• Needs and Challenges in Modelling Malaria for Emergency Contexts

      Boëte, C; Guardiola, M; Lasry, E; Burza, S; Moriana, S; Robertson, W (Elsevier, 2020-05-29)
      While modelling is an essential component for an understanding of the epidemiology of malaria, and for designing better control measures, it rarely considers the particular contexts encountered in emergency settings. By linking these situations with the transmission parameters our aim is to correct this bias and call for a better collaboration between relief actors.
    • Novel Approaches to Control Malaria in Forested Areas of Southeast Asia.

      von Seidlein, L; Peto, TJ; Tripura, R; Pell, C; Yeung, S; Kindermans, JM; Dondorp, A; Maude, R (Elsevier, 2019-05-07)
      The emergence and spread of drug resistance in the Greater Mekong Subregion (GMS) have added urgency to accelerate malaria elimination while reducing the treatment options. The remaining foci of malaria transmission are often in forests, where vectors tend to bite during daytime and outdoors, thus reducing the effectiveness of insecticide-treated bed nets. Limited periods of exposure suggest that chemoprophylaxis could be a promising strategy to protect forest workers against malaria. Here we discuss three major questions in optimizing malaria chemoprophylaxis for forest workers: which antimalarial drug regimens are most appropriate, how frequently the chemoprophylaxis should be delivered, and how to motivate forest workers to use, and adhere to, malaria prophylaxis.
    • Operational response to malaria epidemics: are rapid diagnostic tests cost-effective?

      Rolland, E; Checchi, F; Pinoges, L; Balkan, S; Guthmann, J P; Guerin, P J; Epicentre, Paris, France. (Wiley-Blackwell, 2006-04)
      OBJECTIVE: To compare the cost-effectiveness of malaria treatment based on presumptive diagnosis with that of malaria treatment based on rapid diagnostic tests (RDTs). METHODS: We calculated direct costs (based on experience from Ethiopia and southern Sudan) and effectiveness (in terms of reduced over-treatment) of a free, decentralised treatment programme using artesunate plus amodiaquine (AS + AQ) or artemether-lumefantrine (ART-LUM) in a Plasmodium falciparum epidemic. Our main cost-effectiveness measure was the incremental cost per false positive treatment averted by RDTs. RESULTS: As malaria prevalence increases, the difference in cost between presumptive and RDT-based treatment rises. The threshold prevalence above which the RDT-based strategy becomes more expensive is 21% in the AS + AQ scenario and 55% in the ART-LUM scenario, but these thresholds increase to 58 and 70%, respectively, if the financing body tolerates an incremental cost of 1 euro per false positive averted. However, even at a high (90%) prevalence of malaria consistent with an epidemic peak, an RDT-based strategy would only cost moderately more than the presumptive strategy: +29.9% in the AS + AQ scenario and +19.4% in the ART-LUM scenario. The treatment comparison is insensitive to the age and pregnancy distribution of febrile cases, but is strongly affected by variation in non-biomedical costs. If their unit price were halved, RDTs would be more cost-effective at a malaria prevalence up to 45% in case of AS + AQ treatment and at a prevalence up to 68% in case of ART-LUM treatment. CONCLUSION: In most epidemic prevalence scenarios, RDTs would considerably reduce over-treatment for only a moderate increase in costs over presumptive diagnosis. A substantial decrease in RDT unit price would greatly increase their cost-effectiveness, and should thus be advocated. A tolerated incremental cost of 1 euro is probably justified given overall public health and financial benefits. The RDTs should be considered for malaria epidemics if logistics and human resources allow.
    • Optimal Health and Disease Management Using Spatial Uncertainty: A Geographic Characterization of Emergent Artemisinin-Resistant Plasmodium Falciparum Distributions in Southeast Asia

