Last data update: Jul 01, 2024. (Total: 47134 publications since 2009)
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Query Trace: Fortes F [original query] |
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Reply to Rasmussen and Ringwald, "Continued Low Efficacy of Artemether-Lumefantrine in Angola?"
Dimbu PR , Horth R , Cândido ALM , Ferreira CM , Caquece F , Garcia LEA , André K , Pembele G , Jandondo D , Bondo BJ , Nieto Andrade B , Labuda S , Ponce de León G , Kelley J , Patel D , Svigel SS , Talundzic E , Lucchi N , Morais JFM , Fortes F , Martins JF , Pluciński MM . Antimicrob Agents Chemother 12/28/2021 65 (6) We thank Rasmussen and Ringwald for further highlighting the importance of routine monitoring of antimalarial drug efficacy in sub-Saharan Africa, including Angola (1). Longitudinal monitoring is critical to identify potential new, persistent, and/or expanding foci of parasite resistance to available drugs. In 3 of the last 4 rounds, artemether-lumefantrine (AL) was estimated to have an efficacy of <90% at one of the three sentinel sites in Angola. To our knowledge, in sub-Saharan Africa, only Angola and Burkina Faso (2) have shown AL efficacy of <90% across multiple therapeutic efficacy study (TES) rounds. Thus, we chose a title to highlight this persistent concern. | | We concur that the significance of the high rates of day 2 slide positivity in Lunda Sul Province is not fully known, and as pointed out, there may be various explanations for this finding. Measuring drug levels is resource intensive and not feasible every year, but this could help rule out underdosing in future studies. However, we believe our study procedures, as described in this and previous studies, are robust and thus make systematic underdosing unlikely. We have always strictly adhered to WHO guidelines, including hemoglobin criteria and analysis of day 1 severe cases, to inform our classifications. |
Neuroinvasive bacillus cereus infection in immunocompromised hosts: Epidemiologic investigation of 5 patients with acute myeloid leukemia
Little JS , Coughlin C , Hsieh C , Lanza M , Huang WY , Kumar A , Dandawate T , Tucker R , Gable P , Vazquez Deida AA , Moulton-Meissner H , Stevens V , McAllister G , Ewing T , Diaz M , Glowicz J , Winkler ML , Pecora N , Kubiak DW , Pearson JC , Luskin MR , Sherman AC , Woolley AE , Brandeburg C , Bolstorff B , McHale E , Fortes E , Doucette M , Smole S , Bunnell C , Gross A , Platt D , Desai S , Fiumara K , Issa NC , Baden LR , Rhee C , Klompas M , Baker MA . Open Forum Infect Dis 2024 11 (3) ofae048 ![]() ![]() BACKGROUND: Bacillus cereus is a ubiquitous gram-positive rod-shaped bacterium that can cause sepsis and neuroinvasive disease in patients with acute leukemia or neutropenia. METHODS: A single-center retrospective review was conducted to evaluate patients with acute leukemia, positive blood or cerebrospinal fluid test results for B cereus, and abnormal neuroradiographic findings between January 2018 and October 2022. Infection control practices were observed, environmental samples obtained, a dietary case-control study completed, and whole genome sequencing performed on environmental and clinical Bacillus isolates. RESULTS: Five patients with B cereus neuroinvasive disease were identified. All patients had acute myeloid leukemia (AML), were receiving induction chemotherapy, and were neutropenic. Neurologic involvement included subarachnoid or intraparenchymal hemorrhage or brain abscess. All patients were treated with ciprofloxacin and survived with limited or no neurologic sequelae. B cereus was identified in 7 of 61 environmental samples and 1 of 19 dietary protein samples-these were unrelated to clinical isolates via sequencing. No point source was identified. Ciprofloxacin was added to the empiric antimicrobial regimen for patients with AML and prolonged or recurrent neutropenic fevers; no new cases were identified in the ensuing year. CONCLUSIONS: B cereus is ubiquitous in the hospital environment, at times leading to clusters with unrelated isolates. Fastidious infection control practices addressing a range of possible exposures are warranted, but their efficacy is unknown and they may not be sufficient to prevent all infections. Thus, including B cereus coverage in empiric regimens for patients with AML and persistent neutropenic fever may limit the morbidity of this pathogen. |
