It is a case of putting the bottom line before our health. This year, a million Americans will succumb to salmonella poisoning. Several hundred will die. Yet in Europe, a cheap vaccine for chickens has slashed the number of cases. Vaccination in Iowa shows US lives can be saved too – but US rules give meat producers no incentive to use a vaccine that doesn't boost their profits.
Salmonella causes more deaths than any other food-borne germ and is the second-most common cause of food-borne illness in the US, according to a new report published by the US Centers for Disease Control and Prevention in Atlanta, Georgia. Poultry, meat and eggs are the biggest source, causing a third of all cases.
But this can be prevented. After a scandal over infected eggs in the UK in the late 1980s, farmers boosted hygiene standards and killed infected flocks. Human cases stayed high until 1998 when British supermarkets started buying eggs only from vaccinated hens, says Sarah O'Brien of the University of Liverpool, UK. Human cases then plummeted with a forty-fold drop between 1993 and 2010.
In the US, a massive recall of eggs due to salmonella in 2010 similarly led to tighter hygiene rules for chicken farms. But the US Food and Drug Administration declared there was "insufficient data on efficacy" to make vaccination compulsory, despite evidence in Europe to the contrary.
Nonetheless, as monitoring programmes have revealed just how widespread the infection is, about a third of US egg producers have started to vaccinate their chickens. That and better hygiene has reduced the number of infected hen houses fivefold in Iowa, the biggest US egg producer, in the past two years, says Darrell Trampel of Iowa State University.
Meat producers have resisted, however, even though there is salmonella on 13 per cent of chicken breasts sold in US supermarkets, says Lance Price of George Washington University in Washington DC. The farmers vaccinate for several poultry diseases, but since salmonella doesn't hurt the birds or affect their growth, says Price – and human illness is not a cost the farmers have to bear – there is no motivation to prevent its spread.
Journal reference: Emerging Infectious Disease, doi.org/kgx
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