The salmonella sickness outbreak that has afflicted about 171 people and hospitalized 11 in 18 states, including Wisconsin, is over, according to officials.

There have been no deaths since the outbreak began Sept. 1. The two cases from Wisconsin occurred in Outagamie and Brown counties. Pam Farrell, nursing supervisor at Student Health Service, said so far she has not seen or heard of any cases at Marquette.

Health officials said they know the outbreak stemmed from a common source.

"We just don't have enough information about it yet," said Christopher Cox, spokesman for the U.S. Centers for Disease Control and Prevention.

The CDC has theories about the outbreak's origin, such as a type of produce, but none have been proven.

"The CDC has pinned down the suspect to tomatoes," said Claire Smith, communications officer for the Wisconsin Department of Health and Family Services. "However, they also stated that no tomatoes now pose a risk to the public and do not need to be taken from grocers."

She also said the CDC will continue to work with states' health departments to investigate the infections that have occurred in the country and determine the origin of the salmonella outburst.

There are about 1.4 million cases of salmonella poisoning each year in the U.S., including more than 1,000 in Wisconsin, but the concern over the current outbreak lies with the fact that all the cases that were recorded seem to come from one source.

Salmonella is a type of bacteria that causes diarrhea, nausea, vomiting, fever, headache and abdominal cramps.

According to the Wisconsin Department of Health and Family Services, salmonella is spread by eating or drinking contaminated food or water, or by direct or indirect contact with fecal matter from infected animals or people. The illness lasts about four to seven days and most people recover without treatment.

About 2,500 types of salmonella exist. Salmonella typhimurium, the type that emerged from the recent outburst, stands as one of the most common strains.

Anyone can contract the sickness from sources such as water, raw meats, poultry, produce and seafood. There are currently no vaccines that can be taken to prevent contracting this bacterium.

However, Cox said there are precautions that can be taken to decrease risk of salmonella.

"Practice good hygiene and wash your produce," he said.

This means washing your hands regularly, in addition to washing food.

"The most important thing I can tell students is to practice good hand washing after coming into contact with anything suspicious of bacteria, including salmonella," Farrell said.

Other important pieces of advice to prevent salmonella sickness include thoroughly cooking meat, not eating or foods that contain raw eggs and keeping uncooked meats separate and away from other foods.