Effect of mass dihydroartemisinin-piperaquine administration in southern Mozambique on the carriage of molecular markers of antimalarial resistance

Background Mass drug administration (MDA) can rapidly reduce the burden of Plasmodium falciparum (Pf). However, concerns remain about its contribution to select for antimalarial drug resistance. Methods We used Sanger sequencing and real-time PCR to determine the proportion of molecular markers associated with antimalarial resistance (k13, pfpm2, pfmdr1 and pfcrt) in Pf isolates collected before (n = 99) and after (n = 112) the implementation of two monthly MDA rounds with dihydroartemisinin­piperaquine (DHAp) for two consecutive years in Magude district of Southern Mozambique. Results None of the k13 polymorphisms associated with artemisinin resistance were observed in the Pf isolates analyzed. The proportion of Pf isolates with multiple copies of pfpm2, an amplification associated with piperaquine resistance, was similar in pre- (4.9%) and post-MDA groups (3.4%; p = 1.000). No statistically significant differences were observed between pre- and post-MDA groups in the proportion of Pf isolates neither with mutations in pfcrt and pfmdr1 genes, nor with the carriage of pfmdr1 multiple copies (p>0.05). Conclusions This study does not show any evidence of increased frequency of molecular makers of antimalarial resistance after MDA with DHAp in southern Mozambique where markers of antimalarial resistance were absent or low at the beginning of the intervention.

Molecular Surveillance for Polymorphisms Associated with Artemisinin-Based Combination Therapy Resistance in Plasmodium falciparum Isolates Collected in the State of Roraima, Brazil.

Given that the C580Y polymorphism in the Plasmodium falciparum propeller domain of the kelch 13 gene (pfk13) was documented in Guyana, monitoring for mutations associated with antimalarial resistance was undertaken in neighboring Roraima state in Brazil. Polymorphisms in the pfmdr1 and pfk13 genes were investigated in 275 P. falciparum samples. No pfk13 mutations were observed. Triple mutants 184F, 1042D, and 1246Y were observed in 100% of the samples successfully sequenced for the pfmdr1 gene, with 20.1% of these having an additional mutation at codon 1034C. Among them, 2.5% of samples harbored two copies of the pfmdr1 gene. We found no evidence of the spread of C580Y parasites to Roraima state, Brazil. As previously observed, the 184F, 1042D, and 1246Y mutations in the pfmdr1 gene appear to be fixed in this region. Continued molecular surveillance is essential to detect any potential migration or local emergence of artemisinin-resistant mutation.

Overview of artemisinin effectiveness during outset years of its implementation in the western Brazilian Amazon.

BACKGROUND: The elimination of malaria depends on the blocking of transmission and of an effective treatment. In Brazil, artemisinin therapy was introduced in 1991, and here we present a performance overview during implementation outset years. METHODS: It is a retrospective cohort (1991 to 2002) of patients treated in a tertiary centre of Manaus, with positive microscopic diagnosis of Plasmodium falciparum malaria, under treatment with using injectable or rectal artemisinin derivatives, and followed over 35-days to evaluate parasite clearance, death and recurrence. FINDINGS: This cohort outcome resulted 97.6% (1554/1593) of patients who completed the 35-day follow-up, 0.6% (10/1593) of death and 1.8% (29/1593) of follow-up loss. All patients that died and those that presented parasitaemia recurrence had pure P. falciparum infections and received monotherapy. Considering patients who completed 35-day treatment, 98.2% (1527/1554) presented asexual parasitaemia clearance until D4 and 1.8% (27/1554) between D5-D10. It is important to highlight that had no correlation between the five treatment schemes and the sexual parasite clearance. Finally, it is noteworthy that we were able to observe also gametocytes carriage during all follow-up (D0-D35). MAIN CONCLUSIONS: Artemisinin derivatives remained effective in the treatment of falciparum malaria during first 12-years of use in north area of Brazil.

In vitro assessment of cytotoxic, genotoxic and mutagenic effects of antimalarial drugs artemisinin and artemether in human lymphocytes.

