Case-based discussion of the acute hepatic porphyrias: Updates on pathogenesis, diagnosis and management

The acute hepatic porphyrias (AHPs) include three autosomal dominant disorders, acute intermittent porphyria, variegate porphyria  and hereditary coproporphyria, and the ultra-rare autosomal recessive 5-aminolevulinic acid dehydratase-deficient porphyria. All four are characterized by episodic acute neurovisceral attacks that can be life-threatening if left untreated. The attacks are precipitated by factors that induce hepatic 5-aminolevulinic acid synthase 1 (ALAS1), resulting in accumulation of the porphyrin precursors, 5-aminolevulinic acid and porphobilinogen, which are believed to cause neurotoxicity. Diagnosis of these rare disorders is often delayed because the symptoms are non-specific with many common aetiologies. However, once clinical suspicion of an AHP is raised, diagnosis can be made by specialized biochemical testing, particularly during attacks. Moderate or severe attacks are treated with intravenous hemin infusions, together with supportive care to relieve pain and other symptoms. Prophylactic treatments are recommended in patients with confirmed recurrent attacks (≥4 attacks in a maximum period of 12 months), the most effective being givosiran, an RNAi therapeutic targeting hepatocyte ALAS1 mRNA. AHP patients with clinically and/or biochemically active disease are at elevated risk for developing long-term complications, including chronic kidney disease, chronic hypertension and hepatocellular carcinoma, thus, surveillance is recommended. Here, using a case-based format, we provide an update on the pathogenesis, diagnosis and treatment of the AHPs based on literature review and clinical experiences.

Improving the timeliness and completeness of childhood vaccination through color-coded bracelets: a pilot study among Fulani tribe populations in Nigeria

Background

Childhood immunization remains one of the most cost-effective public health interventions. Globally, millions of children are not being reached with safe and effective vaccines and Nigeria has the highest number of unprotected children.

Objective

The effects of locally adapted interventions on vaccination timeliness and completeness were studied amongst Fulani populations across 6 health facilities in 2 districts of Bauchi State, Nigeria.

Methods

The intervention group consisted of newborns who received 5-color-coded bracelets representing different immunization contacts, while the control group had no bracelets. Vaccination rates across contacts were followed for 11 months. In addition, mothers of children in the intervention group were voluntarily recruited as peer-to-peer mobilizers (PPM).

Results

In this study, 435 children were studied. Vaccination completeness was higher in the intervention group compared to the control group at all contacts during follow-up. The difference was most noticeable at the fifth contact, with 158/256 (62%) children in the intervention group completing, compared to 73/179 (41%) in the control group (P<0.0001). Vaccination timeliness was better in the intervention group compared to the control one, which reached statistical significance at the second and third vaccination contacts (P<0.05). 68% of women volunteered as PPM and recruited 82 additional children for vaccination.

Conclusion

This study demonstrated the feasibility of a composite intervention (bracelets and PPM) to increase the completeness and timeliness of childhood immunization and provided preliminary evidence for its efficacy among Fulani populations in Nigeria. Findings from this pilot study should be confirmed through a larger cluster randomized controlled trial.

OUP accepted manuscript

Background

Malaria in pregnancy remains a significant cause of morbidity and mortality, affecting the highly endemic countries of sub-Saharan Africa (SSA). Insecticide-treated nets (ITNs) are effective for malaria prevention. However, poor adherence in SSA remains a challenge.

Methods

We conducted a standard questionnaire survey among 710 pregnant women from 37 primary care clinics in the Upper West Region of Ghana from January through May 2019. Using a sequential explanatory design, we integrated the survey data from six focus group discussions with pregnant women.

Results

While 67% of women had some general knowledge about malaria prevention, only 19% knew the specific risks in pregnancy. Determinants of ITN use included ITN ownership (odds ratio [OR] 2.4 [95% confidence interval {CI} 1.3 to 4.4]), good maternal knowledge of the risks of malaria in pregnancy (OR 2.4 [95% CI 1.3 to 4.3]) and more antenatal care (ANC) contacts (OR 1.3 [95% CI 1.0 to 1.5)]. Focus group discussions showed that non-use of ITNs resulted from inappropriate hanging infrastructure, a preference for other malaria prevention alternatives, allergy and heat.