      Grist, EPM; Flegg, JA; Humphreys, G; Mas, IS; Anderson, TJC; Ashley, EA; Day, NPJ; Dhorda, M; Dondorp, AM; Faiz, MA; et al. (BioMed Central, 2016-10-24)
      Artemisinin-resistant Plasmodium falciparum malaria parasites are now present across much of mainland Southeast Asia, where ongoing surveys are measuring and mapping their spatial distribution. These efforts require substantial resources. Here we propose a generic 'smart surveillance' methodology to identify optimal candidate sites for future sampling and thus map the distribution of artemisinin resistance most efficiently.
    • An Optimised Age-Based Dosing Regimen for Single Low-Dose Primaquine For Blocking Malaria Transmission in Cambodia

      Leang, R; Khu, NH; Mukaka, M; Debackere, M; Tripura, R; Kheang, ST; Chy, S; Kak, N; Buchy, P; Tarantola, A; et al. (BioMed Central, 2016-10-27)
      In 2012, the World Health Organization recommended the addition of single low-dose primaquine (SLDPQ, 0.25 mg base/kg body weight) to artemisinin combination therapies to block the transmission of Plasmodium falciparum without testing for glucose-6-phosphate dehydrogenase deficiency. The targeted group was non-pregnant patients aged ≥ 1 year (later changed to ≥ 6 months) with acute uncomplicated falciparum malaria, primarily in countries with artemisinin-resistant P. falciparum (ARPf). No dosing regimen was suggested, leaving malaria control programmes and clinicians in limbo. Therefore, we designed a user-friendly, age-based SLDPQ regimen for Cambodia, the country most affected by ARPf.
    • Paracheck-Pf accuracy and recently treated Plasmodium falciparum infections: is there a risk of over-diagnosis?

      Swarthout, T D; Counihan, H; Senga, R K K; van den Broek, I; Médecins Sans Frontières, London, UK. toddswarth@yahoo.com (Elsevier, 2007)
      BACKGROUND: An assessment of the accuracy of Paracheck Pf, a malaria rapid diagnostic test (RDT) detecting histidine rich protein 2 was undertaken amongst children aged 6-59 months in eastern Democratic Republic of Congo. METHODS: This RDT assessment occurred in conjunction with an ACT efficacy trial. Febrile children were simultaneously screened with both RDT and high quality microscopy and those meeting inclusion criteria were followed for 35 days. RESULTS: 358 febrile children were screened with 180 children recruited for five weeks follow-up. On screening, the RDT accurately diagnosed all 235 true malaria cases, indicating 100% RDT sensitivity. Of the 123 negative slides, the RDT gave 59 false-positive results, indicating 52.0% (64/123) RDT specificity. During follow-up after treatment with an artemisinin-based combination therapy, 98.2% (110/112), 94.6% (106/112), 92.0% (103/112) and 73.5% (50/68) of effectively treated children were still false-positive by RDT at days 14, 21, 28 and 35, respectively. CONCLUSION: Results show that though the use of Paracheck-Pf is as sensitive as microscopy in detecting true malaria cases, a low specificity did present a high frequency of false-positive RDT results. What's more, a duration of RDT false-positivity was found that significantly surpassed the 'fortnight' after effective treatment reported by its manufacturer. Though further research is needed in assessing RDT accuracy, study results showing the presence of frequent false positivity should be taken into consideration to avoid clinicians inappropriately focusing on malaria, not identifying the true cause of illness, and providing unnecessary treatment.
    • Performance and Time to Become Negative After Treatment of Three Malaria Rapid Diagnostic Tests in Low and High Malaria Transmission Settings

      Grandesso, F; Nabasumba, C; Nyehangane, D; Page, AL; Bastard, M; De Smet, M; Boum, Y; Etard, JF (BioMed Central, 2016-10-04)
      The performance of different malaria rapid diagnostic tests (RDT) may be influenced by transmission intensity and by the length of time each test requires to become negative after treatment and patient's recovery.
    • Performance of a Histidine-Rich Protein 2 Rapid Diagnostic Test, Paracheck Pf(R), for Detection of Malaria Infections in Ugandan Pregnant Women.

