Greg Fegan

A malaria control trial using insecticide-treated bed nets and targeted chemoprophylaxis in a rural area of The Gambia, West Africa

The effects of insecticide-impregnated bed nets on mortality and morbidity from malaria have been investigated during one malaria transmission season in a group of rural Gambian children aged 6 months to 5 years. Sleeping under impregnated nets was associated with an overall reduction in mortality of about 60% in children aged 1-4 years. Mortality was not reduced further by chemoprophylaxis with Maloprim given weekly by village health workers throughout the rainy season. Episodes of fever associated with malaria parasitaemia were reduced by 45% among children who slept under impregnated nets. The addition of chemoprophylaxis provided substantial additional benefit against clinical attacks of malaria; 158 episodes were recorded among 946 children who slept under impregnated nets but who also received chemoprophylaxis. Chemoprophylaxis reduced the prevalence of splenomegaly and parasitaemia at the end of the malaria transmission season by 63% and 83% respectively. Thus, insecticide-impregnated bed nets provided significant protection in children against overall mortality, mortality attributed to malaria, clinical attacks of malaria, and malaria infection. The addition of chemoprophylaxis provided substantial additional protection against clinical attacks of malaria and malaria infection but not against death.

Effect of expanded insecticide-treated bednet coverage on child survival in rural Kenya: a longitudinal study.

Summary Background The potential of insecticide-treated bednets (ITNs) to contribute to child survival has been well documented in randomised controlled trials. ITN coverage has increased rapidly in Kenya from 7% in 2004 to 67% in 2006. We aimed to assess the extent to which this investment has led to improvements in child survival. Methods A dynamic cohort of about 3500 children aged 1–59 months were enumerated three times at yearly intervals in 72 rural clusters located in four districts of Kenya. The effect of ITN use on mortality was assessed with Poisson regression to take account of potential effect-modifying and confounding covariates. Findings 100 children died over 2 years. Overall mortality rates were much the same in the first and second years of the study (14·5 per 1000 person-years in the first year and 15·4 per 1000 person-years in the second). After adjustment for age, time period, and a number of other possible confounding variables, ITN use was associated with a 44% reduction in mortality (mortality rate ratio 0·56, 95% CI 0·33–0·96; p=0·04). This level of protection corresponds to about seven deaths averted for every 1000 ITNs distributed. Interpretation A combined approach of social marketing followed by mass free distribution of ITNs translated into child survival effects that are comparable with those seen in previous randomised controlled trials.

Efficacy trial of malaria vaccine SPf66 in Gambian infants

SPf66 malaria vaccine is a synthetic protein with aminoacid sequences derived from pre-erythrocytic and asexual blood-stage proteins of Plasmodium falciparum. SPf66 was found to have a 31% protective efficacy in an area of intensive malaria transmission in Tanzanian children, 1-5 years old. We report a randomised, double-blind, placebo-controlled trial of SPf66 against clinical P falciparum malaria in Gambian infants. 630 children, aged 6-11 months at time of the first dose, received three doses of SPf66 or injected polio vaccine (IPV). Morbidity was monitored during the following rainy season by means of active and passive case detection. Cross-sectional surveys were carried out at the beginning and at the end of the rainy season. An episode of clinical malaria was defined as fever (> or = 37.5 degrees C) and a parasite density of 6000/microL or more. Analysis of efficacy was done on 547 children (316 SPf66/231 IPV). No differences in mortality or in health centre admissions were found between the two groups of children. 347 clinical episodes of malaria were detected during the three and a half months of surveillance. SPf66 vaccine was associated with a protective efficacy against the first or only clinical episode of 8% (95% CI -18 to 29, p = 0.50) and against the overall incidence of clinical episodes of malaria of 3% (95% CI -24 to 24, p = 0.81). No significant differences in parasite rates or in any other index of malaria were found between the two groups of children. The findings of this study differ from previous reports on SPf66 efficacy from South America and from Tanzania. In The Gambia, protection against clinical attacks of malaria during the rainy season after immunisation in children 6-11 months old at time of the first dose was not achieved.

