b'SalmonellaWhat is it? Between 1981 and 1991, the incidence of Salmonella is a group of bacteria presentingthe non-typhoidal types of Salmonella one of the commonest causes of foodincreased by more than 170 per cent. The poisoning in Great Britain. They can alsorate peaked in 1993 168 . cause typhoid and paratyphoid fevers. More than 2,500 different strains of SalmonellaAt that time, the Chief Medical Officer have been identified, most of which rarelyadvised consumers to stop eating raw eggs cause disease. In humans, illness is causedand said that all vulnerable people should by about 10 strains. The most important areeat only eggs that had been thoroughly S. enteritidis (which originates in infectedcooked 169 . Hundreds of thousands of poultry and eggs) and S. typhimuriumbirds were slaughtered, farmers were (which occurs in cows, pigs and turkeys).compensated and a programme of Salmonella can contaminate meat, eggs,disinfection was introduced alongside a milk and other dairy products 167 . voluntary vaccination scheme 170 . The rate of infection in people declined until 2014 History but has since been increasing again 171 . The Salmonella bacterium was first found in pigs in the late 1800s and outbreaks haveThere were more than 10,000 cases occurred throughout the last 100 years.confirmed in England and Wales in 2018 172and it is estimated that for every confirmed case, there are nearly five unreported cases, suggesting over 47,000 total cases in 2018 173 .Routes of transmissionThe bacteria are shed in the faeces of infected animals 174so it is simple for animals on farms to infect one another, particularly as chickens and pigs - the animals most commonly affected - are also the species most commonly intensively reared. Studies show that poor ventilation, high dust levels 175and overcrowding 176aid the spread of Salmonella among chickens, as does keeping sheds permanently 26'