Antivirals for the treatment of mild and moderate COVID-19 in South Africa

While the majority of COVID-19 cases in South Africa (SA) are mild, patients with severe COVID-19 requiring hospitalisation present with significant morbidity and mortality and place a substantial burden on healthcare services. Given the low vaccine uptake in SA and other low- and middle-income countries in sub-Saharan Africa, the high prevalence of comorbidities and limited healthcare system capacity, evidence-based interventions that reduce the risk of severe disease and death should be considered for implementation. Several antiviral classes have been newly developed or repurposed to treat COVID-19 early after infection to retard progression to severe disease and reduce the risk of death, particularly in the elderly and/or in patients with comorbidities. COVID-19 antivirals such as remdesivir, nirmatrelvir/ ritonavir and molnupiravir are safe and cost-effective and have received either full approval or emergency use authorisation from regulators. Using a proposed test-and-treat strategy, judicious use of antivirals could be impactful.

Clinical impact of plasma concentrations of first-line antituberculosis drugs

BACKGROUND

The clinical significance of low antituberculosis (anti-TB) drug concentrations has not been fully elucidated.

OBJECTIVES

To investigate the clinical consequences of first-line drug concentrations in adult patients with drug-susceptible pulmonary TBin South Africa (SA).

METHOD

We conducted a pharmacokinetic study nested within the control arm of the Improving Treatment Success (IMPRESS) trial(NCT02114684) in Durban, SA. During the first 2 months of treatment, participants received weight-based dosing of first-line anti-TBdrugs (rifampicin, isoniazid, pyrazinamide and ethambutol), and had plasma drug concentrations measured at 2 and 6 hours after drugadministration during the 8th week of treatment. Intermediate (8 weeks), end-of-treatment (6 months) and follow-up TB outcomes wereassessed using World Health Organization criteria.

RESULTS

We measured plasma drug concentrations on available samples in 43 participants. Peak drug concentrations were below thetherapeutic range in 39/43 (90.7%) for rifampicin, 32/43 (74.4%) for isoniazid, 27/42 (64.3%) for pyrazinamide and 5/41 (12.2%) forethambutol. At the end of the intensive phase of treatment (week 8), 20.9% (n=9/43) of participants remained culture positive. We did notfind a relationship between the concentrations of first-line drugs and treatment outcomes at week 8. All participants were cured at the endof treatment, and there were no relapses during the 12-month follow-up period.

CONCLUSION

Treatment outcomes were favourable despite low drug concentrations as defined by current reference thresholds.

Altered drug exposures of first-line TB drugs in a moxifloxacin-containing treatment regimen

BACKGROUND: Pharmacokinetic variability arising from drug-drug interactions and pharmacogenetics may influence the effectiveness of treatment regimens for TB. The Improving Treatment Success Trial compared the WHO-recommended standard treatment in TB patients with an experimental regimen substituting ethambutol with moxifloxacin (MFX) in Durban, South Africa.METHODS: Non-linear mixed-effects modelling was used to investigate the population pharmacokinetics of rifampicin (RIF), isoniazid (INH) and pyrazinamide (PZA). A total of 25 single-nucleotide polymorphisms, including pregnane-X-receptor, were selected for analysis.RESULTS: TB drug concentrations were available in a subset of 101 patients: 58 in the MFX arm and 43 in the control arm. Baseline characteristics were well-balanced between study arms: median age and weight were respectively 36 years and 57.7 kg; 75.2% of the patients were living with HIV. Although weight-based drug dosing was the same in the two arms, we found that RIF exposure was increased by 19.3%, INH decreased by 19% and PZA decreased by 19.2% when administered as part of the MFX-containing regimen. Genetic variation in pregnane-X-receptor (rs2472677) was associated with a 25.3% reduction in RIF exposure.CONCLUSION: Optimised weight-based TB treatment dosing is essential when RIF, INH and PZA are co-administered with fluoroquinolones. The reduction in RIF exposure associated with pharmacogenetic variation is worrying.

