No abstract

Salmonella enterica serovar (Salmonella Typhi) is the causative bacterial agent of typhoid fever. Environmental surveillance of wastewater and wastewater-impacted surface waters has proven effective in monitoring various pathogens and has recently been applied to Salmonella Typhi. This study evaluated eight sample collection and concentration methods with 12 variations currently being developed and used for Salmonella Typhi surveillance globally to better understand the performance of each method based on its ability to detect Salmonella Typhi and its feasibility. Salmonella Typhi strains Ty21a and Ty2 were seeded to influent wastewater at known concentrations to evaluate the following methods: grab sampling using electropositive filters, centrifugation, direct enrichment, or membrane filtration and trap sampling using Moore swabs. Concentrated samples underwent nucleic acid extraction and were detected and/or quantified via quantitative polymerase chain reaction (qPCR). Results suggest that all methods tested can be successful at concentrating Salmonella Typhi for subsequent detection by qPCR, although each method has its own strengths and weaknesses, including the Salmonella Typhi concentration it is best suited for, with a range of positive detections observed as low as 0.1–0.001 colony-forming units (CFU) Ty21a/mL and 0.01 CFU Ty2/mL. These factors should be considered when identifying a method for environmental surveillance and will greatly depend on the use case planned.

Examine changing emergency medical services (EMS) utilization and response patterns associated with coronavirus disease 2019 (COVID-19) emergency declaration and stay-at-home orders during the first year of the COVID-19 pandemic. MethodsWe conducted an uncontrolled interrupted time series analysis of EMS calls (January 1, 2019 -March 1, 2021) in Marin County, California analyzing call volume (All calls, n=46,055); patient refusal of EMS care or transport and patient care resolved on scene (Calls with opportunity for transport; n=37,401); and call severity (Transported calls; n=27,887). ResultsPre-COVID-19 (1/1/2019-3/2/2020), EMS transported patients were predominately female (50.6%), 80+ years old (31.6%), and Marin County residents (68.0%). During COVID-19 (3/3/2020-3/1/2021), EMS transported patients were predominately male (52.7%), 35-64 years old (29.8%), and Marin County residents (70.4%). After the first stay-at-home order on 3/17/2020, call volume immediately decreased by 48% (adjusted incidence rate ratio [aIRR]=0.52; 95% CI=0.35,0.79) for children (0-15 years) and 34% for adults 80+ years (aIRR=0.66;95% CI=0.46,0.95). The odds of a transported call being prioritized as severe doubled (adjusted odds ratio [aOR]=2.26; 95% CI=1.11,4.59). Though transport refusals increased by 69% for children after the first order (aOR, 1.69 [95% CI, 1.13-2.52]), immediately following the second order on 12/8/2020, transport refusals decreased by 30% for children but increased 38-40% for adults for for 65-79 years). Calls resolved on scene by EMS increased after the first order among all ages and after the second order for adults 16-79 years. ConclusionsCall volume reduced for children and older adults after the first COVID-19 stay-at-home order. Changes in call severity, patient care refusals, and on-scene care provided by EMS indicated a changing role for EMS during the outbreak.

Salmonella enterica serovar (Salmonella Typhi) is the causative bacterial agent of Typhoid fever. Environmental surveillance of wastewater and wastewater-impacted surface waters has proven effective in monitoring various pathogens, and has recently been applied to Salmonella Typhi. This study evaluated eight sample collection and concentration methods with twelve variations currently being developed and used for Salmonella Typhi surveillance globally to better understand the performance of each method based on their ability to detect Salmonella Typhi and feasibility. Salmonella Typhi strains, Ty21a and Ty2, were seeded to influent wastewater at known concentrations to evaluate the following methods: grab sampling using electropositive filters, centrifugation, direct enrichment, or membrane filtration and trap sampling using Moore swabs. Concentrated samples underwent nucleic acid extraction and were detected and/or quantified via qPCR. Results suggest that all methods tested can be successful at concentrating Salmonella Typhi for subsequent detection by qPCR, although each method has its own strengths and weaknesses including the Salmonella Typhi concentrations they are best suited for with a range of positive detections observed as low as 0.1-0.001 CFU Ty21a/mL and 0.01 CFU Ty2/mL. These factors should be considered when identifying a method for environmental surveillance and will greatly depend on the use case planned.

Typhoid fever, an acute febrile disease caused by infection with the bacterium Salmonella enterica serotype Typhi (S. Typhi), continues to be a leading cause of global morbidity and mortality, especially in developing countries with limited access to safe drinking water and adequate sanitation. Environmental surveillance, the process of detecting and enumerating disease-causing agents in wastewater, enables estimating disease prevalence and trends within a community and is a useful tool to monitor the circulation of typhoid fever in endemic regions. This study presents a computational model, which combines dynamic and probabilistic modeling techniques, to predict – on a spatial and temporal scale – the probability of detecting S. Typhi in a wastewater system. This model may be utilized in communities to inform environmental surveillance sampling plans and may provide useful insight into selecting appropriate sampling locations and times.