Listeria outbreak in the US

Sadly, as with many food borne disease outbreaks, such as the German E Coli O104 outbreak earlier in the year, the number of cases of listeria keep rising in the US and the number of fatalities which currently stands at twenty-one. the problem with listeria being the source of the outbreak is that the incubation (onset) period between when you ate the food and when you have symptoms can be 80 days. This is an incredibly long lag time and as the cantaloupe product was only recalled on September 14th - cases could continue for another month or so.

The epi-curve below (Source: CDC) show how the number of cases have been identified as of the last CDC report on October 7th.


In the US, the CDC report suggests there are about 800 cases of listeria reported annually. In the UK the number of listeria cases reported has risen recently (last ten years) doubling to about 200 a year although 2010 saw a reduction see graph (Source: HPA). There is special concern for pregnant women contracting listeria because it can cause abortion.


Vulnerable groups for foodborne illness are the young, the old, the previously sick (immunocompromised) and pregnant women who are more at risk.

Let us hope that the outbreak will have reached its peak and then will be the time to identify the original source of the listeria.

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