Eve Worrall

El Niño and health

El Niño Southern Oscillation (ENSO) is a climate event that originates in the Pacific Ocean but has wide-ranging consequences for weather around the world, and is especially associated with droughts and floods. The irregular occurrence of El Niño and La Niña events has implications for public health. On a global scale, the human effect of natural disasters increases during El Niño. The effect of ENSO on cholera risk in Bangladesh, and malaria epidemics in parts of South Asia and South America has been well established. The strongest evidence for an association between ENSO and disease is provided by time-series analysis with data series that include more than one event. Evidence for ENSOs effect on other mosquito-borne and rodent-borne diseases is weaker than that for malaria and cholera. Health planners are used to dealing with spatial risk concepts but have little experience with temporal risk management. ENSO and seasonal climate forecasts might offer the opportunity to target scarce resources for epidemic control and disaster preparedness.

Is malaria a disease of poverty? A review of the literature

Objective  To review the evidence on the link between malaria and poverty.

The economics of malaria in pregnancy--a review of the evidence and research priorities.

Malaria in pregnancy is a major public-health problem in the developing world. However, on review of the evidence, we found its economic impact is not well documented. Adequately capturing the economic burden of malaria in pregnancy requires good epidemiological data including effects to the mother and baby, and better understanding of the long-term health and economic costs of malaria in pregnancy. We reviewed evidence on coverage, equity, cost, and cost-effectiveness of interventions to tackle malaria in pregnancy and found that although key interventions are highly cost effective, coverage is currently inadequate and fails to reach the poor. The evidence on interventions to improve treatment of malaria in pregnancy is scarce, and fails to adequately capture the benefits. There is also lack of data on cost-effectiveness of other interventions, especially outside of Africa, in low transmission settings, and for non-falciparum malaria. Research priorities on the economics of malaria in pregnancy are identified.

A model to simulate the impact of timing, coverage and transmission intensity on the effectiveness of indoor residual spraying (IRS) for malaria control

Objective  (i) To develop a temperature‐ and rainfall‐driven model of malaria transmission capable of prediction. (ii) To use the model to examine the relationship between the intervention timing and transmission intensity on the effectiveness of indoor residual spraying (IRS).

Experience of targeting subsidies on insecticide‐treated nets: what do we know and what are the knowledge gaps?

Widespread coverage of vulnerable populations with insecticide‐treated nets (ITNs) constitutes an important component of the Roll Back Malaria (RBM) strategy to control malaria. The Abuja Targets call for 60% coverage of children under 5 years of age and pregnant women by 2005; but current coverage in Africa is unacceptably low. The RBM ‘Strategic Framework for Coordinated National Action in Scaling‐up Insecticide‐Treated Netting Programmes in Africa’ promotes coordinated national action and advocates sustained public provision of targeted subsidies to maximise public health benefits, alongside support and stimulation of the private sector. Several countries have already planned or initiated targeted subsidy schemes either on a pilot scale or on a national scale, and have valuable experience which can inform future interventions. The WHO RBM ‘Workshop on mapping models for delivering ITNs through targeted subsidies’ held in Zambia in 2003 provided an opportunity to share and document these country experiences. This paper brings together experiences presented at the workshop with other information on experiences of targeting subsidies on ITNs, net treatment kits and retreatment services (ITN products) in order to describe alternative approaches, highlight their similarities and differences, outline lessons learnt, and identify gaps in knowledge. We find that while there is a growing body of knowledge on different approaches to targeting ITN subsidies, there are significant gaps in knowledge in crucial areas. Key questions regarding how best to target, how much it will cost and what outcomes (levels of coverage) to expect remain unanswered. High quality, well‐funded monitoring and evaluation of alternative approaches to targeting ITN subsidies is vital to develop a knowledge base so that countries can design and implement effective strategies to target ITN subsidies.

The impact of pyrethroid resistance on the efficacy and effectiveness of bednets for malaria control in Africa

Long lasting pyrethroid treated bednets are the most important tool for preventing malaria. Pyrethroid resistant Anopheline mosquitoes are now ubiquitous in Africa, though the public health impact remains unclear, impeding the deployment of more expensive nets. Meta-analyses of bioassay studies and experimental hut trials are used to characterise how pyrethroid resistance changes the efficacy of standard bednets, and those containing the synergist piperonyl butoxide (PBO), and assess its impact on malaria control. New bednets provide substantial personal protection until high levels of resistance, though protection may wane faster against more resistant mosquito populations as nets age. Transmission dynamics models indicate that even low levels of resistance would increase the incidence of malaria due to reduced mosquito mortality and lower overall community protection over the life-time of the net. Switching to PBO bednets could avert up to 0.5 clinical cases per person per year in some resistance scenarios. DOI: http://dx.doi.org/10.7554/eLife.16090.001

Improving the cost-effectiveness of IRS with climate informed health surveillance systems

BackgroundThis paper examines how the cost-effectiveness of IRS varies depending on the severity of transmission and level of programme coverage and how efficiency could be improved by incorporating climate information into decision making for malaria control programmes as part of an integrated Malaria Early Warning and Response System (MEWS).MethodsA climate driven model of malaria transmission was used to simulate cost-effectiveness of alternative IRS coverage levels over six epidemic and non-epidemic years. Decision rules for a potential MEWS system that triggers different IRS coverage are described. The average and marginal cost per case averted with baseline IRS coverage (24%) and under varying IRS coverage levels (50%, 75% and 100%) were calculated.ResultsAverage cost-effectiveness of 24% coverage varies dramatically between years, from US

National malaria vector control policy: an analysis of the decision to scale-up larviciding in Nigeria

108 per case prevented in low transmission to US

Challenges and opportunities associated with the introduction of next generation long lasting insecticidal nets for malaria control: a case study from Burkina Faso.

0.42 in epidemic years. Similarly for higher coverage (24–100%) cost per case prevented is far higher in low than high transmission years (

Cost and effectiveness comparison of two methods for screening potential blood donors for anaemia in Vietnam

108–