Artemisinin is a substance extracted from the Chinese plant Artemisia annua L. widely used in natural medicine for the treatment of various diseases. Artemether is a substance synthesized from artemisinin, and both drugs are commonly administered in the treatment of malaria. Although considered effective antimalarial drugs, very little is known about the genotoxic, cytotoxic and mutagenic effects of these drugs. Therefore, in the present study, we evaluated the genotoxic, mutagenic and cytotoxic effects of artemisinin (12.5, 25 and 50 µg/mL) and artemether (7.46; 14.92 and 29.84 µg/mL) in cultured human lymphocytes using the comet assay, the micronucleus test and the cytotoxicity assay for detection of necrosis and apoptosis by acridine orange/ethidium bromide staining. Our results showed a significant increase (p < 0.05) in the rate of DNA damage measured by comet assay and in the micronucleus frequency after treatment with both drugs. It was also observed that only artemisinin induced a statistically significant increase (p < 0.05) in the number of lymphocytes with death by necrosis 48 h after treatment. The results demonstrated that these two drugs induce mutagenic, genotoxic and cytotoxic effects in cultured human lymphocytes. Our data indicate the need for caution in the use of such drugs, since genotoxic/mutagenic effects may increase the risk of carcinogenesis.

Challenges in a product development partnership: a malaria treatment case study. / Desafios de uma parceria para o desenvolvimento de produtos: o caso de um tratamento para malária.

This paper examines the development of a treatment - a fixed-dose combination of artesunate and mefloquine - in Brazil, from three points of view: in terms of access to medication; to record and report successes; and to look at the lessons learned. This product development took place in the ambit of a public-private partnership. Semi-structured interviews were held with key actors involved in the different phases of the development, and documents were analyzed. Two important points of reference orienting the design of the study and analysis were: a logical model for access to medication; and evaluation of programs. It is concluded that there were several successes over the course of the project, but insufficient attention was given in the project's architecture to planning of adoption of the product: irregularities in demand caused difficulties in planning and production, and adoption of the product was irregular in the Americas. It is concluded that the project can be considered to have been successful: the product was created, and the aims were met - strengthening of institutional and individual capacities and alliances, and advocacy. However, there were weaknesses in the process, which need to be mitigated in future projects of the same type.

Efficacy of Different Primaquine Regimens to Control Plasmodium falciparum Gametocytemia in Colombia.

Treatment against Plasmodium falciparum malaria includes blood schizonticides to clear asexual parasites responsible for disease. The addition of gametocytocidal drugs can eliminate infectious sexual stages with potential for transmission and the World Health Organization recommends a single dose (SD) of primaquine (PQ) to this end. The efficacy of PQ at 0.75 mg/kg to suppress gametocytemia when administered in single or fractionated doses was evaluated. A clinical controlled study with an open-label design was executed; three groups of 20 subjects were studied sequentially. All subjects were treated with the standard dose of artemether-lumefantrine plus the total dose of 0.75 mg/kg of PQ administered (without previous G6PD testing) in three different ways: Group "0.75d-3" received 0.75 mg/kg on day 3; Group "0.50d-1 + 0.25d-3" received 0.50 mg/kg on day 1 and 0.25 mg/kg on day 3; Group "0.25d-1,2,3" received 0.25 mg/kg on days 1, 2, and 3. Subjects were evaluated on days 1, 4, and 7 by thick smear microscopy and quantitative polymerase chain reaction to determine the carriage of immature and mature gametocytes. There were no adverse events. The three schemes caused a marked reduction (75-85%) in prevalence of gametocytes on day 4 compared with day 1, but only the group that received 0.75 mg/kg on day 3 maintained the reduced gametocyte burden until day 7. None of the three treatments were able to clear gametocyte carriage on days 4 or 7, but the group that received the SD had the lowest prevalence of gametocytes (15%). Further studies are needed to establish a PQ regimen with complete efficacy against gametocytes.

Fixed-Dose Artesunate-Amodiaquine Combination vs Chloroquine for Treatment of Uncomplicated Blood Stage P. vivax Infection in the Brazilian Amazon: An Open-Label Randomized, Controlled Trial.