A position statement and practical guide to the use of particulate filtering facepiece respirators (N95, FFP2, or equivalent) for South African health workers exposed to respiratory pathogens including Mycobacterium tuberculosis and SARS-CoV-2

SUMMARY

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is transmitted mainly by aerosol in particles <10 µm that can remain suspended for hours before being inhaled. Because particulate filtering facepiece respirators ('respirators'; e.g. N95 masks) are more effective than surgical masks against bio-aerosols, many international organisations now recommend that health workers (HWs) wear a respirator when caring for individuals who may have COVID-19. In South Africa (SA), however, surgical masks are still recommended for the routine care of individuals with possible or confirmed COVID-19, with respirators reserved for so-called aerosol-generating procedures. In contrast, SA guidelines do recommend respirators for routine care of individuals with possible or confirmed tuberculosis (TB), which is also transmitted via aerosol. In health facilities in SA, distinguishing between TB and COVID-19 is challenging without examination and investigation, both of which may expose HWs to potentially infectious individuals. Symptom-based triage has limited utility in defining risk. Indeed, significant proportions of individuals with COVID-19 and/or pulmonary TB may not have symptoms and/or test negative. The prevalence of undiagnosed respiratory disease is therefore likely significant in many general clinical areas (e.g. waiting areas). Moreover, a proportion of HWs are HIV-positive and are at increased risk of severe COVID-19 and death.

RECOMMENDATIONS

Sustained improvements in infection prevention and control (IPC) require reorganisation of systems to prioritise HW and patient safety. While this will take time, it is unacceptable to leave HWs exposed until such changes are made. We propose that the SA health system adopts a target of 'zero harm', aiming to eliminate transmission of respiratory pathogens to all individuals in every healthcare setting. Accordingly, we recommend: the use of respirators by all staff (clinical and non-clinical) during activities that involve contact or sharing air in indoor spaces with individuals who: (i) have not yet been clinically evaluated; or (ii) are thought or known to have TB and/or COVID-19 or other potentially harmful respiratory infections;the use of respirators that meet national and international manufacturing standards;evaluation of all respirators, at the least, by qualitative fit testing; andthe use of respirators as part of a 'package of care' in line with international IPC recommendations. We recognise that this will be challenging, not least due to global and national shortages of personal protective equipment (PPE). SA national policy around respiratory protective equipment enables a robust framework for manufacture and quality control and has been supported by local manufacturers and the Department of Trade, Industry and Competition. Respirator manufacturers should explore adaptations to improve comfort and reduce barriers to communication. Structural changes are needed urgently to improve the safety of health facilities: persistent advocacy and research around potential systems change remain essential.

KN95 filtering facepiece respirators distributed in South Africa fail safety testing protocols

BACKGROUND

Given the global shortage of N95 filtering facepiece respirators (FFP2 in Europe) during the COVID-19 pandemic, KN95 masks (Chinese equivalent of the N95 and FFP2) were imported and distributed in South Africa (SA). However, there are hardly any published independent safety data on KN95 masks.

OBJECTIVES

To evaluate the seal, fit and filtration efficiency of several brands of KN95 masks marketed for widespread use in SA healthcare facilities, using standardised testing protocols.

METHODS

The verifiability of manufacturer and technical details was first ascertained, followed by evaluation of the number of layers comprising the mask material. The testing protocol involved a directly observed positive and negative pressure user seal check, which if passed was followed by qualitative fit testing (sodium saccharin) in healthy laboratory or healthcare workers. Quantitative fit testing (3M) was used to validate the qualitative fit testing method. The filtration efficacy and integrity of the mask filter material were evaluated using a particle counter-based testing rig utilising aerosolised saline (expressed as filtration efficacy of 0.3 µm particles). Halyard FLUIDSHIELD 3 N95 and 3M 1860 N95 masks were used as controls.

