Currently, the respiratory route is seen as the most important transmission path for SARS-CoV-2. In this investigation, models of other researchers which had the aim of predicting an infection risk for exposed persons in a room through aerosols emitted by an infectious case-patient were extended. As a novelty – usually neglected – parameters or boundary conditions, namely the non-stationarity of aerosols and the half-life of the aerosolized virus, were included and a new method for determining the quanta emission rate based on measurements of the particle emission rate and respiratory rate at different types of activities was implemented. As a second step, the model was applied to twelve outbreaks to compare the predicted infection risk with the observed attack rate. To estimate a “credible interval” of the predicted infection risk, the quanta emission rate, the respiratory rate as well as the air volume flow were varied. In nine out of twelve outbreaks, the calculated predicted infection risk via aerosols was found to be in the range of the attack rate (with the variation of the boundary conditions) and reasons for the observed larger divergence were discussed. The validation was considered successful and therefore the use of the model could be recommended to predict the risk of an infection via aerosols in given situations. Furthermore, appropriate preventive measures can be designed.

Introduction: Sources of infection of most cases of community-acquired Legionnaires’ disease (CALD) are unknown. Objective: Identification of sources of infection of CALD. Setting: Berlin; December 2016–May 2019. Participants: Adult cases of CALD reported to district health authorities and consenting to the study; age and hospital matched controls. Main outcome measure: Percentage of cases of CALD with attributed source of infection. Methods: Analysis of secondary patient samples for monoclonal antibody (MAb) type (and sequence type); questionnaire-based interviews, analysis of standard household water samples for Legionella concentration followed by MAb (and sequence) typing of Legionella pneumophila serogroup 1 (Lp1) isolates; among cases taking of additional water samples to identify the infectious source as appropriate; recruitment of control persons for comparison of exposure history and Legionella in standard household water samples. For each case an appraisal matrix was filled in to attribute any of three source types (external (non-residence) source, residential non-drinking water (RnDW) source (not directly from drinking water outlet), residential drinking water (RDW) as source) using three evidence types (microbiological results, cluster evidence, analytical-comparative evidence (using added information from controls)). Results: Inclusion of 111 study cases and 202 controls. Median age of cases was 67 years (range 25–93 years), 74 (67%) were male. Among 65 patients with urine typable for MAb type we found a MAb 3/1-positive strain in all of them. Compared to controls being a case was not associated with a higher Legionella concentration in standard household water samples, however, the presence of a MAb 3/1-positive strain was significantly associated (odds ratio (OR) = 4.9, 95% confidence interval (CI) 1.7 to 11). Thus, a source was attributed by microbiological evidence if it contained a MAb 3/1-positive strain. A source was attributed by cluster evidence if at least two cases were exposed to the same source. Statistically significant general source types were attributed by calculating the population attributable risk (analytical-comparative evidence). We identified an external source in 16 (14%) cases, and RDW as source in 28 (25%). Wearing inadequately disinfected dentures was the only RnDW source significantly associated with cases (OR = 3.2, 95% CI 1.3 to 7.8) and led to an additional 8% of cases with source attribution, for a total of 48% of cases attributed. Conclusion: Using the appraisal matrix we attributed almost half of all cases of CALD to an infectious source, predominantly RDW. Risk for LD seems to be conferred primarily by the type of Legionella rather than the amount. Dentures as a new infectious source needs further, in particular, integrated microbiological, molecular and epidemiological confirmation.