BACKGROUND: Despite increasing evidence of the development of Plasmodium vivax chloroquine (CQ) resistance, there have been no trials comparing its efficacy with that of artemisinin-based combination therapies (ACTs) in Latin America. METHODS: This randomized controlled trial compared the antischizontocidal efficacy and safety of a 3-day supervised treatment of the fixed-dose combination artesunate-amodiaquine Winthrop® (ASAQ) versus CQ for treatment of uncomplicated P. vivax infection in Manaus, Brazil. Patients were followed for 42 days. Primary endpoints were adequate clinical and parasitological responses (ACPR) rates at day 28. Genotype-adjustment was performed. RESULTS: From 2012 to 2013, 380 patients were enrolled. In the per-protocol (PP) analysis, adjusted-ACPR was achieved in 100% (165/165) and 93.6% (161/172) of patients in the ASAQ and CQ arm (difference 6.4%, 95% CI 2.7%; 10.1%) at day 28 and in 97.4% (151/155) and 77.7% (129/166), respectively (difference 19.7%, 95% CI 12.9%; 26.5%), at day 42. Apart from ITT D28 assessment, superiority of ASAQ on ACPR was demonstrated. ASAQ presented faster clearance of parasitaemia and fever. Based on CQ blood level measurements, CQ resistance prevalence was estimated at 11.5% (95% CI: 7.5-17.3) up to day 42. At least one emergent adverse event (AE) was recorded for 79/190 (41x6%) in the ASAQ group and for 85/190 (44x7%) in the CQ group. Both treatments had similar safety profiles. CONCLUSIONS: ASAQ exhibited high efficacy against CQ resistant P. vivax and is an adequate alternative in the study area. Studies with an efficacious comparator, longer follow-up and genotype-adjustment can improve CQR characterization. CLINICAL TRIALS REGISTRATION: NCT01378286.

Artesunate modulates expression of matrix metalloproteinases and their inhibitors as well as collagen-IV to attenuate pulmonary fibrosis in rats.

The aim of this study was to determine the effect of artesunate on extracellular matrix (ECM) accumulation and the expression of collagen-IV, matrix metalloproteinase (MMP), and tissue inhibitor of matrix metalloproteinase (TIMP) to understand the pharmacological role of artesunate in pulmonary fibrosis. Eighty Sprague-Dawley rats were randomly assigned to four groups that were administered saline alone, bleomycin (BLM) alone, BLM + artesunate, or artesunate alone for 28 days. Lung tissues from 10 rats in each group were used to obtain lung fibroblast (LF) primary cells, and the rest were used to analyze protein expression. The mRNA expression of collagen-IV, MMP-2, MMP-9, TIMP-1, and TIMP-2 in lung fibroblasts was detected by real-time quantitative reverse transcriptase polymerase chain reaction. The protein levels of collagen-IV, MMP-2, MMP-9, TIMP-1, and TIMP-2 protein in lung tissues were analyzed by western blotting. Artesunate treatment alleviated alveolitis and pulmonary fibrosis induced by bleomycin in rats, as indicated by a decreased lung coefficient and improvement of lung tissue morphology. Artesunate treatment also led to decreased collagen-IV protein levels, which might be a result of its downregulated expression and increased MMP-2 and MMP-9 protein and mRNA levels. Increased TIMP-1 and TIMP- 2 protein and mRNA levels were detected after artesunate treatment in lung tissues and primary lung fibroblast cells and may contribute to enhanced activity of MMP-2 and -9. These findings suggested that artesunate attenuates alveolitis and pulmonary fibrosis by regulating expression of collagen-IV, TIMP-1 and 2, as well as MMP-2 and -9, to reduce ECM accumulation.

Artesunate overcomes drug resistance in multiple myeloma by inducing mitochondrial stress and non-caspase apoptosis.

Although novel drugs have contributed immensely to improving outcomes of patients with multiple myeloma (MM), many patients develop drug resistance and ultimately succumb to MM. Here, we show that artesunate, an anti-malarial drug, reliably induces cell death in vitro in naïve as well as drug-resistant MM cells at concentrations shown to be safe in humans. Artesunate induced apoptosis predominantly through the non-caspase mediated pathway by primarily targeting mitochondria and causing outer mitochondrial membrane permeabilization that led to cytosolic and subsequent nuclear translocation of mitochondrial proteins apoptosis inducing factor (AIF) and endonuclease G (EndoG). Nuclear translocation of AIF and EndoG was accompanied by low levels of reactive oxygen species (ROS) and increased mitochondrial production of superoxide. These effects were present before apoptosis was evident and were related to intracellular levels of bivalent iron (Fe+2). Artesunate's unique mechanism probably was at least partially responsible for, its ability to act synergistically with multiple anti-myeloma agents. Our findings suggest that artesunate acts through iron to affect the mitochondria and induce low ROS and non-caspase-mediated apoptosis. Its potency, toxicity profile, and synergism with other drugs make it an intriguing new candidate for MM treatment.