RESULTS

Twelve KN95 mask brands (total of 36 masks) were evaluated in 7 participants. The mask type and manufacturing details were printed on only 2/12 brands (17%) as per National Institute of Occupational Safety and Health and European Union regulatory requirements. There was considerable variability in the number of KN95 mask layers (between 3 and 6 layers in the 12 brands evaluated). The seal check pass rate was significantly lower in KN95 compared with N95 masks (1/36 (3%) v. 12/12 (100%); p<0.0001). Modification of the KN95 ear-loop tension using head straps or staples, or improving the facial seal using Micropore 3M tape, enhanced seal test performance in 15/36 KN95 masks evaluated (42%). However, none of these 15 passed downstream qualitative fit testing compared with the control N95 masks (0/15 v. 12/12; p<0.0001). Only 4/8 (50%) of the KN95 brands tested passed the minimum filtration requirements for an N95 mask (suboptimal KN95 filtration efficacy varied from 12% to 78%, compared with 56% for a surgical mask and >99% for the N95 masks at the 0.3 µm particle size).

CONCLUSIONS

The KN95 masks tested failed the stipulated safety thresholds associated with protection of healthcare workers against airborne pathogens such as SARS-CoV-2. These preliminary data have implications for the regulation of masks and their distribution to healthcare workers and facilities in SA.

The parental effects of body size on developmental phenotype in Harmonia axyridis

Body size is a trait with many potential impacts on fitness. Adult body size can affect the strength of condition-dependent parental effects that determine offspring phenotypes, with potentially important transgenerational consequences. In a preliminary experiment, larval food deprivation (30 min daily access) created Harmonia axyridis Pallas (Coleoptera: Coccinellidae) females that weighed <50% of controls reared on ad libitum food (eggs of Ephestia kuehniella Zeller). Although only 1/3 of larvae survived to adulthood in the 30 min treatment, adult pairs produced eggs that were not significantly different in size from those of pairs fed ad libitum as larvae. Less extreme larval food deprivation (4 h daily access) was used to create a cohort of H. axyridis that weighed <60% of controls reared on ad libitum food. Small couples had lower 20-day fecundities and reduced egg fertility relative to large couples. Both egg and pupal periods were shortest when both parents were small, and longest when both parents were large, with reciprocal crosses intermediate. There were no consistent effects of parental body size on larval development time, but the progeny of small females mated to large males pupated later than other treatments. Progeny of large pairs had the heaviest adult weights at emergence, and progeny of small pairs, the lightest, with the progeny of reciprocal crosses intermediate. Small females produced the lightest female offspring, whereas small males sired the lightest male offspring, suggesting stronger responses to epigenetic signals from parents of the same sex. These results indicate that H. axyridis cohorts maturing with abundant food will produce progeny with larger potential body size and fitness, whereas those experiencing food limitation will confer size and fitness limitations to the subsequent generation, with potentially important implications for short-term population dynamics.

A systematic review and meta-analysis of first-line tuberculosis drug concentrations and treatment outcomes

Low serum concentrations of first-line tuberculosis (TB) drugs have been widely reported. However, the impact of low serum concentrations on treatment outcome is less well studied. A systematic search of MEDLINE/Pubmed and the Cochrane Central Register of Controlled Trials up to 31 March 2018 was conducted for articles describing drug concentrations of first-line TB drugs and treatment outcome in adult patients with drug-susceptible TB. The search identified 3073 unique publication abstracts, which were reviewed for suitability: 21 articles were acceptable for inclusion in the qualitative analysis comprising 13 prospective observational cohorts, 4 retrospective observational cohorts, 1 case-control study and 3 randomised controlled trials. Data for meta-analysis were available for 15 studies, 13 studies of rifampicin (RMP), 10 of isoniazid (INH), 8 of pyrazinamide (PZA) and 4 of ethambutol (EMB). This meta-analysis revealed that low PZA concentration appears to increase the risk of poor outcomes (8 studies, n = 2727; RR 1.73, 95%CI 1.10-2.72), low RMP concentrations may slightly increase the risk of poor outcomes (13 studies, n = 2753; RR 1.40, 95%CI 0.91-2.16), whereas low concentrations of INH (10 studies, n = 2640; RR 1.32, 95%CI 0.66-2.63) and EMB (4 studies, n = 551; RR 1.12, 95%CI 0.41-3.05) appear to make no difference to treatment outcome. There was no significant publication bias or between-study heterogeneity in any of the analyses. The potential clinical impact of low concentrations of PZA and RMP warrants further evaluation. Also, comprehensive assessments of the complex pharmacokinetic-pharmacodynamic relationships in the treatment of TB are urgently needed.