      Dhorda, Mehul; Piola, Patrice; Nyehangane, Dan; Tumwebaze, Benon; Nalusaji, Aisha; Nabasumba, Carolyn; Turyakira, Eleanor; McGready, Rose; Ashley, Elizabeth; Guerin, Philippe J; et al. (Am.J.trop.Med.Hyg., 2012-01-01)
      Abstract. Improved laboratory diagnosis is critical to reduce the burden of malaria in pregnancy. Peripheral blood smears appear less sensitive than Plasmodium falciparum histidine-rich protein 2-based rapid diagnostic tests (RDTs) for placental malaria infections in studies conducted at delivery. In this study, 81 women in Uganda in the second or third trimester of pregnancy were followed-up until delivery. At each visit, peripheral blood was tested by blood smear, RDT, and nested species-specific polymerase chain reaction (PCR). Sensitivity and specificity of the tests was calculated with PCR, which detected 22 infections of P. falciparum, as the gold standard. The sensitivity and specificity of blood smears were 36.4% (95% confidence interval [CI] = 18.0-59.2%) and 99.6% (95% CI = 97.7-100%), respectively. The corresponding values for RDT were 31.8% (95% CI = 14.7-54.9%) and 100% (95% CI = 98.3-100%). The RDTs could replace blood smears for diagnosis of malaria in pregnancy by virtue of their relative ease of use. Field-based sensitive tests for malaria in pregnancy are urgently needed.
    • Plasmodium falciparum: sensitivity in vivo to chloroquine, pyrimethamine/sulfadoxine and mefloquine in western Myanmar.

      Smithuis, F; Monti, F; Grundl, M; Oo, A Z; Kyaw, T T; Phe, O; White, N J; Artsen Zonder Grenzen, Médecins Sans Frontières-Holland, Yangon, Myanmar, Thailand. (Elsevier, 2008-02-07)
      In Rakhine State, on the western border of Myanmar, the efficacy of chloroquine (CQ) and pyrimethamine/ sulfadoxine (PS), the current treatments for uncomplicated Plasmodium falciparum malaria in this area, was evaluated in an open comparative study of 289 patients, stratified prospectively into 3 age groups. Chloroquine treatment was associated with more rapid clinical recovery (P = 0.03), but the overall cure rates were worse than for PS treatment; failure to clear parasitaemia or recrudescence within 14 d occurred in 72% (102/141) of cases treated with CQ compared to 47% (69/148) of those who received PS (P < 0.0001, adjusted for age). Failure rates at day 28 increased to 82% (116/141) in the CQ group and 67% (99/148) in the PS group (P = 0.003). The risk of treatment failure was significantly higher in children under 15 years old than in adults for both CQ (relative risk [RR] = 2.6; 95% confidence interval [95% CI] 1.3-5.2) and PS (RR = 2.2; 95% CI 1.4-3.3). Mefloquine (15 mg base/kg) proved to be highly effective as a treatment for CQ and PS resistant P. falciparum; only 2 of 75 patients (3%) had early treatment failures (< or = day 7), and the overall failure rate by day 42 was 7%. There is a very high level of chloroquine and PS resistance in P.falciparum on the western border of Myanmar, but mefloquine was effective in the area.
    • Plasmodium prevalence and artemisinin-resistant falciparum malaria in Preah Vihear Province, Cambodia: a cross-sectional population-based study

      Bosman, Philippe; Stassijns, Jorgen; Nackers, Fabienne; Canier, Lydie; Kim, Nimol; Khim, Saorin; Alipon, Sweet C; Chuor Char, Meng; Chea, Nguon; Dysoley, Lek; et al. (BioMed Central, 2014-10-06)
      Intensified efforts are urgently needed to contain and eliminate artemisinin-resistant Plasmodium falciparum in the Greater Mekong subregion. Medecins Sans Frontieres plans to support the Ministry of Health in eliminating P. falciparum in an area with artemisinin resistance in the north-east of Cambodia. As a first step, the prevalence of Plasmodium spp. and the presence of mutations associated with artemisinin resistance were evaluated in two districts of Preah Vihear Province.
    • Plasmodium vivax resistance to chloroquine in Dawei, southern Myanmar.

