Recurrent seasonal outbreak of an emerging serotype of Shiga toxin-producing Escherichia coli (STEC O55:H7 Stx2a) in the south west of England, July 2014 to September 2015.

The first documented British outbreak of Shiga toxin-producing Escherichia coli (STEC) O55:H7 began in the county of Dorset, England, in July 2014. Since then, there have been a total of 31 cases of which 13 presented with haemolytic uraemic syndrome (HUS). The outbreak strain had Shiga toxin (Stx) subtype 2a associated with an elevated risk of HUS. This strain had not previously been isolated from humans or animals in England. The only epidemiological link was living in or having close links to two areas in Dorset. Extensive investigations included testing of animals and household pets. Control measures included extended screening, iterative interviewing and exclusion of cases and high risk contacts. Whole genome sequencing (WGS) confirmed that all the cases were infected with similar strains. A specific source could not be identified. The combination of epidemiological investigation and WGS indicated, however, that this outbreak was possibly caused by recurrent introductions from a local endemic zoonotic source, that a highly similar endemic reservoir appears to exist in the Republic of Ireland but has not been identified elsewhere, and that a subset of cases was associated with human-to-human transmission in a nursery.

Trends in the levels of Escherichia coli in commercially harvested bivalve shellfish from England and Wales, 1999-2008.

Temporal trends in Escherichia coli concentrations in bivalve shellfish were examined using data collected from 57 production areas around the coast of England and Wales during 1999-2008. Downward trends were detected in annual geometric means of E. coli in shellfish from 12% of the sampling points. The percentage of class B areas (E. coli ≤ 4600/100 g shellfish in 90% of samples) increased from 69% to 86% during the 10-year period. The improvement in the microbial quality of shellfish is associated with sewerage improvement schemes largely implemented during 2000-2005. Upward trends were detected in 9% of the points. The causes of these increases are not known. It is recommended that quantitative sanitary profiling of shellfish waters and cost-benefit appraisal over long-term planning horizons are considered as part of sewerage investment programmes under the Water Framework Directive. This would allow greater scope to secure protection and improvement of shellfish water quality.

Nutrient hydrochemistry for a groundwater-dominated catchment: the Hampshire Avon, UK.

The patterns in nitrate and phosphorus sources, loads and concentrations in a groundwater-dominated lowland catchment, the Hampshire Avon, are examined and water quality signatures are used to identify a typology of headwater stream types. The major separations in water quality are linked to geology and groundwater chemistry as modified by the impacts of point source sewage effluents. The water quality of the major tributaries and the main stem of the River Avon are linked to the relative contributions of these source types, the impact of further direct effluent inputs to the main channel and in-stream processing. The tributaries and main stem of the Avon act as net sinks for total reactive phosphorus (TRP). Low concentrations of TRP were found in the Chalk groundwater and the groundwater system acts as an efficient buffer, removing and retaining TRP from water draining from the catchment surface into the aquifer. Thermodynamic analysis of calcium carbonate (CaCO3) solubility controls indicates that this natural 'self-cleansing mechanism' system within the groundwater may be directly linked to CaCO3-P co-precipitation within the aquifer matrix.