Extrapulmonary tuberculosis in the setting of HIV hyperendemicity at a tertiary hospital in Durban, South Africa

Background: South Africa has the highest burden of tuberculosis/human immunodeficiency virus (TB/HIV) co-infection in the world, with the province of KwaZulu-Natal representing the global epicentre of TB/HIV. While significant progress has been made to improve the diagnosis of pulmonary tuberculosis, the diagnosis of extrapulmonary TB (EPTB) remains a significant challenge in resource-constrained settings. Methods: A retrospective chart review was conducted, and included all adult patients diagnosed with EPTB at a tertiary hospital in Durban, South Africa, between January 1, 2016 and March 31, 2016.Results: There were 188 new cases of TB during the study period, with 80 patients diagnosed with EPTB. The mean age of patients was 34.73 (SD ± 9.44) years. Forty-two (52.5%) patients were female, while 76 (96%) were black. The most common risk factor for EPTB was HIV co-infection (88.8%). The median CD4 cell count was 68 (IQR 32–165) cells/mm3. Pleural (36.3%), lymph node (28.7%) and abdominal (27.5%) involvement were the most common sites of disease Weight loss, fever, night sweats and cough were amongst the most common symptoms reported. A microbiologically confirmed diagnosis was made in only 65% of cases. In the majority of cases, more than one diagnostic method was used to confirm the presence of TB in distant organs.Conclusion: Immunosuppression, most commonly by HIV, remains the most significant risk factor for the development of EPTB. Advancements in Xpert MTB/Rif and computed tomography have assisted in increasing the diagnostic armamentarium of EPTB. Despite improved access to antiretroviral therapy over the past years, advanced HIV disease remains a significant challenge to TB control.

Quantifying pearl millet response to high temperature stress: thresholds, sensitive stages, genetic variability and relative sensitivity of pollen and pistil

The objectives were to (1) quantify high temperature (HT) stress impacts at different growth stages (season long, booting to seed-set and booting to maturity) on various yield components; (2) identify the most sensitive stage(s) to short episodes of HT stress during reproductive development; (3) understand the genetic variations for HT stress tolerance based on cardinal temperatures for pollen germination; and (4) determine relative sensitivity of pollen and pistil to HT stress and associated tolerance or susceptible mechanisms in pearl millet. High temperature stress (≥36/26°C) imposed at different stages and durations caused decrease in number of seeds, individual seed weight and seed yield. Two periods (10-12 days and 2-0 days before anthesis) were identified as most sensitive to short episodes of stress, causing maximum decreases in pollen germination percentage and seeds numbers. HT stresses of ≥36/26°C results in floret sterility. Pistils were relatively more sensitive than pollen grains, causing decreased number of seeds and seed yield. HT stress increased the reactive oxygen species contents and decreased the activity of the antioxidant enzymes in both pollen and pistils. Under HT stress, pistils had relatively higher reactive oxygen species and lower antioxidant enzymes activity compared with pollen grains, which explains greater susceptibility of pistils.

