Can you get sick from raw swordfish?

Quick Answer

Yes, you can get sick from eating raw or undercooked swordfish. Swordfish contains parasites and bacteria that can cause foodborne illnesses if the fish is not cooked to a proper internal temperature. Eating raw or undercooked swordfish puts you at risk for parasitic infections, vibriosis, scombroid poisoning, and mercury poisoning. To reduce your risk, swordfish should be cooked to an internal temperature of at least 145°F.

What illnesses can you get from raw swordfish?

There are several illnesses that you can get from consuming raw or undercooked swordfish:

Parasitic infections

Swordfish often harbor parasitic roundworms in their flesh that can be transmitted to humans who eat the raw or undercooked fish. Parasites like anisakis simplex can attach to the stomach and intestine linings, causing symptoms like nausea, vomiting, diarrhea, abdominal pain, and fever.¹

Vibriosis

Vibriosis is caused by vibrio bacteria that live in coastal waters. Raw swordfish can contain vibrio such as Vibrio parahaemolyticus. Ingesting raw swordfish contaminated with vibrio can lead to watery diarrhea, abdominal cramping, nausea, vomiting, fever and chills within 24 hours. In rare cases it can become very serious. ²

Scombroid poisoning

Scombroid poisoning is caused by eating fish that contain high levels of histamine. Improperly refrigerated swordfish can harbor high levels of bacteria that convert histidine into histamine. Consuming fish with high histamine can cause symptoms like hives, itching, nausea, vomiting, diarrhea, headache, palpitations, dizziness, and peppery taste within a few minutes to a few hours after ingestion.³

Mercury poisoning

Swordfish contain relatively high levels of mercury. Consuming raw or undercooked swordfish can expose you to high doses of mercury. Mercury is a heavy metal that acts as a neurotoxin. Symptoms of mercury poisoning include tingling in the extremities, muscle weakness, trouble speaking, hearing, and seeing, lack of coordination, and mental disturbances. Young children and pregnant women are especially susceptible.⁴

What are the risks of eating raw swordfish?

There are a few key risks associated with consuming raw or undercooked swordfish:

• Foodborne illness – Raw swordfish can harbor harmful bacteria, viruses, and parasites that can lead to illnesses like vibriosis, scombroid poisoning, parasitic infections, and norovirus.
• Mercury exposure – The high mercury levels in swordfish can accumulate in your body over time and lead to mercury poisoning.
• Reactions in sensitive groups – Raw swordfish poses greater risks for people with compromised immune systems, older adults, young children, and pregnant women.
• Allergic reactions – Some people may have allergic reactions to compounds present in raw swordfish.
• Antibiotic resistance – Raw fish may contain antibiotic-resistant bacteria that can be difficult to treat if an infection occurs.

Due to these risks, the FDA recommends cooking swordfish to an internal temperature of 145°F prior to consumption. Pregnant women and young children should take extra precautions due to mercury exposure risks.

What diseases can you get from swordfish?

In addition to the general illnesses that can occur from eating raw fish, swordfish specifically can transmit the following diseases:

Anisakiasis

Anisakiasis is caused by anisakid nematode parasites. When humans ingest the live larvae from undercooked fish, the larvae can burrow into the stomach or intestinal wall, causing symptoms like nausea, vomiting, and abdominal pain. Swordfish is one of the fish most commonly infected with anisakid nematodes.⁵

Ciguatera fish poisoning

Ciguatera toxins produced by dinoflagellates in reef areas can accumulate up the food chain into fish like swordfish. Eating contaminated swordfish can cause ciguatera fish poisoning leading to abdominal pain, nausea, vomiting, and neurological symptoms like tingling, numbness, and paralysis within 1-6 hours of ingestion.⁶

Scombroid poisoning

As mentioned earlier, scombroid poisoning can result from ingesting swordfish with high histamine levels due to improper storage. Symptoms usually start within a few minutes to an hour after eating contaminated swordfish.

Viral infections

Eating raw or undercooked swordfish can expose you to foodborne viruses like norovirus, hepatitis A, and rotavirus that can cause gastroenteritis.⁷ Proper cooking helps kill these viruses.

Who is most at risk when eating raw swordfish?

