Food poisoning outbreaks can go on for quite some time. For instance, a UK outbreak of listeriosis associated with pâté in the late 80s lasted for about three years, affecting at least 350 people and killing about 90 of them. The usual reason for a protracted outbreak is a failure to find the source and deal with it. That was certainly the case with the British Listeria outbreak, but that was mainly because foodborne listeriosis was a relatively new phenomenon at the time and no one knew much about it. Today we are much better equipped for tracking outbreaks back to their sources quickly, though highly complex supply chains can still occasionally defeat investigators. The on-going Salmonella Heidelberg outbreak in the USA is rather different. It began in March last year and has so far affected at least 574 people, mostly in California. According to CDC an average of eight new cases are still being reported every week, although there does seem to be some evidence of a downward trend. The striking difference between this and other long-lasting outbreaks is that the source of this one was identified as long ago as last July.
So why is this outbreak still going on when a clear link with Foster Farms brand raw chicken meat has been established? Both CDC and the USDA are of the opinion that raw poultry meat is sometimes contaminated with Salmonella and that the end-user should take some responsibility for safety by adopting good hygiene practices in the kitchen. Therefore Foster Farms has not been requested to recall any product and is still processing, packing and marketing chicken as normal. This is not because the problem has been resolved – Dr Robert Tauxe at CDC has said that recent cases were found to have eaten newly purchased chicken rather than meat from the freezer – but more likely because Salmonella contamination in poultry is regarded as endemic. This is not to say that nothing is being done. Dr Tauxe has said that Foster Farms has introduced a number of changes at its facilities, as well as interventions at farm level, although these will take time to have a positive effect. Officials from the USDA have also intensified sampling at three Foster Farms plants in California where Salmonella has been detected.
American consumers might be forgiven for thinking that this response is not really good enough, especially as the outbreak strain of Salmonella Heidelberg is resistant to several antibiotics and has caused 37% of its victims to be admitted to hospital. Is it really acceptable to rely largely on consumers to protect themselves from this threat? Unfortunately in the short term there are few practical alternatives. This outbreak represents a much wider problem with intensive poultry production in the USA and many other countries. Low-level Salmonella contamination is common and will occasionally cause outbreaks. Furthermore, overuse of antibiotics to control endemic infections in flocks is contributing to an increase in bacterial resistance, potentially resulting in more dangerous outbreaks. The solution is a series of interventions designed to eliminate Salmonella at every stage in the production chain. Salmonella-free poultry is possible – it has been on sale in Denmark since 1996 – and Foster Farms itself has had some success in reducing contamination levels at its Washington plant after it was linked to an earlier outbreak. The poultry industry has the tools to start eliminating endemic Salmonella from its products and it’s becoming harder to justify not doing so.