https://www.thelancet.com/pdfs/journals/lancet/PIIS0140-6736(12)60484-X.pdf

Emergence of artemisinin-resistant malaria on the western border of Thailand: a longitudinal study

Artemisinin combination therapies are the first-line treatments for uncomplicated Plasmodium falciparum malaria in most malaria-endemic countries. Recently, partial artemisinin-resistant P. falciparum malaria has emerged on the Cambodia-Thailand border. Exposure of the parasite population to artemisinin monotherapies in subtherapeutic doses for over 30 years, and the availability of substandard artemisinins, have probably been the main driving force in the selection of the resistant phenotype in the region. A multifaceted containment programme has recently been launched, including early diagnosis and appropriate treatment, decreasing drug pressure, optimising vector control, targeting the mobile population, strengthening management and surveillance systems, and operational research. Mathematical modelling can be a useful tool to evaluate possible strategies for containment.

Artemisinin resistance: current status and scenarios for containment

Nature Reviews Microbiology 8, 272–280 (2010), doi:10.1038/nrmicro2331 In the above article, the structure of artesunate shown in Fig 1c was incorrect. The correct structure is shown here. We apologize to the authors and to readers for this error.

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Erratum: Artemisinin resistance: current status and scenarios for containment

https://www.thelancet.com/pdfs/journals/lancet/PIIS0140-6736(10)61270-6.pdf

Shrinking the malaria map: progress and prospects

Mathematical models of mosquito-borne pathogen transmission originated in the early twentieth century to provide insights into how to most effectively combat malaria. The foundations of the Ross–Macdonald theory were established by 1970. Since then, there has been a growing interest in reducing the public health burden of mosquito-borne pathogens and an expanding use of models to guide their control. To assess how theory has changed to confront evolving public health challenges, we compiled a bibliography of 325 publications from 1970 through 2010 that included at least one mathematical model of mosquito-borne pathogen transmission and then used a 79-part questionnaire to classify each of 388 associated models according to its biological assumptions. As a composite measure to interpret the multidimensional results of our survey, we assigned a numerical value to each model that measured its similarity to 15 core assumptions of the Ross–Macdonald model. Although the analysis illustrated a growing acknowledgement of geographical, ecological and epidemiological complexities in modelling transmission, most models during the past 40 years closely resemble the Ross–Macdonald model. Modern theory would benefit from an expansion around the concepts of heterogeneous mosquito biting, poorly mixed mosquito-host encounters, spatial heterogeneity and temporal variation in the transmission process.

/pdf/a-systematic-review-of-mathematical-models-of-mosquito-borne-3xw8f36b1z.pdf

A systematic review of mathematical models of mosquito-borne pathogen transmission: 1970–2010

Background
Artemisinin combination therapy (ACT) is now the recommended first-line treatment for falciparum malaria throughout the world. Initiatives to eliminate malaria are critically dependent on its efficacy. There is recent worrying evidence that artemisinin resistance has arisen on the Thai-Cambodian border. Urgent containment interventions are planned and about to be executed. Mathematical modeling approaches to intervention design are now integrated into the field of malaria epidemiology and control. The use of such an approach to investigate the likely effectiveness of different containment measures with the ultimate aim of eliminating artemisinin-resistant malaria is described.

/pdf/the-last-man-standing-is-the-most-resistant-eliminating-42cpo6s4gu.pdf

The last man standing is the most resistant: eliminating artemisinin-resistant malaria in Cambodia

For many countries, as Professor Greenwood points out, the answer to his question is a resounding ‘yes’1 Perhaps the more pertinent question is, with so many more interventions now available, ‘how?’ The two most important new tools that have been added to our malaria control arsenal since the 1950s are artemisinin combination therapies and insecticide-treated bed nets These are most likely to be effective when used together, in combination with indoor residual spraying where there are suitable vectors The problem we are faced with is a lack of experience of using such an elimination strategy on a large scale, leading to a lack of data, particularly on the best way to roll out ACTs In the past, mass screening and treatment, mass drug administration and large-scale replacement of first-line therapies have all been attempted, with varying degrees of success In the context of newly arisen artemisinin resistance and the diminishing effectiveness of the pyrethroid insecticides, particular care must be taken to preserve the effectiveness of these compounds for as long as possible, whilst achieving maximum impact in a wide variety of epidemiological settings

Another powerful tool that we did not have in the 1950s is sophisticated computer-based mathematical modelling This facilitates the use of the limited data currently available to make predictions about future events In other words, it provides a rational framework on which to base decisions made using limited but diverse and complex inter-related information, such as population demographics, pharmacokinetics and pharmacodynamics, treatment-seeking behaviour, spatially distributed risk factors, the presence of antimalarial resistance, etc Identifying, preparing and calibrating such data sets for each country for the application of mathematical models is a huge challenge in itself2 The accuracy of modelling predictions improves in an iterative process as more data become available Hence, the more intense the malaria elimination efforts are and as long as data are rigorously collected, the more useful and informative modelling becomes The Bill and Melinda Gates Foundation and others have realized the potential of mathematical modelling to help guide malaria elimination and eradication Malaria elimination/eradication modelling is still in its infancy (a PubMed search for mathematical modelling papers with the keywords ‘malaria’, ‘elimination’ or ‘eradication’ produced only two articles)3,4 so these groups have provided significant funding to focus modelling efforts on this problem

Professor Greenwood states that new tools are likely to be required in order to eliminate malaria in high-transmission areas1 If, eventually, we do have the luxury of an effective malaria vaccine or powerful new gametocytocidal drugs they are likely to be expensive and their scale-up will inevitably be based on limited trial data in the initial stages Mathematical modelling will be indispensible in helping to maximize their impact

Wirichada Pontavornpinyo

Papers

The last man standing is the most resistant: eliminating artemisinin-resistant malaria in Cambodia

The role of mathematical modelling in malaria elimination and eradication (Comment on: Can malaria be eliminated?).