Frequency, kinetics and determinants of viable SARS-CoV-2 in bioaerosols from ambulatory COVID-19 patients infected with the Beta, Delta or Omicron variants

Airborne transmission of SARS-CoV-2 aerosol remains contentious. Importantly, whether cough or breath-generated bioaerosols can harbor viable and replicating virus remains largely unclarified. We performed size-fractionated aerosol sampling (Andersen cascade impactor) and evaluated viral culturability in human cell lines (infectiousness), viral genetics, and host immunity in ambulatory participants with COVID-19. Sixty-one percent (27/44) and 50% (22/44) of participants emitted variant-specific culture-positive aerosols <10μm and <5μm, respectively, for up to 9 days after symptom onset. Aerosol culturability is significantly associated with lower neutralizing antibody titers, and suppression of transcriptomic pathways related to innate immunity and the humoral response. A nasopharyngeal Ct <17 rules-in ~40% of aerosol culture-positives and identifies those who are probably highly infectious. A parsimonious three transcript blood-based biosignature is highly predictive of infectious aerosol generation (PPV > 95%). There is considerable heterogeneity in potential infectiousness i.e., only 29% of participants were probably highly infectious (produced culture-positive aerosols <5μm at ~6 days after symptom onset). These data, which comprehensively confirm variant-specific culturable SARS-CoV-2 in aerosol, inform the targeting of transmission-related interventions and public health containment strategies emphasizing improved ventilation.

Airborne bacteria in veterinary surgical theatres in South Africa

The bioaerosol composition of the theatre environment plays a determining role in the development of surgical site infections (SSIs). It has been demonstrated that the concentration of viable airborne bacteria is influenced by the level of room occupancy, utilisation of surgical attire and importantly, proper ventilation systems, which are often lacking in the average veterinary facility. The aim of this study was to evaluate the airborne bacterial load encountered in non-environmentally controlled small animal veterinary theatres during routine surgical sterilisations, and to correlate these findings with the managerial practices at the facility. Four veterinary facilities with differing throughputs and managerial practices were recruited into the study. Blood agar settle plates, open from first incision to last suture, were used to quantify organisms that could settle in an incision. The 45 plates yielded 487 bacterial isolates (53 species). The Micrococcus (28.8%) and Staphylococcus (16.8%) genera were predominant. Of the isolates 61.8% were classified as human/small animal commensals and 37.2% belonged to species previously implicated in small animal SSIs. Specific trends were additionally evident in the bioaerosol loads. High room occupancy, lack of surgical attire and exposure to the outside environment were associated with higher bacterial counts. Accumulation from consecutive procedures was identified and linked to total occupancy time of the room. Current mitigation measures were not ideal to minimise the SSI risk. Routine, frequent and thorough cleaning in combination with surgical attire utilisation is recommended to reduce the bioburden for patient benefit.

An Assessment of the Potential Economic Impacts of the Invasive Polyphagous Shot Hole Borer (Coleoptera: Curculionidae) in South Africa

Studies addressing the economic impacts of invasive alien species are biased towards ex-post assessments of the costs and benefits of control options, but ex-ante assessments are also required to deal with potentially damaging invaders. The polyphagous shot hole borer Euwallacea fornicatus (Coleoptera: Curculionidae) is a recent and potentially damaging introduction to South Africa. We assessed the potential impact of this beetle by working across economic and biological disciplines and developing a simulation model that included dynamic mutualistic relations between the beetle and its symbiotic fungus. We modeled the potential growth in beetle populations and their effect on the net present cost of damage to natural forests, urban trees, commercial forestry, and the avocado industry over 10 yr. We modeled high, baseline, and low scenarios using discount rates of 8, 6, and 4%, and a plausible range of costs and mortality rates. Models predicted steady growth in the beetle and fungus populations, leading to average declines in tree populations of between 3.5 and 15.5% over 10 yr. The predicted net present cost was 18.45 billion international dollars (Int. $), or about 0.66% of the country's GDP for our baseline scenario ($2.7 billion to $164 billion for low and high scenarios). Most of the costs are for the removal of urban trees that die as a result of the beetle and its fungal symbiont, as has been found in other regions. We conclude that an ex-ante economic assessment system dynamics model can be useful for informing national strategies on invasive alien species management.

Genetic contributions to autism spectrum disorder

Autism spectrum disorder (autism) is a heterogeneous group of neurodevelopmental conditions characterized by early childhood-onset impairments in communication and social interaction alongside restricted and repetitive behaviors and interests. This review summarizes recent developments in human genetics research in autism, complemented by epigenetic and transcriptomic findings. The clinical heterogeneity of autism is mirrored by a complex genetic architecture involving several types of common and rare variants, ranging from point mutations to large copy number variants, and either inherited or spontaneous (de novo). More than 100 risk genes have been implicated by rare, often de novo, potentially damaging mutations in highly constrained genes. These account for substantial individual risk but a small proportion of the population risk. In contrast, most of the genetic risk is attributable to common inherited variants acting en masse, each individually with small effects. Studies have identified a handful of robustly associated common variants. Different risk genes converge on the same mechanisms, such as gene regulation and synaptic connectivity. These mechanisms are also implicated by genes that are epigenetically and transcriptionally dysregulated in autism. Major challenges to understanding the biological mechanisms include substantial phenotypic heterogeneity, large locus heterogeneity, variable penetrance, and widespread pleiotropy. Considerable increases in sample sizes are needed to better understand the hundreds or thousands of common and rare genetic variants involved. Future research should integrate common and rare variant research, multi-omics data including genomics, epigenomics, and transcriptomics, and refined phenotype assessment with multidimensional and longitudinal measures.