Sensitivity of sorghum pollen and pistil to high-temperature stress

High temperature (HT) decreases seed set percentage in sorghum (Sorghum bicolor [L.] Moench). The relative sensitivity of pollen and particularly pistil and the mechanistic response that induces tolerance or susceptibility to HT are not well known and hence are the major objectives of this research. The male sterile (ATx399) and fertile (RTx430) lines were exposed to 30/20 °C (optimum temperature), 36/26 °C (HT1 ), and 39/29 °C (HT2 ) from the start of booting to seed set in a controlled environment. Similarly, in the field, HT stress was imposed using heat tents. HT stress decreased pollen germination. Relatively high levels of reactive oxygen species and decreased antioxidant enzyme activity and phospholipid unsaturation were observed in pollen compared to pistil under HT. The severe cell organelle damage was observed in pollen and pistil at 36/26 and 39/29 °C, respectively. The seed set percentage was higher in HT-stressed pistil pollinated with optimum-temperature pollen. Direct and reciprocal crosses indicate that pollen was more sensitive with larger decreases in seed set percentage than pistil under HT stress. The negative impact was greater in pollen than pistil at lower temperatures. Overall, pollen was more sensitive than pistil to HT stress because it is more susceptible to oxidative damage than pistil.

Hidden leprosy cases in tribal population groups and how to reach them through a collaborative effort

BACKGROUND

Tribal populations are an underserved population group and access to health services is a major challenge for them. Since leprosy treatment is integrated with the general health services, identifying leprosy cases is not be easy in these settings and they remain as endemic reservoirs, unless greater efforts are made to reach them.

METHODOLOGY

An active search operation was conducted in the tribal colonies in four pre-identified Health & Nutrition Clusters, Nellore district, Andhra Pradesh, India, in 2013. After a brief training, village health nurses and selected volunteers covered all the households, showing flash cards with photos of leprosy cases and enquiring if there was any resident with a similar condition. Suspects were listed and examined by the district leprosy supervisor and field coordinators from Damien Foundation. Follow up interviews were done after one year to assess the treatment completion rate.

RESULTS

Village health workers covered 47,574 people living in the tribal colonies and identified 325 leprosy suspects. Among them, 70 were confirmed as new leprosy cases. The prevalence of previously undetected leprosy cases was found to be 14.7/10,000. Out of 70 cases, 19 (27%) were children, 35 (50%) were female, 32 (45.7%) were classified as MB leprosy, 6 (8.6%) had a leprosy reaction and 11 (15.7%) persons had Grade 2 disability at the time of diagnosis. The treatment completion rate was found to be 74% at the end of one year.

CONCLUSION

The study reveals a very high burden of leprosy among the tribal population and demonstrates how resources can be mobilized from government, NGO and local community sources to promote early case detection among underserved population groups.

Relationship between stimulation train characteristics and dynamic human skeletal muscle performance

AIM

The purpose of the present study was to investigate the effect of activation frequency on dynamic human muscle performance for a range of train durations and number of pulses during free limb movement.

METHODS

The quadriceps femoris muscles of 10 subjects were activated with stimulation trains with different activation frequency, train durations and number of pulses. The peak excursion produced in response to each train was the dependent measure of muscle performance.

RESULTS

The excursion-frequency (for a 300-ms train duration) and excursion-train duration (for trains with frequencies of 10, 30 or 59 Hz) relationships could each be fit with a two-parameter exponential equation (R(2) values > 0.97). Because the number of pulses in a stimulation train is a function of both train duration and frequency, the excursion produced as a function of the number of pulses was characterized by a three-parameter exponential equation that represented this combined relationship. The relationship between the measured and predicted excursions in response to a wide range of stimulation trains had a R(2) = 0.96. In addition, one-way repeated measures analyses of variance (anovas) showed that the frequency at which the maximum excursion was produced increased with an increase in the number of pulses in the trains tested.

CONCLUSION

These results show the importance of train duration and the number of pulses contained within a train on the relationship between activation frequency and human skeletal muscle performance.

Pregnenolone metabolism in testicular homogenates of macaques (Macaca fascicularis): some effects of relaxin and freezing

The metabolism of varying quantities of pregnenolone has been studied in nuclei-free homogenates from Macaca fascicularis testes by using capillary gas chromatography, after derivatization of metabolites as O-methyl oximes/trimethylsilyl ethers. Evidence was obtained indicating that both pathways for testosterone biosynthesis were operating. 5-Androstene-3 beta, 17 beta-diol was formed in especially high quantities. Two 16-androstenes, namely 5,16-androstadien-3 beta-ol and 5 alpha-androst-16-en-3 beta-ol, were also quantitatively important as metabolites. Co-incubation of stored homogenates with relaxin resulted in 80-100% reduction of the formation of all metabolites quantified except for 5 alpha-androst-16-en-3-one, which was stimulated. Freezing the homogenates at -10 degrees C for 3 weeks resulted in marked 4- to 6-fold reduction in the yields of testosterone and of the 5-ene and 4-ene metabolites from pregnenolone.

