Last data update: Nov 11, 2024. (Total: 48109 publications since 2009)
Records 1-30 (of 46 Records) |
Query Trace: Halsey ES[original query] |
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Trends of Plasmodium falciparum molecular markers associated with resistance to artemisinins and reduced susceptibility to lumefantrine in Mainland Tanzania from 2016 to 2021
Bakari C , Mandara CI , Madebe RA , Seth MD , Ngasala B , Kamugisha E , Ahmed M , Francis F , Bushukatale S , Chiduo M , Makene T , Kabanywanyi AM , Mahende MK , Kavishe RA , Muro F , Mkude S , Mandike R , Molteni F , Chacky F , Bishanga DR , Njau RJA , Warsame M , Kabula B , Nyinondi SS , Lucchi NW , Talundzic E , Venkatesan M , Moriarty LF , Serbantez N , Kitojo C , Reaves EJ , Halsey ES , Mohamed A , Udhayakumar V , Ishengoma DS . Malar J 2024 23 (1) 71 BACKGROUND: Therapeutic efficacy studies (TESs) and detection of molecular markers of drug resistance are recommended by the World Health Organization (WHO) to monitor the efficacy of artemisinin-based combination therapy (ACT). This study assessed the trends of molecular markers of artemisinin resistance and/or reduced susceptibility to lumefantrine using samples collected in TES conducted in Mainland Tanzania from 2016 to 2021. METHODS: A total of 2,015 samples were collected during TES of artemether-lumefantrine at eight sentinel sites (in Kigoma, Mbeya, Morogoro, Mtwara, Mwanza, Pwani, Tabora, and Tanga regions) between 2016 and 2021. Photo-induced electron transfer polymerase chain reaction (PET-PCR) was used to confirm presence of malaria parasites before capillary sequencing, which targeted two genes: Plasmodium falciparum kelch 13 propeller domain (k13) and P. falciparum multidrug resistance 1 (pfmdr1). RESULTS: Sequencing success was ≥ 87.8%, and 1,724/1,769 (97.5%) k13 wild-type samples were detected. Thirty-seven (2.1%) samples had synonymous mutations and only eight (0.4%) had non-synonymous mutations in the k13 gene; seven of these were not validated by the WHO as molecular markers of resistance. One sample from Morogoro in 2020 had a k13 R622I mutation, which is a validated marker of artemisinin partial resistance. For pfmdr1, all except two samples carried N86 (wild-type), while mutations at Y184F increased from 33.9% in 2016 to about 60.5% in 2021, and only four samples (0.2%) had D1246Y mutations. pfmdr1 haplotypes were reported in 1,711 samples, with 985 (57.6%) NYD, 720 (42.1%) NFD, and six (0.4%) carrying minor haplotypes (three with NYY, 0.2%; YFD in two, 0.1%; and NFY in one sample, 0.1%). Between 2016 and 2021, NYD decreased from 66.1% to 45.2%, while NFD increased from 38.5% to 54.7%. CONCLUSION: This is the first report of the R622I (k13 validated mutation) in Tanzania. N86 and D1246 were nearly fixed, while increases in Y184F mutations and NFD haplotype were observed between 2016 and 2021. Despite the reports of artemisinin partial resistance in Rwanda and Uganda, this study did not report any other validated mutations in these study sites in Tanzania apart from R622I suggesting that intensified surveillance is urgently needed to monitor trends of drug resistance markers and their impact on the performance of ACT. |
Out of Africa: increasing reports of artemether-lumefantrine treatment failures of uncomplicated plasmodium falciparum infection
Halsey ES , Plucinski MM . J Travel Med 2023 30 (8) The introduction of artemisinin-based combination therapies (ACTs) to treat Plasmodium falciparum infection in the early 2000s provided relief against the growing ineffectiveness of formerly dependable treatments such as chloroquine and sulfadoxine-pyrimethamine. Since then, six ACTs have been added to the World Health Organization’s list of recommended treatments for uncomplicated P. falciparum infection (Box 1). Of those six, artemether-lumefantrine (AL) is the most widely used, accounting for up to 85% of all ACTs procured by large donors for sub-Saharan Africa1 and is at the greatest threat of losing efficacy. Just as a traveller returning to the USA from Tanzania provided the first confirmation of high-grade chloroquine resistance in Africa in the 1970s,2 once again travellers may be offering a unique glimpse of an antimalarial’s worsening efficacy. |
STARTER checklist for antimalarial therapeutic efficacy reporting
Plucinski MM , Ashley EA , Bassat Q , Venkatesan M , Rosenthal PJ , Halsey ES . Malar J 2022 21 (1) 187 Efficacious antimalarials are a cornerstone of the global effort to control and eliminate malaria. However, the spread of drug resistance threatens gains achieved over the early years of this century. Of particular concern is widespread artemisinin resistance in Southeast Asia and its recent emergence in Africa, threatening the efficacy of artemisinin-based combination therapies that currently offer our best treatments for malaria [1]. Prompt identification of the emergence and spread of antimalarial drug resistance is crucial to guarantee effective case management. At a country level, efficacy data are used by ministries of health and their partners to determine national treatment guidelines. Because parasites do not respect political and administrative boundaries, coordination of surveillance and control strategies at the regional and global level is necessary to guide larger containment strategies. |
Plasmodium falciparum pfhrp2 and pfhrp3 gene deletions from persons with symptomatic malaria infection in Ethiopia, Kenya, Madagascar, and Rwanda
Rogier E , McCaffery JN , Nace D , Svigel SS , Assefa A , Hwang J , Kariuki S , Samuels AM , Westercamp N , Ratsimbasoa A , Randrianarivelojosia M , Uwimana A , Udhayakumar V , Halsey ES . Emerg Infect Dis 2022 28 (3) 608-616 Histidine-rich protein 2 (HRP2)-based rapid diagnostic tests detect Plasmodium falciparum malaria and are used throughout sub-Saharan Africa. However, deletions in the pfhrp2 and related pfhrp3 (pfhrp2/3) genes threaten use of these tests. Therapeutic efficacy studies (TESs) enroll persons with symptomatic P. falciparum infection. We screened TES samples collected during 2016-2018 in Ethiopia, Kenya, Rwanda, and Madagascar for HRP2/3, pan-Plasmodium lactate dehydrogenase, and pan-Plasmodium aldolase antigen levels and selected samples with low levels of HRP2/3 for pfhrp2/3 genotyping. We observed deletion of pfhrp3 in samples from all countries except Kenya. Single-gene deletions in pfhrp2 were observed in 1.4% (95% CI 0.2%-4.8%) of Ethiopia samples and in 0.6% (95% CI 0.2%-1.6%) of Madagascar samples, and dual pfhrp2/3 deletions were noted in 2.0% (95% CI 0.4%-5.9%) of Ethiopia samples. Although this study was not powered for precise prevalence estimates, evaluating TES samples revealed a low prevalence of pfhrp2/3 deletions in most sites. |
Symptomatic plasmodium vivax infection in Rwanda
McCaffery JN , Munyaneza T , Uwimana A , Nace D , Lucchi N , Halsey ES , Rogier E . Open Forum Infect Dis 2022 9 (3) ofac025 We report a Plasmodium vivax infection in a Rwandan child misdiagnosed with Plasmodium falciparum and administered artemether-lumefantrine. Antigen detection revealed an absence of P falciparum histidine-rich protein 2 (HRP2) and presence of Plasmodium vivax lactate dehydrogenase. Nested and real-time polymerase chain reactions verified that the sample only contained P vivax deoxyribonucleic acid. |
Efficacy and safety of artemether-lumefantrine and dihydroartemisinin-piperaquine for the treatment of uncomplicated Plasmodium falciparum malaria and prevalence of molecular markers associated with artemisinin and partner drug resistance in Uganda.