      Guthmann, J P; Pittet, A; Lesage, A; Imwong, M; Lindegardh, N; Min Lwin, M; Zaw, T; Annerberg, A; de Radiguès, X; Nosten, F; et al. (Wiley-Blackwell, 2008-01)
      OBJECTIVE: To assess the efficacy of chloroquine in the treatment of Plasmodium vivax malaria in in Dawei District, southern Myanmar. METHODS: Enrolled patients at Sonsinphya clinic >6 months of age were assessed clinically and parasitologically every week for 28 days. To differentiate new infections from recrudescence, we genotyped pre- and post-treatment parasitaemia. Blood chloroquine was measured to confirm resistant strains. RESULTS: Between December 2002 and April 2003, 2661 patients were screened, of whom 252 were included and 235 analysed. Thirty-four per cent (95% CI: 28.1-40.6) of patients had recurrent parasitaemia and were considered treatment failures. 59.4% of these recurrences were with a different parasite strain. Two (0.8%) patients with recurrences on day 14 had chloroquine concentrations above the threshold of 100 ng/ml and were considered infected with chloroquine resistant parasites. 21% of failures occurred during the first 3 weeks of follow-up: early recurrence and median levels of blood chloroquine comparable to those of controls suggested P. vivax resistance. CONCLUSIONS: Plasmodium vivax resistance to chloroquine seems to be emerging in Dawei, near the Thai-Burmese border. While chloroquine remains the first-line drug for P. vivax infections in this area of Myanmar, regular monitoring is needed to detect further development of parasite resistance.
    • Polymorphisms in Plasmodium falciparum Chloroquine Resistance Transporter and Multidrug Resistance 1 Genes: Parasite Risk Factors that Affect Treatment Outcomes for P. falciparum Malaria after Artemether-Lumefantrine and Artesunate-Amodiaquine

      Venkatesan, Meera; Gadalla, Nahla B; Stepniewska, Kasia; Dahal, Prabin; Nsanzabana, Christian; Moriera, Clarissa; Price, Ric N; Mårtensson, Andreas; Rosenthal, Philip J; Dorsey, Grant; et al. (2014-07-21)
      Adequate clinical and parasitologic cure by artemisinin combination therapies relies on the artemisinin component and the partner drug. Polymorphisms in the Plasmodium falciparum chloroquine resistance transporter (pfcrt) and P. falciparum multidrug resistance 1 (pfmdr1) genes are associated with decreased sensitivity to amodiaquine and lumefantrine, but effects of these polymorphisms on therapeutic responses to artesunate-amodiaquine (ASAQ) and artemether-lumefantrine (AL) have not been clearly defined. Individual patient data from 31 clinical trials were harmonized and pooled by using standardized methods from the WorldWide Antimalarial Resistance Network. Data for more than 7,000 patients were analyzed to assess relationships between parasite polymorphisms in pfcrt and pfmdr1 and clinically relevant outcomes after treatment with AL or ASAQ. Presence of the pfmdr1 gene N86 (adjusted hazards ratio = 4.74, 95% confidence interval = 2.29 - 9.78, P < 0.001) and increased pfmdr1 copy number (adjusted hazards ratio = 6.52, 95% confidence interval = 2.36-17.97, P < 0.001: were significant independent risk factors for recrudescence in patients treated with AL. AL and ASAQ exerted opposing selective effects on single-nucleotide polymorphisms in pfcrt and pfmdr1. Monitoring selection and responding to emerging signs of drug resistance are critical tools for preserving efficacy of artemisinin combination therapies; determination of the prevalence of at least pfcrt K76T and pfmdr1 N86Y should now be routine.
    • Population Pharmacokinetics of Lumefantrine in Pregnant and Nonpregnant Women With Uncomplicated Plasmodium falciparum Malaria in Uganda

