at least one net, compared to 89.7% of the wealthiest quintile. In India, the same trend was observed though somewhat less pronounced (73.6%vs. 93.7%). Multivariate analysis showed that poverty was an important independent predictor for not having a bednet in the HH [OR 5.39 (2.90-10.03)]. CONCLUSION: Given the inequity in commercial bednet ownership, free distribution of insecticide-treated bednets to the general population seems imperative to achieve a mass effect on vector density.