Conclusions

Specific maternal knowledge of malaria risks in pregnancy was low and influenced the regular use of ITNs. Community and ANC-based malaria interventions should prioritize increasing knowledge of the specific risks of malaria.

Transmission of Severe Acute Respiratory Syndrome Coronavirus 2 in Households with Children, Southwest Germany, May-August 2020

Resolving the role of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission in households with members from different generations is crucial for containing the current pandemic. We conducted a large-scale, multicenter, cross-sectional seroepidemiologic household transmission study in southwest Germany during May 11-August 1, 2020. We included 1,625 study participants from 405 households that each had ≥1 child and 1 reverse transcription PCR-confirmed SARS-CoV-2-infected index case-patient. The overall secondary attack rate was 31.6% and was significantly higher in exposed adults (37.5%) than in children (24.6%-29.2%; p = <0.015); the rate was also significantly higher when the index case-patient was >60 years of age (72.9%; p = 0.039). Other risk factors for infectiousness of the index case-patient were SARS-CoV-2-seropositivity (odds ratio [OR] 27.8, 95% CI 8.26-93.5), fever (OR 1.93, 95% CI 1.14-3.31), and cough (OR 2.07, 95% CI 1.21-3.53). Secondary infections in household contacts generate a substantial disease burden.

Uptake challenges of intermittent preventive malaria therapy among pregnant women and their health care providers in the Upper West Region of Ghana: A mixed-methods study

BACKGROUND

Malaria in pregnancy remains a major public health problem in endemic countries, especially in sub-Saharan Africa (SSA). Existing interventions such as intermittent preventive therapy in pregnancy (IPTp) using sulfadoxine-pyrimethamine (SP) are effective against placental malaria. However, low uptake of this intervention is a challenge in SSA. This study assessed factors affecting IPTp-SP uptake among pregnant women as well as their health care providers, including health system-related factors.

METHODS

From November 2018 until May 2019 a mixed-methods study was conducted in one urban and one rural district of the Upper West Region of Ghana. A multi-stage sampling technique was used to recruit 740 3rd trimester pregnant women and 74 health service providers from 37 antenatal care (ANC) facilities. Quantitative data was collected through a standard questionnaire from pregnant women and ANC service providers. Three focus group discussions (FGDs) were conducted in each district with pregnant women who had defaulted on their IPTp doses to collect information about the challenges in accessing IPTp-SP. The primary outcome was the uptake of IPTp-SP during antenatal care visits. In addition, the health care provider and health system-related factors on the administration of SP were assessed, as well as details of folic acid (FA) supplementation. Data were analysed using descriptive statistics and Poisson regression.

RESULTS

Responses from 697 pregnant women were analysed. Of these, 184 (26.4%) had taken the third dose of SP (SP3) in line with international guidelines. IPTp-SP uptake was low and significantly associated with the number of maternal ANC contacts and their gestational age at 1st ANC contact. Most pregnant women were regularly co-administered SP together with 5 mg of FA, in contrast to the international recommendations of 0.4 mg FA. The main challenges to IPTp-SP uptake were missed ANC contacts, knowledge deficiencies among pregnant women of the importance of IPTp, and frequent drug stock outs, which was confirmed both from the ANC providers as well as from the pregnant women. Further challenges reported were provider negligence/absenteeism, adverse drug reactions, and mobile residency of pregnant women.

CONCLUSIONS

The uptake of IPTp-SP in the study area is still very low, which is partly explained by frequent drug stock outs at health facilities, staff absenteeism, knowledge deficiencies among pregnant women, and missed ANC contacts. The high dosing of co-administered FA is against international recommendations. These observations need to be addressed by the national public health authorities.

Prevalence of SARS-CoV-2 Infection in Children and Their Parents in Southwest Germany

Importance

School and daycare closures were enforced as measures to confine the novel coronavirus disease 2019 (COVID-19) pandemic, based on the assumption that young children may play a key role in severe acute respiratory coronavirus 2 (SARS-CoV-2) spread. Given the grave consequences of contact restrictions for children, a better understanding of their contribution to the COVID-19 pandemic is of great importance.

