Just a Gut Reaction

No episode of "The Love Boat" ever showed passengers with gastrointestinal problems. Captain Stubing and Gopher would never have stood for it.

by Maureen Kovacik

The modern-day reality however is that more than 23 million people in the U.S. each year are affected by the Norwalk or a related virus, an intestinal bug that gets most noticed when it hits the cruise industry. The virus is transmitted by the fecal-oral route, and is best prevented by careful hand washing. Norwalk spreads quickly when people come into contact with others who have the disease.

Norwalk

"Norwalk virus can be an enormous problem on cruise ships," said Mary Estes, Ph.D., a BCM professor of molecular virology and microbiology. "Hundreds of people on a number of different cruise lines became ill just last year."

In 1968, a group of students and teachers at a Norwalk, Ohio, elementary school all came down with a mysterious stomach virus that involved nausea and vomiting. More than 30 percent of the children's family members also became ill. In 1972, when a scientist found a 27-nanometer viral particle in an infectious stool filtrate from the outbreak, the name Norwalk virus was born, and the town of 16,000 has had more than its 15 minutes of fame.

For a long time, the virus was very difficult to study because it does not cause illness in animals and will not grow in the laboratory. In 1990, its genome was sequenced in Estes' laboratory, enabling researchers to study the virus further.

"The genome sequencing helped us understand the history of the disease," said Estes. "Knowing the virus structure is critical."

With that basis, Estes and colleagues, David Graham, M.D., a BCM professor of medicine and chief of gastroenterology, and Robert Atmar, M.D., a BCM associate professor of medicine, have found host factors that make people more prone to develop Norwalk illness. People who are secretors and with type O blood are more likely to become ill with the virus, while people with type B are more resistant.

"We are currently studying people ages 18 to 50 to determine how much virus is needed to cause illness," said Estes. "This is an important step in developing a vaccine to curb this problem."

You don't have to abandon ship...just wash your hands

It sounds incredibly serious, but in most cases, the Norwalk virus is not a life-threatening illness, nor will it cause any long-term effects. People usually recover within two to three days without hospitalization. Symptoms might include nausea, vomiting, diarrhea, and stomach cramps. The good news is, unlike some illnesses, you can prevent spread of the Norwalk virus by taking a few simple steps:

• Always wash your hands with soap and warm water before and after going to the restroom and before preparing or eating food.
• Cook all shellfish thoroughly before eating.
• Wash raw vegetables in soap and warm water before eating.
• Ensure proper disposal of human waste.
• People with symptoms of Norwalk-virus should never prepare or touch food.

"There is new evidence that people could carry this virus around for up to three weeks after the original symptoms go away," said Estes. "So any breakdown in hand washing after using the restroom can really put others at risk for catching the illness."

Cruise ships are not the only problem. The virus has reared its ugly head in schools, nursing homes, hotels, summer camps, water sports, families, the military, hospitals and throughout communities. The virus can cause serious infections and it has been associated with deaths in the elderly as well as with chronic diarrhea in transplant patients who are taking immunosuppressive drugs. Dr. Atmar has recently found that children hospitalized for gastroenteritis frequently have Norwalk virus if they don't have rotavirus, another gastrointestinal virus that causes severe disease.

"In fact, thousands of Hurricane Katrina evacuees became victims of the Norwalk virus," said Estes. "The illness spread pretty quickly among those being housed at the Reliant Astrodome complex, where conditions were less than ideal."

There are currently no commonly available tests to check for Norwalk virus, but Estes hopes the future will be much brighter when it comes to tackling this illness.

"It must be frustrating for those people who save their money for a five-day cruise and end up sick two of the five days of their trip with the Norwalk virus," said Estes. "We hope to find a vaccine that will not only prevent this illness, but also other gastrointestinal illnesses that affect a large number of people."

Patient Care

The Tiny Faces of AIDS

A New Medical School for Botswana

A Kingdom with Hope

Research

Stars and Workhorses: A Varied Future for Stem Cells

Just a Gut Reaction

Unfolding the Tiniest Problems

A Higher Calling

Education

BCM's Own Mr. Wizard

A 'Marriage' with Medicine

Community Service

Glasses for the Homeless

Going Beyond the Borders

Alumni & Development

From Center to Center

The Story Behind the Jewish Building

From a One-Room School to Medical Research

College News

The Bards of Baylor

A World of Difference

Volume 2, Issue 1, Spring 2006

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