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Since the beginning of the coronavirus 2019 (covid-19) pandemic, healthcare workers have shown a remarkable resilience and professional dedication despite a fear of becoming infected and infecting others. 1 In a linked paper (doi:10.1136/bmj.m3582), Shah and colleagues now report robust and concerning findings regarding the risks of covid-19 among health workers and their households. 2 In a large register based cohort study, comprising the entire Scottish healthcare workforce, the authors compared the risk of covid-19 related hospital admission between patient facing and non-patient facing workers, their household members, and the general population. Absolute risks were low, but during the first three months of the pandemic patient facing healthcare workers were three times more likely to be admitted with covid-19 than non-patient facing healthcare workers. Risk was doubled among household members of front facing workers, in analyses adjusted for sex, age, ethnicity, socioeconomic status, and comorbidity.

A total of 301 adult questing Ixodes ricinus ticks were collected at 15 different locations along the south and east coasts of Sweden to determine the Borrelia genospecies diversity. Thirty-two ticks (11%) were found to be positive by nested PCR with Borrelia burgdorferi sensu lato-specific primers. Species determination was based on partial sequencing of the 16S rRNA gene and the flagellin gene. Five different Borrelia species were found. The nucleotide sequence of the Borrelia DNA found in two ticks differed extensively from the nucleotide sequences of the Borrelia DNA found in the other ticks, and analysis revealed that they were closely related to the relapsing fever borrelia species Borrelia miyamotoi. This is the first report of a B. miyamotoi-like borrelia in I. ricinus and in Europe. Moreover, the Borrelia DNA of two ticks (6%) clustered within the B. valaisiana complex. B. valaisiana has not previously been reported in Sweden. B. afzelii DNA was found in 14 ticks (44%), and B. garinii DNA was found in 10 ticks (31%). B. burgdorferi sensu stricto DNA was found in four ticks (13%). We conclude that all of the known human-pathogenic species (B. garinii, B. afzelii, and B. burgdorferi sensu stricto) and B. valaisiana found elsewhere in Europe are also present in the Swedish host-seeking tick population and that a B. miyamotoi-like Borrelia species seems to be present in I. ricinus ticks in Europe.Ticks transmit many clinically important pathogens of the genus Borrelia. These spirochetes are responsible for two groups of human disease: Lyme borreliosis (LB) and relapsing fever (RF). LB is the most prevalent tick-borne zoonosis in Europe and North America and affects the skin, joints, heart, and nervous system (31). Borreliae that cause LB are transmitted by hard ticks of the genus Ixodes. In Europe the principal vector is Ixodes ricinus. The disease is caused by spirochetes of the Borrelia burgdorferi sensu lato complex, which consists of 10 different named genospecies. Three species, all found in Europe, are known to be pathogenic for humans: B. burgdorferi sensu strico, B. garinii (4), and B. afzelii (4, 9). Another two species, B. valaisiana (34) and B. lusitaniae (17), have been isolated from European ticks. The pathogenic capabilities of the last two species are still uncertain, although B. valaisiana DNA has been amplified by PCR from patients with LB (29). Two additional Borrelia species have been found in European patients with LB; B. bissettii sp. nov. (26) has been isolated from patients in Slovakia (25), and a novel Borrelia species has been isolated from a patient in The Netherlands (35). There has been an increasing interest in the clinical and diagnostic implications of the different Borrelia species, since an association between the clinical manifestations of LB and the infective species has been suggested (3, 9, 22, 33). The infective Borrelia species also influences the immune response (8, 30).Tick-borne RF, with periodic febrile episodes as the main symptom, is caused by a genetically and e...

Background Noroviruses are the major cause of viral gastroenteritis. Disease transmission is difficult to prevent and outbreaks in health-care facilities commonly occur. Contact with infected persons and contaminated environments are believed to be the main routes of transmission. However, noroviruses have recently been found in aerosols and airborne transmission has been suggested. The aim of our study was to investigate associations between symptoms of gastroenteritis and the presence of airborne norovirus, and to investigate the size of norovirus-carrying particles. Methods Air sampling was repeatedly performed close to 26 patients with norovirus infections. Samples were analyzed for norovirus RNA by reverse transcription quantitative polymerase chain reaction. The times since each patient’s last episodes of vomiting and diarrhea were recorded. Size-separating aerosol particle collection was performed. Results Norovirus RNA was found in 21 (24%) of 86 air samples from 10 different patients. Only air samples during outbreaks, or before a succeeding outbreak, tested positive for norovirus RNA. Airborne norovirus RNA was also strongly associated with a shorter time period since the last vomiting episode (odds ratio 8.1; P = .04 within 3 hours since the last vomiting episode). The concentrations of airborne norovirus ranged from 5–215 copies/m3, and detectable amounts of norovirus RNA were found in particles <0.95 µm and >4.51 µm. Conclusions The results suggest that recent vomiting is the major source of airborne norovirus and imply a connection between airborne norovirus and outbreaks. The presence of norovirus RNA in submicrometre particles indicates that airborne transmission can be an important transmission route.

Background Transmission of covid-19 can occur through inhalation of fine droplets or aerosols containing infectious virus. The objective of this study was to identify situations, patient characteristics, environmental parameters and aerosol-generating procedures (AGPs) associated with airborne SARS-CoV-2 virus. Methods Air samples were collected near hospitalised covid-19 patients and analysed by RT-qPCR. Results were related to distance to the patient, most recent patient diagnostic PCR Ct-value, room ventilation and ongoing potential AGP. Results In total 310 air samples were collected, and of these 26 (8%) were positive. Of the 231 samples from patient rooms, 22 (10%) were positive for SARS-CoV-2. Positive air samples were associated with a low patient Ct-value (OR 5.0 for a Ct-value <25 vs >25, p=0.01, 95% confidence interval 1.18 to 29.5) and a shorter physical distance to the patient (OR 2.0 for every meter closer to the patient, p=0.05, CI 1.0 to 3.8). A mobile HEPA-filtration unit in the room decreased the proportion of positive samples (OR 0.3, p=0.02, CI 0.12 to 0.98). No association was observed between SARS-CoV-2 positive air samples and mechanical ventilation, high flow nasal cannula, nebulizer treatment or non-invasive ventilation. An association was found with positive expiratory pressure (PEP) training (p<0.01) and a trend towards association for airway manipulation, including bronchoscopies and in- and extubations. Conclusions Our results show that major risk factors for airborne SARS-CoV-2 include short physical distance, high patient viral load and poor room ventilation. AGPs, as traditionally defined, seem to be of secondary importance.