Therapeutic response to four artemisinin-based combination therapies in Angola, 2021
Dimbu PR , Labuda S , Ferreira CM , Caquece F , André K , Pembele G , Pode D , João MF , Pelenda VM , Nieto Andrade B , Horton B , Kennedy C , Svigel SS , Zhou Z , Morais JFM , Rosário Jd , Fortes F , Martins JF , Plucinski MM . Antimicrob Agents Chemother 2024 e0152523 Monitoring antimalarial efficacy is important to detect the emergence of parasite drug resistance. Angola conducts in vivo therapeutic efficacy studies (TESs) every 2 years in its fixed sentinel sites in Benguela, Lunda Sul, and Zaire provinces. Children with uncomplicated Plasmodium falciparum malaria were treated with artemether-lumefantrine (AL), artesunate-amodiaquine (ASAQ), dihydroartemisinin-piperaquine (DP), or artesunate-pyronaridine (ASPY) and followed for 28 (AL and ASAQ) or 42 days (DP and ASPY) to assess clinical and parasitological response to treatment. Two drugs were sequentially assessed in each site in February-July 2021. The primary indicator was the Kaplan-Meier estimate of the PCR-corrected efficacy at the end of the follow-up period. A total of 622 patients were enrolled in the study and 590 (95%) participants reached a study endpoint. By day 3, ≥98% of participants were slide-negative in all study sites and arms. After PCR correction, day 28 AL efficacy was 88.0% (95% CI: 82%-95%) in Zaire and 94.7% (95% CI: 90%-99%) in Lunda Sul. For ASAQ, day 28 efficacy was 92.0% (95% CI: 87%-98%) in Zaire and 100% in Lunda Sul. Corrected day 42 efficacy was 99.6% (95% CI: 99%-100%) for ASPY and 98.3% (95% CI: 96%-100%) for DP in Benguela. High day 3 clearance rates suggest no clinical evidence of artemisinin resistance. This was the fourth of five rounds of TES in Angola showing a corrected AL efficacy <90% in a site. For Zaire, AL has had an efficacy <90% in 2013, 2015, and 2021. ASAQ, DP, and ASPY are appropriate choices as artemisinin-based combination therapies in Angola. |
Molecular Markers of Sulfadoxine-Pyrimethamine Resistance in Samples from Children with Uncomplicated Plasmodium falciparum at Three Sites in Angola in 2019.
Rosillo SR , Dimbu PR , Cândido ALM , Oh JM , Ferreira CM , Nieto Andrade B , Labuda S , Horth R , Kelley J , Morais JFM , Fortes F , Martins JF , Talundzic E , Pluciński MM . Antimicrob Agents Chemother 2023 67 (4) e0160122 ![]() ![]() Sulfadoxine-pyrimethamine (SP) is used for prevention of malaria in pregnant women in Angola. We sequenced the Plasmodium falciparum dihydrofolate reductase (pfdhfr) and dihydropteroate synthase (pfdhps) genes, implicated in SP resistance, in samples collected during a 2019 study of artemisinin-based combination therapy efficacy in Benguela, Lunda Sul, and Zaire provinces. A total of 90 day 0 and day of failure samples were individually sequenced, while 508 day 0 samples from participants without recurrent parasitemia were pooled after DNA extraction into 61 pools. The N51I, C59R, and S108N pfdhfr mutations and A437G pfdhps mutations were present at high proportions in all provinces (weighted allele frequencies, 62% to 100%). The K540E pfdhps mutation was present at lower proportions (10% to 14%). The A581G pfdhps mutation was only observed in Zaire, at a 4.6% estimated prevalence. The I431V and A613S mutations were also only observed in Zaire, at a prevalence of 2.8% to 2.9%. The most common (27% to 66%) reconstructed haplotype in all three provinces was the canonical quadruple pfdhfr pfdhps mutant. The canonical quintuple mutant was absent in Lunda Sul and Benguela and present in 7.9% of samples in Zaire. A single canonical sextuple (2.6%) mutant was observed in Zaire Province. Proportions of the pfdhps K540E and A581G mutations were well below the World Health Organization thresholds for meaningful SP resistance (prevalence of 95% for K540E and 10% for A581G). Samples from therapeutic efficacy studies represent a convenient source of samples for monitoring SP resistance markers. |
Continued low efficacy of artemether-lumefantrine in Angola, 2019.