Ebong C , Sserwanga A , Namuganga JF , Kapisi J , Mpimbaza A , Gonahasa S , Asua V , Gudoi S , Kigozi R , Tibenderana J , Bwanika JB , Bosco A , Rubahika D , Kyabayinze D , Opigo J , Rutazana D , Sebikaari G , Belay K , Niang M , Halsey ES , Moriarty LF , Lucchi NW , Souza SSS , Nsobya SL , Kamya MR , Yeka A . Malar J 2021 20 (1) 484 BACKGROUND: In Uganda, artemether-lumefantrine (AL) is first-line therapy and dihydroartemisinin-piperaquine (DP) second-line therapy for the treatment of uncomplicated malaria. This study evaluated the efficacy and safety of AL and DP in the management of uncomplicated falciparum malaria and measured the prevalence of molecular markers of resistance in three sentinel sites in Uganda from 2018 to 2019. METHODS: This was a randomized, open-label, phase IV clinical trial. Children aged 6 months to 10 years with uncomplicated falciparum malaria were randomly assigned to treatment with AL or DP and followed for 28 and 42 days, respectively. Genotyping was used to distinguish recrudescence from new infection, and a Bayesian algorithm was used to assign each treatment failure a posterior probability of recrudescence. For monitoring resistance, Pfk13 and Pfmdr1 genes were Sanger sequenced and plasmepsin-2 copy number was assessed by qPCR. RESULTS: There were no early treatment failures. The uncorrected 28-day cumulative efficacy of AL ranged from 41.2 to 71.2% and the PCR-corrected cumulative 28-day efficacy of AL ranged from 87.2 to 94.4%. The uncorrected 28-day cumulative efficacy of DP ranged from 95.8 to 97.9% and the PCR-corrected cumulative 28-day efficacy of DP ranged from 98.9 to 100%. The uncorrected 42-day efficacy of DP ranged from 73.5 to 87.4% and the PCR-corrected 42-day efficacy of DP ranged from 92.1 to 97.5%. There were no reported serious adverse events associated with any of the regimens. No resistance-associated mutations in the Pfk13 gene were found in the successfully sequenced samples. In the AL arm, the NFD haplotype (N86Y, Y184F, D1246Y) was the predominant Pfmdr1 haplotype, present in 78 of 127 (61%) and 76 of 110 (69%) of the day 0 and day of failure samples, respectively. All the day 0 samples in the DP arm had one copy of the plasmepsin-2 gene. CONCLUSIONS: DP remains highly effective and safe for the treatment of uncomplicated malaria in Uganda. Recurrent infections with AL were common. In Busia and Arua, the 95% confidence interval for PCR-corrected AL efficacy fell below 90%. Further efficacy monitoring for AL, including pharmacokinetic studies, is recommended. Trial registration The trail was also registered with the ISRCTN registry with study Trial No. PACTR201811640750761. |
Missed Plasmodium falciparum and Plasmodium vivax Mixed Infections in Ethiopia Threaten Malaria Elimination.
Leonard CM , Mohammed H , Tadesse M , McCaffery JN , Nace D , Halsey ES , Girma S , Assefa A , Hwang J , Rogier E . Am J Trop Med Hyg 2021 106 (2) 667-670 Plasmodium falciparum and Plasmodium vivax are co-endemic in Ethiopia. This study investigated whether mixed infections were missed by microscopy from a 2017 therapeutic efficacy study at two health facilities in Ethiopia. All patients (N = 304) were initially classified as having single-species P. falciparum (n = 148 samples) or P. vivax infections (n = 156). Dried blood spots were tested for Plasmodium antigens by bead-based multiplex assay for pan-Plasmodium aldolase, pan-Plasmodium lactate dehydrogenase, P. vivax lactate dehydrogenase, and histidine-rich protein 2. Of 304 blood samples, 13 (4.3%) contained both P. falciparum and P. vivax antigens and were analyzed by polymerase chain reaction for species-specific DNA. Of these 13 samples, five were confirmed by polymerase chain reaction for P. falciparum/P. vivax co-infection. One sample, initially classified as P. vivax by microscopy, was found to only have Plasmodium ovale DNA. Plasmodium falciparum/P. vivax mixed infections can be missed by microscopy even in the context of a therapeutic efficacy study with multiple trained readers. |
Plasmodium falciparum pfhrp2 and pfhrp3 gene deletions among patients in the DRC enrolled from 2017 to 2018.
McCaffery JN , Nace D , Herman C , Singh B , Sompwe EM , Nkoli PM , Ngoyi DM , Kahunu GM , Halsey ES , Rogier E . Sci Rep 2021 11 (1) 22979 Rapid diagnostic tests (RDTs) detecting histidine-rich protein 2 (HRP2) and HRP3 are widely used throughout sub-Saharan Africa (SSA) to diagnose Plasmodium falciparum malaria. However, multiple SSA countries have reported pfhrp2 and pfhrp3 (pfhrp2/3) gene deletions. Blood samples (n = 1109) collected from patients with P. falciparum infection from six health facilities throughout the Democratic Republic of the Congo (DRC) from March 2017 to January 2018 were evaluated for pfhrp2/3 deletions. Samples were assayed for HRP2, pan-Plasmodium LDH (pLDH) and aldolase (pAldolase) antigens by bead-based multiplex antigen assay. Samples with low HRP2 concentration compared to pLDH and pAldolase antigens were selected for further pfhrp2/3 genotyping PCRs. The majority of blood samples (93.3%, 1035/1109) had high concentrations of the HRP2 antigen. Single deletions of pfhrp2 were identified in 0.27% (3/1109) of screened samples, with one sample from each of the Kapolowe, Mikalayi, and Rutshuru study sites. A pfhrp3 single deletion (0.09%, 1/1109) was found in the Kapolowe site. Dual pfhrp2 and pfhrp3 deletions were not observed. Due to, the low numbers of pfhrp2 deletions and the sporadic locations of these deletions, the use of HRP2-based RDTs appears to still be appropriate for these locations in DRC. |
Efficacy of artesunate-amodiaquine and artemether-lumefantrine for uncomplicated Plasmodium falciparum malaria in Madagascar, 2018.
Dentinger CM , Rakotomanga TA , Rakotondrandriana A , Rakotoarisoa A , Rason MA , Moriarty LF , Steinhardt LC , Kapesa L , Razafindrakoto J , Svigel SS , Lucchi NW , Udhayakumar V , Halsey ES , Ratsimbasoa CA . Malar J 2021 20 (1) 432 BACKGROUND: Since 2005, artemisinin-based combination therapy (ACT) has been recommended to treat uncomplicated falciparum malaria in Madagascar. Artesunate-amodiaquine (ASAQ) and artemether-lumefantrine (AL) are the first- and second-line treatments, respectively. A therapeutic efficacy study was conducted to assess ACT efficacy and molecular markers of anti-malarial resistance. METHODS: Children aged six months to 14 years with uncomplicated falciparum malaria and a parasitaemia of 1000-100,000 parasites/µl determined by microscopy were enrolled from May-September 2018 in a 28-day in vivo trial using the 2009 World Health Organization protocol for monitoring anti-malarial efficacy. Participants from two communes, Ankazomborona (tropical, northwest) and Matanga (equatorial, southeast), were randomly assigned to ASAQ or AL arms at their respective sites. PCR correction was achieved by genotyping seven neutral microsatellites in paired pre- and post-treatment samples. Genotyping assays for molecular markers of resistance in the pfk13, pfcrt and pfmdr1 genes were conducted. RESULTS: Of 344 patients enrolled, 167/172 (97%) receiving ASAQ and 168/172 (98%) receiving AL completed the study. For ASAQ, the day-28 cumulative PCR-uncorrected efficacy was 100% (95% CI 100-100) and 95% (95% CI 91-100) for Ankazomborona and Matanga, respectively; for AL, it was 99% (95% CI 97-100) in Ankazomborona and 83% (95% CI 76-92) in Matanga. The day-28 cumulative PCR-corrected efficacy for ASAQ was 100% (95% CI 100-100) and 98% (95% CI 95-100) for Ankazomborona and Matanga, respectively; for AL, it was 100% (95% CI 99-100) in Ankazomborona and 95% (95% CI 91-100) in Matanga. Of 83 successfully sequenced samples for pfk13, no mutation associated with artemisinin resistance was observed. A majority of successfully sequenced samples for pfmdr1 carried either the NFD or NYD haplotypes corresponding to codons 86, 184 and 1246. Of 82 successfully sequenced samples for pfcrt, all were wild type at codons 72-76. CONCLUSION: PCR-corrected analysis indicated that ASAQ and AL have therapeutic efficacies above the 90% WHO acceptable cut-off. No genetic evidence of resistance to artemisinin was observed, which is consistent with the clinical outcome data. However, the most common pfmdr1 haplotypes were NYD and NFD, previously associated with tolerance to lumefantrine. |
Molecular surveillance for polymorphisms associated with artemisinin-based combination therapy resistance in Plasmodium falciparum isolates collected in Mozambique, 2018.