Objective

To describe the rate of SARS-CoV-2 infections and the seroprevalence of SARS-CoV-2 antibodies in children aged 1 to 10 years, compared with a corresponding parent of each child, in a population-based sample.

Design, Setting, and Participants

This large-scale, multicenter, cross-sectional investigation (the COVID-19 BaWü study) enrolled children aged 1 to 10 years and a corresponding parent between April 22 and May 15, 2020, in southwest Germany.

Exposures

Potential exposure to SARS-CoV-2.

Main Outcomes and Measures

The main outcomes were infection and seroprevalence of SARS-CoV-2. Participants were tested for SARS-CoV-2 RNA from nasopharyngeal swabs by reverse transcription-polymerase chain reaction and SARS-CoV-2 specific IgG antibodies in serum by enzyme-linked immunosorbent assays and immunofluorescence tests. Discordant results were clarified by electrochemiluminescence immunoassays, a second enzyme-linked immunosorbent assay, or an in-house Luminex-based assay.

Results

This study included 4964 participants: 2482 children (median age, 6 [range, 1-10] years; 1265 boys [51.0%]) and 2482 parents (median age, 40 [range, 23-66] years; 615 men [24.8%]). Two participants (0.04%) tested positive for SARS-CoV-2 RNA. The estimated SARS-CoV-2 seroprevalence was low in parents (1.8% [95% CI, 1.2-2.4%]) and 3-fold lower in children (0.6% [95% CI, 0.3-1.0%]). Among 56 families with at least 1 child or parent with seropositivity, the combination of a parent with seropositivity and a corresponding child with seronegativity was 4.3 (95% CI, 1.19-15.52) times higher than the combination of a parent who was seronegative and a corresponding child with seropositivity. We observed virus-neutralizing activity for 66 of 70 IgG-positive serum samples (94.3%).

Conclusions and Relevance

In this cross-sectional study, the spread of SARS-CoV-2 infection during a period of lockdown in southwest Germany was particularly low in children aged 1 to 10 years. Accordingly, it is unlikely that children have boosted the pandemic. This SARS-CoV-2 prevalence study, which appears to be the largest focusing on children, is instructive for how ad hoc mass testing provides the basis for rational political decision-making in a pandemic.

Safety and efficacy of artesunate-amodiaquine combined with either methylene blue or primaquine in children with falciparum malaria in Burkina Faso: A randomized controlled trial

Artemisinin resistance is threatening global efforts for malaria control and elimination. Primaquine (PQ) and methylene blue (MB) are gametocytocidal drugs that can be combined with artemisinin-based combination therapy (ACT) to reduce malaria transmission, including resistant strains. Children (6-59 months) with uncomplicated falciparum malaria in Burkina Faso were treated with artesunate-amodiaquine (AS-AQ) and randomized to MB (15 mg/kg/day for 3 days) or PQ (0.25 mg/kg at day 2) with the aim to show non-inferiority of the MB regimen with regard to haematological recovery at day 7 (primary endpoint). MB-AS-AQ could not be shown to be non-inferior to PQ-AS-AQ (mean Hb difference between treatment groups on day 7 was -0.352, 95% CI -0.832-0.128, p = 0.0767), however, haemoglobin recovery following treatment was alike in the two study arms (day 7: mean 0.2±1.4 g/dl vs. 0.5±0.9 g/dl, p = 0.446). Occurrence of adverse events was similar in both groups, except for vomiting, which was more frequent in the MB than in the PQ arm (20/50 vs 7/50, p = 0.003). Adequate clinical and parasitological response was above 95% in both groups, but significantly more asexual parasites were cleared in the MB arm compared to the PQ arm already on day 1 (48/50, 96%, vs 40/50, 80%, p = 0.014). Moreover, P. falciparum gametocyte prevalence and density were lower in the MB arm than in the PQ arm, which reached statistical significance on day 2 (prevalence: 2/50, 4%, vs 15/49, 31%, p<0.001; density: 9.6 vs 41.1/μl, p = 0.024). However, it should be considered that PQ was given only on day 2. MB-ACT appears to be an interesting alternative to PQ-ACT for the treatment of falciparum malaria. While there is a need to further improve MB formulations, MB-ACT may already be considered useful to reduce falciparum malaria transmission intensity, to increase treatment efficacy, and to reduce the risk for resistance development and spread. Trial registration: ClinicalTrials.gov NCT02851108.