Dimbu PR , Horth R , Cândido ALM , Ferreira CM , Caquece F , Garcia LEA , André K , Pembele G , Jandondo D , Bondo BJ , Nieto Andrade B , Labuda S , Ponce de León G , Kelley J , Patel D , Svigel SS , Talundzic E , Lucchi N , Morais JFM , Fortes F , Martins JF , Pluciński MM . Antimicrob Agents Chemother 2020 65 (2) ![]() ![]() BACKGROUND: Biennial therapeutic efficacy monitoring is a crucial activity for ensuring efficacy of currently used artemisinin-based combination therapy in Angola. METHODS: Children with acute uncomplicated P. falciparum infection in sentinel sites in Benguela, Zaire, and Lunda Sul Provinces were treated with artemether-lumefantrine (AL) or artesunate amodiaquine (ASAQ) and followed for 28 days to assess clinical and parasitological response. Molecular correction was performed using seven microsatellite markers. Samples from treatment failures were genotyped for the pfk13, pfcrt, and pfmdr1 genes. RESULTS: Day 3 clearance rates were ≥95% in all arms. Uncorrected Day-28 Kaplan-Meier efficacy estimates ranged from 84.2 to 90.1% for the AL arms, and 84.7 to 100% for the ASAQ arms. Corrected Day-28 estimates were 87.6% (95% Confidence interval [CI]: 81-95%) for the AL arm in Lunda Sul, 92.2% (95%CI: 87-98%) for AL in Zaire, 95.6% (95%CI: 91-100%) for ASAQ in Zaire, 98.4% (95%CI: 96-100%) for AL in Benguela, and 100% for ASAQ in Benguela and Lunda Sul. All 103 analyzed samples had wildtype pfk13 sequences. The 76T pfcrt allele was found in most (92%, 11/12) ASAQ late failure samples but only 16% (4/25) of AL failure samples. The N86 pfmdr1 allele was found in 97% (34/35) of treatment failures. CONCLUSION: AL efficacy in Lunda Sul was below the 90% World Health Organization threshold, the third time in four rounds that this threshold was crossed for an AL arm in Angola. In contrast, observed ASAQ efficacy has not been below 95% to date in Angola, including this latest round. |
Attrition, physical integrity and insecticidal activity of long-lasting insecticidal nets in sub-Saharan Africa and modelling of their impact on vectorial capacity
Briet O , Koenker H , Norris L , Wiegand R , Vanden Eng J , Thackeray A , Williamson J , Gimnig JE , Fortes F , Akogbeto M , Yadouleton AW , Ombok M , Bayoh MN , Mzilahowa T , Abílio AP , Mabunda S , Cuamba N , Diouf E , Konaté L , Hamainza B , Katebe-Sakala C , Ponce de León G , Asamoa K , Wolkon A , Smith SC , Swamidoss I , Green M , Gueye S , Mihigo J , Morgan J , Dotson E , Craig AS , Tan KR , Wirtz RA , Smith T . Malar J 2020 19 (1) 310 BACKGROUND: Long-lasting insecticidal nets (LLINs) are the primary malaria prevention and control intervention in many parts of sub-Saharan Africa. While LLINs are expected to last at least 3 years under normal use conditions, they can lose effectiveness because they fall out of use, are discarded, repurposed, physically damaged, or lose insecticidal activity. The contributions of these different interrelated factors to durability of nets and their protection against malaria have been unclear. METHODS: Starting in 2009, LLIN durability studies were conducted in seven countries in Africa over 5 years. WHO-recommended measures of attrition, LLIN use, insecticidal activity, and physical integrity were recorded for eight different net brands. These data were combined with analyses of experimental hut data on feeding inhibition and killing effects of LLINs on both susceptible and pyrethroid resistant malaria vectors to estimate the protection against malaria transmission-in terms of vectorial capacity (VC)-provided by each net cohort over time. Impact on VC was then compared in hypothetical scenarios where one durability outcome measure was set at the best possible level while keeping the others at the observed levels. RESULTS: There was more variability in decay of protection over time by country than by net brand for three measures of durability (ratios of variance components 4.6, 4.4, and 1.8 times for LLIN survival, use, and integrity, respectively). In some countries, LLIN attrition was slow, but use declined rapidly. Non-use of LLINs generally had more effect on LLIN impact on VC than did attrition, hole formation, or insecticide loss. CONCLUSIONS: There is much more variation in LLIN durability among countries than among net brands. Low levels of use may have a larger impact on effectiveness than does variation in attrition or LLIN degradation. The estimated entomological effects of chemical decay are relatively small, with physical decay probably more important as a driver of attrition and non-use than as a direct cause of loss of effect. Efforts to maximize LLIN impact in operational settings should focus on increasing LLIN usage, including through improvements in LLIN physical integrity. Further research is needed to understand household decisions related to LLIN use, including the influence of net durability and the presence of other nets in the household. |
