Some foods can occasionally carry parasites if they are raw, undercooked, or contaminated during production or handling. While headlines often exaggerate the risk, doctors and food safety experts do recommend taking certain precautions. Here are four foods that are most commonly associated with parasitic infections.
1. Raw or Undercooked Pork
Possible parasites
- Trichinella spiralis (causes trichinellosis)
- Taenia solium
How infection occurs
Eating undercooked pork containing parasite larvae can allow them to survive digestion and infect the body.
Symptoms
- Muscle pain
- Fever
- Swelling around the eyes
- Diarrhoea
- Fatigue
Prevention
- Cook pork to an internal temperature of 63°C (145°F) followed by a 3-minute rest (or according to current food safety guidance).
- Avoid tasting undercooked pork.
- Buy meat from reputable suppliers.
2. Raw or Undercooked Fish (Sushi, Sashimi, Ceviche)
Possible parasites
- Anisakis simplex
- Fish tapeworms (such as Diphyllobothrium latum)
How infection occurs
Wild marine fish can contain parasite larvae. Eating them raw may allow the larvae to infect the digestive tract.
Symptoms
- Sudden stomach pain
- Nausea
- Vomiting
- Allergic reactions
- Intestinal blockage (rare)
Prevention
- Eat sushi from reputable establishments.
- Fish intended for raw consumption is typically frozen to temperatures that kill most parasites before serving.
- Proper cooking also eliminates these parasites.
3. Raw Oysters and Other Shellfish
Possible parasites and pathogens
Shellfish are more commonly linked to bacteria and viruses than parasites, but contaminated waters can expose them to various infectious organisms, including some parasitic protozoa.
Examples include:
- Cryptosporidium
- Giardia duodenalis (less commonly associated)
Symptoms
- Diarrhoea
- Vomiting
- Abdominal cramps
- Dehydration
Prevention
- Eat shellfish from approved sources.
- Cook shellfish thoroughly, especially if you are pregnant or have a weakened immune system.
4. Unwashed Fruits and Vegetables
Possible parasites
- Toxoplasma gondii
- Cyclospora cayetanensis
- Giardia duodenalis (through contaminated water)
How contamination happens
Produce may become contaminated through:
- Soil
- Contaminated irrigation water
- Animal faeces
- Improper handling
Symptoms
- Diarrhoea
- Stomach cramps
- Nausea
- Fever
- Fatigue
Prevention
- Wash fresh produce thoroughly under running water.
- Peel fruits when appropriate.
- Refrigerate fresh produce promptly.
Who Is Most at Risk?
Certain groups are more likely to develop severe illness from foodborne parasites:
- Pregnant women
- Young children
- Older adults
- People with weakened immune systems
- Organ transplant recipients
General Food Safety Tips
To reduce the risk of parasitic infections:
- Cook meat and seafood thoroughly.
- Wash fruits and vegetables before eating.
- Avoid cross-contamination by using separate cutting boards for raw meat and ready-to-eat foods.
- Wash hands before preparing food and after handling raw meat.
- Drink clean, safe water, especially when travelling.
- Purchase seafood and meat from reputable suppliers.
Bottom line
These foods are not inherently dangerous, and millions of people eat them safely every day. The risk mainly comes from consuming them raw, undercooked, or from unreliable sources. Following good food hygiene and proper cooking practices greatly reduces the chance of acquiring a foodborne parasitic infection.