food_poisoning
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food poisoning
Introduction
- illness after eating food may be caused by either:
- toxins in the food produced by bacterial contamination of the food
- symptoms tend to occur very soon after ingestion eg. Staph, E.coli toxins, botulism (or may take days)
- bacterial or viral contamination of the food resulting in infection
- many foods stored in the “danger zone” of 5-60degC for some hours may become tainted with excessive growths of pathogenic bacteria
- food that needs to be chilled should be kept below 5degC, and hot food should be maintained and served above 60degC
- meats should be cooked to the minimum recommended temperatures for the type of meat
- boiling suspect water is a good way to eliminate hepatitis A and giardia
- unlike heating, freezing foods does not usually kill pathogens it just slows their growth substantially
- avoid eggs that are dirty or cracked
- avoid eating foods past their expiry date
- unpasteurised milk causes 840x more illnesses and 45x more hospitalisations from illness than pasteurised milk - esp. Campylobacter, Cryptosporidium, E. coli, Listeria, Brucella, and Salmonella (and potentially viruses including avian influenza) 1).
- symptoms may be delayed by months eg. Listeria monocytogenes / Listeriosis, parasites
- allergy reactions
- type 1 HS reactions such as:
- eggs in infants
- peanuts, cashews, walnuts
- shellfish
- quinine (rare severe kidney injury via immune-mediated thrombotic microangiopathy (TMA))
- food intolerances
- inability to absorb the amount of sugars, etc
- organic disease and other causes of food “intolerance”
causes of food poisoning
- Norovirus was the primary contaminant in fruits and vegetables during foodborne illness outbreaks in the European Union (EU) and the United States (US) during 2004-12, followed by bacterial pathogens - three bacterial pathogens, Listeria monocytogenes, Escherichia coli (mainly Shiga toxin-producing E. coli (STEC) ), and Salmonella enterica, were responsible for 82% of hospitalizations and deaths due to foodborne illnesses in the US during 2009-15 2)
- fruit and vegetable supplies can be contaminated by enteric pathogens (mainly via pathogens in soil) via:
- production sites were previously used for waste disposal or animal rearing
- extreme weather events such as dust storms and flooding
- germinating seeds attracting enteric pathogens in soil
- sowing of pre-contaminated seeds
- contaminated irrigation water
- bacterial pathogens can survive on leaves for several weeks to months via various colonization methods such as biofilms, cellulose synthase complex, internalizing into plant tissue through surface pores, etc.
- risk of crop contamination by enteric pathogens increases as urban populations extend into the countryside
- a US 2025 study suggested that 18% of UTI's are due to the same E.coli strain contaminating meat (esp. poultry) and that lower socioeconomic areas, women and older men were most at risk3)
| organism | time to symptoms | food source | duration |
|---|---|---|---|
| food toxin mediated | |||
| Bacillus cereus | 1-2hrs | rice | 12-24hrs |
| Staphylococcus aureus | 2-6hrs | meat, milk | 6-24hrs - mainly vomiting |
| Clostridium botulinum | 18-36hrs | canned food | weeks |
| ciguatera toxin | 15min-24hrs | reef fish | neurologic symptoms as well as gastro |
| scombroid | 10-30min | spoiled fish | anaphylactoid response due to ingestion of biogenic amines, especially histamine |
| blue-green algae (BGA) toxins in waterways | blue-green algae water | ||
| pathogenic | |||
| Salmonella | 8-48hrs | poultry, eggs, salads, water | 1-7 days, often blood diarrhoea |
| Vibrio parahaemolyticus | 12-48hrs | crabs, shellfish | 2-5 days |
| norovirus | 12-48hrs | shellfish, salads, direct spread | 1-3 days |
| Clostridium perfringens | 8-22hrs | meat | 12-48hrs mainly diarrhoea |
| enterohaemorrhagic E.coli | 1-7 days | meat | 7-21 days |
| enterotoxigenic E.coli | 3-5 days | meat | acute watery diarrhoea |
| pathogenic E.coli strains | meat, esp. poultry | UTIs4) | |
| Campylobacter | 1-10 days | poultry, milk, salads, water | diarrhoea may be bloody, minimal if any vomiting |
| Shewannella haliotis | 3-49 days | raw fish, shellfish, most cases are in Asia in Summer | may cause hepatobiliary infections, bacteraemia, appendicitis with abscesses in elderly, those with hepatibiliary disease or the immunocompromised |
| typhoid | 5-21 days | water, food handlers | weeks; initial green pea soup diarrhoea then ramping fevers |
| paratyphoid | more abrupt onset, and milder than typhoid | water, food handlers | |
| shigella | 1-3 days | water, food handlers (also STI) | dysentery type |
| cholera | 1-5 days | water, food handlers | profuse watery diarrhoea |
| giardiasis | 3-25 days | water, salads | 1 to several weeks |
| cryptosporidium | 1-12 days | water, salads | 1-2wks if not immunocompromised; mainly diarrhoea |
| toxoplasmosis | creek water, rare red meats (heat > 66degC or freezing kills the parasite) - a study in 2020 showed that Australian lamb mince meat had over 40% chance of being infected5), water soiled by cats | lifelong infection; may cause retinitis and floaters; dangerous to foetus or neonates or immunocompromised | |
| other parasites | rare meats (esp. pork, fish, snails, etc); aquatic plants; | various, esp. GIT, tissue, liver, lung infections and rarely CNS - in 2023 a Canberra woman had a 8cm long live Ophidascaris robertsi python roundworm in her brain after using aquatic plants from nearby lake in cooking |
food_poisoning.1761257302.txt.gz · Last modified: 2025/10/23 22:08 by gary1