      Kloprogge, F; Piola, P; Dhorda, M; Muwanga, S; Turyakira, E; Apinan, S; Lindegårdh, N; Nosten, F; Day, N P J; White, N J; et al. (2013)
      Pregnancy alters the pharmacokinetic properties of many antimalarial compounds. The objective of this study was to evaluate the pharmacokinetic properties of lumefantrine in pregnant and nonpregnant women with uncomplicated Plasmodium falciparum malaria in Uganda after a standard fixed oral artemether-lumefantrine treatment. Dense venous (n = 26) and sparse capillary (n = 90) lumefantrine samples were drawn from pregnant patients. A total of 17 nonpregnant women contributed with dense venous lumefantrine samples. Lumefantrine pharmacokinetics was best described by a flexible absorption model with multiphasic disposition. Pregnancy and body temperature had a significant impact on the pharmacokinetic properties of lumefantrine. Simulations from the final model indicated 27% lower day 7 concentrations in pregnant women compared with nonpregnant women and a decreased median time of 0.92 and 0.42 days above previously defined critical concentration cutoff values (280 and 175 ng/ml, respectively). The standard artemether-lumefantrine dose regimen in P. falciparum malaria may need reevaluation in nonimmune pregnant women.CPT: Pharmacometrics & Systems Pharmacology (2013) 2, e83; doi:10.1038/psp.2013.59; advance online publication 13 November 2013.
    • Population Pharmacokinetics of Piperaquine after Two Different Treatment Regimens with Dihydroartemisinin-Piperaquine in Patients with Plasmodium falciparum Malaria in Thailand.

      Tarning, J; Ashley, E A; Lindegardh, N; Stepniewska, K; Phaiphun, L; Day, N P J; McGready, R; Ashton, M; Nosten, F; White, N J; et al. (American Society for Microbiology, 2008-03)
      The population pharmacokinetics of piperaquine in adults and children with uncomplicated Plasmodium falciparum malaria treated with two different dosage regimens of dihydroartemisinin-piperaquine were characterized. Piperaquine pharmacokinetics in 98 Burmese and Karen patients aged 3 to 55 years were described by a two-compartment disposition model with first-order absorption and interindividual random variability on all parameters and were similar with the three- and four-dose regimens. Children had a lower body weight-normalized oral clearance than adults, resulting in longer terminal elimination half-lives and higher total exposure to piperaquine (area under the concentration-time curve from 0 to 63 days [AUC(day 0-63)]). However, children had lower plasma concentrations in the therapeutically relevant posttreatment prophylactic period (AUC(day 3-20)) because of smaller body weight-normalized central volumes of distribution and shorter distribution half-lives. Our data lend further support to a simplified once-daily treatment regimen to improve treatment adherence and efficacy and indicate that weight-adjusted piperaquine doses in children may need to be higher than in adults.
    • Predictors of the Quality of Health Worker Treatment Practices for Uncomplicated Malaria at Government Health Facilities in Kenya.