Efficacy and safety of methylene blue in the treatment of malaria: a systematic review

BACKGROUND

Methylene blue (MB) was the first synthetic antimalarial to be discovered and was used during the late 19th and early 20th centuries against all types of malaria. MB has been shown to be effective in inhibiting Plasmodium falciparum in culture, in the mouse model and in rhesus monkeys. MB was also shown to have a potent ex vivo activity against drug-resistant isolates of P. falciparum and P. vivax. In preclinical studies, MB acted synergistically with artemisinin derivates and demonstrated a strong effect on gametocyte reduction in P. falciparum. MB has, thus, been considered a potentially useful partner drug for artemisinin-based combination therapy (ACT), particularly when elimination is the final goal. The aim of this study was to review the scientific literature published until early 2017 to summarise existing knowledge on the efficacy and safety of MB in the treatment of malaria.

METHODS

This systematic review followed PRISMA guidelines. Studies reporting on the efficacy and safety of MB were systematically searched for in relevant electronic databases according to a pre-designed search strategy. The search (without language restrictions) was limited to studies of humans published until February 2017.

RESULTS

Out of 474 studies retrieved, a total of 22 articles reporting on 21 studies were eligible for analysis. The 21 included studies that reported data on 1504 malaria patients (2/3 were children). Older studies were case series and reports on MB monotherapy while recent studies were mainly controlled trials of combination regimens. MB was consistently shown to be highly effective in all endemic areas and demonstrated a strong effect on P. falciparum gametocyte reduction and synergy with ACT. MB treatment was associated with mild urogenital and gastrointestinal symptoms as well as blue coloration of urine. In G6PD-deficient African individuals, MB caused a slight but clinically non-significant haemoglobin reduction.

CONCLUSIONS

More studies are needed to define the effects of MB in P. falciparum malaria in areas outside Africa and against P. vivax malaria. Adding MB to ACT could be a valuable approach for the prevention of resistance development and for transmission reduction in control and elimination programs.

SYSTEMATIC REVIEW REGISTRATION

This study is registered at PROSPERO (registration number CRD42017062349 ).

Molecular characterisation of acute intermittent porphyria in a cohort of South African patients and kinetic analysis of two expressed mutants

AIMS

Acute intermittent porphyria (AIP) is a disorder of the haem biosynthetic pathway caused by mutations in the hydroxymethylbilane synthase (HMBS) gene. Knowledge of the spectrum of mutations present in South Africa is limited. This study presents the molecular profile of 20 South African patients with AIP, and the kinetic analysis of one novel expressed mutated HMBS enzyme and a previously identified mutation at the same position.

METHODS

Genomic DNA was isolated from affected probands and selected family members, the HMBS gene amplified and mutations characterised by direct sequencing and restriction enzyme analysis. One of the novel mutations (p.Lys98Glu), a previously characterised mutation at the same position (p.Lys98Arg), and the wild-type enzyme were expressed, purified and subjected to partial kinetic characterisation.

RESULTS

Four new mutations, p.Lys98Glu, p.Asp230Aspfs_*20, c.161-1G>A and c.422+3_6delAAGT, are described. Seven previously described mutations were found, while four patients revealed no mutations. Mutation analysis of five offspring of one of the probands carrying the p.Trp283X mutation revealed two asymptomatic carriers. Kinetic analysis showed that the p.Lys98Glu mutation results in loss of substrate affinity, whereas the previously described p.Lys98Arg mutation causes the loss of binding between the enzyme and its dipyrromethane cofactor, rendering the enzyme inactive.

