146
views
0
recommends
+1 Recommend
0 collections
    12
    shares
      • Record: found
      • Abstract: found
      • Article: not found

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

      Read this article at

      ScienceOpenPublisherPMC
      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Summary

          Background

          Artemisinin-resistant falciparum malaria has arisen in western Cambodia. A concerted international effort is underway to contain artemisinin-resistant Plasmodium falciparum, but containment strategies are dependent on whether resistance has emerged elsewhere. We aimed to establish whether artemisinin resistance has spread or emerged on the Thailand–Myanmar (Burma) border.

          Methods

          In malaria clinics located along the northwestern border of Thailand, we measured six hourly parasite counts in patients with uncomplicated hyperparasitaemic falciparum malaria (≥4% infected red blood cells) who had been given various oral artesunate-containing regimens since 2001. Parasite clearance half-lives were estimated and parasites were genotyped for 93 single nucleotide polymorphisms.

          Findings

          3202 patients were studied between 2001 and 2010. Parasite clearance half-lives lengthened from a geometric mean of 2·6 h (95% CI 2·5–2·7) in 2001, to 3·7 h (3·6–3·8) in 2010, compared with a mean of 5·5 h (5·2–5·9) in 119 patients in western Cambodia measured between 2007 and 2010. The proportion of slow-clearing infections (half-life ≥6·2 h) increased from 0·6% in 2001, to 20% in 2010, compared with 42% in western Cambodia between 2007 and 2010. Of 1583 infections genotyped, 148 multilocus parasite genotypes were identified, each of which infected between two and 13 patients. The proportion of variation in parasite clearance attributable to parasite genetics increased from 30% between 2001 and 2004, to 66% between 2007 and 2010.

          Interpretation

          Genetically determined artemisinin resistance in P falciparum emerged along the Thailand–Myanmar border at least 8 years ago and has since increased substantially. At this rate of increase, resistance will reach rates reported in western Cambodia in 2–6 years.

          Funding

          The Wellcome Trust and National Institutes of Health.

          Related collections

          Most cited references 28

          • Record: found
          • Abstract: found
          • Article: not found

          Qinghaosu (artemisinin): the price of success.

           Andrew White (2008)
          Artemisinin and its derivatives have become essential components of antimalarial treatment. These plant-derived peroxides are unique among antimalarial drugs in killing the young intraerythrocytic malaria parasites, thereby preventing their development to more pathological mature stages. This results in rapid clinical and parasitological responses to treatment and life-saving benefit in severe malaria. Artemisinin combination treatments (ACTs) are now first-line drugs for uncomplicated falciparum malaria, but access to ACTs is still limited in most malaria-endemic countries. Improved agricultural practices, selection of high-yielding hybrids, microbial production, and the development of synthetic peroxides will lower prices. A global subsidy would make these drugs more affordable and available. ACTs are central to current malaria elimination initiatives, but there are concerns that tolerance to artemisinins may be emerging in Cambodia.
            Bookmark
            • Record: found
            • Abstract: found
            • Article: not found

            Intercontinental spread of pyrimethamine-resistant malaria.

            Here we present molecular evidence demonstrating that malaria parasites bearing high-level pyrimethamine resistance originally arrived in Africa from southeast Asia. The resistance alleles carried by these migrants are now spreading across Africa at an alarming rate, signaling the end of affordable malaria treatment and presenting sub-Saharan Africa with a public health crisis.
              Bookmark
              • Record: found
              • Abstract: found
              • Article: not found

              Artemisinin resistance: current status and scenarios for containment.

              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.
                Bookmark

                Author and article information

                Contributors
                Journal
                Lancet
                Lancet
                Lancet
                Lancet Publishing Group
                0140-6736
                1474-547X
                26 May 2012
                26 May 2012
                : 379
                : 9830
                : 1960-1966
                Affiliations
                [a ]Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
                [b ]Shoklo Malaria Research Unit, Mae Sot, Tak, Thailand
                [c ]Texas Biomedical Research Institute, San Antonio, Texas, USA
                [d ]Centre for Tropical Medicine, Churchill Hospital, Oxford, UK
                [e ]Worldwide Antimalarial Resistance Network, Oxford, UK
                Author notes
                [* ]Correspondence to: Prof François Nosten, Shoklo Malaria Research Unit, PO Box 46, Mae Sot, Tak, Thailand 63110 francois@ 123456tropmedres.ac
                Article
                LANCET60484
                10.1016/S0140-6736(12)60484-X
                3525980
                22484134
                © 2012 Elsevier Ltd. All rights reserved.

                This document may be redistributed and reused, subject to certain conditions.

                Categories
                Articles

                Medicine

                Comments

                Comment on this article