Pathology of illness: S. aureus is an opportunistic pathogen that typically causes infection via open wounds. S. aureus forms a wide range of substances associated with infectivity and illness, including the heat stable enterotoxins that cause food poisoning (Ash 1997). Eleven antigenic types of staphylococcal enterotoxins are currently recognised, with types A and D being involved in most food poisoning outbreaks. The toxins are thought to stimulate neuroreceptors in the intestinal tract which trigger vomiting (Stewart 2003).
Symptoms generally appear around 3 hours after ingestion (range 1–6 hours) and are self-limiting (Ash 1997). Common symptoms are nausea, vomiting, retching, abdominal cramping, and prostration. In more severe cases, headache, muscle cramping and transient changes in blood pressure and pulse rate may occur. Recovery usually takes 1–3 days, but can take longer in severe cases (Ash 1997). All people are susceptible to staphylococcal food poisoning, however the intensity/severity may vary, depending of individual sensitivities. Death from staphylococcal food poisoning is very rare, although it has occurred amongst the elderly (Ash 1997).
Infectious dose/dose response: The amount of enterotoxin that must be ingested to cause illness is not known exactly, but it is generally believed to be in the range 0.1–1.0 µg/kg (ICMSF 1996). Toxin levels within this range are typically reached when S. aureus populations exceed 100 000/g (Ash 1997).
Epidemiological data: Staphylococcal food poisoning associated with seafood consumption has not been reported in Australia (1987–2001). However, a limited number of outbreaks have occurred in other countries such as Canada and the United Kingdom (Sweet et al. 1989; Panisello et al. 2000).
