The promise and potential challenges of intermittent preventive treatment for malaria in infants (IPTi)

Division of Epidemiology and Population Studies, Fogarty International Center, National Institutes of Health, Bethesda, MD 20892, USA.
Malaria Journal (Impact Factor: 3.49). 02/2005; 4:33. DOI: 10.1186/1475-2875-4-33
Source: PubMed

ABSTRACT Intermittent preventive treatment (IPT) administers a full therapeutic course of an anti-malarial drug at predetermined intervals, regardless of infection or disease status. It is recommended by the World Health Organization (WHO) for protecting pregnant women from the adverse effects of malaria (IPTp) and shows great potential as a strategy for reducing illness from malaria during infancy (IPTi). Administered concurrently with standard immunizations, IPTi is expected to reduce the frequency of clinical disease, but to allow blood-stage infections to occur between treatments, thus allowing parasite-specific immunity to develop. While wide deployment of IPTi is being considered, it is important to assess other potential effects. Transmission conditions, drug choice and administration schedule will likely affect the possibility of post-treatment rebound in child morbidity and mortality and the increased spread of parasite drug resistance and should be considered when implementing IPTi.

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    ABSTRACT: Trials of intermittent preventive treatment in infants (IPTi) and children (IPTc) have shown promising results in reducing malaria episodes but with varying efficacy and cost-effectiveness. The effects of different intervention and setting characteristics are not well known. We simulate the effects of the different target age groups and delivery channels, seasonal or year-round delivery, transmission intensity, seasonality, proportions of malaria fevers treated and drug characteristics. We use a dynamic, individual-based simulation model of Plasmodium falciparum malaria epidemiology, antimalarial drug action and case management to simulate DALYs averted and the cost per DALY averted by IPTi and IPTc. IPT cost components were estimated from economic studies alongside trials. IPTi and IPTc were predicted to be cost-effective in most of the scenarios modelled. The cost-effectiveness is driven by the impact on DALYs, particularly for IPTc, and the low costs, particularly for IPTi which uses the existing delivery strategy, EPI. Cost-effectiveness was predicted to decrease with low transmission, badly timed seasonal delivery in a seasonal setting, short-acting and more expensive drugs, high frequencies of drug resistance and high levels of treatment of malaria fevers. Seasonal delivery was more cost-effective in seasonal settings, and year-round in constant transmission settings. The difference was more pronounced for IPTc than IPTi due to the different proportions of fixed costs and also different assumed drug spacing during the transmission season. The number of DALYs averted was predicted to decrease as a target five-year age-band for IPTc was shifted from children under 5 years into older ages, except at low transmission intensities. Modelling can extend the information available by predicting impact and cost-effectiveness for scenarios, for outcomes and for multiple strategies where, for practical reasons, trials cannot be carried out. Both IPTi and IPTc are generally cost-effective but could be rendered cost-ineffective by characteristics of the setting, drug or implementation.
    PLoS ONE 04/2011; 6(4):e18391. DOI:10.1371/journal.pone.0018391 · 3.53 Impact Factor
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    ABSTRACT: To develop a decision-support tool to help policy-makers in sub-Saharan Africa assess whether intermittent preventive treatment in infants (IPTi) would be effective for local malaria control. An algorithm for predicting the effect of IPTi was developed using two approaches. First, study data on the age patterns of clinical cases of Plasmodium falciparum malaria, hospital admissions for infection with malaria parasites and malaria-associated death for different levels of malaria transmission intensity and seasonality were used to estimate the percentage of cases of these outcomes that would occur in children aged <10 years targeted by IPTi. Second, a previously developed stochastic mathematical model of IPTi was used to predict the number of cases likely to be averted by implementing IPTi under different epidemiological conditions. The decision-support tool uses the data from these two approaches that are most relevant to the context specified by the user. Findings from the two approaches indicated that the percentage of cases targeted by IPTi increases with the severity of the malaria outcome and with transmission intensity. The decision-support tool, available on the Internet, provides estimates of the percentage of malaria-associated deaths, hospitalizations and clinical cases that will be targeted by IPTi in a specified context and of the number of these outcomes that could be averted. The effectiveness of IPTi varies with malaria transmission intensity and seasonality. Deciding where to implement IPTi must take into account the local epidemiology of malaria. The Internet-based decision-support tool described here predicts the likely effectiveness of IPTi under a wide range of epidemiological conditions.
    Bulletin of the World Health Organisation 11/2010; 88(11):807-14. DOI:10.2471/BLT.09.072397 · 5.11 Impact Factor
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    ABSTRACT: Few data are available about malaria epidemiological situation in Niger. However, implementation of new strategies such as vaccination or seasonal treatment of a target population requires the knowledge of baseline epidemiological features of malaria. A population-based study was conducted to provide better characterization of malaria seasonal variations and population groups the most at risk in this particular area. From July 2007 to December 2009, presumptive cases of malaria among a study population living in a typical Sahelian village of Niger were recorded, and confirmed by microscopic examination. In parallel, asymptomatic carriers were actively detected at the end of each dry season in 2007, 2008 and 2009. Among the 965 presumptive malaria cases recorded, 29% were confirmed by microscopic examination. The incidence of malaria was found to decrease significantly with age (p < 0.01). The mean annual incidence was 0.254. The results show that the risk of malaria was higher in children under ten years (p < 0.0001). The number of malaria episodes generally followed the temporal pattern of changes in precipitation levels, with a peak of transmission in August and September. One-thousand and ninety subjects were submitted to an active detection of asymptomatic carriage of whom 16% tested positive; asymptomatic carriage decreased with increasing age. A higher prevalence of gametocyte carriage among asymptomatic population was recorded in children aged two to ten years, though it did not reach significance. In Southern Niger, malaria transmission mostly occurs from July to October. Children aged two to ten years are the most at risk of malaria, and may also represent the main reservoir for gametocytes. Strategies such as intermittent preventive treatment in children (IPTc) could be of interest in this area, where malaria transmission is highly seasonal. Based on these preliminary data, a pilot study could be implemented in Zindarou using IPTc targeting children aged two to ten years, during the three months of malaria transmission, together with an accurate monitoring of drug resistance.
    Malaria Journal 10/2013; 12(1):379. DOI:10.1186/1475-2875-12-379 · 3.49 Impact Factor

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