Cooking seafood thoroughly is one of the most reliable ways to kill these parasites. The U.S. Centers for Disease Control and Prevention recommends cooking seafood to an internal temperature of at least 145°F (63°C).
Does Freezing Fish Make It Safe?
Freezing can kill certain parasites, but the effectiveness depends on the temperature, the duration of freezing, the species of parasite, and the size and type of fish.
For this reason, putting fish in an ordinary household freezer for 24 hours should not be assumed to eliminate every parasite. Commercial parasite-destruction procedures use specific time-and-temperature combinations. Fish intended for raw consumption should come from suppliers who follow applicable food-safety controls.
Even when freezing has successfully controlled parasites, it does not necessarily eliminate all bacteria, viruses, or other hazards. Proper handling and temperature control remain essential.
Shellfish and Raw Oysters
Oysters, clams, and mussels can accumulate microorganisms from the water in which they grow. Some parasitic contamination can occur, but raw shellfish are also associated with bacterial and viral infections.
Cooking shellfish thoroughly reduces many risks. Shells that remain closed after cooking should be discarded, but the fact that a shell opens does not guarantee that the shellfish is free of every harmful microorganism.
People who are pregnant, older, immunocompromised, or otherwise at increased risk of severe foodborne illness should be particularly cautious about raw or undercooked seafood.
4. Fresh Fruits and Vegetables: Clean Does Not Always Mean Contamination-Free
Fresh produce supplies fiber, vitamins, minerals, and beneficial plant compounds. It should remain an important part of a balanced diet. The goal is not to avoid fruits and vegetables, but to prepare them safely.
Produce may become contaminated when it comes into contact with polluted irrigation water, contaminated soil, animal feces, dirty equipment, or unclean hands.
Toxoplasma gondii
Toxoplasma gondii is a parasite that can cause toxoplasmosis. People may acquire it through undercooked meat, contaminated soil, or food and water contaminated with the parasite.
Many healthy people have no symptoms or develop only mild, flu-like illness. However, infection can be serious for people with weakened immune systems. Infection during pregnancy can also harm the developing baby.
Pregnant people and those with significant immune suppression should follow medical guidance on food safety and avoid higher-risk exposures. Washing produce under running water, cooking food appropriately, and washing hands after gardening or handling soil can help reduce risk.
Giardia and Other Intestinal Parasites
Giardia is a microscopic parasite that can cause giardiasis, an intestinal illness often associated with contaminated water. Transmission can also occur when food is contaminated during preparation by an infected person or through unsafe water used to wash or prepare it.
Symptoms may include diarrhea, gas, abdominal cramps, nausea, and greasy stools. Some people experience prolonged symptoms, while others have few or none.
Produce contamination is not always visible. A vegetable may look clean but still have been exposed to contaminated water or handling surfaces. This is why washing remains important even when food comes from a supermarket or appears fresh.
The Right Way to Wash Produce
Follow these practical steps:
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Wash your hands with soap and water before handling food.
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Rinse fruits and vegetables under clean, running water before eating, cutting, or cooking them.
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Rub produce gently with your hands to loosen dirt and surface contamination.
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Use a clean produce brush for firm items such as cucumbers or potatoes.
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Remove damaged or bruised areas when appropriate.
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Peel produce when suitable, while remembering that peeling does not replace handwashing and safe handling.
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Avoid washing produce with soap, household detergent, or bleach. These products are not intended for direct use on food and may leave harmful residues.
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Keep washed produce away from raw meat, seafood, and unclean kitchen surfaces.
Washing reduces contamination but does not sterilize food or guarantee the removal of every parasite. When produce is known or suspected to be contaminated, washing alone may not be sufficient.
5. Unpasteurized Milk and Dairy Products
Raw milk is milk that has not undergone pasteurization, a controlled heat treatment designed to destroy harmful microorganisms.
Raw milk and products made from it can carry a range of disease-causing organisms. Although food-safety discussions sometimes focus on parasites, the risks associated with unpasteurized dairy also include bacteria such as Campylobacter, Salmonella, and certain strains of E. coli.
Cryptosporidium can also spread through contaminated water and, in some circumstances, through contaminated food. It causes cryptosporidiosis, which commonly produces watery diarrhea and abdominal cramps. The illness may be particularly dangerous for people with weakened immune systems.
Pasteurization significantly reduces the risk from many disease-causing microorganisms. For everyday consumption, choose pasteurized milk and dairy products from reputable suppliers, and store them according to the label instructions.
Do not assume that homemade cheese, yogurt, or other dairy products are safe simply because they are fermented or sour. Fermentation does not reliably eliminate every pathogen.
People who are pregnant, very young children, older adults, and people with weakened immune systems should be especially cautious about consuming raw dairy products.
6. Contaminated Water: A Frequently Overlooked Source
Water can transmit parasites when it becomes contaminated with human or animal feces. This can happen through inadequate sanitation, polluted surface water, unsafe wells, damaged water systems, or poor hygiene during food preparation.