Browsing by Subject "Malarial parasites"

Now showing 1 - 4 of 4
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    Open Access
    Effect of artemether-lumefantrine policy and improved vector control on malaria burden in KwaZulu-Natal, South Africa
    (Public Library of Science, 2005) Barnes, Karen I; Durrheim, David N; Little, Francesca; Jackson, Amanda; Mehta, Ushma; Allen, Elizabeth; Dlamini, Sicelo S; Tsoka, Joyce; Bredenkamp, Barry; Mthembu, D Jotham
    In KwaZulu-Natal strengthening of vector control and a change in antimalarial treatment policy to use of artemether-lumefantrine has been associated with a decrease in malaria cases, admissions, and deaths.
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    Five years of antimalarial resistance marker surveillance in Gaza Province, Mozambique, following artemisinin-based combination therapy roll out
    (Public Library of Science, 2011) Raman, Jaishree; Mauff, Katya; Muianga, Pedro; Mussa, Abdul; Maharaj, Rajendra; Barnes, Karen I
    Antimalarial drug resistance is a major obstacle to malaria control and eventual elimination. The routine surveillance for molecular marker of resistance is an efficient way to assess drug efficacy, which remains feasible in areas where malaria control interventions have succeeded in substantially reducing malaria transmission. Community based asexual parasite prevalence surveys were conducted annually in sentinel sites in Gaza Province, Mozambique from 2006 until 2010, before, during and after antimalarial policy changes to artesunate plus sulfadoxine-pyrimethamine in 2006 and to artemether-lumefantrine in 2008. Genetic analysis of dhfr , dhps , crt , and mdr1 resistant genes was conducted on 3 331 (14.4%) Plasmodium falciparum PCR positive samples collected over the study period from 23 229 children aged 2 to 15 years. The quintuple dhfr/dhps mutation associated with sulfadoxine-pyrimethamine resistance increased from 56.2% at baseline to 75.8% by 2010. At baseline the crt 76T and mdr1 86Y mutants were approaching fixation, 96.1% and 74.7%, respectively. Following the deployment of artemisinin-based combination therapy, prevalence of both these chloroquine-resistance markers began declining, reaching 32.4% and 30.9%, respectively, by 2010. All samples analysed over the 5-year period possessed a single copy of the mdr1 gene. The high and increasing prevalence of the quintuple mutation supports the change in drug policy from artesunate plus sulfadoxine-pyrimethamine to artemether-lumefantrine in Mozambique. As chloroquine related drug pressure decreased in the region, so did the molecular markers associated with chloroquine resistance ( crt 76T and mdr1 86Y). However, this reversion to the wild-type mdr186N predisposes parasites towards developing lumefantrine resistance. Close monitoring of artemether-lumefantrine efficacy is therefore essential, particularly given the high drug pressure within the region where most countries now use artemether-lumefantrine as first line treatment.
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    Open Access
    Hitting a Moving Target: A Model for Malaria Elimination in the Presence of Population Movement
    (Public Library of Science, 2015) Silal, Sheetal Prakash; Little, Francesca; Barnes, Karen Irma; White, Lisa Jane
    South Africa is committed to eliminating malaria with a goal of zero local transmission by 2018. Malaria elimination strategies may be unsuccessful if they focus only on vector biology, and ignore the mobility patterns of humans, particularly where the majority of infections are imported. In the first study in Mpumalanga Province in South Africa designed for this purpose, a metapopulation model is developed to assess the impact of their proposed elimination-focused policy interventions. A stochastic, non-linear, ordinary-differential equation model is fitted to malaria data from Mpumalanga and neighbouring Maputo Province in Mozambique. Further scaling-up of vector control is predicted to lead to a minimal reduction in local infections, while mass drug administration and focal screening and treatment at the Mpumalanga-Maputo border are predicted to have only a short-lived impact. Source reduction in Maputo Province is predicted to generate large reductions in local infections through stemming imported infections. The mathematical model predicts malaria elimination to be possible only when imported infections are treated before entry or eliminated at the source suggesting that a regionally focused strategy appears needed, for achieving malaria elimination in Mpumalanga and South Africa.
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    Population pharmacokinetics of artesunate and dihydroartemisinin following intra-rectal dosing of artesunate in malaria patients
    (Public Library of Science, 2006) Simpson, Julie A; Agbenyega, Tsiri; Barnes, Karen I; Perri, Gianni Di; Folb, Peter; Gomes, Melba; Krishna, Sanjeev; Krudsood, Srivicha; Looareesuwan, Sornchai; Mansor, Sharif
    A study of the population pharmacokinetics of intra-rectal artesunate in patients with moderately severe falciparum malaria found the pharmacokinetic properties of dihydroartemisinin were affected only by gender and body weight.