'Stomach Bug' Cases Are Surging In LA County: What To Know About The New Norovirus Strain

LOS ANGELES, CA — Cases of norovirus — commonly known as the "stomach bug" — are on the rise in California. Doctors are warning that a new subvariant could make people even more sick this season.

The Los Angeles County Department of Public Health said that Norovirus concentrations detected in wastewater over a recent three-week period increased 154% in the city of Los Angeles and over 250% in the county, ABC 7 reported.

"Based on past trends, Public Health expects norovirus activity to rise between November to April, when outbreaks are more common during the cooler months," officials said in a statement

Meantime, the number of people testing positive for norovirus has been on an upward trend in the Western U.S.: In the week ending Nov. 1, 9.14% of tests turned back positive, compared to 13.43% the week ending Nov. 29, according to data from the U.S. Centers for Disease Control and Prevention.

Norovirus, often called food poisoning or the stomach flu, is a contagious virus that causes vomiting and diarrhea. It spreads easily from person to person and from contaminated food and surfaces. Hand sanitizer is usually ineffective in killing the virus, according to the California Department of Public Health.

Norovirus is extremely common, but the recent emergence of a new strain — GII.17 — can result in 50% more illness than typical, according to the CDC.

The strain became more prominent during last year's surge and was responsible for about 75% of outbreaks of the disease nationally, the Los Angeles Times reported.

“Whenever there is a new strain, it’s really easy for it to start spreading rapidly, and that’s what we saw last year,” Dr. Scott Roberts, a professor at Yale School of Medicine, told Today.com.

It unclear whether this new variant is more transmissible than the previously most-common GII.4, but it's possible that more people are susceptible to infection because they don't have immunity, according to the publication.

Norovirus can contaminate food that's grown or washed in contaminated water or if it's prepared by someone who is infected with the virus, state health officials said. It's the No. 1 cause of foodborne illness in the U.S., according to the CDC.

Additionally, it spreads very easily from person to person — through direct contact between two people — and can survive for weeks on surfaces and objects, according to health officials.

Outbreaks frequently occur in healthcare settings, schools, daycares and cruise ships, health officials said.

State health officials offered these tips to avoid the spread of norovirus:

• Practice good hand washing techniques using soap and water — hand sanitizers are usually not effective against norovirus.
• Thoroughly wash fruits and vegetables.
• Cook shellfish thoroughly.
• If you're sick, stay home: Isolate for at least two days after you feel better.
• Do not prepare food or care for others when you're sick with norovirus or have diarrhea
• Clean and disinfect contaminated surfaces or objects with a bleach solution in order to kill norovirus