An outbreak of salmonella has sickened at least 141 persons in 20 states from Texas to Massachusetts and in the District of Columbia. It's been traced to a yellowfin tuna product used in raw seafood dishes such as sushi, sashimi and ceviche.

Many of the people who became ill reported eating a sushi selection called spicy tuna.

Since the fish may have passed through many distributors before ultimately reaching the restaurant or grocery store and may not have been clearly labeled, the FDA sums up its advice as: 'when in doubt, don't eat it.'

The outbreak has been traced to a product called Nakaochi Scrape, which is tuna scraped directly off the bones (backmeat). It's rarely sold directly to consumers but most often to restaurants and grocery stores for use in raw food dishes. To the eye, it looks like a ground product, not firm fish flesh.

On April 13, Moon Marine Corporation, also known as MMI, of Cupertino, California, recalled 58,828 pounds of frozen yellowfin product suspected of being tainted with Salmonella Bareilly. It was labeled as Nakaochi Scrape AA or AAA.

The FDA advises consumers to check with the establishment before eating or purchasing any raw fish dish or product, to make sure that it does not contain any of the recalled fish.

Since the fish may have passed through many distributors before ultimately reaching the restaurant or grocery store and may not have been clearly labeled, the FDA sums up its advice as: "when in doubt, don't eat it."

The largest number of cases so far has been in New York (28), with Wisconsin second (14).

The state by state numbers: Alabama (2), Arkansas (1), Connecticut (6), District of Columbia (2), Florida (1), Georgia (6), Illinois (13), Louisiana (3), Maryland (14), Massachusetts (9), Mississippi (2), Missouri (4), New Jersey (8), New York (28), North Carolina (2), Pennsylvania (6), Rhode Island (5), South Carolina (3), Texas (4), Virginia (8), and Wisconsin (14).

The earliest illnesses occurred January 28, and the outbreak is ongoing. So far there have been 21 hospitalizations and no deaths reported.

The most common symptoms of salmonella infection are diarrhea, abdominal cramps and fever. Symptoms occur within eight to 72 hours of eating the contaminated food. While only a nuisance for most people, the illness can be severe or even life threatening for infants, older people, pregnant women and people with weakened immune systems. Anyone who suspects that they have been infected should see their doctor.

This is the third salmonella outbreak of 2012. The Centers for Disease Control and Prevention (CDC) reported 11 in 2011. Prominent recent outbreaks have been traced to contaminated ground turkey (2011), whole eggs (2010) and peanut butter (2009).

The CDC posts updates on the current outbreak at its website, CDC.gov.