The effect of morphine on the biosynthesis of catecholamines in the rat brain

In vivo studies involved monitoring the effect of morphine administration on catecholamine biosynthesis by the brain while in vitro studies involved studying the effect of morphine on the uptake of tritiated tyrosine by synaptosomes and its subsequent incorporation into the catecholamines. The extremely low levels of these endogenous compounds required the use of High Performance Liquid Chromatography with electrochemical detection. Intra-peritoneal injection of morphine at a dosage of 10 mg/kg did not produce appreciable changes in the catecholamine levels but a dosage of 30 mg/kg morphine was found to elevate dihydroxy phenylacetic acid content. At a dosage of 60 mg/kg, dopamine levels were elevated while noradrenaline was depleted. Morphine, at a concentration of 1 x 10(-5)M increases the incorporation of tritiated tyrosine into dopamine and dihydroxy phenylacetic acid in synaptosomal preparations.

Intracellular distribution of pregnenolone metabolites in testis of macaque (Macaca fascicularis)

The metabolism of pregnenolone in subcellular fractions of the testes of the macaque (Macaca fascicularis) has been studied using capillary gas chromatography to characterize and quantify the metabolites, after their conversion into the O-methyloxime and/or trimethylsilyl ether derivatives. The microsomal incubations yielded the greatest quantities of metabolites, with lesser amounts in the mitochondrial fraction. The cytosolic fraction contained no significant quantity of metabolites after incubation, except for 5alpha-androst-16-en-3 beta-ol. This, and other odorous androst-16-enes, found in the microsomal fraction, are of particular interest in the context of animal communication because of their possible pheromonal role. Pregnenolone was converted into androst-5-ene-3 beta,17 beta-diol, androst-4-ene-3,17-dione and testosterone, suggesting that both classical pathways for testosterone synthesis were operating. Testosterone was further converted into 5 alpha-reduced androstanediols, especially in the microsomal fraction.

Behaviour of effector cells, synovial fluids, and sera from rheumatoid arthritis patients in antibody-dependent cell-mediated cytotoxicity

Antibody-dependent cell-mediated cytotoxicity (ADCC) was examined in patients with rheumatoid arthritis (RA). The cytotoxicity of peripheral blood leucocytes from patients with RA was similar to that found in normal persons, whereas ADCC was less effective in RA synovial fluid cells. It is possible that the activity in these cells is lower because of immune complexes and other factors being absorbed from the synovial fluid itself. Although patients' sera had little effect on normal peripheral blood leucocytes, synovial fluid from RA patients was markedly inhibitory in ADCC. The degree of inhibition correlated significantly with the clinical status of the patients.

Intra-articular and circulating immune complexes and antiglobulins (IgG and IgM) in rheumatoid arthritis; correlation with clinical features

Solid phase radioimmunometric methods have been used to assay immune complexes and IgG and IgM antiglobulins in paired samples of synovial fluid and serum from patients with rheumatoid arthritis (RA) or osteoarthrosis. Over 60% of RA patients had some increase in complexes in their sera, while nearly 90% had synovial fluid complexes. Moreover, the levels of complexes within the joint were much higher than in the serum. Both IgG and IgM antiglobulins were raised in most RA patients. The levels of IgG antiglobulins--and to a less extent IgM antiglobulins--were nearly always higher in synovial fluid than in the corresponding serum sample.A strong correlation was found between the levels of immune complex and IgG antiglobulin. A marked association was seen between the presence of subcutaneous nodules and increased IgG antiglobulins.