Chidimatembue A , Svigel SS , Mayor A , Aíde P , Nhama A , Nhamussua L , Nhacolo A , Bassat Q , Salvador C , Enosse S , Saifodine A , De Carvalho E , Candrinho B , Zulliger R , Goldman I , Udhayakumar V , Lucchi NW , Halsey ES , Macete E . Malar J 2021 20 (1) 398 BACKGROUND: Due to the threat of emerging anti-malarial resistance, the World Health Organization recommends incorporating surveillance for molecular markers of anti-malarial resistance into routine therapeutic efficacy studies (TESs). In 2018, a TES of artemether-lumefantrine (AL) and artesunate-amodiaquine (ASAQ) was conducted in Mozambique, and the prevalence of polymorphisms in the pfk13, pfcrt, and pfmdr1 genes associated with drug resistance was investigated. METHODS: Children aged 6-59 months were enrolled in four study sites. Blood was collected and dried on filter paper from participants who developed fever within 28 days of initial malaria treatment. All samples were first screened for Plasmodium falciparum using a multiplex real-time PCR assay, and polymorphisms in the pfk13, pfcrt, and pfmdr1 genes were investigated by Sanger sequencing. RESULTS: No pfk13 mutations, associated with artemisinin partial resistance, were observed. The only pfcrt haplotype observed was the wild type CVMNK (codons 72-76), associated with chloroquine sensitivity. Polymorphisms in pfmdr1 were only observed at codon 184, with the mutant 184F in 43/109 (39.4%) of the samples, wild type Y184 in 42/109 (38.5%), and mixed 184F/Y in 24/109 (22.0%). All samples possessed N86 and D1246 at these two codons. CONCLUSION: In 2018, no markers of artemisinin resistance were documented. Molecular surveillance should continue to monitor the prevalence of these markers to inform decisions on malaria treatment in Mozambique. |
In vivo efficacy and safety of artemether-lumefantrine and amodiaquine-artesunate for uncomplicated Plasmodium falciparum malaria in Mozambique, 2018.
Nhama A , Nhamússua L , Macete E , Bassat Q , Salvador C , Enosse S , Candrinho B , Carvalho E , Nhacolo A , Chidimatembue A , Saifodine A , Zulliger R , Lucchi N , Svigel SS , Moriarty LF , Halsey ES , Mayor A , Aide P . Malar J 2021 20 (1) 390 BACKGROUND: Artemisinin-based combination therapy (ACT) has been the recommended first-line treatment for uncomplicated malaria in Mozambique since 2006, with artemether-lumefantrine (AL) and amodiaquine-artesunate (AS-AQ) as the first choice. To assess efficacy of currently used ACT, an in vivo therapeutic efficacy study was conducted. METHODS: The study was conducted in four sentinel sites: Montepuez, Moatize, Mopeia and Massinga. Patients between 6 and 59 months old with uncomplicated Plasmodium falciparum malaria (2000-200,000 parasites/µl) were enrolled between February and September of 2018, assigned to either an AL or AS-AQ treatment arm, and monitored for 28 days. A Bayesian algorithm was applied to differentiate recrudescence from new infection using genotyping data of seven neutral microsatellites. Uncorrected and PCR-corrected efficacy results at day 28 were calculated. RESULTS: Totals of 368 and 273 patients were enrolled in the AL and AS-AQ arms, respectively. Of these, 9.5% (35/368) and 5.1% (14/273) were lost to follow-up in the AL and AS-AQ arms, respectively. There were 48 and 3 recurrent malaria infections (late clinical and late parasitological failures) in the AL and AS-AQ arms, respectively. The day 28 uncorrected efficacy was 85.6% (95% confidence interval (CI) 81.3-89.2%) for AL and 98.8% (95% CI 96.7-99.8%) for AS-AQ, whereas day 28 PCR-corrected efficacy was 97.9% (95% CI 95.6-99.2%) for AL and 99.6% (95% CI 97.9-100%) for AS-AQ. Molecular testing confirmed that 87.4% (42/48) and 33.3% (1/3) of participants with a recurrent malaria infection in the AL and AS-AQ arms were new infections; an expected finding in a high malaria transmission area. Adverse events were documented in less than 2% of participants for both drugs. CONCLUSION: Both AL and AS-AQ have therapeutic efficacies well above the 90% WHO recommended threshold and remain well-tolerated in Mozambique. Routine monitoring of therapeutic efficacy should continue to ensure the treatments remain efficacious. Trial registration Clinicaltrials.gov: NCT04370977. |
Therapeutic Efficacy of Artemisinin-Based Combination Therapies in Democratic Republic of the Congo and Investigation of Molecular Markers of Antimalarial Resistance.
Moriarty LF , Nkoli PM , Likwela JL , Mulopo PM , Sompwe EM , Rika JM , Mavoko HM , Svigel SS , Jones S , Ntamabyaliro NY , Kaputu AK , Lucchi N , Subramaniam G , Niang M , Sadou A , Ngoyi DM , Muyembe Tamfum JJ , Schmedes SE , Plucinski MM , Chowell-Puente G , Halsey ES , Kahunu GM . Am J Trop Med Hyg 2021 105 (4) 1067-1075 Routine assessment of the efficacy of artemisinin-based combination therapies (ACTs) is critical for the early detection of antimalarial resistance. We evaluated the efficacy of ACTs recommended for treatment of uncomplicated malaria in five sites in Democratic Republic of the Congo (DRC): artemether-lumefantrine (AL), artesunate-amodiaquine (ASAQ), and dihydroartemisinin-piperaquine (DP). Children aged 6-59 months with confirmed Plasmodium falciparum malaria were treated with one of the three ACTs and monitored. The primary endpoints were uncorrected and polymerase chain reaction (PCR)-corrected 28-day (AL and ASAQ) or 42-day (DP) cumulative efficacy. Molecular markers of resistance were investigated. Across the sites, uncorrected efficacy estimates ranged from 63% to 88% for AL, 73% to 100% for ASAQ, and 56% to 91% for DP. PCR-corrected efficacy estimates ranged from 86% to 98% for AL, 91% to 100% for ASAQ, and 84% to 100% for DP. No pfk13 mutations previously found to be associated with ACT resistance were observed. Statistically significant associations were found between certain pfmdr1 and pfcrt genotypes and treatment outcome. There is evidence of efficacy below the 90% cutoff recommended by WHO to consider a change in first-line treatment recommendations of two ACTs in one site not far from a monitoring site in Angola that has shown similar reduced efficacy for AL. Confirmation of these findings in future therapeutic efficacy monitoring in DRC is warranted. |
Plasmodium falciparum kelch 13 Mutations, 9 Countries in Africa, 2014-2018.
