Diseases in shrimp
Shrimp are shellfish like crabs, lobster, and prawns. Never eat any raw seafood, and make sure that any shrimp you eat is cooked thoroughly.
Shrimp are shellfish like crabs, lobster, and prawns. They have a sweet taste, are firm or tender in texture, and are popular seafood. Shrimp are a good source of protein, minerals, and vitamins. Compared to meat, shellfish are a healthier source of protein, as they have little fat and saturated fatty acids.
Still, shrimp are often contaminated with disease-causing bacteria and have been associated with disease outbreaks. So, can you eat raw shrimp safely?
Most shrimp are commercially grown in farms. Heavy stocking densities, the use of chemicals and drugs, and unhygienic practices in harvesting and packing can cause contamination by disease-causing bacteria and viruses. The ponds used for shrimp culture also draw water from rivers that may receive untreated human sewage. This is a source of disease-causing organisms that contaminate the shrimp.
Common bacteria that contaminate shrimp farms include Vibrio and Salmonella species. These bacteria have been detected in the shrimp farm water supplies, pond water, feeding materials, shrimp at the farms, and frozen shrimp being exported. Both these bacteria varieties can cause severe diseases.
Contamination of the water supply can also infect shrimp with Escherichia coli. The ice used for conserving shrimp may be a source of contamination. The E. coli infecting shrimp can be toxin-producing.
Viruses that infect shrimp include caliciviruses (including norovirus) and hepatitis A virus. Shrimp may become contaminated during harvesting, processing, or preparation. Storage at the wrong temperature, contamination by an infected food handler, or cross-contamination through contact with other seafood or water can also infect shrimp.
Salmonellosis
Salmonella are disease-causing bacteria, and several species can contaminate shrimp. They cause abdominal cramps, diarrhea, and fever. Some salmonella can cause enteric fever (typhoid fever). Other illnesses you may get after consuming Salmonella include urinary tract infections and bacteremia (bloodstream infection).
Salmonella infection isn't rare — the US has over a million infections a year. The symptoms may begin 6 hours to 6 days after eating contaminated shrimp. You may be sick for 4 to 7 days, and the illness can be severe enough to require hospitalization. Your doctor may prescribe antibiotics if you have severe illness.
You should talk to your doctor if you have a high fever, bloody stools, severe diarrhea or vomiting, or signs of dehydration.
An outbreak of Salmonella illness in 2021 was caused by frozen precooked shrimp. Many people across several states fell sick, and some were hospitalized. Several lots of contaminated shrimp products were recalled.
Vibrio infections
Vibrio are bacteria that cause intestinal infections. About 30 species of Vibrio are known, and many of them can cause infections and disease in humans. The most common species infecting shrimp (and then humans) is Vibrio parahaemolyticus.
Vibrio infection illness usually begins 24 hours after eating contaminated seafood. You may have stomach cramps, watery diarrhea, nausea, vomiting, fever, and chills. The illness may last 3 days, and the accompanying diarrhea can cause dehydration. You should take a lot of fluids by mouth to prevent and reverse dehydration.
Vibrio infections can be severe. They cause 500 hospitalizations and 100 deaths in the U.S. each year. Your doctor may prescribe antibiotics if your condition seems severe.
Norovirus
A norovirus infection causes a disease with vomiting, nausea, diarrhea, and abdominal cramps. You may also experience muscle pain, fever, or headache.
Norovirus disease symptoms usually begin 12 to 48 hours after consumption of infected shrimp. The illness lasts 1 to 3 days. Frequent vomiting and diarrhea may cause dehydration, especially in children and older people.
Shrimp — nutritional benefits and additional risks
Considering the risks associated with shrimp, why would you eat them?
Shrimp, like other seafood, are valuable for a healthy diet. A 3-ounce (85-gram) portion provides:
Protein: 20 grams
Energy: 95 calories.
Total fats: 1 gram
Saturated fats: 0.1 grams
Polyunsaturated fats: 0.4 grams
Shrimp provides high-quality proteins with few calories and very little saturated fat. They also provide minerals like copper, iodine, selenium, and zinc. Shellfish are good sources of long-chain omega-3 fatty acids, though not as good as oily fish like herrings and sardines. Omega-3 fatty acids benefit heart health.
You should include two portions (5 ounces or 140 grams each) of fish or shellfish like shrimp a week in your diet. American diets tend to depend on red meat for protein requirements. Replacing it with seafood will reduce the saturated fats in your diet and reduce your risk of colon cancer.
Many types of fish contain mercury and other contaminants and are considered unsafe for daily consumption. Shrimp are generally safe to eat, though, and you can eat them as often as you like. Among shellfish, only brown crab meat is considered unsafe.
Pregnancy concerns
Fish provides nutrients for you and your baby, but you should be especially careful about infections during pregnancy. Never eat any raw seafood, and make sure that any shrimp you eat is cooked thoroughly.
Allergies
Shellfish allergy is common and can cause severe reactions. Cross-allergy is also common — if you've had an allergic reaction to prawns or oysters, you should be wary of shrimps, too. Cooking shellfish doesn't reduce the possibility of allergic reactions.
Shrimp safety
Some safety measures you can take include:
Buy shrimps only from reputable sources. Shrimp harvested from unsafe waters can have high levels of contaminants. These toxins are not eliminated by cooking and can cause vomiting, diarrhea, headache, breathing difficulty, disorientation, and memory loss.
Pick up shrimp last when shopping, and go directly home to refrigerate them. Shrimp spoils rapidly outside of a refrigerator.
Opt for steaming, baking, or grilling shrimp. These methods retain the nutrients, kill bacteria and viruses, and are healthier choices than frying. Frying in oil or batter also increases the fat content of fish and shellfish.
Shrimp should be cooked until the flesh is white and opaque.
When buying shrimp, make sure it smells fresh. Rancid, fishy, sour, or ammonia smells are signs of spoiled shrimp. If your cooked shrimp smells sour, rancid, or fishy, you shouldn't eat it. Similarly, if you smell ammonia odor at all, do not eat the shrimp.
Eating raw shrimp provides you the same nutritional benefits as cooked shrimp, and you may prefer the taste. However, shrimp often carry dangerous infections, and cooking them well is crucial for safety.
Medically Reviewed on 10/3/2022
References
SOURCES:
Centers for Disease Control and Prevention: "The final update on a multistate outbreak of Vibrio parahaemolyticus infections linked to fresh crab meat," "Salmonella," "Salmonella. Investigation details," "The Symptoms of Norovirus."
Clinical Microbiology Review: "Epidemiology of seafood-associated infections in the United States."
Letters in Applied Microbiology: "Detection of pathogenic Escherichia coli and microbiological quality of chilled shrimp sold in street markets."
National Health Service: "Fish and shellfish," "Red meat and the risk of bowel cancer."
Revue Scientifique et Technique: "Problems associated with shellfish farming."
US Department of Agriculture: "Nutritive Value of Foods."
US Department of Health and Human Services. Food Safety: "Cook to a Safe Minimum Internal Temperature," "Safe Selection and Handling of Fish and Shellfish."