Further evidence for an anti-inflammatory role of artesunate in experimental cerebral malaria.

BACKGROUND: Cerebral malaria (CM) is a clinical syndrome resulting from Plasmodium falciparum infection. A wide range of clinical manifestations follow the disease including cognitive dysfunction, seizures and coma. CM pathogenesis remains incompletely understood and without treatment this condition is invariably fatal. Artesunate has been accepted as the most effective drug for treating severe malaria. Besides its antiparasitic activity, an anti-inflammatory property has also been reported. In the current study, the immunomodulatory role of artesunate was investigated using a Plasmodium berghei ANKA model of CM, trough evaluation of behavioural changes and cytokines expression in hippocampus and in frontal cortex. METHODS: C57Bl/6 mice were infected with P. berghei by intraperitoneal route, using a standardized inoculation of 106 parasitized erythrocytes. Memory function was evaluated using the step-down inhibitory avoidance test. The mRNA expression of IFN-γ, IL-1ß, IL-6 and TNF in the frontal cortex and hippocampus of control and infected mice on day 5 post-infection were estimated by quantitative real time PCR. Plasmodium berghei -infected mice also received intraperitoneally a single dose of artesunate (32 mg/kg) on day 4 post-infection, and 24 hours after treatment behavioural and immunological analysis were performed. The protein levels of cytokines IL-2, IL-6, IL-10, IL-17, IFN-γ, TNF in the serum, frontal cortex and hippocampus of controls and P. berghei -infected mice treated or not treated with artesunate were determined using a cytometric bead array (CBA) kit. The survival and neurological symptoms of CM were also registered. RESULTS: CM mice presented a significant impairment of aversive memory compared to controls on day 5 post-infection. A higher mRNA expression of pro-inflammatory cytokines was found in the hippocampus and frontal cortex of infected mice. A single dose of artesunate was also able to decrease the expression of inflammatory cytokines in the hippocampus and frontal cortex of P. berghei-infected mice. In parallel, a significant improvement in neurological symptoms and survival were observed in artesunate treated mice. CONCLUSIONS: In summary, the current study provided further evidence that CM affects key brain areas related to cognition process. In addition, different patterns of cytokine expression during the course of CM could be modulated by a single administration of the anti-malarial artesunate.

Possible artemisinin-based combination therapy-resistant malaria in Nigeria: a report of three cases.

Artemisinin-based combination therapy-resistant malaria is rare in Sub-Saharan Africa. The World Health Organization identifies monitoring and surveillance using day-3 parasitaemia post-treatment as the standard test for identifying suspected artemisinin resistance. We report three cases of early treatment failure due to possible artemisinin-based combination therapy-resistant Plasmodium falciparum malaria. All cases showed adequate clinical and parasitological responses to quinine. This study reveals a need to re-evaluate the quality and efficacy of artemisinin-based combination therapy agents in Nigeria and Sub-Saharan Africa.

Possible artemisinin-based combination therapy-resistant malaria in Nigeria: a report of three cases

Artemisinin-based combination therapy-resistant malaria is rare in Sub-Saharan Africa. The World Health Organization identifies monitoring and surveillance using day-3 parasitaemia post-treatment as the standard test for identifying suspected artemisinin resistance. We report three cases of early treatment failure due to possible artemisinin-based combination therapy-resistant Plasmodium falciparum malaria. All cases showed adequate clinical and parasitological responses to quinine. This study reveals a need to re-evaluate the quality and efficacy of artemisinin-based combination therapy agents in Nigeria and Sub-Saharan Africa.

Effects of the combined artesunate and mefloquine antimalarial drugs on rat embryos.