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. |
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. |
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. |
Post-treatment HRP2 clearance in patients with uncomplicated Plasmodium falciparum malaria
Plucinski MM , Dimbu PR , Fortes F , Abdulla S , Ahmed S , Gutman J , Kachur SP , Badiane A , Ndiaye D , Talundzic E , Lucchi N , Aidoo M , Udhayakumar V , Halsey E , Rogier E . J Infect Dis 2017 217 (5) 685-692 Background: Response to antimalarial treatment is assessed using serial microscopy. New techniques for accurate measurement of the Plasmodium falciparum histidine rich protein 2 (HRP2) antigen have made monitoring antigen concentration over time a potential alternative for assessing treatment response. Methods: Post-treatment HRP2 concentration was measured in longitudinal samples from 537 participants with P. falciparum malaria from efficacy trials in Angola, Tanzania, and Senegal. The HRP2 half-life was estimated using a first-order kinetics clearance model. The association between HRP2 concentration three days post-treatment and recrudescence of infection was assessed. Results: Despite substantial variation in HRP2 concentration at baseline, HRP2 concentration in patients consistently showed a first-order exponential decline. The median half-life of HRP2 was estimated to be 4.5 days (interquartile range: 3.3-6.6) in Angola, 4.7 days (4.0-5.9) in Tanzania, and 3.0 days (2.1-4.5) in Senegal. The day 3 HRP2 concentration was predictive of eventual recrudescence, with an area under the receiver operating characteristic curve of 0.86 (95% confidence interval: 0.73-0.99). Conclusions: Consistent HRP2 clearance dynamics following successful antimalarial treatment imply a common underlying biological clearance mechanism. Patients that ultimately failed treatment did not exhibit this same pattern of clearance, even in the absence of other indications of inadequate response to treatment. |
Estimating the added utility of highly sensitive histidine-rich protein 2 detection in outpatient clinics in Sub-Saharan Africa
Plucinski MM , Rogier E , Dimbu PR , Fortes F , Halsey ES , Aidoo M . Am J Trop Med Hyg 2017 97 (4) 1159-1162 Most malaria testing is by rapid diagnostic tests (RDTs) that detect Plasmodium falciparum histidine-rich protein 2 (HRP2). Recently, several RDT manufacturers have developed highly sensitive RDTs (hsRDTs), promising a limit of detection (LOD) orders of magnitude lower than conventional RDTs. To model the added utility of hsRDTs, HRP2 concentration in Angolan outpatients was measured quantitatively using an ultrasensitive bead-based assay. The distribution of HRP2 concentration was bimodal in both afebrile and febrile patients. The conventional RDT was able to detect 81% of all HRP2-positive febrile patients and 52-77% of HRP2-positive afebrile patients. The added utility of hsRDTs was estimated to be greater in afebrile patients, where an hsRDT with a LOD of 200 pg/mL would detect an additional 50-60% of HRP2-positive persons compared with a conventional RDT with a LOD of 3,000 pg/mL. In febrile patients, the hsRDT would detect an additional 10-20% of cases. Conventional RDTs already capture the vast majority of symptomatic HRP2-positive individuals, and hsRDTs would have to reach a sufficiently low LOD approaching 200 pg/mL to provide added utility in identifying HRP2-positive, asymptomatic individuals. |
Evaluating malaria case management at public health facilities in two provinces in Angola