A malaria control trial using insecticide-treated bed nets and targeted chemoprophylaxis in a rural area of The Gambia, West Africa: 6. The impact of the interventions on mortality and morbidity from malaria

Abstract The effects of insecticide-impregnated bed nets on mortality and morbidity from malaria have been investigated during one malaria transmission season in a group of rural Gambian children aged 6 months to 5 years. Sleeping under impregnated nets was associated with an overall reduction in mortality of about 60% in children aged 1–4 years. Mortality was not reduced further by chemoprophylaxis with Maloprim ® given weekly by village health workers throughout the rainy season. Episodes of fever associated with malaria parasitaemia were reduced by 45% among children who slept under impregnated nets. The addition of chemoprophylaxis provided substantial additional benefit against clinical attacks of malaria; 158 episodes were recorded among 946 children who slept under impregnated nets but who also received chemoprophylaxis. Chemoprophylaxis reduced the prevalence of splenomegaly and parasitaemia at the end of the malaria transmission season by 63% and 83% respectively. Thus, insecticide-impregnated bed nets provided significant protection in children against overall mortality, mortality attributed to malaria, clinical attacks of malaria, and malaria infection. The addition of chemoprophylaxis provided substantial additional protection against clinical attacks of malaria and malaria infection but not against death.

A Phase 2b Randomised Trial of the Candidate Malaria Vaccines FP9 ME-TRAP and MVA ME-TRAP among Children in Kenya

Objective: The objective was to measure the efficacy of the vaccination regimen FFM ME-TRAP in preventing episodes of clinical malaria among children in a malaria endemic area. FFM ME-TRAP is sequential immunisation with two attenuated poxvirus vectors (FP9 and modified vaccinia virus Ankara), which both deliver the pre-erythrocytic malaria antigen construct multiple epitope–thrombospondin-related adhesion protein (ME-TRAP). Design: The trial was randomised and double-blinded. Setting: The setting was a rural, malaria-endemic area of coastal Kenya. Participants: We vaccinated 405 healthy 1- to 6-year-old children. Interventions: Participants were randomised to vaccination with either FFM ME-TRAP or control (rabies vaccine). Outcome Measures: Following antimalarial drug treatment children were seen weekly and whenever they were unwell during nine months of monitoring. The axillary temperature was measured, and blood films taken when febrile. The primary analysis was time to a parasitaemia of over 2,500 parasites/μl. Results: The regime was moderately immunogenic, but the magnitude of T cell responses was lower than in previous studies. In intention to treat (ITT) analysis, time to first episode was shorter in the FFM ME-TRAP group. The cumulative incidence of febrile malaria was 52/190 (27%) for FFM ME-TRAP and 40/197 (20%) among controls (hazard ratio = 1.52). This was not statistically significant (95% confidence interval [CI] 1.0–2.3; p = 0.14 by log-rank). A group of 346 children were vaccinated according to protocol (ATP). Among these children, the hazard ratio was 1.3 (95% CI 0.8–2.1; p = 0.55 by log-rank). When multiple malaria episodes were included in the analyses, the incidence rate ratios were 1.6 (95% CI 1.1–2.3); p = 0.017 for ITT, and 1.4 (95% CI 0.9–2.1); p = 0.16 for ATP. Haemoglobin and parasitaemia in cross-sectional surveys at 3 and 9 mo did not differ by treatment group. Among children vaccinated with FFM ME-TRAP, there was no correlation between immunogenicity and malaria incidence. Conclusions: No protection was induced against febrile malaria by this vaccine regimen. Future field studies will require vaccinations with stronger immunogenicity in children living in malarious areas.

HIV infection, malnutrition, and invasive bacterial infection among children with severe malaria.

