Browsing by Author "Raman, Jaishree"

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    Open Access
    Absence of kelch13 artemisinin resistance markers but strong selection for lumefantrine-tolerance molecular markers following 18 years of artemisinin-based combination therapy use in Mpumalanga Province, South Africa (2001–2018)
    (2019-08-22) Raman, Jaishree; Kagoro, Frank M; Mabuza, Aaron; Malatje, Gillian; Reid, Anthony; Frean, John; Barnes, Karen I
    Abstract Background The ability of Plasmodium falciparum parasites to develop resistance to widely used anti-malarials threatens malaria control and elimination efforts. Regular drug efficacy monitoring is essential for ensuring effective treatment policies. In low transmission settings where therapeutic efficacy studies are often not feasible, routine surveillance for molecular markers associated with anti-malarial resistance provides an alternative for the early detection of emerging resistance. Such a longitudinal survey of changes in the prevalence of selected molecular markers of resistance was conducted in the malaria-endemic regions of Mpumalanga Province, South Africa, where malaria elimination at a district-level is being pursued. Methods Molecular analyses to determine the prevalence of alleles associated with resistance to lumefantrine (mdr86N, crt76K and mdr1 copy number variation) and sulfadoxine–pyrimethamine (dhfr triple, dhps double, SP quintuple) were conducted between 2001 and 2018, while artemisinin resistance markers (kelch13 mutations) were assessed only in 2018. Results Parasite DNA was successfully amplified from 1667/2393 (70%) of malaria-positive rapid diagnostic tests routinely collected at primary health care facilities. No artemisinin resistance-associated kelch13 mutations nor amplification of the mdr1 gene copy number associated with lumefantrine resistance were observed. However, prevalence of both the mdr86N and crt76K alleles increased markedly over the study period, with all isolates collected in 2018 carrying these markers. SP quintuple mutation prevalence increased steadily from 14% in 2001 to 96% in 2018. Mixed alleles at any of the codons assessed were rare by 2018. Conclusion No kelch13 mutations confirmed or suspected to be associated with artemisinin resistance were identified in 2018. Although parasites carrying the mdr86N and crt76K alleles associated with reduced lumefantrine susceptibility were strongly selected for over the study period, nearing fixation by 2018, the marker for lumefantrine resistance, namely increased mdr1 copy number, was not observed in this study. The increase in mdr86N and crt76K allele prevalence together with intense regional artemether–lumefantrine drug pressure, raises concern regarding the sustained artemether–lumefantrine efficacy. Regular, rigorous anti-malarial resistance marker surveillance across all three South African malaria-endemic provinces to inform case management is recommended.
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    Efficacy of sulphadoxine-pyrimethamine with or without artesunate for the treatment of uncomplicated Plasmodium falciparum malaria in southern Mozambique: a randomized controlled trial
    (BioMed Central Ltd, 2009) Allen, Elizabeth N; Little, Francesca; Camba, Tunisio; Cassam, Yasmin; Raman, Jaishree; Boulle, Andrew; Barnes, Karen I
    BACKGROUND: An artemisinin-based combination therapy, artesunate (AS) plus sulphadoxine-pyrimethamine (SP), was compared to SP monotherapy to provide evidence of further treatment options in southern Mozambique. METHODS: Between 2003 and 2005, 411 patients over one year and 10 kg with uncomplicated Plasmodium falciparum malaria were randomly allocated SP (25/1.25 mg per kg day 0) or AS/SP (as above plus 4 mg/kg artesunate days 0, 1 and 2). Allocation was concealed, but treatment was open-label except to microscopists. The primary objective was the relative risk of treatment failure, which was assessed using World Health Organization response definitions modified to a 42-day follow-up. RESULTS: Of the 411 subjects enrolled, 359 (87.3%) completed the follow up period (SP n = 175, AS/SP n = 184). A survival analysis including 408 subjects showed that the polymerase chain