Schmedes SE , Patel D , Dhal S , Kelley J , Svigel SS , Dimbu PR , Adeothy AL , Kahunu GM , Nkoli PM , Beavogui AH , Kariuki S , Mathanga DP , Koita O , Ishengoma D , Mohamad A , Hawela M , Moriarty LF , Samuels AM , Gutman J , Plucinski MM , Udhayakumar V , Zhou Z , Lucchi NW , Venkatesan M , Halsey ES , Talundzic E . Emerg Infect Dis 2021 27 (7) 1902-1908 The spread of drug resistance to antimalarial treatments poses a serious public health risk globally. To combat this risk, molecular surveillance of drug resistance is imperative. We report the prevalence of mutations in the Plasmodium falciparum kelch 13 propeller domain associated with partial artemisinin resistance, which we determined by using Sanger sequencing samples from patients enrolled in therapeutic efficacy studies from 9 sub-Saharan countries during 2014-2018. Of the 2,865 samples successfully sequenced before treatment (day of enrollment) and on the day of treatment failure, 29 (1.0%) samples contained 11 unique nonsynonymous mutations and 83 (2.9%) samples contained 27 unique synonymous mutations. Two samples from Kenya contained the S522C mutation, which has been associated with delayed parasite clearance; however, no samples contained validated or candidate artemisinin-resistance mutations. |
Therapeutic efficacy of artemether-lumefantrine and artesunate-amodiaquine for the treatment of uncomplicated Plasmodium falciparum malaria in Mali, 2015-2016.
Diarra Y , Koné O , Sangaré L , Doumbia L , Haidara DBB , Diallo M , Maiga A , Sango HA , Sidibé H , Mihigo J , Nace D , Ljolje D , Talundzic E , Udhayakumar V , Eckert E , Woodfill CJ , Moriarty LF , Lim P , Krogstad DJ , Halsey ES , Lucchi NW , Koita OA . Malar J 2021 20 (1) 235 BACKGROUND: The current first-line treatments for uncomplicated malaria recommended by the National Malaria Control Programme in Mali are artemether-lumefantrine (AL) and artesunate-amodiaquine (ASAQ). From 2015 to 2016, an in vivo study was carried out to assess the clinical and parasitological responses to AL and ASAQ in Sélingué, Mali. METHODS: Children between 6 and 59 months of age with uncomplicated Plasmodium falciparum infection and 2000-200,000 asexual parasites/μL of blood were enrolled, randomly assigned to either AL or ASAQ, and followed up for 42 days. Uncorrected and PCR-corrected efficacy results at days 28 and 42. were calculated. Known markers of resistance in the Pfk13, Pfmdr1, and Pfcrt genes were assessed using Sanger sequencing. RESULTS: A total of 449 patients were enrolled: 225 in the AL group and 224 in the ASAQ group. Uncorrected efficacy at day 28 was 83.4% (95% CI 78.5-88.4%) in the AL arm and 93.1% (95% CI 89.7-96.5%) in the ASAQ arm. The per protocol PCR-corrected efficacy at day 28 was 91.0% (86.0-95.9%) in the AL arm and 97.1% (93.6-100%) in the ASAQ arm. ASAQ was significantly (p < 0.05) better than AL for each of the aforementioned efficacy outcomes. No mutations associated with artemisinin resistance were identified in the Pfk13 gene. Overall, for Pfmdr1, the N86 allele and the NFD haplotype were the most common. The NFD haplotype was significantly more prevalent in the post-treatment than in the pre-treatment isolates in the AL arm (p < 0.01) but not in the ASAQ arm. For Pfcrt, the CVIET haplotype was the most common. CONCLUSIONS: The findings indicate that both AL and ASAQ remain effective for the treatment of uncomplicated malaria in Sélingué, Mali. |
Association of Plasmodium falciparum kelch13 R561H genotypes with delayed parasite clearance in Rwanda: an open-label, single-arm, multicentre, therapeutic efficacy study.
Uwimana A , Umulisa N , Venkatesan M , Svigel SS , Zhou Z , Munyaneza T , Habimana RM , Rucogoza A , Moriarty LF , Sandford R , Piercefield E , Goldman I , Ezema B , Talundzic E , Pacheco MA , Escalante AA , Ngamije D , Mangala JN , Kabera M , Munguti K , Murindahabi M , Brieger W , Musanabaganwa C , Mutesa L , Udhayakumar V , Mbituyumuremyi A , Halsey ES , Lucchi NW . Lancet Infect Dis 2021 21 (8) 1120-1128 BACKGROUND: Partial artemisinin resistance is suspected if delayed parasite clearance (ie, persistence of parasitaemia on day 3 after treatment initiation) is observed. Validated markers of artemisinin partial resistance in southeast Asia, Plasmodium falciparum kelch13 (Pfkelch13) R561H and P574L, have been reported in Rwanda but no association with parasite clearance has been observed. We aimed to establish the efficacy of artemether-lumefantrine and genetic characterisation of Pfkelch13 alleles and their association with treatment outcomes. METHODS: This open-label, single-arm, multicentre, therapeutic efficacy study was done in 2018 in three Rwandan sites: Masaka, Rukara, and Bugarama. Children aged 6-59 months with P falciparum monoinfection and fever were eligible and treated with a 3-day course of artemether-lumefantrine. Treatment response was monitored for 28 days using weekly microscopy screenings of blood samples for P falciparum. Mutations in Pfkelch13 and P falciparum multidrug resistance-1 (Pfmdr1) genes were characterised in parasites collected from enrolled participants. Analysis of flanking microsatellites surrounding Pfkelch13 was done to define the origins of the R561H mutations. The primary endpoint was PCR-corrected parasitological cure on day 28, as per WHO protocol. FINDINGS: 228 participants were enrolled and 224 (98·2%) reached the study endpoint. PCR-corrected efficacies were 97·0% (95% CI 88-100) in Masaka, 93·8% (85-98) in Rukara, and 97·2% (91-100) in Bugarama. Pfkelch13 R561H mutations were present in 28 (13%) of 218 pre-treatment samples and P574L mutations were present in two (1%) pre-treatment samples. 217 (90%) of the 240 Pfmdr1 haplotypes observed in the pretreatment samples, had either the NFD (N86Y, Y184F, D1246Y) or NYD haplotype. Eight (16%) of 51 participants in Masaka and 12 (15%) of 82 participants in Rukara were microscopically positive 3 days after treatment initiation, which was associated with pre-treatment presence of Pfkelch13 R561H in Masaka (p=0·0005). Genetic analysis of Pfkelch13 R561H mutations suggest their common ancestry and local origin in Rwanda. INTERPRETATION: We confirm evidence of emerging artemisinin partial resistance in Rwanda. Although artemether-lumefantrine remains efficacious, vigilance for decreasing efficacy, further characterisation of artemisinin partial resistance, and evaluation of additional antimalarials in Rwanda should be considered. FUNDING: The US President's Malaria Initiative. TRANSLATION: For the French translation of the abstract see Supplementary Materials section. |
Variation in Calculating and Reporting Antimalarial Efficacy against Plasmodium falciparum in Sub-Saharan Africa: A Systematic Review of Published Reports
Plucinski MM , Hastings IM , Moriarty LF , Venkatesan M , Felger I , Halsey ES . Am J Trop Med Hyg 2021 104 (5) 1820-1829 Antimalarials, in particular artemisinin-based combination therapies (ACTs), are critical tools in reducing the global burden of malaria, which is concentrated in sub-Saharan Africa. Performing and reporting antimalarial efficacy studies in a transparent and standardized fashion permit comparison of efficacy outcomes across countries and time periods. This systematic review summarizes study compliance with WHO laboratory and reporting guidance pertaining to antimalarial therapeutic efficacy studies and evaluates how well studies from sub-Saharan Africa adhered to these guidelines. We included all published studies (January 2020 or before) performed in sub-Saharan Africa where ACT efficacy for treatment of uncomplicated Plasmodium falciparum infection was reported. The primary outcome was a composite indicator for study methodology consistent with WHO guidelines for statistical analysis of corrected efficacy, defined as an article presenting a Kaplan-Meier survival analysis of corrected efficacy or reporting a per-protocol analysis where new infections were excluded from the numerator and denominator. Of 581 articles screened, we identified 279 for the review. Molecular correction was used in 83% (232/279) to distinguish new infections from recrudescences in subjects experiencing recurrent parasitemia. Only 45% (99/221) of articles with therapeutic efficacy as a primary outcome and performing molecular correction reported corrected efficacy outcomes calculated in a way consistent with WHO recommendations. These results indicate a widespread lack of compliance with WHO-recommended methods of analysis, which may result in biases in how antimalarial effectiveness is being measured and reported from sub-Saharan Africa. |
Low prevalence of highly sulfadoxine-resistant dihydropteroate synthase alleles in Plasmodium falciparum isolates in Benin.