CONCLUSIONS

This study comprises the most comprehensive characterisation of HMBS gene mutations in patients with AIP in South Africa. The biochemical characterisation of expressed HMBS mutants reveals insight into the mechanism of catalytic activity loss, which may inspire investigation into individualised therapy based on the molecular lesion identified.

Dynamics of dual-polarization VCSEL-based optical frequency combs under optical injection locking

The present experimental work studies the dynamics of dual-polarization optical frequency combs (OFCs) based on gain switching (GS) vertical-cavity surface-emitting laser (VCSEL) diodes under optical injection locking (OIL). This study presents two main results. First, we have obtained an overall comb formed by two orthogonally polarized sub-combs with comparable span and power. The overall comb shows enhanced optical span and flatness and high coherence between its modes. The second result is that we have been able to control the polarization state of the overall comb by tuning the polarization state of the injected light by locking the same single teeth of the comb. This produces an overall comb with single polarization that is parallel or orthogonal. These are novel findings that provide for the development of efficient and compact OFCs based on GS VCSEL sources with versatile polarization dynamics.

Safety of insecticide-treated mosquito nets for infants and their mothers: randomized controlled community trial in Burkina Faso

Background

Insecticide-treated bed nets (ITNs) are now the main tool for malaria prevention in endemic areas. Synthetic pyrethroids are the only group of insecticides recommended by the World Health Organization for the use on ITNs. There are only few studies which have specifically investigated potential adverse effects of frequent exposure to ITNs in the vulnerable group of young infants and their mothers.

Methods

This study was nested into a large randomized controlled ITN effectiveness trial. Ninety newborns and their mothers were selected from the study population for participation. Together with their mothers they were protected with ITNs from birth (group A, n = 45) or from age 6 months (group B, n = 45) and followed up for 18 weeks (daily visits in the first 4 weeks, weekly visits thereafter). Potential side effects related to synthetic pyrethroids (deltamethrin) exposure were systematically investigated by trained field staff. The frequency and duration of respective symptoms was compared between the two study groups.

Results

A total of 180 participants (90 mothers and 90 infants) were followed up over the study period without any loss to follow up. There were no significant differences in the frequency and duration of side effects between the two study groups, except that the frequency of headache was significantly higher in group A compared to group B mothers (p = 0.01).

Conclusions

The study provides further evidence for ITNs being sufficiently safe in children and even in newborns. The association with headache in mothers could be explained by them handling the ITNs more intensely or it could be a chance finding.

Improving maternal and newborn health: effectiveness of a community health worker program in rural Kenya

Background

Volunteer community health workers (CHWs) form an important element of many health systems, and in Kenya these volunteers are the foundation for promoting behavior change through health education, earlier case identification, and timely referral to trained health care providers. This study examines the effectiveness of a community health worker project conducted in rural Kenya that sought to promote improved knowledge of maternal newborn health and to increase deliveries under skilled attendance.

Methods

The study utilized a quasi-experimental nonequivalent design that examined relevant demographic items and knowledge about maternal and newborn health combined with a comprehensive retrospective birth history of women’s children using oral interviews of women who were exposed to health messages delivered by CHWs and those who were not exposed. The project trained CHWs in three geographically distinct areas.

Results

Mean knowledge scores were higher in those women who reported being exposed to the health messages from CHWs, Eburru 32.3 versus 29.2, Kinale 21.8 vs 20.7, Nyakio 26.6 vs 23.8. The number of women delivering under skilled attendance was higher for those mothers who reported exposure to one or more health messages, compared to those who did not. The percentage of facility deliveries for women exposed to health messages by CHWs versus non-exposed was: Eburru 46% versus 19%; Kinale 94% versus 73%: and Nyakio 80% versus 78%.

Conclusion

The delivery of health messages by CHWs increased knowledge of maternal and newborn care among women in the local community and encouraged deliveries under skilled attendance.