The Association between Maternal Depression, Infant Characteristics and Need for Assistance in A Low-Income-Country

BACKGROUND

Depression in the peripartum period is prevalent in low-income-countries. The identification of women needing referral is often lacking and on the other hand, women in need of support and treatment do not make use of existing support.

OBJECTIVES

To identify risk factors for fetal and postnatal consequences of depression in pregnancy and to investigate further management once women at risk have been identified.

METHODS

The Safe Passage Study was a large prospective multicenter international study. Extensive information, including the Edinburgh postnatal depression scale (EPDS), was collected during the study. At risk women were referred to the study's social worker (SW). Women were categorized according to risk on their EPDS results. Risk categories were characterized and investigated for infant outcomes.

RESULTS

Data from 5,489 women were available for analysis and revealed a 51% prevalence of prenatal depression. Fourteen percent of at-risk women attended SW appointments, while 36% accepted the SW referral but persistently failed to attend. At risk women were significantly younger, had less formal education, had lower monthly income, and lived in more crowded conditions. They used significantly more alcohol and cigarettes. Their infants had shorter gestational ages, lower birth weights and were more growth restricted. Infants of depressed women who missed appointments weighed less and were more growth restricted.

CONCLUSION

Women with high EPDSs had less favorable socioeconomic conditions, used more alcohol or tobacco during pregnancy, and their infants weighed less with more growth restriction. Women who repeatedly missed their appointments came from the poorest socioeconomic conditions and their infants had worse birth outcomes.

Genetics of schizophrenia in the South African Xhosa

Africa, the ancestral home of all modern humans, is the most informative continent for understanding the human genome and its contribution to complex disease. To better understand the genetics of schizophrenia, we studied the illness in the Xhosa population of South Africa, recruiting 909 cases and 917 age-, gender-, and residence-matched controls. Individuals with schizophrenia were significantly more likely than controls to harbor private, severely damaging mutations in genes that are critical to synaptic function, including neural circuitry mediated by the neurotransmitters glutamine, γ-aminobutyric acid, and dopamine. Schizophrenia is genetically highly heterogeneous, involving severe ultrarare mutations in genes that are critical to synaptic plasticity. The depth of genetic variation in Africa revealed this relationship with a moderate sample size and informed our understanding of the genetics of schizophrenia worldwide.

Inflation of 430-parsec bipolar radio bubbles in the Galactic Centre by an energetic event

The Galactic Centre contains a supermassive black hole with a mass of four million Suns¹ within an environment that differs markedly from that of the Galactic disk. Although the black hole is essentially quiescent in the broader context of active galactic nuclei, X-ray observations have provided evidence for energetic outbursts from its surroundings². Also, although the levels of star formation in the Galactic Centre have been approximately constant over the past few hundred million years, there is evidence of increased short-duration bursts³, strongly influenced by the interaction of the black hole with the enhanced gas density present within the ring-like central molecular zone⁴ at Galactic longitude |l| < 0.7 degrees and latitude |b| < 0.2 degrees. The inner 200-parsec region is characterized by large amounts of warm molecular gas⁵, a high cosmic-ray ionization rate⁶, unusual gas chemistry, enhanced synchrotron emission^7,8, and a multitude of radio-emitting magnetized filaments⁹, the origin of which has not been established. Here we report radio imaging that reveals a bipolar bubble structure, with an overall span of 1 degree by 3 degrees (140 parsecs × 430 parsecs), extending above and below the Galactic plane and apparently associated with the Galactic Centre. The structure is edge-brightened and bounded, with symmetry implying creation by an energetic event in the Galactic Centre. We estimate the age of the bubbles to be a few million years, with a total energy of 7 × 10⁵² ergs. We postulate that the progenitor event was a major contributor to the increased cosmic-ray density in the Galactic Centre, and is in turn the principal source of the relativistic particles required to power the synchrotron emission of the radio filaments within and in the vicinity of the bubble cavities.

Respiratory manifestations of rigid spine syndrome

Thoracic abnormalities and respiratory muscle function were investigated in nine patients with rigid spine syndrome. A severe restrictive chest wall defect and limited mobility of the spine associated with clinically significant respiratory muscle weakness were present in all patients. Respiratory muscle strength and endurance were less than 60% of control values. Slight to moderate scoliosis was present in five patients and absent in four. Scoliosis appeared to have only a minor additional effect on respiratory muscle function. Six patients were emaciated, and one patient was underweight, but no relationship was seen between body mass index and respiratory muscle strength. Respiratory muscle function was more impaired in patients with hypoventilation than in normocapnic patients. Respiratory muscle involvement appears to be a significant feature of rigid spine syndrome, terminating in hypercapnic ventilatory failure in some patients.