Svigel SS , Adeothy A , Kpemasse A , Houngbo E , Sianou A , Saliou R , Patton ME , Dagnon F , Halsey ES , Tchevoede A , Udhayakumar V , Lucchi NW . Malar J 2021 20 (1) 72 BACKGROUND: In 2004, in response to high levels of treatment failure associated with sulfadoxine-pyrimethamine (SP) resistance, Benin changed its first-line malaria treatment from SP to artemisinin-based combination therapy for treatment of uncomplicated Plasmodium falciparum malaria. Resistance to SP is conferred by accumulation of single nucleotide polymorphisms (SNPs) in P. falciparum genes involved in folate metabolism, dihydrofolate reductase (Pfdhfr) and dihydropteroate synthase (Pfdhps), targeted by pyrimethamine and sulfadoxine, respectively. Because SP is still used for intermittent preventive treatment in pregnant women (IPTp) and seasonal malaria chemoprevention (SMCP) in Benin, the prevalence of Pfdhfr and Pfdhps SNPs in P. falciparum isolates collected in 2017 were investigated. METHODS: This study was carried out in two sites where the transmission of P. falciparum malaria is hyper-endemic: Klouékanmey and Djougou. Blood samples were collected from 178 febrile children 6-59 months old with confirmed uncomplicated P. falciparum malaria and were genotyped for SNPs associated with SP resistance. RESULTS: The Pfdhfr triple mutant IRN (N51I, C59R, and S108N) was the most prevalent (84.6%) haplotype and was commonly found with the Pfdhps single mutant A437G (50.5%) or with the Pfdhps double mutant S436A and A437G (33.7%). The quintuple mutant, Pfdhfr IRN/Pfdhps GE (A437G and K540E), was rarely observed (0.8%). The A581G and A613S mutant alleles were found in 2.6 and 3.9% of isolates, respectively. Six isolates (3.9%) were shown to harbour a mutation at codon I431V, recently identified in West African parasites. CONCLUSIONS: This study showed that Pfdhfr triple IRN mutants are near fixation in this population and that the highly sulfadoxine-resistant Pfdhps alleles are not widespread in Benin. These data support the continued use of SP for chemoprevention in these study sites, which should be complemented by periodic nationwide molecular surveillance to detect emergence of resistant genotypes. |
Malaria Risk and Prevention in Asian Migrants to Angola.
Martins JF , Marques C , Nieto-Andrade B , Kelley J , Patel D , Nace D , Herman C , Barratt J , Ponce de Leon G , Talundzic E , Rogier E , Halsey ES , Plucinski MM . Am J Trop Med Hyg 2020 103 (5) 1918-1926 The number of Asian migrants working in sub-Saharan developing countries like Angola has been increasing. Their malaria risk, prevention, and care-seeking practices have not been characterized. A cross-sectional survey was conducted in 733 Chinese and Southeast Asian migrants in Angola. Respondents were interviewed and provided blood samples. Samples were analyzed to detect Plasmodium antigen and characterize host anti-Plasmodium response. Positive samples were genotyped using the pfs47 marker. Most respondents (72%; 95% CI: 68-75) reported using bed nets, but less than 1% reported using chemoprophylaxis. Depending on the assay, 1-4% of respondents had evidence of active malaria infection. By contrast, 55% (95% CI: 52-59) were seropositive for Plasmodium antibodies. Most infections were Plasmodium falciparum, but infection and/or exposure to Plasmodium vivax and Plasmodium malariae was also detected. Seroprevalence by time in Angola showed most exposure occurred locally. One respondent had sufficiently high parasitemia for pfs47 genotyping, which showed that the infection was likely locally acquired despite recent travel to home country. Asian migrants to Angola are at substantial risk of malaria. Employers should consider enhanced malaria prevention programs, including chemoprophylaxis; embassies should encourage prevention practices. Angolan healthcare workers should be aware of high malaria exposure in Asian migrants. |
COVID-19 in Americans aboard the Diamond Princess cruise ship.
Plucinski MM , Wallace M , Uehara A , Kurbatova EV , Tobolowsky FA , Schneider ZD , Ishizumi A , Bozio CH , Kobayashi M , Toda M , Stewart A , Wagner RL , Moriarty LF , Murray R , Queen K , Tao Y , Paden C , Mauldin MR , Zhang J , Li Y , Elkins CA , Lu X , Herzig CTA , Novak R , Bower W , Medley AM , Acosta AM , Knust B , Cantey PT , Pesik NT , Halsey ES , Cetron MS , Tong S , Marston BJ , Friedman CR . Clin Infect Dis 2020 72 (10) e448-e457 BACKGROUND: The Diamond Princess cruise ship was the site of a large outbreak of coronavirus disease 2019 (COVID-19). Of 437 Americans and their travel companions on the ship, 114 (26%) tested positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). METHODS: We interviewed 229 American passengers and crew after disembarkation following a ship-based quarantine to identify risk factors for infection and characterize transmission onboard the ship. RESULTS: The attack rate for passengers in single-person cabins or without infected cabinmates was 18% (58/329), compared with 63% (27/43) for those sharing a cabin with an asymptomatic infected cabinmate, and 81% (25/31) for those with a symptomatic infected cabinmate. Whole genome sequences from specimens from passengers who shared cabins clustered together. Of 66 SARS-CoV-2-positive American travelers with complete symptom information, 14 (21%) were asymptomatic while on the ship. Among SARS-CoV-2-positive Americans, 10 (9%) required intensive care, of whom 7 were ≥70 years. CONCLUSION: Our findings highlight the high risk of SARS-CoV-2 transmission on cruise ships. High rates of SARS-CoV-2 positivity in cabinmates of individuals with asymptomatic infections suggest that triage by symptom status in shared quarters is insufficient to halt transmission. A high rate of intensive care unit admission among older individuals complicates the prospect of future cruise travel during the pandemic, given typical cruise passenger demographics. The magnitude and severe outcomes of this outbreak were major factors contributing to the Centers for Disease Control and Prevention's decision to halt cruise ship travel in U.S. waters in March 2020. |
Assessment of molecular markers of anti-malarial drug resistance among children participating in a therapeutic efficacy study in western Kenya.