Temperature characteristics of surface micromachined MEMS-VCSEL with large tuning range

Several Applications for tunable laser diodes have strict constraints in terms of overall power consumption. Furthermore, the implementation in harsh environments with large temperature fluctuations is necessary. Due to the constraint in power consumption, the application of active cooling might not be an option. For this reason we investigate the temperature characteristics of an electrically pumped MEMS-VCSEL with wide continuous wavelength tuning. For the first time, a mode hop free single mode (side mode suppression ratio (SMSR) > 40dB) tuning range of 45nm at 70°C is demonstrated with a MEMS-VCSEL. An increase of the tuning range from 85nm at 20°C to 92nm at 40°C is measured and explained. In contrast to fixed wavelength VCSEL, the investigated device shows a negative temperature induced wavelength shift of -4.5nmK(-1), which is caused by the MEMS-mirror. At 1560nm, the fibre-coupled optical output power is above 0.6mW over the entire temperature range between 20°C to 70°C and shows a maximum of > 3mW at 20°C.

Haemolysis risk in methylene blue treatment of G6PD-sufficient and G6PD-deficient West-African children with uncomplicated falciparum malaria: a synopsis of four RCTs

PURPOSE

Methylene blue (MB), which was recently tested in a number of clinical malaria studies in Burkina Faso, is currently investigated for its benefit when added to artemisinin-based combination therapy. Together with a number of other antimalarials, MB is on the list of drugs which potentially induce haemolysis in patients with G6PD deficiency. Ruling out safety concerns is of major importance during drug development.

METHODS

A pooled analysis was performed with patient data from four clinical studies conducted in West African children with falciparum malaria between 2003 and 2007. The primary endpoints were haemoglobin levels over time as well as haemolysis in G6PD-deficient (n = 199) and G6PD-sufficient (n = 806) children treated with MB-containing (n = 844) compared to children without MB-containing (n = 161) drug regimens.

RESULTS

In the chosen model, the haemoglobin time course was significantly influenced by the G6PD genotype and the MB dose. In children with hemi- or homozygous G6PD (A-) deficiency, MB treatment with 15 mg/kg per day was associated with a significant reduction in Hb values which reached a minimum of 8.5 g/dl. Two episodes of haemolysis occurred (out of 1005 children); one in a girl heterozygous for G6PD deficiency and one in a hemizygous boy, both had received MB.

CONCLUSIONS

MB treatment of malaria in Africa is associated with slightly reduced haemoglobin values in children with a full G6PD defect compared to non-G6PD deficient children. This effect appears to be of limited clinical relevance but needs to be monitored.

Surface micromachined tunable 1.55 μm-VCSEL with 102 nm continuous single-mode tuning

For the first time a vertical-cavity surface-emitting laser (VCSEL) with a single-mode wavelength-tuning over 102 nm in the range of 1550 nm is demonstrated. The fiber-coupled optical output power has a maximum of 3.5 mW and is > 2 mW over the entire tuning range. The sidemode suppression ratios are > 45 dB. The wavelength tuning is achieved with the micro-electro mechanical actuation of a mirror membrane fabricated with surface micro-machining for on-wafer mass production. The mirror membrane consists of low cost dielectric materials (SiOx/SiNy) deposited with low temperature (< 100°C) Plasma Enhanced Chemical Vapor Deposition (PECVD).

Development of a fixed bed bioreactor for the expansion of human hematopoietic progenitor cells

The ex vivo expansion of hematopoietic progenitor cells is of great interest for a variety of clinical applications, e.g. bone marrow transplantation or gene therapy. Therefore it is of general interest to develop a culture system, able to mimic the in vivo hematopoesis, which is a prerequisite for long-term hematopoietic culture. Our approach was to modify a continuously perfused bioreactor for cultivation and expansion of human hematopoietic stem cells. Therefore we immobilized stromal cells (human primary stromal cells or the murine cell line M2-10B4) in porous glass carriers in a fixed bed reactor and cocultivated human hematopoietic progenitor cells for several weeks. After inoculation of mononuclear cells derived from umbilical cord blood or peripheral blood stem cells both adherent and non adherent cells were harvested and analyzed by flow cytometry and short-term colony assays. During cultivation there was a permanent production of progenitor cells and mature blood cells derived from the immobilized cells in the carriers. We could demonstrate the immobilization of hematopoietic progenitor cells of the myeloid system detectable in short-term colony assays. Additionally we could observe the expansion of very early progenitor cells (CFU-GEMM) up to 4.2-fold and later progenitor cells (CFU-GM and BFU-E) up to 7-fold and 1.8-fold, respectively.

