Updated

Federal health officials are reporting that the current listeria outbreak is the deadliest food-borne disease outbreak in more than a decade, with 13 deaths and 72 laboratory-confirmed cases in 18 different states.

This number is expected to rise in coming weeks because the bacteria has an unusually long incubation period, meaning an infected person may appear healthy for up to two months before showing symptoms.

I’ve been getting a lot of concerned e-mails, so I’ve decided to answer some of your questions about the outbreak.

What is listeria?

Listeria monocytogenes is a gram-positive bacterium that can cause the disease listeriosis. It is contracted by eating foods or drinking liquids that have been contaminated with animal feces or soil. A person can also be infected by drinking inadequately treated or non-pasteurized liquids.

What are the symptoms of listeriosis?

Symptoms of listeria include fever, muscle aches, nausea and diarrhea, and usually last for about a week before clearing up. However, in serious cases, the bacteria can spread to the brain, causing headaches, fever, confusion and seizures.

Who is at risk of getting listeriosis?

Approximately 1,600 people become ill with listeriosis annually in the United States, and of them, 260 die. People at especially high risk include:

-Pregnant women

-Newborn babies

-Elderly people

-Patients with diabetes, cancer, alcoholism, liver or kidney disease

-AIDS patients

-Patients undergoing any immune-suppression therapy

How does listeria affect pregnant women?

Pregnant women are at greater risk of developing listeriosis because their immune systems are compromised. While pregnant women who are otherwise healthy typically only have minor symptoms, they are also at risk of miscarriage, premature birth, and newborn infection or death.

How can I protect myself from listeriosis?

Listeria bacteria can contaminate many types of raw foods, including fruits, vegetables, cheeses, meats and seafood. It has even been found in certain processed foods. To prevent infection, the Centers for Disease Control and Prevention recommends: thoroughly cooking raw meat, washing fruits and vegetables thoroughly before eating, keeping uncooked meats and poultry separate from vegetables and cooked foods, avoiding unpasteurized milk or eat foods with unpasteurized milk in them, washing hands and cutlery after handling unprepared foods, and consuming perishable foods as soon as possible.

What do I do if I think I have listeriosis?

Go to your doctor for a physical exam. Tell your doctor if you have recently been exposed to a contaminated food source during a listeria outbreak. Your doctor will likely order a blood or spinal fluid test to confirm the diagnosis.

How is listeriosis treated?

The majority of listeriosis infections spontaneously clear after seven days. However, patients at increased risk – such as pregnant women – usually require immediate IV antibiotic treatment to prevent the disease from progressing. Effective early treatment can literally be a matter of life or death for these patients. The length of antibiotic treatment generally depends on the severity of the infection.

Which foods are involved in the current listeria outbreak?

Public health officials have identified cantaloupes grown at Jensen Farms' production fields in Granada, Colo., as the source of the outbreak. Jensen Farms issued a voluntary recall of its Rocky Ford brand cantaloupes two weeks ago. There are also recalls for several products using cut cantaloupes from Jensen Farms. No other brands of cantaloupes are involved in the recall.