Plucinski MM , Ferreira M , Ferreira CM , Burns J , Gaparayi P , Joao L , da Costa O , Gill P , Samutondo C , Quivinja J , Mbounga E , de Leon GP , Halsey ES , Dimbu PR , Fortes F . Malar J 2017 16 (1) 186 BACKGROUND: Malaria accounts for the largest portion of healthcare demand in Angola. A pillar of malaria control in Angola is the appropriate management of malaria illness, including testing of suspect cases with rapid diagnostic tests (RDTs) and treatment of confirmed cases with artemisinin-based combination therapy (ACT). Periodic systematic evaluations of malaria case management are recommended to measure health facility readiness and adherence to national case management guidelines. METHODS: Cross-sectional health facility surveys were performed in low-transmission Huambo and high-transmission Uige Provinces in early 2016. In each province, 45 health facilities were randomly selected from among all public health facilities stratified by level of care. Survey teams performed inventories of malaria commodities and conducted exit interviews and re-examinations, including RDT testing, of a random selection of all patients completing outpatient consultations. Key health facility readiness and case management indicators were calculated adjusting for the cluster sampling design and utilization. RESULTS: Availability of RDTs or microscopy on the day of the survey was 71% (54-83) in Huambo and 85% (67-94) in Uige. At least one unit dose pack of one formulation of an ACT (usually artemether-lumefantrine) was available in 83% (66-92) of health facilities in Huambo and 79% (61-90) of health facilities in Uige. Testing rates of suspect malaria cases in Huambo were 30% (23-38) versus 69% (53-81) in Uige. Overall, 28% (13-49) of patients with uncomplicated malaria, as determined during the re-examination, were appropriately treated with an ACT with the correct dose in Huambo, compared to 60% (42-75) in Uige. Incorrect case management of suspect malaria cases was associated with lack of healthcare worker training in Huambo and ACT stock-outs in Uige. CONCLUSIONS: The results reveal important differences between provinces. Despite similar availability of testing and ACT, testing and treatment rates were lower in Huambo compared to Uige. A majority of true malaria cases seeking care in health facilities in Huambo were not appropriately treated with anti-malarials, highlighting the importance of continued training and supervision of healthcare workers in malaria case management, particularly in areas with decreased malaria transmission. |
Bead-based immunoassay allows sub-picogram detection of histidine-rich protein 2 from Plasmodium falciparum and estimates reliability of malaria rapid diagnostic tests
Rogier E , Plucinski M , Lucchi N , Mace K , Chang M , Lemoine JF , Candrinho B , Colborn J , Dimbu R , Fortes F , Udhayakumar V , Barnwell J . PLoS One 2017 12 (2) e0172139 Detection of histidine-rich protein 2 (HRP2) from the malaria parasite Plasmodium falciparum provides evidence for active or recent infection, and is utilized for both diagnostic and surveillance purposes, but current laboratory immunoassays for HRP2 are hindered by low sensitivities and high costs. Here we present a new HRP2 immunoassay based on antigen capture through a bead-based system capable of detecting HRP2 at sub-picogram levels. The assay is highly specific and cost-effective, allowing fast processing and screening of large numbers of samples. We utilized the assay to assess results of HRP2-based rapid diagnostic tests (RDTs) in different P. falciparum transmission settings, generating estimates for true performance in the field. Through this method of external validation, HRP2 RDTs were found to perform well in the high-endemic areas of Mozambique and Angola with 86.4% and 73.9% of persons with HRP2 in their blood testing positive by RDTs, respectively, and false-positive rates of 4.3% and 0.5%. However, in the low-endemic setting of Haiti, only 14.5% of persons found to be HRP2 positive by the bead assay were RDT positive. Additionally, 62.5% of Haitians showing a positive RDT test had no detectable HRP2 by the bead assay, likely indicating that these were false positive tests. In addition to RDT validation, HRP2 biomass was assessed for the populations in these different settings, and may provide an additional metric by which to estimate P. falciparum transmission intensity and measure the impact of interventions. |
Efficacy of artemether-lumefantrine, artesunate-amodiaquine, and dihydroartemisinin-piperaquine for treatment of uncomplicated Plasmodium falciparum malaria in Angola, 2015.