Selection of pfmdr1 and pfcrt alleles in amodiaquine treatment failure in north-western Burkina Faso

In 111 children under five years of age and with uncomplicated malaria in Nouna, north-western Burkina Faso, amodiaquine treatment failed in 75% (after PCR-based exclusion of new infections, 32%). In these, we assessed the role of Plasmodium falciparum pfmdr1 and pfcrt polymorphisms in amodiaquine resistance. Except for pfmdr1 1246Y (prevalence, 5%), no P. falciparum allele predicted treatment outcome. Pfcrt 76T as well as pfmdr1 86Y, 86Y-184F-1246D, and 86Y-184Y-1246Y were positively selected in treatment failures, and pfmdr1 86N-184F-1246D negatively. The weak association of pfmdr1/pfcrt alleles with amodiaquine treatment outcome suggests further factors to be involved in the unsatisfactory low efficacy of the drug and limits the usefulness of these markers in this area.

Efficacy of amodiaquine in the treatment of uncomplicated falciparum malaria in young children of rural north-western Burkina Faso

Background

Combination therapy has become a new paradigm in malaria treatment. Amodiaquine is a common partner drug in different malaria combination therapies used or investigated in sub-Saharan Africa, but data on its efficacy as a single drug are scarce.

Methods

The objective of the study was to determine the efficacy of amodiaquine against falciparum malaria in neighbouring rural and urban areas of north-western Burkina Faso. The study was designed as an uncontrolled trial in children aged 6–59 months with uncomplicated falciparum malaria in the Nouna Health District.

Results

During the rainy season 2005, 117 children were enrolled, 62 from the rural and 55 from the urban study area. The crude adequate clinical and parasitological response (ACPR) rate was 103/117 (88%) by day 14 but decreased to 28/117 (24%) by day 28. After PCR correction for reinfections, ACPR rates were 108/117 (92%) and 71/117 (61%) by day 14 and day 28, respectively. There were no significant differences in efficacy between urban and rural areas. The Plasmodium falciparum crt K76T mutation not predict AQ failure, but was selected in parasites re-appearing following treatment. No serious adverse events occurred and only 16 other adverse events were recorded.

Conclusion

Compared to chloroquine, amodiaquine is more effective against uncomplicated falciparum malaria in Burkina Faso. However, a considerable degree of amodiaquine resistance already exists and it is currently unclear how this resistance will develop when amodiaquine in combination with other drugs is used on a large scale.

Trial registration

Current Controlled Trials ISRCTN73824458.

Precisely tunable continuous-wave terahertz source with interferometric frequency control

We realized a tunable continuous-wave terahertz source with megahertz frequency resolution. The system is based on optical heterodyning of two near-infrared distributed feedback diode lasers, each laser being stabilized by electronic feedback from a low-finesse quadrature interferometer. The control loop permits precisely linear laser frequency scans over >1200 GHz, and a beat signal linewidth of 1 MHz at 80 ms time scale. Using GaAs photomixers and log-periodic antennae, we achieve a signal-to-noise ratio of the terahertz power of >70 dB at 100 GHz and 100 ms integration time, and still approximately 30 dB at 1 THz. As an example for high-resolution terahertz spectroscopy, we characterize the transmission properties of a subwavelength metal grating.

Safety and efficacy of methylene blue combined with artesunate or amodiaquine for uncomplicated falciparum malaria: a randomized controlled trial from Burkina Faso

BACKGROUND

Besides existing artemisinin-based combination therapies, alternative safe, effective and affordable drug combinations against falciparum malaria are needed. Methylene blue (MB) was the first synthetic antimalarial drug ever used, and recent studies have been promising with regard to its revival in malaria therapy. The objective of this study was to assess the safety and efficacy of two MB-based malaria combination therapies, MB-artesunate (AS) and MB-amodiaquine (AQ), compared to the local standard of care, AS-AQ, in Burkina Faso.

