What is salmonella and why is it a concern with eggs?
Salmonella is a bacteria that can cause foodborne illness, known as salmonellosis. There are over 2,500 different serotypes of Salmonella bacteria, with Salmonella Enteritidis being most commonly associated with poultry and eggs.
Salmonella infections are one of the most common causes of food poisoning in the United States, with over 1 million cases estimated to occur each year. Most people infected with Salmonella develop diarrhea, fever, and stomach cramps between 6 hours to 6 days after ingesting the bacteria. The illness usually lasts 4 to 7 days and most people recover without treatment. However, salmonellosis can be serious or even life-threatening for vulnerable populations such as the elderly, infants, or those with compromised immune systems.
Eggs can sometimes be contaminated with Salmonella bacteria. Inside an egg, there is a protective barrier between the shell and the inner contents that helps prevent bacteria from getting inside. However, eggs can become infected in a chicken’s ovaries or oviducts before the shell forms around them. The chicken can appear healthy while still passing the bacteria onto the egg before it is laid. Salmonella can also get onto the outside of egg shells from contact with fecal matter or the environment, such as in the nest box.
Proper cooking and handling of eggs destroys any potential Salmonella bacteria present. However, eating raw or undercooked egg products increases your risk of getting a Salmonella infection.
What are the symptoms of a salmonella infection?
The most common symptoms of salmonellosis include:
– Diarrhea – Can range from mild and watery to severe and bloody
– Fever – Usually between 100-102°F
– Abdominal cramps
– Nausea and vomiting – More common in children
– Chills
– Headache
– Loss of appetite
Symptoms typically start 6 hours to 6 days after ingesting Salmonella bacteria, with most people developing symptoms within 12-72 hours. The illness usually lasts for 4-7 days and does not require treatment in healthy individuals as it resolves on its own.
Some people may experience more severe symptoms that require prompt medical attention:
– High fever (over 102°F)
– Bloody diarrhea
– Prolonged vomiting preventing fluid intake
– Signs of dehydration – Excessive thirst, dry mouth, little or no urination
– Inability to keep liquids down
– Diarrhea for more than 3 days
Infants, elderly adults, and people with compromised immune systems are at highest risk of severe illness from a Salmonella infection. Seek medical care immediately if someone in these vulnerable groups develops salmonellosis.
How do eggs get contaminated with salmonella?
There are a few different ways that Salmonella bacteria can get into or onto eggs:
– Infected hens – Salmonella can infect the reproductive organs of hens and get inside the egg before the shell forms around it. The hen appears healthy while laying contaminated eggs.
– Fecal contamination – Feces from infected hens can get on the outside of egg shells through contact in the nest box or conveyor belts and equipment.
– Environmental exposure – Rodents, insects, or other animals that enter the chicken coop can spread Salmonella bacteria that can get on egg shells.
– Cross-contamination – Salmonella on the outside of egg shells can be transferred to the inside contents if the eggshell becomes cracked. Improper food handling can also spread bacteria from raw egg products onto prepared foods or surfaces.
In general, Salmonella infections of eggs occur before the egg is laid or from contamination of the outside shell. Proper cleaning, food handling, cooking, and refrigeration drastically reduces risk of Salmonella from eggs. The inside of an uncracked, fresh egg is rarely contaminated.
How to tell if an egg has salmonella
It is almost impossible to tell if an egg contains Salmonella bacteria just by looking at the outside of the intact shell. Here are a few signs that may indicate an egg is contaminated:
– Sunken or flattened air cell – The air pocket inside the egg may appear flattened or sunken in if bacteria has penetrated the inside contents before the shell hardened. However, this can also occur naturally as the egg ages.
– Pink, red, brown, or gray spots on the outside shell – These may indicate fecal contamination on the outside of the shell.
– Pale yolks with blood spots or meat spots – Can signal contamination, though these can also occur naturally and are safe to eat when eggs are fully cooked.
– Off odors when cracked open – An egg infected internally before the shell formed may have a foul or rotten smell when cracked open.
– Presence of rodent or insect pests – May increase likelihood of contamination in the environment.
While these signs may raise suspicion, the only way to confirm the presence of Salmonella bacteria is through laboratory testing. Most often, contaminated eggs look, smell, and taste completely normal. Following proper handling and cooking procedures is the best way to prevent illness from Salmonella in eggs.
How to reduce your risk of salmonella from eggs
You can take the following precautions to help reduce your risk of Salmonella infection from eggs:
– Purchase eggs from retailers that keep them refrigerated at 40°F or below.
– Check that egg cartons are clean and not damaged. Do not purchase cracked eggs.