reaction-adjusted cure rates were 90.4% (95% confidence interval [CI] 84.9%-93.9%) and 98.0% (95% CI 94.8%-99.3%) for SP and AS/SP respectively. Multivariable analysis showed that treatment with AS/SP decreased the relative hazard of treatment failure by 80% compared to SP (hazard ratio [HR] 0.2; 95% CI 0.1-0.6) and age over seven years decreased the relative hazard of failure by 70% (HR 0.3; 95% CI 0.1-0.9), when compared to younger age. However, having a quintuple dhfr/dhps mutation increased the relative hazard of failure compared to fewer mutations (HR 3.2; 95% CI 1.3-7.5) and baseline axillary temperature increased the relative hazard of failure by 50% for each degreesC increase (HR 1.5; 95% CI 1.1-2.2). CONCLUSION: While both treatments were efficacious, AS plus SP significantly decreased the relative hazard of treatment failure compared to SP monotherapy Artesunate plus sulphadoxine-pyrimethamine, but not sulphadoxine-pyrimethamine monotherapy, met the current WHO criteria of >95% efficacy for policy implementation.TRIAL REGISTRATION:NCT00203736 and NCT00203814
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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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    Safety and tolerability of single low-dose primaquine in a low-intensity transmission area in South Africa: an open-label, randomized controlled trial
    (2019-06-24) Raman, Jaishree; Allen, Elizabeth; Workman, Lesley; Mabuza, Aaron; Swanepoel, Hendrik; Malatje, Gillian; Frean, John; Wiesner, Lubbe; Barnes, Karen I
    Abstract Background To reduce onward falciparum malaria transmission, the World Health Organization recommends adding single low-dose (SLD) primaquine to artemisinin-based combination treatment in low transmission areas. However, uptake of this recommendation has been relatively slow given concerns about whether individual risks justify potential community benefit. This study was undertaken to generate comprehensive local data on the risk–benefit profile of SLD primaquine deployment in a pre-elimination area in South Africa. Methods This randomized, controlled open-label trial investigated adding a single low primaquine dose on day 3 to standard artemether–lumefantrine treatment for uncomplicated falciparum malaria. Efficacy, safety and tolerability of artemether–lumefantrine and primaquine treatment were assessed on days 3, 7, 14, 28 and 42. Lumefantrine concentrations were assayed from dried blood spot samples collected on day 7. Results Of 217 patients screened, 166 were enrolled with 140 randomized on day 3, 70 to each study arm (primaquine and no primaquine). No gametocytes were detected by either microscopy or PCR in any of the follow-up samples collected after randomization on day 3, precluding assessment of primaquine efficacy. Prevalence of the CYP2D6*4, CYP2D6*10 and CYP2D6*17 mutant alleles was low with allelic frequencies of 0.02, 0.11 and 0.16, respectively; none had the CYP2D6*4/*4 variant associated with null activity. Among 172 RDT-positive patients G6PD-genotyped, 24 (14%) carried the G6PD deficient (A−) variant. Median haemoglobin concentrations were similar between treatment arms throughout follow-up. A third of participants had a haemoglobin drop > 2 g/dL; this was not associated with primaquine treatment but may be associated with G6PD genotype [52.9% (9/17) with A− genotype vs. 31% (36/116) with other genotypes (p = 0.075)]. Day 7 lumefantrine concentrations and the number and nature of adverse events were similar between study arms; only one serious adverse event occurred (renal impairment in the no primaquine arm). The artemether–lumefantrine PCR-corrected adequate clinical and parasitological response rate was 100%, with only one re-infection found among the 128 patients who completed 42-day follow-up. Conclusions Safety, tolerability, CYP2D6 and G6PD variant data from this study support the deployment of the WHO-recommended SLD primaquine without G6PD testing to advance malaria elimination in South African districts with low-intensity residual transmission. Trial registration Pan African Clinical Trial Registry, PACTR201611001859416. Registered 11 November 2016, https://pactr.samrc.ac.za/TrialDisplay.aspx?TrialID=1859