Chebore W , Zhou Z , Westercamp N , Otieno K , Shi YP , Sergent SB , Rondini KA , Svigel SS , Guyah B , Udhayakumar V , Halsey ES , Samuels AM , Kariuki S . Malar J 2020 19 (1) 291 BACKGROUND: Anti-malarial drug resistance remains a major threat to global malaria control efforts. In Africa, Plasmodium falciparum remains susceptible to artemisinin-based combination therapy (ACT), but the emergence of resistant parasites in multiple countries in Southeast Asia and concerns over emergence and/or spread of resistant parasites in Africa warrants continuous monitoring. The World Health Organization recommends that surveillance for molecular markers of resistance be included within therapeutic efficacy studies (TES). The current study assessed molecular markers associated with resistance to Artemether-lumefantrine (AL) and Dihydroartemisinin-piperaquine (DP) from samples collected from children aged 6-59 months enrolled in a TES conducted in Siaya County, western Kenya from 2016 to 2017. METHODS: Three hundred and twenty-three samples collected pre-treatment (day-0) and 110 samples collected at the day of recurrent parasitaemia (up to day 42) were tested for the presence of drug resistance markers in the Pfk13 propeller domain, and the Pfmdr1 and Pfcrt genes by Sanger sequencing. Additionally, the Pfpm2 gene copy number was assessed by real-time polymerase chain reaction. RESULTS: No mutations previously associated with artemisinin resistance were detected in the Pfk13 propeller region. However, other non-synonymous mutations in the Pfk13 propeller region were detected. The most common mutation found on day-0 and at day of recurrence in the Pfmdr1 multidrug resistance marker was at codon 184F. Very few mutations were found in the Pfcrt marker (< 5%). Within the DP arm, all recrudescent cases (8 sample pairs) that were tested for Pfpm2 gene copy number had a single gene copy. None of the associations between observed mutations and treatment outcomes were statistically significant. CONCLUSION: The results indicate absence of Pfk13 mutations associated with parasite resistance to artemisinin in this area and a very high proportion of wild-type parasites for Pfcrt. Although the frequency of Pfmdr1 184F mutations was high in these samples, the association with treatment failure did not reach statistical significance. As the spread of artemisinin-resistant parasites remains a possibility, continued monitoring for molecular markers of ACT resistance is needed to complement clinical data to inform treatment policy in Kenya and other malaria-endemic regions. |
Public Health Responses to COVID-19 Outbreaks on Cruise Ships - Worldwide, February-March 2020.
Moriarty LF , Plucinski MM , Marston BJ , Kurbatova EV , Knust B , Murray EL , Pesik N , Rose D , Fitter D , Kobayashi M , Toda M , Canty PT , Scheuer T , Halsey ES , Cohen NJ , Stockman L , Wadford DA , Medley AM , Green G , Regan JJ , Tardivel K , White S , Brown C , Morales C , Yen C , Wittry B , Freeland A , Naramore S , Novak RT , Daigle D , Weinberg M , Acosta A , Herzig C , Kapella BK , Jacobson KR , Lamba K , Ishizumi A , Sarisky J , Svendsen E , Blocher T , Wu C , Charles J , Wagner R , Stewart A , Mead PS , Kurylo E , Campbell S , Murray R , Weidle P , Cetron M , Friedman CR . MMWR Morb Mortal Wkly Rep 2020 69 (12) 347-352 An estimated 30 million passengers are transported on 272 cruise ships worldwide each year* (1). Cruise ships bring diverse populations into proximity for many days, facilitating transmission of respiratory illness (2). SARS-CoV-2, the virus that causes coronavirus disease (COVID-19) was first identified in Wuhan, China, in December 2019 and has since spread worldwide to at least 187 countries and territories. Widespread COVID-19 transmission on cruise ships has been reported as well (3). Passengers on certain cruise ship voyages might be aged >/=65 years, which places them at greater risk for severe consequences of SARS-CoV-2 infection (4). During February-March 2020, COVID-19 outbreaks associated with three cruise ship voyages have caused more than 800 laboratory-confirmed cases among passengers and crew, including 10 deaths. Transmission occurred across multiple voyages of several ships. This report describes public health responses to COVID-19 outbreaks on these ships. COVID-19 on cruise ships poses a risk for rapid spread of disease, causing outbreaks in a vulnerable population, and aggressive efforts are required to contain spread. All persons should defer all cruise travel worldwide during the COVID-19 pandemic. |
Clearance dynamics of lactate dehydrogenase and aldolase following antimalarial treatment for Plasmodium falciparum infection
Plucinski MM , McElroy PD , Dimbu PR , Fortes F , Nace D , Halsey ES , Rogier E . Parasit Vectors 2019 12 (1) 293 BACKGROUND: Lingering post-treatment parasite antigen in blood complicates malaria diagnosis through antigen detection. Characterization of antigen clearance dynamics is important for interpretation of positive antigen detection tests. RESULTS: We used a bead-based serological assay to measure lactate dehydrogenase (LDH), aldolase (Aldo), and histidine-rich protein 2 (HRP2) levels in 196 children with Plasmodium falciparum malaria treated with effective antimalarials and followed for 28 to 42 days as part of therapeutic efficacy studies in Angola. Compared to pre-treatment levels, antigen concentrations two days after treatment declined by 99.7% for LDH, 96.3% for Aldo, and 54.6% for HRP2. After Day 2, assuming a first-order kinetics clearance model, half-lives of the antigens were 1.8 days (95% CI: 1.5-2.3) for LDH, 3.2 days (95% CI: 3.0-3.4) for Aldo, and 4.8 days (95% CI: 4.7-4.9) for HRP2. CONCLUSIONS: LDH and Aldo show substantially different clearance rates than HRP2, and their presence is largely indicative of active infection. |
Malaria parasite density in individuals with different rapid diagnostic test results and concentrations of HRP2 antigen
Plucinski MM , Dimbu R , Fortes F , Murphy SC , Smith NT , Cruz KR , Seilie AM , Halsey ES , Aidoo M , Rogier E . Am J Trop Med Hyg 2019 100 (5) 1202-1203 Low-density malaria infections are a source of human morbidity in endemic settings and potentially contribute to ongoing malaria transmission. Conventional rapid diagnostic tests (RDTs) were designed to detect clinically relevant parasite and antigen levels, but it is largely unknown what proportion of parasite (and antigen positive) infections are missed by conventional RDTs. Furthermore, RDTs can also provide false positives from lingering histidine-rich protein 2 (HRP2) antigenemia from a past infection. We analyzed 207 samples from Angolan outpatients with a bead-based HRP2 antigen assay and by qRT-PCR for the presence of parasite nucleic acids. Among patients HRP2 positive but negative by conventional RDT, the rate of qRT-PCR positivity was 45% (95% CI: 35-56%), with a median parasitemia of 3.4 parasites/microL (interquartile range: 0.14-4.8). Only 15% (7-26%) of HRP2-negative samples were found to have parasite nucleic acids. A substantial proportion of persons with blood HRP2 antigen concentrations not detected by the conventional RDT were found to have evidence of active infection, but at low parasite density levels. |
Efficacy and safety of artemether-lumefantrine for the treatment of uncomplicated malaria and prevalence of Pfk13 and Pfmdr1 polymorphisms after a decade of using artemisinin-based combination therapy in mainland Tanzania.