      Zurovac, D; Rowe, A K; Ochola, S A; Noor, A M; Midia, B; English, M; Snow, R W; Médecins Sans Frontières-France, P.O. Box 39719, Nairobi, Kenya. dzurovac@wtnairobi.mimcom.net (Published by Oxford University Press, 2004-10)
      BACKGROUND: When replacing failing drugs for malaria with more effective drugs, an important step towards reducing the malaria burden is that health workers (HW) prescribe drugs according to evidence-based guidelines. Past studies have shown that HW commonly do not follow guidelines, yet few studies have explored with appropriate methods why such practices occur. METHODS: We analysed data from a survey of government health facilities in four Kenyan districts in which HW consultations were observed, caretakers and HW were interviewed, and health facility assessments were performed. The analysis was limited to children 2-59 months old with uncomplicated malaria. Treatment was defined as recommended (antimalarial recommended by national guidelines), a minor error (effective, but non-recommended antimalarial), or inappropriate (no effective antimalarial). RESULTS: We evaluated 1006 consultations performed by 135 HW at 81 facilities: 567 children received recommended treatment, 314 had minor errors, and 125 received inappropriate treatment (weighted percentages: 56.9%, 30.4%, and 12.7%). Multivariate logistic regression analysis revealed that programmatic interventions such as in-service malaria training, provision of guidelines and wall charts, and more frequent supervision were significantly associated with better treatment quality. However, neither in-service training nor possession of the guideline document showed an effect by itself. More qualified HW made more errors: both major and minor errors (but generally more minor errors) when second-line drugs were in stock, and more major errors when second-line drugs were not in stock. Child factors such as age and a main complaint of fever were also associated with treatment quality. CONCLUSIONS: Our results support the use of several programmatic strategies that can redress HW deficiencies in malaria treatment. Targeted cost-effectiveness trials would help refine these strategies and provide more precise guidance on affordable and effective ways to strengthen and maintain HW practices.
    • Prevalence and Diagnostics of Congenital Malaria in Rural Burundi, a Cross-Sectional Study

      Stassijns, J; van den Boogaard, W; Pannus, P; Nkunzimana, A; Rosanas-Urgell, A (BioMed Central, 2016-08-30)
      Congenital malaria, defined as the presence of asexual forms of malaria parasites in the peripheral blood during the first 7 days of life, remains a neglected area of research. Knowledge gaps exist about prevalence and management of malaria in this age group. The objective of this study was to evaluate the prevalence of congenital malaria and the validity of a rapid diagnostic test (RDT) for its diagnosis in rural Burundi.
    • Prevalence of malaria and anemia among pregnant women residing in malaria-endemic forest villages in India

      Qureshi, Ihtesham Aatif; Arlappa, Nimmathota; Qureshi, Mohtashim Arbaab (Elsevier, 2014-07-19)
    • Prevalence of malaria infection among under five year tribal children residing in malaria endemic forest villages

      Qureshi, Ihtesham; Qureshi, Mohtashim; Gudepu, Rohit; Arlappa, Nimmathota (F1000Research, 2014-11-20)
    • A randomized open study to assess the efficacy and tolerability of dihydroartemisinin-piperaquine for the treatment of uncomplicated falciparum malaria in Cambodia.

      Janssens, B; Van Herp, M; Goubert, L; Chan, S; Uong, S; Nong, S; Socheat, D; Brockman, A; Ashley, E A; Van Damme, W; et al. (Wiley-Blackwell, 2007-02)
      OBJECTIVES: To compare the efficacy and tolerability of dihydroartemisinin-piperaquine (DHA-PQP) with that of a 3-day regimen of mefloquine and artesunate (MAS3) for the treatment of uncomplicated falciparum malaria in Cambodia. METHOD: Randomized open-label non-inferiority study over 64 days. RESULTS: Four hundred and sixty-four patients were included in the study. The polymerase chain reaction genotyping-adjusted cure rates on day 63 were 97.5% (95% confidence interval, CI, 93.8-99.3) for DHA-PQP and 97.5% (95% CI, 93.8-99.3) for MAS3, P = 1. There were no serious adverse events, but significantly more episodes of vomiting (P = 0.03), dizziness (P = 0.002), palpitations (P = 0.04), and sleep disorders (P = 0.03) reported in the MAS3 treatment group, consistent with the side-effect profile of mefloquine. CONCLUSIONS: DHA-PQP was as efficacious as MAS3, but much better tolerated, making it more appropriate for use in a routine programme setting. This highly efficacious, safe and more affordable fixed-dose combination could become the treatment of choice for Plasmodium falciparum malaria in Cambodia.