Plucinski MM , Dimbu PR , Macaia AP , Ferreira CM , Samutondo C , Quivinja J , Afonso M , Kiniffo R , Mbounga E , Kelley JS , Patel DS , He Y , Talundzic E , Garrett DO , Halsey ES , Udhayakumar V , Ringwald P , Fortes F . Malar J 2017 16 (1) 62 ![]() BACKGROUND: Recent anti-malarial resistance monitoring in Angola has shown efficacy of artemether-lumefantrine (AL) in certain sites approaching the key 90% lower limit of efficacy recommended for artemisinin-based combination therapy. In addition, a controversial case of malaria unresponsive to artemisinins was reported in a patient infected in Lunda Sul Province in 2013. METHODS: During January-June 2015, investigators monitored the clinical and parasitological response of children with uncomplicated Plasmodium falciparum infection treated with AL, artesunate-amodiaquine (ASAQ), or dihydroartemisinin-piperaquine (DP). The study comprised two treatment arms in each of three provinces: Benguela (AL, ASAQ), Zaire (AL, DP), and Lunda Sul (ASAQ, DP). Samples from treatment failures were analysed for molecular markers of resistance for artemisinin (K13) and lumefantrine (pfmdr1). RESULTS: A total of 467 children reached a study endpoint. Fifty-four treatment failures were observed: four early treatment failures, 40 re-infections and ten recrudescences. Excluding re-infections, the 28-day microsatellite-corrected efficacy was 96.3% (95% CI 91-100) for AL in Benguela, 99.9% (95-100) for ASAQ in Benguela, 88.1% (81-95) for AL in Zaire, and 100% for ASAQ in Lunda Sul. For DP, the 42-day corrected efficacy was 98.8% (96-100) in Zaire and 100% in Lunda Sul. All treatment failures were wild type for K13, but all AL treatment failures had pfmdr1 haplotypes associated with decreased lumefantrine susceptibility. CONCLUSIONS: No evidence was found to corroborate the specific allegation of artemisinin resistance in Lunda Sul. The efficacy below 90% of AL in Zaire matches findings from 2013 from the same site. Further monitoring, particularly including measurement of lumefantrine blood levels, is recommended. |
Population Genetic Analysis Reveals a High Genetic Diversity in the Brazilian Cryptococcus gattii VGII Population and Shifts the Global Origin from the Amazon Rainforest to the Semi-arid Desert in the Northeast of Brazil.
