Rebound mortality and the cost-effectiveness of malaria control: potential impact of increased mortality in late childhood following the introduction of insecticide treated nets. (9/490)

The efficacy and relative cost-effectiveness of insecticide-treated nets (ITNs) for the control of malaria in children under 5 years of age have recently been demonstrated by several large-scale trials. However, it has been suggested that long-term use of ITNs in areas of high transmission could lead to mortality rebound in later childhood, which would reduce the cost-effectiveness of the intervention, and at the extreme could lead to negative overall effects. A model is presented in which the cost and disability adjusted life years (DALYs) per child aged 1-119 months were estimated for a sub-Saharan African population with and without an ITN intervention. The rebound rate, defined as the percentage increase in age-specific all-cause mortality and malaria specific-morbidity, was varied to estimate the threshold at which the intervention was no longer cost-effective. Rebound was considered over two possible age ranges: 5-9 years and 3-6 years. With mortality and morbidity reductions due to ITNs in children aged 1-59 months and rebound in the 5-9 years age class, one could be reasonably certain that the cost per DALY averted is below $150 up to a rebound rate of 39%. Up to an 84% rebound rate it is highly likely that the intervention will be DALY-averting, that is the DALYs averted by the intervetion outweigh DALYs incurred through rebound effects. These thresholds are sensitive to the age range over which reductions and rebound in morbidity and mortality occur. With reductions confined to children aged 1-35 months and rebound in the 3-6 years age class, the cost per DALY is highly likely to fall below $150 only up to a 2.5% rebound rate, and with a rate in excess of 11% one can no longer be reasonably certain that the intervention is DALY-averting. These rates apply to the whole population. If there is no rebound amongst children who did not comply with the intervention, the actual increases in morbidity and mortality required to reach these thresholds amongst compliers would be much higher. The age range over which rebound occurs is a critical determinant of the thresholds at which one can no longer be reasonably certain that ITNs remain cost-effective in the long term. Based on empirical estimates of age-specific malaria mortality in sub-Saharan Africa, it appears unlikely that this threshold rate would be reached if rebound occurs over the 5-9 years age range. By contrast, if rebound occurs over the ages of 3-6 years, the increase in mortality rates required to reach this threshold falls within the observed range of malaria-specific mortality rates for this age group. It is essential that long-term surveillance is included as part of ITN interventions, with particular attention to the age range over which rebound may occur.  (+info)

Bednet impregnation for Chagas disease control: a new perspective. (10/490)

BACKGROUND: To determine the efficacy and acceptability of deltamethrin-impregnated bednets in controlling Chagas disease in South America. METHODS: In three endemic departments of Colombia, a qualitative study on people's knowledge about Chagas disease, vectors, preventive measures and their willingness for collaboration in control operations was undertaken. Additionally, in an entomological study with 100 laboratory-bred Chagas vectors (Rhodnius prolixus), vectors were released for 5 nights (20 each night) in an experimental room, with the human bait protected for one night by an unimpregnated and for four nights by a deltamethrin-impregnated bednet (13 mg/m2). Vectors were stained with fluorescent powder for observation, collected after 10 h exposure in the experimental room and observed for a further 72 h. RESULTS: The study population did not know anything about Chagas disease, but believed the vector to transmit cutaneous leishmaniasis. Therefore willingness to take part in control operations was high. The experimental hut study showed a vector mortality rate of 95% in a room with impregnated nets and of 10% in a room with unimpregnated nets. CONCLUSION: This study opens a new perspective for Chagas disease control in integrated vector borne disease prevention programmes.  (+info)

Malaria prevention in travelers. (11/490)

The prevention of malaria in travelers is becoming a more challenging clinical and public health problem because of the global development of drug-resistant Plasmodium strains of malaria and the increasing popularity of travel to exotic locales. Travelers can reduce their risk of acquiring malaria by using bed netting, wearing proper clothing and applying an insect repellent that contains N,N-diethyl-meta-toluamide. Chloroquine, once the standard agent for weekly malaria prophylaxis, is no longer reliably effective outside the Middle East and Central America because of the emergence of resistant Plasmodium falciparum strains. Mefloquine is now the most effective and most recommended antimalarial agent on the U.S. market; however, the side effects of this agent have begun to limit its acceptance. Doxycycline is effective for malaria prophylaxis in travelers who are unable to take mefloquine. Daily proguanil taken in conjunction with weekly chloroquine is an option for pregnant patients traveling to sub-Saharan Africa. Terminal prophylaxis with two weeks of primaquine phosphate can eliminate an asymptomatic carrier state and the later development of malaria in newly returned long-term travelers with probable exposure to Plasmodium vivax or Plasmodium ovale. Travelers who elect not to take an antimalarial agent or who are at high risk for malaria and are more than 24 hours from medical care can use self-treatment regimens such as those featuring pyrimethamine-sulfadoxine. Conventional agents may be contraindicated in certain travelers, especially pregnant women and small children, and several prophylactic agents are not available in the United States. Azithromycin and a number of malaria vaccines are currently under investigation.  (+info)

Risk factors for Plasmodium vivax infection in the Lacandon forest, southern Mexico. (12/490)