– Refrigerate eggs as soon as possible after purchase, ideally stored at 40°F or below.
– Discard any eggs that are cracked when checking the carton.
– Wash hands, utensils, dishes, and work surfaces thoroughly with soap and warm water before and after contact with raw eggs.
– Only consume raw or undercooked eggs if pasteurized. Avoid eating raw cookie dough, cake batter, sauces, and drinks containing raw eggs.
– Cook eggs thoroughly until the yolk and white are firm. Scrambled eggs should not be runny.
– When baking or cooking casseroles or dishes containing eggs, use an instant-read food thermometer to verify an internal temperature of 160°F.
– Avoid leaving cooked egg dishes at room temperature for more than 2 hours. Refrigerate leftovers promptly.
– Be extra cautious handling eggs and serving undercooked eggs to those at higher risk – infants, pregnant women, older adults, and those with weakened immune systems.
Following good food safety practices from purchase to storage to preparation greatly reduces your chances of getting sick from Salmonella in eggs. When in doubt, cook thoroughly!
What should I do if I suspect my egg has salmonella?
If you believe an egg you cracked open or used in cooking may be contaminated with Salmonella bacteria, you should:
– Throw out the suspect egg(s) andany dish you added them to.
– Sanitize any surfaces, dishes, utensils, equipment, hands, etc. that may have touched the contaminated egg. Use a disinfectant or chlorine bleach solution.
– Mark leftovers containing eggs from that carton and cook thoroughly before eating, at least 160°F.
– Check yourself and any others who may have consumed the egg or dishes made with it for symptoms. Monitor for fever, diarrhea, abdominal cramps, and other signs of salmonellosis for up to a week.
– See a doctor if severe symptoms develop, especially for those at higher risk like infants, elderly, or immunocompromised individuals. Inform the doctor you may have salmonellosis from a contaminated egg.
– Report the suspected contamination to the place of purchase and/or egg producer listed on the carton so they can investigate their supply chain.
– Consider submitting samples to a lab for Salmonella testing to help identify outbreak strains. Your doctor or local health department can assist with testing.
While it’s very difficult to confirm Salmonella just by looking at an egg, following proper precautions and cooking methods is the best way to avoid illness from contaminated eggs. Speak with your doctor if salmonellosis is suspected.
How can salmonella in eggs be prevented?
There are measures egg producers, regulators, retailers, and consumers can take to help prevent Salmonella infections from eggs:
**For Egg Producers**
– Follow good management and sanitation practices for chicken coops to reduce contamination.
– Test chicks before transferring to laying houses to identify infected birds early.
– Monitor for rodents, insects, wild birds that could transmit bacteria.
– Refrigerate eggs quickly after gathering to slow bacteria growth.
– Follow egg washing regulations and procedures.
– Test environment samples and egg shells for Salmonella presence.
**For Government Agencies**
– Implement testing requirements and regulatory standards for egg producers.
– Support research on interventions and prevention methods.
– Facilitate coordination between regulators and industry.
– Investigate outbreaks and enforce actions for contaminated products.
**For Retailers**
– Source eggs from producers following good management practices.
– Keep eggs refrigerated at 40°F or below after receiving deliveries.
– Quickly remove and discard any damaged, cracked, or dirty eggs.
– Rotate stock and train staff on egg handling procedures.
**For Consumers**
– Buy eggs from refrigerated cases at stores, not room temperature displays.
– Refrigerate eggs at home right away, storing at 40°F or below.
– Cook eggs thoroughly until yolks are firm. Use a food thermometer.
– Avoid eating raw or undercooked egg products.
– Wash hands and surfaces thoroughly after contact with raw eggs.
– Monitor refrigerators for proper temperature.
With sound prevention measures at all stages of production and handling, Salmonella contamination of eggs can be minimized. However, proper cooking and handling by consumers provides the ultimate defense against illness.
Conclusion
Salmonella bacteria can sometimes contaminate eggs, either inside the shell or externally through feces and the environment. It is difficult to determine just by looking if an intact egg contains salmonella. The signs to be aware of are sunken air cells, blood spots, off odors, cracked shells, and presence of pests. However, contamination often produces no visible difference in the egg.
To avoid salmonella infection from eggs, it is important to purchase clean, refrigerated eggs from reputable retailers. Always cook eggs thoroughly until both yolk and white are firm, cook egg dishes to 160°F, and avoid consuming raw or undercooked eggs. Refrigerate promptly after cooking. Good hygiene like hand washing when handling raw eggs is also essential. By following safe handling and cooking procedures, you can greatly reduce the small risk of salmonellosis associated with eggs.