Ishengoma DS , Mandara CI , Francis F , Talundzic E , Lucchi NW , Ngasala B , Kabanywanyi AM , Mahende MK , Kamugisha E , Kavishe RA , Muro F , Mohamed A , Mandike R , Mkude S , Chacky F , Paxton L , Greer G , Kitojo CA , Njau R , Martin T , Venkatesan M , Warsame M , Halsey ES , Udhayakumar V . Malar J 2019 18 (1) 88 BACKGROUND: The World Health Organization recommends regular therapeutic efficacy studies (TES) to monitor the performance of first and second-line anti-malarials. In 2016, efficacy and safety of artemether-lumefantrine (AL) for the treatment of uncomplicated falciparum malaria were assessed through a TES conducted between April and October 2016 at four sentinel sites of Kibaha, Mkuzi, Mlimba, and Ujiji in Tanzania. The study also assessed molecular markers of artemisinin and lumefantrine (partner drug) resistance. METHODS: Eligible patients were enrolled at the four sites, treated with standard doses of AL, and monitored for 28 days with clinical and laboratory assessments. The main outcomes were PCR corrected cure rates, day 3 positivity rates, safety of AL, and prevalence of single nucleotide polymorphisms in Plasmodium falciparum kelch 13 (Pfk13) (codon positions: 440-600) and P. falciparum multi-drug resistance 1 (Pfmdr1) genes (codons: N86Y, Y184F and D1246Y), markers of artemisinin and lumefantrine resistance, respectively. RESULTS: Of 344 patients enrolled, three withdrew, six were lost to follow-up; and results were analysed for 335 (97.4%) patients. Two patients had treatment failure (one early treatment failure and one recrudescent infection) after PCR correction, yielding an adequate clinical and parasitological response of > 98%. Day 3 positivity rates ranged from 0 to 5.7%. Common adverse events included cough, abdominal pain, vomiting, and diarrhoea. Two patients had serious adverse events; one died after the first dose of AL and another required hospitalization after the second dose of AL (on day 0) but recovered completely. Of 344 samples collected at enrolment (day 0), 92.7% and 100% were successfully sequenced for Pfk13 and Pfmdr1 genes, respectively. Six (1.9%) had non-synonymous mutations in Pfk13, none of which had been previously associated with artemisinin resistance. For Pfmdr1, the NFD haplotype (codons N86, 184F and D1246) was detected in 134 (39.0%) samples; ranging from 33.0% in Mlimba to 45.5% at Mkuzi. The difference among the four sites was not significant (p = 0.578). All samples had a single copy of the Pfmdr1 gene. CONCLUSION: The study indicated high efficacy of AL and the safety profile was consistent with previous reports. There were no known artemisinin-resistance Pfk13 mutations, but there was a high prevalence of a Pfmdr1 haplotype associated with reduced sensitivity to lumefantrine (but no reduced efficacy was observed in the subjects). Continued TES and monitoring of markers of resistance to artemisinin and partner drugs is critical for early detection of resistant parasites and to inform evidence-based malaria treatment policies. Trial Registration ClinicalTrials.gov NCT03387631. |
Malaria case management commodity supply and use by community health workers in Mozambique, 2017
Davlantes E , Salomao C , Wate F , Sarmento D , Rodrigues H , Halsey ES , Lewis L , Candrinho B , Zulliger R . Malar J 2019 18 (1) 47 BACKGROUND: Community health workers (CHWs) provide preventive care and integrated community case management (iCCM) to people with low healthcare access worldwide. CHW programmes have helped reduce mortality in myriad countries, but little data on malaria supply chain management has been shared. This project evaluated the current composition, use, and delivery of malaria iCCM kit commodities in Mozambique-rapid diagnostic tests (RDTs) and artemether-lumefantrine (AL) treatments-to better tailor existing resources to the needs of CHWs in diverse practice settings. METHODS: Health facilities in Maputo (low malaria burden), Inhambane (moderate), and Nampula (high) Provinces were selected using probability proportionate to the number of CHWs at each facility. All CHWs and their supervisors at selected facilities were interviewed using a structured questionnaire to document experiences with kit commodities. Data were analysed to assess CHW commodity stock levels by province and season. RESULTS: In total, 216 CHWs and 56 supervisors were interviewed at 56 health facilities. CHWs reported receiving an average of 6.7 kits in the last year, although they are intended to receive kits monthly. One-tenth of CHWs reported receiving kits with missing RDTs, and 28% reported lacking some AL treatments. Commodity use was highest in the rainy season. Stockouts were reported by CHWs in all provinces, more commonly in the rainy season. Facility-level stockouts of RDTs or some AL formulation in the past year were reported by 66% of supervisors. Use of CHW kit materials by health facilities was reported by 43% of supervisors; this was most common at facilities experiencing stockouts. CONCLUSIONS: Variations in geographic and seasonal malaria commodity needs should be considered in CHW kit distribution planning in Mozambique. Improvements in provision of complete, monthly CHW kits are needed in parallel with improvements in the broader commodity system strengthening. The findings of this evaluation can help other CHW programmes determine best practices for management of iCCM supply chains. |
Performance of antigen concentration thresholds for attributing fever to malaria among outpatients in Angola
Plucinski MM , Rogier E , Dimbu R , Fortes F , Halsey ES , Aidoo M , Smith T . J Clin Microbiol 2019 57 (3) The density of malaria parasites is a key determinant in whether or not an infected individual develops fever. While the pyrogenic threshold for malaria parasite density has been well-studied, there is no analogous data on the level of antigen associated with fever during infection. Samples from 797 afebrile and 457 febrile outpatients from two provinces in Angola with known concentrations of histidine rich protein 2 (HRP2), aldolase, and lactate dehydrogenase (LDH) antigens were analyzed by Bayesian latent-class modeling to attribute malaria etiology to the fevers and to estimate the sensitivity and specificity of different antigen thresholds for detecting malaria fevers. Amongst patients positive for aldolase or LDH at levels detectable by a bead-based assay, concentrations of these two antigens did not differ between afebrile and febrile patients. In contrast, the concentration of HRP2 was substantially higher in febrile HRP2+ patients compared to afebrile HRP2+ patients. When considering HRP2 concentration, the malaria attributable fraction of fever was 0.092 in the Huambo province and 0.39 in Uige. Diagnostic tests detecting HRP2 with levels of detection in the 3,000-10,000 pg/muL range would provide ideal sensitivity and specificity for determining malaria etiology in febrile persons. |
Screening for Pfhrp2/3-Deleted Plasmodium falciparum, Non-falciparum, and Low-Density Malaria Infections by a Multiplex Antigen Assay.