A study was conducted to characterize the risk of Plasmodium vivax infection in the Lacandon forest, southern Mexico. Blood samples and questionnaire data were collected in 1992. Malaria cases (n = 137) were identified by the presence of symptoms and a positive thick blood smear. The control group included individuals with negative antibody titres and no history of malaria (n = 4994). From 7628 individuals studied, 1006 had anti-P. vivax antibodies. Seroprevalence increased with age. Risk factors associated with infection included: place of birth outside the village of residence (odds ratio, OR 11.67; 95% CI 5.21-26.11); no use of medical services (OR 4.69, 95% CI 3.01-7.29), never using bed-nets (OR 3.98, 95 % CI 1.23-12.86) and poor knowledge of malaria transmission, prevention and treatment (OR 2.30, 95 % CI 1.30-4.07). Health education represents the best recommendation for controlling the disease in the area.  (+info)

Use of duvets and the risk of sudden infant death syndrome. (13/490)

BACKGROUND: The use of duvets in infancy is not recommended in the UK and Australia because of a reported association with sudden infant death syndrome (SIDS). AIMS: To examine the association between the use of duvets and the risk of SIDS. METHODS: A nationwide case control study (393 cases, 1592 controls). The use of duvets was assessed by interview with the parent or guardian. RESULTS: The use of duvets was associated with an increased risk of SIDS (odds ratio (OR) = 1.65; 95% confidence interval (CI), 1.31 to 2.08); however, after adjustment for potential confounders there was no increased risk of SIDS (OR = 1.04; 95% CI, 0.77 to 1.38). Furthermore, subgroup analysis did not identify any group in which the use of duvets was associated with an increased risk of SIDS. CONCLUSIONS: This study does not support the recommendation to avoid duvets.  (+info)

Insecticide-treated curtains reduce the prevalence and intensity of malaria infection in Burkina Faso. (14/490)

A large, randomized controlled trial to investigate the impact of insecticide-treated curtains (ITC) on child mortality was conducted in an area of seasonal, holoendemic malaria in Burkina Faso. 158 communities totalling some 90,000 people were censused and grouped into 16 geographical clusters, 8 of which were randomly selected to receive ITC in June-July 1994, just prior to the rainy season. In September-October 1995, at the peak period of malaria transmission, a cross-sectional survey was conducted in 84 of the villages. A random sample of 905 children aged 6-59 months was identified and visited. 763 children (84%) were present at the time of the visit and recruited into the study. Mothers were asked about fever in the past 24 h, the child's temperature was taken, and a sample of blood collected to identify and quantify malaria infections and to measure haemoglobin (Hb) levels. Children protected by ITC were less likely to be infected with Plasmodium falciparum (risk ratio = 0.92; 95% CI 0.86, 0.98) or P. malariae (risk ratio = 0.42, 95% CI 0.19, 0.95). The mean intensity of P. falciparum infections was lower among children protected by ITC (899 vs. 1583 trophozoites/microliter; P < 0.001), while the mean Hb level was 0.4 g/dl higher (P < 0.001). While we found no evidence that ITC had an impact on the prevalence of malaria-associated fever episodes, the confidence intervals around our estimates of the impact of ITC on malaria morbidity were wide. We conclude that widespread implementation of ITC in this area of high malaria transmission led to a modest reduction in the prevalence of malaria infection and to a more substantial reduction in the intensity of these infections which caused increased Hb levels. We were unable to demonstrate any impact of ITC on malaria morbidity, but the wide confidence intervals around our point estimates do not preclude the possibility of a substantial impact.  (+info)

Maintenance and sustained use of insecticide-treated bednets and curtains three years after a controlled trial in western Kenya. (15/490)

In large experimental trials throughout Africa, insecticide-treated bednets and curtains have reduced child mortality in malaria-endemic communities by 15%-30%. While few questions remain about the efficacy of this intervention, operational issues around how to implement and sustain insecticide-treated materials (ITM) projects need attention. We revisited the site of a small-scale ITM intervention trial, 3 years after the project ended, to assess how local attitudes and practices had changed. Qualitative and quantitative methods, including 16 focus group discussions and a household survey (n = 60), were employed to assess use, maintenance, retreatment and perceptions of ITM and the insecticide in former study communities. Families that had been issued bednets were more likely to have kept and maintained them and valued bednets more highly than those who had been issued curtains. While most households retained their original bednets, none had treated them with insecticide since the intervention trial was completed 3 years earlier. Most of those who had been issued bednets repaired them, but none acquired new or replacement nets. In contrast, households that had been issued insecticide-treated curtains often removed them. Three (15%) of the households issued curtains had purchased one or more bednets since the study ended. In households where bednets had been issued, children 10 years of age and younger were a third as likely to sleep under a net as were adults (relative risk (RR) = 0. 32; 95% confidence interval (95%CI) = 0.19, 0.53). Understanding how and why optimal ITM use declined following this small-scale intervention trial can suggest measures that may improve the sustainability of current and future ITM efforts.  (+info)

The evidence base on the cost-effectiveness of malaria control measures in Africa. (16/490)

This review assesses the range and quality of the evidence base on the cost-effectiveness of malaria prevention and treatment in sub-Saharan Africa. Fourteen studies are reviewed, covering insecticide-treated nets, residual spraying, chemoprophylaxis for children, chemoprophylaxis or intermittent treatment for pregnant women, a hypothetical vaccine, and changing the first line drug for treatment. The available evidence provides some guidance to decision-makers. However, the potential to inform policy debates is limited by the gross lack of information on the costs and effects of many interventions, the very small number of cost-effectiveness analyses available, the lack of evidence on the costs and effects of packages of measures, and the problems in generalizing or comparing studies that relate to specific settings and use different methodologies and outcome measures.  (+info)