Key recommendations include updating UK health guidelines to pregnant women, and a call for more studies on the extent and concentration of the Toxoplasma gondii parasite in the nation’s food.
Toxoplasmosis is an infection caused by this parasite - pictured within a human cell - that occurs worldwide in most warm-blooded mammals, including humans, and the US Department of Agriculture (USDA) says it is the third-leading cause of death from foodbourne illness worldwide.
According to the UK National Health Service (NHS), food sources include undercooked or raw meat, raw cured meat (including Parma ham, salami) and unpasteurised goat’s milk, and the infection can pass between humans from a pregnant woman to an unborn baby.
Although toxoplasmosis usually only causes mild flu-like symptoms in adults, the ACMSF said it can be fatal to babies, and has been linked with associated jaundice, eye infections and seizures.
The FSA’s scientific advisory committee was asked to consider whether current evidence indicates a food safety issue that needs to be addressed, what food sources could present a significant risk and identify further work needed on UK prevalence and foodborne sources of toxoplasmosis.
Life-threatening symptoms
In its subsequent draft report – open for consultation until March 7 – the ACMSF concluded that the largest disease burden of toxoplasmosis would likely relate to immune-compromised people with “more severe and potentially life-threatening” symptoms.
The committee said accurate figures were unavailable for toxoplasmosis, but estimated that 350,000 people are infected with toxoplasma each year in the UK, with 20-25% showing symptoms.
Lack of accurate data for overall incidence and symptom severity prevented an accurate estimate of disease burden and its economic impact in the UK, according to the ACMSF.
But the body said it was reasonable to assume that the impact would not be significantly different from US and Dutch assessments that “the costs of the relatively small proportion of cases with severe disease make toxoplasmosis one of the most costly gastro-intestinal infections”.
Toxoplasma sources included a variety of meats, the ACMSF said, although it added – albeit pointing to limited evidence – that beef and housed chicken seemed less commonly infected than other meats.
The committee explained that T.gondii has three infectious stages, and that during the first two: tachyzoites (where it is usually destroyed by gastric digestion) and bradyzoites, the organism was relatively fragile,
However, it warned that oocysts (in the environment or feline hosts) and tissue cysts (containing bradyzoites, and formed as immunity develops after an infection) were relatively resistant to food preparation and processing.
Scientific work needed
According to the committee, washing salads and vegetables may remove some oocyst surface contamination, but inactivation of more resistant tissue cyst required adequate cooking, while curing meats may also inactivate these cysts.
But the ACMSF said the risk assessment process would be boosted by further studies to determine extent and concentration of toxoplasma contamination in the nation’s food.
Work could also be done to assess the effect of microbiological reduction/destruction processes such as salad washing, milk fermentation and various meat curing methods on toxoplasma, the body added.
And given conflicting consumer advice relating to toxoplasmosis within different country's, the FSA’s advisory committee also recommended that current UK advice to pregnant women (contained within general NHS guidelines) be reviewed in light of current knowledge and different foreign guidelines.
A full copy of the draft report, 'Risk Profile in Relation to Toxoplasma in the Food Chain', is available here.