Artemisinins combination therapy (ACT) is the first choice therapy for falciparum malaria. Data on the safety of ACTs in pregnancy are limited and controversial and the use is not recommended on the first trimester. To evaluate the effects of isolated and combined artesunate (AS)/mefloquine (MQ) on embryo rats, pregnant rats were treated orally with AS (15 and 40 mg/kg body weight (bwt)/day), MQ (30 and 80 mg/kg bwt/day) and AS/MQ (15/30 and 40/80 mg/kg bwt/day) on days 9-11 post coitum (pc). The dams were euthanized on day 12 pc and gestational and embryos histological parameters were evaluated. Embryolethality and histopathological anomalies were significant when AS was given alone or combined with MQ. Combination of AS and MQ did not enhance their toxicity compared to their separate administrations; on the other side, there was a reduction in the toxic effects of the AS when combined with MQ. Isolated MQ did not induce developmental toxicity.

Artesunate + amodiaquine versus artemether-lumefantrine for the treatment of uncomplicated Plasmodium falciparum malaria in the Colombian Pacific region: a noninferiority trial / Artesunato + amodiaquina versus artemether-limefantrina para o tratamento da malaria não complicada por Plamodium falciparum no Pacifico Colombiano: um estudo de não inferioridade

INTRODUCTION: In Colombia, there are no published studies for the treatment of uncomplicated Plasmodium falciparum malaria comparing artemisinin combination therapies. Hence, it is intended to demonstrate the non-inferior efficacy/safety profiles of artesunate + amodiaquine versus artemether-lumefantrine treatments. METHODS: A randomized, controlled, open-label, noninferiority (Δ≤5%) clinical trial was performed in adults with uncomplicated P. falciparum malaria using the 28‑day World Health Organization validated design/definitions. Patients were randomized 1:1 to either oral artesunate + amodiaquine or artemether-lumefantrine. The primary efficacy endpoint: adequate clinical and parasitological response; secondary endpoints: - treatment failures defined per the World Health Organization. Safety: assessed through adverse events. RESULTS: A total of 105 patients was included in each group: zero censored observations. Mean (95%CI - Confidence interval) adequate clinical and parasitological response rates: 100% for artesunate + amodiaquine and 99% for artemether-lumefantrine; the noninferiority criteria was met (Δ=1.7%). There was one late parasitological therapeutic failure (1%; artemether-lumefantrine group), typified by polymerase chain reaction as the MAD20 MSP1 allele. The fever clearance time (artesunate + amodiaquine group) was significantly shorter (p=0.002). Respectively, abdominal pain for artesunate + amodiaquine and artemether-lumefantrine was 1.9% and 3.8% at baseline (p=0.68) and 1% and 13.3% after treatment (p<0.001). CONCLUSIONS: Uncomplicated P. falciparum malaria treatment with artesunate + amodiaquine is noninferior to the artemether-lumefantrine standard treatment. The efficacy/safety profiles grant further studies in this and similar populations.

INTRODUÇÃO: Na Colômbia não existem estudos publicados sobre o tratamento da malária não complicada por Plasmodium falciparum comparando as terapias combinadas com artemisinina. Destarte, quer se demonstrar a não inferioridade dos perfis de eficácia/segurança dos tratamentos com artesunato+amodiaquina versus artemeter-lumefantrina. MÉTODOS: Foi realizado um estudo clínico de não inferioridade (∆≤5%), aleatório, controlado, aberto, em adultos com malária não complicada por P. falciparum usando o desenho validado de 28 dias e os desenhos validados/definidos pela Organização Mundial da Saúde. Os pacientes foram aleatorizados (1:1) para ambos artesunato+amodiaquina ou artemeter-lumefantrina orais. Critérios primários de eficácia: resposta clínica e parasitológica adequada; Criterios de eficácia secundários: as falhas de tratamento definidos pela Organização Mundial da Saúde. A segurança: avaliada através de eventos adversos. RESULTADOS: Foram incursos 105 pacientes em cada grupo: zero observações censuradas. As taxas médias da resposta clínica e parasitológica adequada (95% IC - intervalo de confiança): 100% para artesunato+amodiaquina e 99% para artemeter-lumefantrina; atingiu-se o critério de não inferioridade (∆=1.7%). Houve uma falha terapêutica parasitológica tardia (1%; grupo artemeter-lumefantrina), caracterizada mediante reação em cadeia da polimerase como o alelo MAD20 MSP1. Tempo de remissão da febre (grupo artesunato+amodiaquina), foi significativamente mais curto (p=0.002). Dor abdominal, para artesunato+amodiaquina e artemeter-lumefantrina, respectivamente, 1.9% e 3.8% (p=0.68) na linha de base, 1% e 13.3% pós-tratamento (p<0.001). CONCLUSÕES: O tratamento com artesunato+amodiaquina da malária não complicada por P. falciparum é não inferior ao tratamento normal com artemeter-lumefantrina. Os perfis de eficácia/segurança justificam estudos adicionais nesta e outras populações semelhantes.