Souto AC , Bonfietti LX , Ferreira-Paim K , Trilles L , Martins M , Ribeiro-Alves M , Pham CD , Martins L , Dos Santos W , Chang M , Brito-Santos F , Santos DC , Fortes S , Lockhart SR , Wanke B , Melhem MS , Lazera MS , Meyer W . PLoS Negl Trop Dis 2016 10 (8) e0004885 ![]() Cryptococcus neoformans and Cryptococcus gattii are responsible globally for almost one million cryptococcosis cases yearly, mostly in immunocompromised patients, such as those living with HIV. Infections due to C. gattii have mainly been described in tropical and subtropical regions, but its adaptation to temperate regions was crucial in the species evolution and highlighted the importance of this pathogenic yeast in the context of disease. Cryptococcus gattii molecular type VGII has come to the forefront in connection with an on-going emergence in the Pacific North West of North America. Taking into account that previous work pointed towards South America as an origin of this species, the present work aimed to assess the genetic diversity within the Brazilian C. gattii VGII population in order to gain new insights into its origin and global dispersal from the South American continent using the ISHAM consensus MLST typing scheme. Our results corroborate the finding that the Brazilian C. gattii VGII population is highly diverse. The diversity is likely due to recombination generated from sexual reproduction, as evidenced by the presence of both mating types in clinical and environmental samples. The data presented herein strongly supports the emergence of highly virulent strains from ancestors in the Northern regions of Brazil, Amazonia and the Northeast. Numerous genotypes represent a link between Brazil and other parts of the world reinforcing South America as the most likely origin of the C. gattii VGII subtypes and their subsequent global spread, including their dispersal into North America, where they caused a major emergence. |
Reply to "No robust evidence of lumefantrine resistance"
Plucinski MM , Talundzic E , Morton L , Dimbu PR , Macaia AP , Fortes F , Goldman I , Lucchi N , Stennies G , MacArthur JR , Udhayakumar V . Antimicrob Agents Chemother 2015 59 (9) 5867-8 Results from regular drug efficacy monitoring should always be interpreted in the context of the many limitations inherent to attributing apparent treatment failures to antimalarial resistance, as concisely summarized by Hamed and Kuhen (1). Notably, in study settings where direct supervision of the evening doses of artemether-lumefantrine (AL) is operationally infeasible or culturally unacceptable, low efficacy can also potentially be attributed to inaccurate dosing or underdosing. Details of how we strived to guarantee participant compliance with evening doses in lieu of direct supervision are found in our original report (2). Importantly, procedures were identical in both provinces, and we have no indication that participant adherence to the evening doses or food consumption guidelines was different in Zaire Province, where we found lower efficacy of AL. While lack of direct observation of doses and nonadherence to guidelines regarding food consumption with drug administration have been shown to be associated with lower blood lumefantrine levels, they have not been directly associated with decreased efficacy of AL (3, 4). | | While in vitro susceptibility testing requires infrastructure rarely found at drug efficacy monitoring sites, there is a long history of complementing clinical outcome data with testing for known molecular markers of resistance (5). Samples from treatment failures with mutations associated with resistance provide more evidence of resistance than clinical outcome data alone. In our study, the detection of pfmdr1 haplotypes previously associated with decreased sensitivity to lumefantrine (6) and the absence of mutations associated with artemisinin resistance in AL treatment failures support the hypothesis of lumefantrine resistance. | | Notably, the NFD and NYD pfmdr1 haplotypes predominated not only in recrudescent infections but also in reinfections in the AL arms. Contrary to Hamed and Kuhen's assertion, reinfections observed during follow-up do provide important data on efficacy. For the calculation of uncorrected efficacy, an important outcome for therapeutic efficacy studies, both reinfections and recrudescences are considered treatment failures. The reporting and interpretation of uncorrected efficacy results are standard components of drug efficacy monitoring for two primary reasons (7,–9). First, uncorrected efficacy estimates are not subject to the limitations and potential biases of using genotyping data to differentiate reinfection from recrudescence. Second, uncorrected efficacy results provide data concerning the posttreatment prophylactic effect of the partner drug in artemisinin-based combination therapies and thus the proportion of clients that will require retreatment, data of increasing interest to malaria control programs. The reinfection rates in the AL arms in Zaire and Uíge Provinces provide a good example of the potential utility of reinfection rates. The reinfection rate in Zaire (13%) was measured as more than twice the rate in Uíge (5.1%). This was despite our screening data, where 