FAYETTEVILLE — It’s too soon to know whether sicknesses caused by noroviruses are more widespread or severe this year than in a typical season in Arkansas or if they are simply getting more media attention because of outbreaks in schools, a doctor with the Arkansas Department of Health said.
This year’s contagious illness causes patients to throw up and have diarrhea, and the symptoms clear on their own in 24-60 hours, said Dr. Gary Wheeler, branch chief of infectious diseases for the department. Testing isn’t often needed, so the illnesses’ prevalence is hard to quantify, he and other health officials said last week.
The norovirus can be spread any time of year, but its season typically runs from October to March or April, peaking in January and February.
“The severity of norovirus we’ve seen this year does not distinguish it from the syndromes of norovirus we’ve seen in the past,” Wheeler said. “We don’t routinely count heads as you would with other diseases.”
A norovirus is a type of viral gastroenteritis, an infection that causes inflammation of the stomach and small and large intestines, according the federal Centers for Disease Control and Prevention in Atlanta. Other types include rotavirus and adenovirus.
Unlike its cousin rotavirus, there is no vaccine against a norovirus.
The illness is spread by close contact with infected people, by consuming contaminated food or drinks, or by touching contaminated surfaces where a norovirus can remain active for several days or weeks.
For those most vulnerable to severe dehydration, such as young children, the elderly or the immune-com-promised, hospitalization or death can occur.
“Noroviruses are the leading cause of epidemic gastroenteritis, including foodborne outbreaks, in the United States,” the CDC wrote Jan. 25 in a weekly report.
A new strain of norovirus first identified in Australia in March 2012, named “GII.4 Sydney,” has since caused outbreaks of acute gastroenteritis in multiple countries, according to the report, including an early onset of winter norovirus in the United Kingdom.
In the United States, GII.4 Sydney spread rapidly.
Between September and December 2012, GII.4 Sydney was found responsible for 53 percent of the reported 266 norovirus outbreaks in the U.S., the report said.
OUTBREAKS THIS SEASON
Because of the limited testing, statistics on which strains are responsible for Arkansas’ outbreaks aren’t available, Wheeler said.
Wheeler recalled that there was an outbreak in Pulaski County shortly after he joined the Health Department on Aug. 1, and the GII.4 Sydney strain was ruled out as the cause.
According to newspaper archives, about 140 students at Pulaski Heights Middle School were sickened by a norovirus strain in late August. The school responded by hiring a company to sanitize the school building and buses.
A norovirus led to the closure of Springdale’s Hellstern Middle School on Jan. 18, after one-third of its 900 students became ill. The closure helped curtail the illnesses, and after a three-day weekend only 76 students were absent.
Later in January, the Lincoln School District closedfor part of a school week because of a stomach ailment that struck about 250 of its 1,200 students.
The Arkansas Department of Education doesn’t actively track schools that have closed because of illnesses, said its chief of staff, Phyllis Stewart.
If the schools eventually ask for a waiver of the required minimum of 178 days of instruction for the school year, the department would hear about it, Stewart said. So far, schools that have closed because of norovirus or flulike symptoms - such as Eureka Springs and Mayflower - have indicated that they plan to make up the days.
TESTING NOT DONE
Tests to detect noroviruses “are not in routine use,” according to the CDC website’s “frequently asked questions” on viral gastroenteritis, cdc.gov/ncidod/dvrd/revb/gastro/ faq.htm.
Such tests aren’t usually needed to help patients recover, said Dr. Virgincita Fuentes-Rodriguez, a thirdyear resident at the University of Arkansas for Medical Sciences in Little Rock.
A norovirus runs its course quickly. The doctor doesn’t need to know whether it or another virus is the cause because the advice to the patient will be the same: Replace lost fluids and stay home to avoid infecting others.
“We don’t really have a definitive diagnosis right away,” Fuentes-Rodriguez said of the clinical cases.
A norovirus is highly infectious, said Fuentes-Rodriguez, Wheeler and Kristen Gibson, a scientist at the University of Arkansas, whose academic career includes 10 years studying noroviruses. They emphasize the importance of proper hand-washing.
“If you do become ill with this virus and you’re in the food chain - you’re a food handler - you should call in sick that day,” Wheeler said. “About a third of the norovirus outbreaks are associated with foodborne spread of the disease.”
In the home, a sick person should not prepare food for others in the family, they said.
Gibson is a researcher atthe University of Arkansas System’s Division of Agriculture and an assistant professor of Food Sciences at its Fayetteville campus’s Bumpers College.
Clinical trials have shown that it can take an average of 100 norovirus particles to infect a person, Gibson said. Based on what she’s read, Fuentes-Rodriguez agreed.
“With 18 particles of that virus, you can get the illness itself,” Fuentes-Rodriguez said. “But during your acute illness phase, you shed billions of the virus.
“So you can imagine, just one sick person who does not practice good hand-washing could definitely infect a whole school.”COMPARISON TO FLU
A norovirus is so highly infectious that Gibson recommended in a statement issued to the public last week that households with both sick and uninfected people designate separate bathrooms for those suffering from it.
“In addition - and this may seem harsh - the bathroom used by the person with norovirus should be disinfected with chlorine bleach solution. And the best candidate for the job is the person who is, or was, actually sick,” she wrote in a university news release about the norovirus.
Norovirus symptoms rarely include a fever as is seenwith influenza, a more deadly illness with a typical season and peak that is almost identical to noroviruses.
People can confuse them, however, since young children’s flu can sometimes include throwing up and diarrhea. And, Gibson said, it is possible to contract a norovirus and flu at the same time.
Researchers haven’t been able to develop a vaccine for a norovirus because it can’t be grown in a laboratory.
“We can’t culture norovirus,” Gibson said in her laboratory Wednesday. “We can’t grow norovirus, like you can with the flu.”
Instead, she and other scientists culture something similar to a norovirus so they can study how it behaves. As with some vaccines in the past, an artificial virus could be developed one day that could trick the body into mounting an immune response that coulddefeat a norovirus.
A norovirus has what scientists call a “protein capsid” that makes it tougher than a flu virus, Gibson said as she held a bottle of a red liquid containing mouse cells that her lab uses to culture cells for norovirus studies.
“It’s just like a protein shell,” she said. Whereas flu viruses only have to navigate in the respiratory tract, noroviruses have to make it through the harsh environment of the gastrointestinal tract, stomach acids and all.
Gibson, who earned her doctorate at Johns Hopkins Bloomberg School of Public Health in 2010, has conducted studies that included cooking temperatures’ effect against a norovirus and one on how the common damp terry-cloth bar towel often succeeds in spreading the virus. When injected with 100,000 norovirus particles, the bar rag transferred 800 to the surface - far more than is needed to infect someone.
Northwest Arkansas, Pages 7 on 02/11/2013