BACKGROUND Human immunodeficiency virus (HIV) infection, malnutrition, and invasive bacterial infection (IBI) are reported among children with severe malaria. However, it is unclear whether their cooccurrence with falciparum parasitization and severe disease happens by chance or by association among children in areas where malaria is endemic. METHODS We examined 3068 consecutive children admitted to a Kenyan district hospital with clinical features of severe malaria and 592 control subjects from the community. We performed multivariable regression analysis, with each case weighted for its probability of being due to falciparum malaria, using estimates of the fraction of severe disease attributable to malaria at different parasite densities derived from cross-sectional parasitological surveys of healthy children from the same community. RESULTS HIV infection was present in 133 (12%) of 1071 consecutive parasitemic admitted children (95% confidence interval [CI], 11%-15%). Parasite densities were higher in HIV-infected children. The odds ratio for admission associated with HIV infection for admission with true severe falciparum malaria was 9.6 (95% CI, 4.9-19); however, this effect was restricted to children aged 1 year. Malnutrition was present in 507 (25%) of 2048 consecutive parasitemic admitted children (95% CI, 23%-27%). The odd ratio associated with malnutrition for admission with true severe falciparum malaria was 4.0 (95% CI, 2.9-5.5). IBI was detected in 127 (6%) of 2048 consecutive parasitemic admitted children (95% CI, 5.2%-7.3%). All 3 comorbidities were associated with increased case fatality. CONCLUSIONS HIV, malnutrition and IBI are biologically associated with severe disease due to falciparum malaria rather than being simply alternative diagnoses in co-incidentally parasitized children in an endemic area.

A Multifaceted Intervention to Implement Guidelines and Improve Admission Paediatric Care in Kenyan District Hospitals: A Cluster Randomised Trial

Philip Ayieko and colleagues report the outcomes of a cluster-randomized trial carried out in eight Kenyan district hospitals evaluating the effects of a complex intervention involving improved training and supervision for clinicians. They found a higher performance of hospitals assigned to the complex intervention on a variety of process of care measures, as compared to those receiving the control intervention.

Risk factors for persisting neurological and cognitive impairments following cerebral malaria

Background: Persisting neurological and cognitive impairments are common after cerebral malaria. Although risk factors for gross deficits on discharge have been described, few studies have examined those associated with persistent impairments. Methods: The risk factors for impairments following cerebral malaria were determined by examining hospital records of 143 children aged 6–9 years, previously admitted with cerebral malaria, who were assessed at least 20 months after discharge to detect motor, speech and language, and other cognitive (memory, attention, and non-verbal functioning) impairments. Results: The median age on admission was 30 months (IQR 19–42) and the median time from discharge to assessment was 64 months (IQR 40–78). Thirty four children (23.8%) were defined as having impairments: 14 (9.8%) in motor, 16 (11.2%) in speech and language, and 20 (14.0%) in other cognitive functions. Previous seizures (OR 5.6, 95% CI 2.0 to 16.0), deep coma on admission (OR 28.8, 95% CI 3.0 to 280), focal neurological signs observed during admission (OR 4.6, 95% CI 1.1 to 19.6), and neurological deficits on discharge (OR 4.5, 95% CI 1.4 to 13.8) were independently associated with persisting impairments. In addition, multiple seizures were associated with motor impairment, age <3 years, severe malnutrition, features of intracranial hypertension, and hypoglycaemia with language impairments, while prolonged coma, severe malnutrition, and hypoglycaemia were associated with impairments in other cognitive functions. Conclusions: Risk factors for persisting neurological and cognitive impairments following cerebral malaria include multiple seizures, deep/prolonged coma, hypoglycaemia, and clinical features of intracranial hypertension. Although there are overlaps in impaired functions and risk factors, the differences in risk factors for specific functions may suggest separate mechanisms for neuronal damage. These factors could form the basis of future preventive strategies for persisting impairments.