Plucinski MM , Herman C , Jones S , Dimbu R , Fortes F , Ljolje D , Lucchi N , Murphy SC , Smith NT , Cruz KR , Seilie AM , Halsey ES , Udhayakumar V , Aidoo M , Rogier E . J Infect Dis 2018 219 (3) 437-447 Background: Detection of Plasmodium antigens provides evidence of malaria infection status and is the basis for most malaria diagnosis worldwide. Methods: We developed a sensitive bead-based multiplex assay for laboratory use which simultaneously detects the pan-Plasmodium pAldo, pan-Plasmodium pLDH, and P. falciparum PfHRP2 antigens. The assay was validated against purified recombinant antigens, mono-species malaria infections, and non-infected blood samples. To test against samples collected in an endemic setting, Angolan outpatient samples (n=1267) were assayed. Results: Of 466 Angolan samples positive for at least one antigen, the most common antigen profiles were PfHRP2+/pAldo+/pLDH+ (167, 36%), PfHRP2+/pAldo-/pLDH- (163, 35%), and PfHRP2+/pAldo+/pLDH- (129, 28%). Antigen profile was predictive of qRT-PCR positivity and parasite density. Eight Angolan samples (1.7%) had either no or very low levels of PfHRP2 but were positive for one or both of the other antigens. PCR analysis confirmed three (0.6%) were P. ovale infections, and two (0.4%) represented P. falciparum parasites lacking Pfhrp2 and/or Pfhrp3. Conclusions: These are the first reports of P. falciparum Pfhrp2/3 deletion mutants in Angola. High-throughput multiplex antigen detection can inexpensively screen for low density P. falciparum, non-falciparum, and Pfhrp2/3-deleted malaria parasites to provide population-level antigen estimates and identify specimens requiring further molecular characterization. |
Adherence to Ebola-specific malaria case management guidelines at health facilities in Guinea during the West African Ebola epidemic
Hennessee I , Guilavogui T , Camara A , Halsey ES , Marston B , McFarland D , Freeman M , Plucinski MM . Malar J 2018 17 (1) 230 BACKGROUND: Malaria case management in the context of the 2014-2016 West African Ebola virus disease (EVD) epidemic was complicated by a similar initial clinical presentation of the two diseases. In September 2014, the World Health Organization (WHO) released recommendations titled, "Guidance on temporary malaria control measures in Ebola-affected countries", which aimed at reducing the risk of EVD transmission and improving malaria outcomes. This guidance recommended malaria diagnostic testing of fever cases only if adequate personal protective equipment (PPE) was available, defined as examination gloves, face shield, disposable gown, boots, and head cover; otherwise presumptive anti-malarial treatment was recommended. The extent to which health workers adhered to these guidelines in affected countries has not been assessed. METHODS: A cross-sectional survey was conducted in 118 health units in Guinea in November 2014 to produce a representative and probabilistic sample of health facilities and patients. Adherence to the EVD-specific malaria case management guidelines during the height of the EVD epidemic was assessed. Associations between case management practices and possible determinants were calculated using multivariate logistic regression, controlling for expected confounders and the complex sample design. RESULTS: Most (78%) facilities reported availability of examination gloves, but adequate PPE was available at only 27% of facilities. Only 28% of febrile patients received correct malaria case management per the WHO temporary malaria case management guidelines. The most common error was diagnostic testing in the absence of adequate PPE (45% of febrile patients), followed by no presumptive treatment in the absence of adequate PPE (14%). Having had a report of an EVD case at a health facility and health worker-reported participation in EVD-specific malaria trainings were associated with lower odds of diagnostic testing and higher odds of presumptive treatment. CONCLUSIONS: Adherence to guidance on malaria case management in EVD-affected countries was low at the height of the EVD epidemic in Guinea, and there was substantial malaria diagnostic testing in the absence of adequate PPE, which could have contributed to increased EVD transmission in the healthcare setting. Conversely, low presumptive treatment when diagnostic tests were not performed may have led to additional morbidity and mortality among malaria positive patients. National malaria control programs may consider preparing contingency plans for future implementation of temporary changes to malaria case management guidelines to facilitate uptake by health workers. Additional training on standard and transmission-based precautions should help health workers understand how to protect themselves in the face of emerging and unknown pathogens. |
Efficacy and safety of artemether-lumefantrine, artesunate-amodiaquine, and dihydroartemisinin-piperaquine for the treatment of uncomplicated Plasmodium falciparum malaria in three provinces in Angola, 2017.
Davlantes E , Dimbu PR , Ferreira CM , Florinda Joao M , Pode D , Felix J , Sanhangala E , Andrade BN , Dos Santos Souza S , Talundzic E , Udhayakumar V , Owens C , Mbounga E , Wiesner L , Halsey ES , Martins JF , Fortes F , Plucinski MM . Malar J 2018 17 (1) 144 BACKGROUND: The Angolan government recommends three artemisinin-based combinations for the treatment of uncomplicated Plasmodium falciparum malaria: artemether-lumefantrine (AL), artesunate-amodiaquine (ASAQ), and dihydroartemisinin-piperaquine (DP). Due to the threat of emerging anti-malarial drug resistance, it is important to periodically monitor the efficacy of artemisinin-based combination therapy (ACT). This study evaluated these medications' therapeutic efficacy in Benguela, Lunda Sul, and Zaire Provinces. METHODS: Enrollment occurred between March and July 2017. Study participants were children with P. falciparum monoinfection from each provincial capital. Participants received a 3-day course of a quality-assured artemisinin-based combination and were monitored for 28 (AL and ASAQ arms) or 42 days (DP arm). Each ACT was assessed in two provinces. The primary study endpoints were: (1) follow-up without complications and (2) failure to respond to treatment or development of recurrent P. falciparum infection. Parasites from each patient experiencing recurrent infection were genotyped to differentiate new infection from recrudescence of persistent parasitaemia. These parasites were also analysed for molecular markers associated with ACT resistance. RESULTS: Of 608 children enrolled in the study, 540 (89%) reached a primary study endpoint. Parasitaemia was cleared within 3 days of medication administration in all participants, and no early treatment failures were observed. After exclusion of reinfections, the corrected efficacy of AL was 96% (91-100%, 95% confidence interval) in Zaire and 97% (93-100%) in Lunda Sul. The corrected efficacy of ASAQ was 100% (97-100%) in Benguela and 93% (88-99%) in Zaire. The corrected efficacy of DP was 100% (96-100%) in Benguela and 100% in Lunda Sul. No mutations associated with artemisinin resistance were identified in the pfk13 gene in the 38 cases of recurrent P. falciparum infection. All 33 treatment failures in the AL and ASAQ arms carried pfmdr1 or pfcrt mutations associated with lumefantrine and amodiaquine resistance, respectively, on day of failure. CONCLUSIONS: AL, ASAQ, and DP continue to be efficacious against P. falciparum malaria in these provinces of Angola. Rapid parasite clearance and the absence of genetic evidence of artemisinin resistance are consistent with full susceptibility to artemisinin derivatives. Periodic monitoring of in vivo drug efficacy remains a priority routine activity for Angola. |
Prevalence of molecular markers of artemisinin and lumefantrine resistance among patients with uncomplicated Plasmodium falciparum malaria in three provinces in Angola, 2015.
Ljolje D , Dimbu PR , Kelley J , Goldman I , Nace D , Macaia A , Halsey ES , Ringwald P , Fortes F , Udhayakumar V , Talundzic E , Lucchi NW , Plucinski MM . Malar J 2018 17 (1) 84 BACKGROUND: Artemisinin-based combination therapy is the first-line anti-malarial treatment for uncomplicated Plasmodium falciparum infection in Angola. To date, the prevalence of polymorphisms in the pfk13 gene, associated with artemisinin resistance, and pfmdr1, associated with lumefantrine resistance, have not been systematically studied in Angola. METHODS: DNA was isolated from pretreatment and late treatment failure dried blood spots collected during the 2015 round of therapeutic efficacy studies in Benguela, Lunda Sul, and Zaire Provinces in Angola. The pfk13 propeller domain and pfmdr1 gene were sequenced and analysed for polymorphisms. Pfmdr1 copy number variation was assessed using a real-time PCR method. The association between pfmdr1 and pfk13 mutations and treatment failure was investigated. RESULTS: The majority of pretreatment (99%, 466/469) and all late treatment failure (100%, 50/50) samples were wild type for pfk13. Three of the pretreatment samples (1%) carried the A578S mutation commonly observed in Africa and not associated with artemisinin resistance. All 543 pretreatment and day of late treatment failure samples successfully analysed for pfmdr1 copy number variation carried one copy of pfmdr1. The NYD haplotype was the predominant pfmdr1 haplotype, present in 63% (308/491) of pretreatment samples, followed by NFD, which was present in 32% (157/491) of pretreatment samples. The pfmdr1 N86 allele was overrepresented in day of late treatment failure samples from participants receiving artemether-lumefantrine (p value 0.03). CONCLUSIONS: The pretreatment parasites in patients participating in therapeutic efficacy studies in 2015 in Angola's three sentinel sites showed genetic evidence of susceptibility to artemisinins, consistent with clinical outcome data showing greater than 99% day 3 clearance rates. The lack of increased pfmdr1 copy number is consistent with previous reports from sub-Saharan Africa. Although pfmdr1 NYD and NFD haplotypes were overrepresented in artemether-lumefantrine late treatment failure samples, their role as markers of resistance was unclear given that these haplotypes were also present in the majority of successfully treated patients in the artemether-lumefantrine treatment arms. |
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