Study on the developmental toxicity of combined artesunate and mefloquine antimalarial drugs on rats.

Antimalarial drug combinations containing artemisinins (ACTs) have become first choice therapies for Plasmodium falciparum malaria. Data on safety of ACTs in pregnancy are limited and no previous study has been conducted on the developmental toxicity of artesunate-mefloquine combinations on the first trimester of gestation. To evaluate the developmental toxicity of an artesunate/mefloquine combination, pregnant rats were treated orally with artesunate (15 and 40 mg/kg bwt/day), mefloquine (30 and 80 mg/kg bwt/day) and artesunate/mefloquine (15/30 and 40/80 mg/kg bwt/day) on gestation days 9-11. Dams were C-sectioned on day 20, and their uteri and fetuses removed and examined for soft tissue and skeleton abnormalities. Artesunate increased embryolethality and the incidence of limb long bone malformations on the absence of overt maternal toxicity. Mefloquine (80 mg/kg bwt/day) was maternally toxic and enhanced fetal variations. Combination of artesunate and mefloquine did not enhance their toxicity compared to the toxicity observed after its separate administration. Embryotoxicity of artesunate was apparently attenuated when it is co-administered with mefloquine.

Therapeutic efficacy of artemether-lumefantrine for Plasmodium vivax infections in a prospective study in Guyana.

BACKGROUND: In Guyana, chloroquine + primaquine is used for the treatment of vivax malaria. A worldwide increase of chloroquine resistance in Plasmodium vivax led to questioning of the current malaria treatment guidelines. A therapeutic efficacy study was conducted using artemether-lumefantrine + primaquine against P. vivax to evaluate a treatment alternative for chloroquine. METHODS: From 2009 to 2010, a non-controlled study in two hospitals in Guyana was conducted. A total 61 patients with P. vivax infection were treated with artemether-lumefantrine as a six-dose regimen twice a day for three days with additional 0.25 mg/kg/d primaquine at day 0 for 14 days. Clinical and parasitological parameters were followed on days 0,1,2,3,7,14 and 28 in agreement with WHO guidelines. Plasmodium vivax DNA from eight patients was analysed for pvmdr1, molecular marker of resistance. RESULTS: Artemether-lumefantrine cleared 100% of parasites on day 1, but two patients (3%) had recurrence of parasites on day 28, suggesting relapse. No pvmdr1 Y976F polymorphism was detected. The treatment regimen was well tolerated. CONCLUSIONS: In Guyana, artemether-lumefantrine represents an adequate treatment option against P. vivax when combined with primaquine. Availability of this alternative will be of great importance in case of emerging chloroquine resistance against P. vivax.

Effect of artesunate-mefloquine fixed-dose combination in malaria transmission in Amazon basin communities.

BACKGROUND: Studies in South-East Asia have suggested that early diagnosis and treatment with artesunate (AS) and mefloquine (MQ) combination therapy may reduce the transmission of Plasmodium falciparum malaria and the progression of MQ resistance. METHODS: The effectiveness of a fixed-dose combination of AS and MQ (ASMQ) in reducing malaria transmission was tested in isolated communities of the Juruá valley in the Amazon region.Priority municipalities within the Brazilian Legal Amazon area were selected according to pre-specified criteria. Routine national malaria control programmatic procedures were followed. Existing health structures were reinforced and health care workers were trained to treat with ASMQ all confirmed falciparum malaria cases that match inclusion criteria. A local pharmacovigilance structure was implemented. Incidence of malaria and hospitalizations were recorded two years before, during, and after the fixed-dose ASMQ intervention. In total, between July 2006 and December 2008, 23,845 patients received ASMQ. Two statistical modelling approaches were applied to monthly time series of P. falciparum malaria incidence rates, P. falciparum/Plasmodium vivax infection ratio, and malaria hospital admissions rates. All the time series ranged from January 2004 to December 2008, whilst the intervention period span from July 2006 to December 2008. RESULTS: The ASMQ intervention had a highly significant impact on the mean level of each time series, adjusted for trend and season, of 0.34 (95% CI 0.20 - 0.58) for the P. falciparum malaria incidence rates, 0.67 (95% CI 0.50 - 0.89) for the P. falciparum/P. vivax infection ratio, and 0.53 (95% CI 0.41 - 0.69) for the hospital admission rates. There was also a significant change in the seasonal (or monthly) pattern of the time series before and after intervention, with the elimination of the malaria seasonal peak in the rainy months of the years following the introduction of ASMQ. No serious adverse events relating to the use of fixed-dose ASMQ were reported. CONCLUSIONS: In the remote region of the Juruá valley, the early detection of malaria by health care workers and treatment with fixed-dose ASMQ was feasible and efficacious, and significantly reduced the incidence and morbidity of P. falciparum malaria.

