48 Year Old Mystery Solved
Human noroviruses – the leading viral cause of acute diarrhea around the world – have been difficult to study because scientists had not found a way to grow them in the lab. Now, more than 40 years after Dr. Albert Kapikian identified human noroviruses as a cause of severe diarrhea, scientists at Baylor College of Medicine have, for the first time, succeeded at growing noroviruses in laboratory cultures of human intestinal epithelial cells. This work, published in Science, represents a major step forward in the study of human gastroenteritis viruses because it establishes a system in which a number of norovirus strains can be grown, which will allow researchers to explore and develop procedures to prevent and treat infection and to better understand norovirus biology.
WHAT IS NOROVIRUS
Norovirus infection, also known as the stomach flu or viral gastroenteritis, is an illness that affects between 19 and 21 million adults each year, according to The Centers for Disease Control and Prevention. The illness can cause a variety of symptoms, including: vomiting, diarrhea (usually watery), abdominal pain, low-grade fever, fatigue, body aches, nausea.
Symptoms usually appear within 48 hours of exposure to the virus. There’s no specific test to diagnose this type of infection. Doctors can typically make a diagnosis based on your symptoms, and then might order a stool sample for confirmation.
There’s also no cure for norovirus. You have to let the infection run its course, but you should begin showing signs of improvement within one to three days.
Norovirus and Pregnancy
Pregnancy can be an exciting time in a new mom’s life. And understandably, staying healthy becomes a priority. You may do everything possible to avoid getting ill or having an accident. But at the same time, you’ll come into contact with many people who might get you sick. So there’s always the risk that you’ll feel under the weather at some point.
Will Norovirus Affect My Baby?A weaker immune system is one of the risk factors for norovirus. Since pregnancy can compromise the immune system, there is a higher risk of infection. Vomiting or being unable to eat due to the infection, may create worry about unborn child not receiving proper nutrition. But while norovirus might affect appetite or ability to keep foods down, there’s no immediate risk to unborn child. If you don’t drink enough while recovering from norovirus and the body doesn’t maintain enough fluids, this can affect your electrolyte balance and increase the risk for a urinary tract infection. This is a painful condition that can cause stomach pain, bloody urine, and painful urination. Severe dehydration can even lead to acute kidney failure, but this is a rare complication of norovirus infection. Dehydration and urinary tract infections are both risk factors for premature labor. Severe dehydration can reduce the amount of amniotic fluid, which can trigger contractions or premature labor.
How it is Transmitted
If you think norovirus outbreaks occur mostly on cruise ships, you may want to think again, especially before dining out.
You Can Get Norovirus from Eating at a Restaurant, Not Just on a Cruise, CDC warns.
According to the Centers for Disease Control and Prevention’s (CDC) recent Vital Signs report, outbreaks of norovirus on cruise ships represent only about one percent of all reported norovirus outbreaks. Food borne norovirus outbreaks can occur any place food is served. Factors contributing to food contamination reported were bare-hand contact with ready-to- eat food. Rates of severe outcomes, such as hospitalization and death, are greatest in children less than five years of age, and in adults 65 years and older.
Norovirus is hard to kill. It remains on food, kitchen surfaces, and utensils. It can remain infectious on foods even at freezing temperatures and until heated above 140°F. Norovirus also stays on countertops and serving utensils for up to two weeks and is resistant to many disinfectants and hand sanitizers, according to the CDC.
Norovirus is highly contagious. The best way you can protect yourself is by avoiding contact with people who might be sick with the virus.
“The human body responds to food by secreting enzymes from the pancreas and bile from the liver into the small intestine. Pancreatic enzymes digest the large molecules and bile solubilizes fats,” said Dr. David Y. Graham, professor of medicine and molecular virology and microbiology at Baylor and the Michael E. DeBakey Veterans Affairs Medical Center. “Viruses that cause gastroenteritis, such as rotavirus, utilize pancreatic enzymes to trigger their replication, but these enzymes had no effect on norovirus. We asked, if pancreatic enzymes were not important, was bile a key component allowing the virus to recognize where it was and replicate?”
“When we added bile to the cultures, norovirus strains that didn’t grow before now grew in large numbers!” said Estes.
The co-first author Dr. Sue Crawford, an assistant professor of molecular virology and microbiology at Baylor, said “This new cultivation system will finally allow us to gain an insight into how this virus causes disease.”