In September 2024, a school-aged child (P1), unvaccinated against diphtheria, was hospitalised with severe respiratory diphtheria caused by toxigenic Corynebacterium diphtheriae. P1 subsequently died from the disease. The child’s mother (P2) had pharyngitis 9 days before the onset of symptoms of P1 and subsequently tested positive for C. diphtheriae . In multilocus sequence typing (MLST), the C. diphtheriae isolates from P1 and P2 were of sequence type (ST) 574. In core genome (cg)MLST, they were clonal, suggesting recent human-to-human transmission. This indicates the first autochthonous respiratory diphtheria outbreak by toxigenic C. diphtheriae in Germany since 1984 with epidemiologically- and molecularly-confirmed transmission. Furthermore, the isolates were close to isolates from patients with cutaneous diphtheria among people experiencing homelessness in two major German cities in 2023 and 2024, and to isolates from an outbreak among newly arriving migrants across several European countries, including Germany, detected in 2022. This indicates transmission beyond vulnerable groups. Our findings illustrate the potential of C. diphtheriae spreading further from patients with cutaneous diphtheria and even causing outbreaks of respiratory diphtheria. Given the potentially serious complications of respiratory diphtheria, including death, equitably achieving and maintaining high vaccination coverage among the whole population, especially among vulnerable people is essential.

Background: Toxic alcohols are chemicals with common metabolic characteristics resulting in severe morbidities and mortalities. The current study aimed to assess the efficacy of six scoring systems: The Poison Severity Score (PSS), Acute Physiology and Chronic Health Evaluation (APACHE) II score, Sequential Organ Failure Assessment (SOFA) score, Rapid Acute Physiology Score (RAPS), Rapid Emergency Medicine Score (REMS), and Modified Early Warning Score (MEWS) in stratifying the patients exposed to toxic alcohol based on liability of organ failure, prolonged hospital stay, and need for an antidote. Methods: A seven-year retrospective cross-sectional study was conducted using medical records of adult patients admitted to a poison control center. Results: About 42.6% were complicated with adverse outcomes. Methanol was the worst toxic alcohol and the only cause of blindness and death. About 27.1% of methanol-exposed patients suffered from acute kidney injury, 15.3% suffered from hemodynamic instability and neurological dysfunction, and 8.5% suffered from respiratory failure. An APACHE II score above 8 was the best predictor of unfavorable outcomes, exhibiting the highest area under the curve (0.972), followed by the SOFA score. The APACHE II score was praised for being the best discriminator of an expected prolonged hospital stay. Yet, the simple scores, including RAPS and REMS, showed good performance as unfavorable outcome predictors with no significant variations to PSS, APACHE II score, and SOFA scores. Conclusion: The current study concluded that though the APACHE II and SOFA scores were superior to others, the RAPS and REMS are good, simple, and effective alternatives, particularly when resources are restricted.

Background/Objectives: Nosocomial outbreaks of viral respiratory infections strain healthcare systems and endanger patients and healthcare workers (HCWs). We describe two large nosocomial outbreaks with the SARS-CoV-2 Alpha variant, during its initial emergence in Germany, to assess transmission dynamics, effectiveness of control measures, and challenges in managing highly transmissible respiratory viruses. Methods: Confirmed cases were inpatients, HCWs, or their contacts testing SARS-CoV-2-positive since 1 January 2021 (Hospital A [HA])) or 21 January 2021 (Hospital B [HB])) with N501Y and delH69/V70 spike gene mutations. We conducted case interviews, reviewed medical records and shift schedules, and performed sequencing, genome reconstruction, and phylogenetic analysis. We describe cases, transmission chains, and control measures. Results: HA reported 18 patient cases, 20 HCW cases, and 33 community cases (N = 71). HB reported 48 patient cases, 43 HCW cases (13 in a COVID-19 ward), and 27 community cases (N = 118). In-hospital transmission occurred patient-to-patient, HCW-to-patient, patient-to-HCW, and HCW-to-HCW. HA halted admissions immediately after the initial cases; HB implemented measures gradually. Regular testing detected pre-symptomatic (HA = 6; HB = 18) and asymptomatic cases (HA = 3; HB = 13). Testing of agency staff was incomplete. The suspected primary case was an HCW in HA and a patient in HB who required resuscitation shortly after admission. Conclusions: Early COVID-19 outbreaks offer valuable lessons for managing emerging nosocomial outbreaks of highly transmissible respiratory viruses. Our findings provide empirical evidence for effective interventions, including rapid response, testing, HCW protection, and rigorous contact tracing in high-risk emergency situations. Managing agency staff remains a major challenge.