Efficacy of different primaquine-based antimalarial regimens against Plasmodium falciparum gametocytemia.

This study compared the efficacy against Plasmodium falciparum gametocytes of four regimens: amodiaquine-sulfadoxine/pyrimethamine (AQ-SP) and mefloquine-artesunate (MQ-AS), with and without primaquine (PQ) administered with the second dose of the schizonticide (AQ-SP; AQ-SP-PQ; MQ-AS; MQ-AS-PQ). Efficacy was determined by thick smear on days 1, 4 and 8 after the beginning of treatment. A total of 82 patients (19-23/group) were recruited. After AQ-SP administration, gametocytemia steadily increased until day 8. With AQ-SP-PQ, a marked decline in gametocytemia was detected on days 4 and 8. MQ-AS treatment resulted in reduced gametocytemia on days 4 and 8, and with MQ-AS-PQ it was reduced even further. None of the treatments cleared gametocytemia by day 8. Currently, artemisinin-based combination therapies plus PQ are the recommended treatment option against falciparum malaria; however, further studies are required to optimize the use of PQ. Issues to be addressed include the optimal time of administration, treatment duration, optimal daily and total dose, and day of evaluation of the gametocytocidal effect. In falciparum malaria, the WHO recommends a maximum of 4days of treatment; consequently, an effective regimen must clear asexual parasites and symptoms within this time frame. The same criteria should be taken into account when evaluating the anti-gametocyte activity.

Randomized, prospective, three-arm study to confirm the auditory safety and efficacy of artemether-lumefantrine in Colombian patients with uncomplicated Plasmodium falciparum malaria.

The safety of artemether-lumefantrine in patients with acute, uncomplicated Plasmodium falciparum malaria was investigated prospectively using the auditory brainstem response (ABR) and pure-tone thresholds. Secondary outcomes included polymerase chain reaction-corrected cure rates. Patients were randomly assigned in a 3:1:1 ratio to either artemether-lumefantrine (N = 159), atovaquone-proguanil (N = 53), or artesunate-mefloquine (N = 53). The null hypothesis (primary outcome), claiming that the percentage of patients with a baseline to Day-7 ABR Wave III latency increase of > 0.30 msec is ≥ 15% after administration of artemether-lumefantrine, was rejected; 2.6% of patients (95% confidence interval: 0.7-6.6) exceeded 0.30 msec, i.e., significantly below 15% (P < 0.0001). A model-based analysis found no apparent relationship between drug exposure and ABR change. In all three groups, average improvements (2-4 dB) in pure-tone thresholds were observed, and polymerase chain reaction-corrected cure rates were > 95% to Day 42. The results support the continued safe and efficacious use of artemether-lumefantrine in uncomplicated falciparum malaria.

High dose artesunate in combination with mefloquine: pharmacovigilance in the Venezuelan Amazon.

Forty-six patients in a remote health post of Amazonas, Venezuela, accidentally received artesunate in a dose of 10 mg/kg/day combined with mefloquine. This corresponds to the upper limit of the therapeutic range recommended by the WHO (2-10 mg/kg/day). Side effects were retrospectively investigated and a pharmacovigilance report was written. The main side effects were vomiting and diarrhea. Four patients developed complications with signs of dehydration. It is suggested to re-assess the therapeutic range of artesunate when given in combination with mefloquine and to establish a worldwide centralized antimalarial toxicity reporting system.