67% of the children screened tested positive for malaria in Uíge, compared to 53% in Zaire, indicating that transmission was almost certainly higher in Uíge at the time of our study. This unexpectedly high rate of reinfection in Zaire could therefore point to a parasite population that is less sensitive to lumefantrine and that consequently has a higher likelihood of successfully invading patients with subtherapeutic doses of lumefantrine following AL treatment (10). | | Finally, we would like to reaffirm that while certain screened children had parasitemia levels above 100,000 parasites/μl, only children with parasitemia levels between 2,000 and 100,000 parasites/μl were enrolled in the study, as described in Materials and Methods. Given that no children with parasitemia levels above 100,000 parasites/μl were enrolled in any of the study arms at either site, differences in hyperparasitemia rates between the Uíge and Zaire AL arms cannot explain the difference in efficacy as Hamed and Kuhen suggest. |
Efficacy of artemether-lumefantrine and dihydroartemisinin-piperaquine for the treatment of uncomplicated malaria in children in Zaire and Uige provinces, Angola
Plucinski MM , Talundzic E , Morton L , Dimbu PR , Macaia AP , Fortes F , Goldman I , Lucchi N , Stennies G , MacArthur JR , Udhayakumar V . Antimicrob Agents Chemother 2014 59 (1) 437-43 ![]() The development of resistance to antimalarials is a major challenge for global malaria control. Artemisinin-based combination therapies, the newest class of antimalarials, are used worldwide but there have been reports of artemisinin resistance in Southeast Asia. In February-May 2013, we conducted open-label, nonrandomized therapeutic efficacy studies of artemether-lumefantrine (AL) and dihydroartemisinin-piperaquine (DP) in Zaire and Uige Provinces in northern Angola. The parasitological and clinical responses to treatment in children with uncomplicated P. falciparum monoinfection were measured over 28 days and the main outcome was PCR-corrected adequate clinical and parasitological response (ACPR) proportion on day 28. Parasites from treatment failures were analyzed for the presence of putative molecular markers of resistance to lumefantrine and artemisinins, including the recently identified mutations in the K13-propeller gene. In the 320 children finishing the study, 25 treatment failures were observed, 24 in the AL arms and one in the DP arm. The PCR-corrected ACPR proportion on day 28 for AL was 88% (95% CI: 78-95) in Zaire and 97% (91-100) in Uige. For DP, it was 100% (95-100) in Zaire, and 100% (96-100) in Uige. None of the treatment failures had molecular evidence of artemisinin resistance. In contrast, 91% of AL treatment failures had markers associated with lumefantrine resistance on day of failure. The absence of molecular markers for artemisinin resistance and the observed efficacies of both drug combinations suggest no evidence of artemisinin resistance in northern Angola. There is evidence of increased lumefantrine resistance in Zaire, which should continue to be monitored. |
Listeria marthii sp. nov., isolated from the natural environment, Finger Lakes National Forest
Graves LM , Helsel LO , Steigerwalt AG , Morey RE , Daneshvar MI , Roof SE , Orsi RH , Fortes ED , Millilo SR , den Bakker HC , Wiedmann M , Swaminathan B , Sauders BD . Int J Syst Evol Microbiol 2009 69 (6) 1280-1288 Four isolates (FSL S4-120T, FSL S4-696, FSL S4-710, and FSL S4-965) of Gram-positive, motile, facultatively anaerobic, non-sporeforming bacilli that were phenotypically similar to Listeria spp. were isolated from soil, standing water, and flowing water samples obtained from the natural environment in the Finger Lakes National Forest, New York, USA. The four isolates were closely related to one another and were determined to be the same species by whole genome DNA-DNA hybridization studies (>82% relatedness at 55 degrees C and >76% relatedness at 70 degrees C with 0.0-0.5% divergence). 16S ribosomal RNA sequence analysis confirmed their close phylogenetic relatedness to L. monocytogenes and L. innocua and more distant relatedness to L. welshimeri, L. seeligeri, L. ivanovii, and L. grayi. Phylogenetic analysis of partial sequences for sigB, gap, and prs showed that these isolates form a well-supported sistergroup to L. monocytogenes. The four isolates were sufficiently different from L. monocytogenes and L. innocua by DNA-DNA hybridization to warrant their designation as a new Listeria species. The four isolates yielded positive reactions in the AccuProbe(R) test that is purported to be specific for L. monocytogenes, did not ferment L-rhamnose, were non-hemolytic on blood agar media, and did not contain a homologue of the L. monocytogenes virulence gene island. On the basis of their phenotypic characteristics and their genotypic distinctiveness from L. monocytogenes and L. innocua, the four isolates should be classified as a new species within the genus Listeria, for which the name Listeria marthii sp. nov. is proposed. The type strain of L. marthii is FSL S4-120T (=ATCC BAA 1595T =BEIR NR 9579T =CCUG 56148T). L. marthii has not been associated with human or animal disease at this time. |
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