Cattle, weather and water: mapping Escherichia coli O157:H7 infections in humans in England and Scotland.

ABSTRACT

Entero-haemorrhagic Escherichia coli O157H7 is a zoonotic pathogen, responsible for a relatively small number of food poisoning and illness outbreaks each year, when compared with other food-borne bacteria capable of causing infections in the population. Nevertheless, E. coli O157H7 is a bacterial pathogen associated with severe human illnesses including bloody diarrhoea and haemolytic uremic syndrome occurring in both outbreak and sporadic settings. In England and Wales approximately 1% of all laboratory-confirmed cases of food poisoning are the result of E. coli O157H7; however, in Scotland this figure increases to 3%. When the size of the population is taken into account and the rate of E. coli O157H7 confirmed cases per 100,000 population is examined, the rate of E. coli 0157H7 infections in Scotland is much greater than England and Wales. The routes of transmission have changed over time, with new routes of transmission such as farm visits emerging. The prevalence of E. coli O157H7 has a seasonal dependency, with greater faecal shedding of the organism in the warmer months; this is directly mirrored in the increased reporting of E. coli O157H7 infection among hospitalized patients. This review attempts to suggest why this phenomenon occurs, paying particular attention to weather, animal movement and private water supplies.