Certain groups of people are at higher risk for illness from consuming raw or undercooked swordfish:

• Pregnant women – Raw swordfish puts pregnant women at risk for listeria infection which can cause pregnancy complications or miscarriage. Mercury in raw swordfish can also harm fetal neurological development.
• Young children – Children’s underdeveloped immune systems make them more prone to infections from bacteria, viruses, and parasites in raw fish. Their smaller body size also puts them at greater risk for mercury poisoning.
• Older adults – Weakened immune systems put seniors at increased risk for foodborne illnesses. And long-term exposure to mercury can exacerbate effects of dementia.
• People with compromised immunity – Conditions like HIV/AIDS, cancer, diabetes, and autoimmune disorders impair immune response to pathogens in raw fish.
• People with liver or kidney problems – Impaired liver or kidney function reduces the body’s ability to process and clear mercury.

In addition to the above groups, anyone with an allergy or sensitivity to fish should avoid raw swordfish.

What are the symptoms of sickness from raw swordfish?

The symptoms of illness from raw swordfish will vary depending on the exact infection or toxin involved:

Parasites

• Nausea, vomiting
• Diarrhea
• Abdominal pain, cramps
• Fever
• Fatigue
• Unintended weight loss

Bacteria

• Watery, bloody diarrhea
• Abdominal cramps
• Nausea, vomiting
• Fever
• Chills
• Headache

Viruses

• Nausea, vomiting
• Diarrhea
• Abdominal pain
• Muscle aches
• Fatigue
• Low-grade fever

Scombroid poisoning

• Flushing, rash
• Headache
• Itching, hives
• Abdominal cramps
• Nausea, vomiting
• Diarrhea
• Palpitations
• Dizziness

Mercury poisoning

• Loss of coordination
• Numbness around the mouth
• Tunnel vision
• Muscle weakness
• Slurred speech
• Memory problems
• Irritability
• Depression

Seek medical attention if symptoms are severe or persistent.

How to cook swordfish safely?

To kill any potentially harmful bacteria, parasites, and viruses, swordfish should be cooked to an internal temperature of at least 145°F/63°C. Here are some tips for safely cooking swordfish:

• Use a food thermometer to check the internal temperature when cooking. Insert the thermometer into the thickest part of the flesh.
• Grill, broil, bake, or pan-sear swordfish steaks over medium-high heat until opaque and flakes easily with a fork.
• Poach swordfish by simmering gently in liquid like wine, broth, or court bouillon until cooked through.
• Bread and pan fry swordfish steaks until golden brown and cooked through.
• When boiling swordfish, cook for at least 3-4 minutes after the water returns to a boil.
• Cook swordfish thoroughly when making dishes like fish tacos, seafood stew, fish curry, etc.
• Don’t eat any parts of swordfish with blackened skin or large bruises.

Properly cooked swordfish should have opaque, pearly white flesh that separates into moist flakes. Discard any fish that still has translucent, raw-looking sections after cooking.

What is the safest way to eat raw swordfish?

While the only way to completely eliminate the risks is to cook swordfish thoroughly, here are some tips to reduce the risks of eating raw swordfish:

• Purchase sushi-grade swordfish from a trusted retailer that follows proper freezing protocols to kill parasites.
• Avoid raw swordfish if you are in a higher risk group like pregnant women, elderly, or immunocompromised.
• Limit your consumption to minimize exposure to heavy metals like mercury.
• Check that raw swordfish smells fresh – it should not have a strong fishy odor.
• Make sure raw swordfish has a shiny, firm texture without bruising.
• Consume raw swordfish dishes like sushi within two days of purchase.
• Opt for vinegar-citrus marinated swordfish dishes like ceviche.
• Avoid cross-contamination by properly sanitizing countertops and utensils after prep.
• Refrigerate leftovers promptly and reheat fully before consuming again.

Conclusion

Raw or undercooked swordfish can harbor a range of pathogenic bacteria, viruses, parasites, and toxins that can lead to foodborne illnesses. To reduce your risk, swordfish should be cooked to an internal temperature of at least 145°F. Proper storage and handling procedures are also essential. Pregnant women and children should avoid raw or undercooked swordfish. If choosing to eat raw swordfish despite the risks, go with sushi-grade fish from a trusted source and take extra care with preparation and storage. Monitor for any symptoms after consumption and see a doctor if they develop. With proper precautions, both raw and cooked swordfish can be enjoyed safely and responsibly.