METHODS AND FINDINGS

Open-label randomised controlled phase II study in 180 children aged 6-10 years with uncomplicated falciparum malaria in Nouna, north-western Burkina Faso. Follow-up was for 28 days and analysis by intention-to-treat. The treatment groups were similar in baseline characteristics and there was only one loss to follow-up. No drug-related serious adverse events and no deaths occurred. MB-containing regimens were associated with mild vomiting and dysuria. No early treatment failures were observed. Parasite clearance time differed significantly among groups and was the shortest with MB-AS. By day 14, the rates of adequate clinical and parasitological response after PCR-based correction for recrudescence were 87% for MB-AS, 100% for MB-AQ (p = 0.004), and 100% for AS-AQ (p = 0.003). By day 28, the respective figure was lowest for MB-AS (62%), intermediate for the standard treatment AS-AQ (82%; p = 0.015), and highest for MB-AQ (95%; p<0.001; p = 0.03).

CONCLUSIONS

MB-AQ is a promising alternative drug combination against malaria in Africa. Moreover, MB has the potential to further accelerate the rapid parasite clearance of artemisinin-based combination therapies. More than a century after the antimalarial properties of MB had been described, its role in malaria control deserves closer attention.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00354380.

Ability of mothers to diagnose fever and anaemia in their young children, in a malaria-endemic region of West Africa

The rapid and correct diagnosis of fever and anaemia at the household level is a prerequisite for the successful management and control of life-threatening disease among young children, particularly in malaria-endemic areas of Africa. The ability of mothers to diagnose fever and anaemia in their young children has recently been explored, as part of a large, birth-cohort study in rural, north-western Burkina Faso. During a cross-sectional survey in six villages, 345 children aged, <3 years and their mothers were investigated. Each mother was asked if she considered her child to be febrile and/or anaemic before that child's temperature and haematocrit were measured, with an electronic thermometer and portable centrifuge, respectively. The recorded prevalences of fever (> or =37.5 degrees C) and anaemia (haematocrit, <25%) in the children were 12.2% and 21.4%, respectively. The mothers' diagnoses had a sensitivity of 76.2% [95% confidence interval (CI)=60.6%-88.0%] for fever and 4.1% (CI=0.8%-11.4%) for anaemia, with corresponding specificities of 87.1% (CI=82.8%-90.7%) and 95.9% (CI=92.9%-98.0%). Mothers in rural Africa appear to be fairly accurate in detecting fever in their children but less accurate in detecting anaemia. While malaria control needs to employ a mix of preventive and curative measures, anaemia control will benefit from community-based malaria-control measures as well as broader approaches addressing the nutritional status of young children.

CO and CO2 spectroscopy using a 60 nm broadband tunable MEMS-VCSEL at approximately 1.55 microm

The spectroscopic application of a new broadband microelectromechanical-system-tunable vertical cavity surface-emitting laser with single-mode coverage of 60 nm (245 cm(-1)) in a single, continuous sweep is described. The operation of the device is illustrated with high-resolution spectra of CO and CO2 over 110 cm(-1) (27 nm) and 67 cm(-1) (17 nm), respectively, with the CO band shown for high-pressure scans between 1 and 3 bars (0.1-0.3 MPa). The achieved tuning range opens up new opportunities for tunable diode laser absorption spectroscopy. The spectra were compared with HITRAN-derived model calculations. The benefits of a sensor based on this laser are greater speed, laser power, and tuning range.

Long-wavelength tunable vertical-cavity surface-emitting lasers and the influence of coupled cavities

In this paper, we present an InP-based micromechanically tunable VCSEL emitting in the 1.55microm wavelength region with a 26nm tuning range. The laser is based on a two-chip concept, allowing for a separate optimization of the curved top mirror and the amplifying component. Current confinement is achieved by a buried tunnel junction. The design of the microcavity ensures fundamental mode operation with a side mode suppression ratio exceeding 49dB even for large apertures. Simulations indicate that the tuning range is limited by coupled cavity effects and reveal important design criteria like an upper boundary regarding the device thickness.