Declining Responsiveness of Plasmodium falciparum Infections to Artemisinin-Based Combination Treatments on the Kenyan Coast

Background The emergence of artemisinin-resistant P. falciparum malaria in South-East Asia highlights the need for continued global surveillance of the efficacy of artemisinin-based combination therapies. Methods On the Kenyan coast we studied the treatment responses in 474 children 6–59 months old with uncomplicated P. falciparum malaria in a randomized controlled trial of dihydroartemisinin-piperaquine vs. artemether-lumefantrine from 2005 to 2008. (ISRCTN88705995) Results The proportion of patients with residual parasitemia on day 1 rose from 55% in 2005–2006 to 87% in 2007–2008 (odds ratio, 5.4, 95%CI, 2.7–11.1; P<0.001) and from 81% to 95% (OR, 4.1, 95%CI, 1.7–9.9; P = 0.002) in the DHA-PPQ and AM-LM groups, respectively. In parallel, Kaplan-Meier estimated risks of apparent recrudescent infection by day 84 increased from 7% to 14% (P = 0.1) and from 6% to 15% (P = 0.05) with DHA-PPQ and AM-LM, respectively. Coinciding with decreasing transmission in the study area, clinical tolerance to parasitemia (defined as absence of fever) declined between 2005–2006 and 2007–2008 (OR body temperature >37.5°C, 2.8, 1.9–4.1; P<0.001). Neither in vitro sensitivity of parasites to DHA nor levels of antibodies against parasite extract accounted for parasite clearance rates or changes thereof. Conclusions The significant, albeit small, decline through time of parasitological response rates to treatment with ACTs may be due to the emergence of parasites with reduced drug sensitivity, to the coincident reduction in population-level clinical immunity, or both. Maintaining the efficacy of artemisinin-based therapy in Africa would benefit from a better understanding of the mechanisms underlying reduced parasite clearance rates. Trial Registration Controlled-Trials.com ISRCTN88705995

Use of over-the-counter malaria medicines in children and adults in three districts in Kenya: implications for private medicine retailer interventions.

BackgroundGlobal malaria control strategies highlight the need to increase early uptake of effective antimalarials for childhood fevers in endemic settings, based on a presumptive diagnosis of malaria in this age group. Many control programmes identify private medicine sellers as important targets to promote effective early treatment, based on reported widespread inadequate childhood fever treatment practices involving the retail sector. Data on adult use of over-the-counter (OTC) medicines is limited. This study aimed to assess childhood and adult patterns of OTC medicine use to inform national medicine retailer programmes in Kenya and other similar settings.MethodsLarge-scale cluster randomized surveys of treatment seeking practices and malaria parasite prevalence were conducted for recent fevers in children under five years and recent acute illnesses in adults in three districts in Kenya with differing malaria endemicity.ResultsA total of 12, 445 households were visited and data collected on recent illnesses in 11, 505 children and 19, 914 adults. OTC medicines were the most popular first response to fever in children with fever (47.0%; 95% CI 45.5, 48.5) and adults with acute illnesses (56.8%; 95% CI 55.2, 58.3). 36.9% (95% CI 34.7, 39.2) adults and 22.7% (95% CI 20.9, 24.6) children using OTC medicines purchased antimalarials, with similar proportions in low and high endemicity districts. 1.9% (95% CI 0.8, 4.2) adults and 12.1% (95% CI 16.3,34.2) children used multidose antimalarials appropriately. Although the majority of children and adults sought no further treatment, self-referral to a health facility within 72 hours of illness onset was the commonest pattern amongst those seeking further help.ConclusionIn these surveys, OTC medicines were popular first treatments for fever in children or acute illnesses in adults. The proportions using OTC antimalarials were similar in areas of high and low malaria endemicity. In all districts, adults were more likely to self-treat with OTC antimalarial medicines than febrile children were to receive them, and less likely to use them in recommended ways. Government health centres were the most common second resort for treatment and were often used within 72 hours. In view of these practices, more research is needed to assess the impact on the popularity of private medicine sellers of strengthened public sector policies on access to malaria treatment and insecticide-treated bed nets. Improved targeting of OTC antimalarials to high risk groups, better communication strategies regarding adult as well as childrens dosages, and facilitating more rapid referral to trained health workers where needed are important challenges to private medicine seller programmes.