Flu season may be mostly behind us, but a nasty, highly contagious stomach bug is rising.<\/p>\n
In recent weeks, hikers in Southern California have been hit with norovirus, according to the\u00a0Pacific Crest Trail Association.<\/p>\n
Outdoor enthusiasts along the iconic trail aren\u2019t the only ones suffering.<\/p>\n
Recent wastewater surveillance reveals an upward trend to \u201chigh\u201d levels of norovirus across much of the country, with rates currently rising in the Northeast.<\/p>\n
From Aug. 1 to May 7, the\u00a0Centers for Disease Control and Prevention\u2019s NoroSTAT program\u00a0recorded 1,194 outbreaks, compared with 2,534 during the same period the previous year \u2014 consistent with past averages.<\/p>\n
\u201cAt the national level, norovirus is still in the HIGH category due to high concentrations over the last 21 days,\u201d Amanda Bidwell, the scientific program manager at WastewaterSCAN, an academic program through Stanford University in partnership with Emory University, said in an email.<\/p>\n
Norovirus is often called the \u201cwinter vomiting disease,\u201d but it\u2019s not unusual for outbreaks to continue through late spring, Bidwell said.<\/p>\n
The wastewater numbers also highlight an outbreak of norovirus in the San Francisco Bay Area, although the numbers nationwide are average for this time of year, said Dr. Linda Yancey, an infectious disease specialist at Memorial Hermann in the Houston area.<\/p>\n
\u201cThere really isn\u2019t anything unusual about this one in California,\u201d Yancey added. \u201cThey just got unlucky.\u201d<\/p>\n
National levels aren\u2019t \u201cunusually high\u201d compared with prior seasons, according to the\u00a0CDC,\u00a0although the agency\u2019s tracking is based on confirmed cases from state agencies and may not be picking up many illnesses.<\/p>\n
\u201cMonitoring\u00a0norovirus in wastewater\u00a0is very helpful for this highly contagious virus, as there is not a lot of clinical data to describe outbreaks because most people recover at home without seeing a healthcare professional,\u201d Bidwell said.<\/p>\n
Currently, several norovirus strains are circulating including GII.4, a common strain that has circulated for years, and GII.17, a more mutated strain that partially evades prior immunity because people haven\u2019t been as exposed to it, Yancey said.<\/p>\n
During the 2024\u201325 season,\u00a0GII.17 surpassed GII.4 as the predominant strain in the U.S., causing about 75% of outbreaks.<\/p>\n
Both variants cause very similar symptoms, even though the virus is known to mutate rapidly, Yancey said.<\/p>\n
\u201cThe newer variant isn\u2019t more contagious in and of itself,\u201d she added. \u201cIt can spread more easily because fewer people have partial immunity to it, so they will get sick and spread the virus.\u201d<\/p>\n
Although primarily a winter illness, norovirus can spike in the late spring, said Aaron Glatt, chief of infectious diseases at Mount Sinai South Nassau on Long Island, New York.<\/p>\n
And the virus spreads easily between people, he added.<\/p>\n
Like measles, norovirus is one of the most contagious known illnesses, with infected patients spreading the virus to up to seven other people on average, Yancey said.<\/p>\n
Seasonal travel and extreme heat may also be to blame.<\/p>\n
Increased holiday traffic brings large groups into close contact, accelerating viral transmission, while rising temperatures force people indoors, facilitating rapid spread in crowded rooms, said Dr. Scott Roberts, the associate medical director of infection prevention at Yale School of Medicine in Connecticut.<\/p>\n
\u201cI have not seen any evidence of a new strain, but as with all viruses, evolution occurs, and unfortunately, our immunity to norovirus is not long-lasting,\u201d Roberts added.<\/p>\n
\u201cNorovirus can occur year-round, but in the Northern Hemisphere it is most commonly seen from November through May,\u201d Bidwell said.<\/p>\n
It commonly spreads in settings where many people are clustered together, like cruise ships, through direct contact with a sick person or by touching a contaminated surface and transferring it to the mouth.<\/p>\n
People often get the infection from contaminated food, like when a sick cook prepares food and then serves it to people, or by drinking water that is not adequately treated.<\/p>\n
Those who consume contaminated ready-to-eat cold foods, such as salads and sandwiches, are at higher risk.<\/p>\n
Norovirus is the most common cause of food poisoning in the U.S.<\/p>\n
Vomiting, diarrhea and stomach cramps usually start 12 to 48 hours after exposure. Some people only complain of diarrhea or vomiting, but a hallmark of norovirus is intense vomiting compared to other stomach bugs.<\/p>\n
It\u2019s possible to test a person\u2019s stool for the virus, but generally doctors diagnose the condition without testing.<\/p>\n
Most healthy adults recover on their own within several days but still can spread the infection for up to two weeks, even after they feel better.<\/p>\n
There is no specific treatment, and antibiotics don\u2019t work since the infection is caused by a virus, not a bacterium.<\/p>\n
Experts recommend oral rehydration fluids rather than sports drinks to replace important nutrients and minerals lost to vomiting and diarrhea \u2014 although drinks like Gatorade may help with mild dehydration.<\/p>\n
But when some get too dehydrated, they may require intravenous fluids to replace what they\u2019ve lost. Vulnerable populations, like young children and older adults, should monitor for warning signs of dehydration, including:<\/p>\n
Decreased urination<\/p>\n<\/div>\n<\/li>\n
Dry mouth<\/p>\n<\/div>\n<\/li>\n
Feeling dizzy when standing up<\/p>\n<\/div>\n<\/li>\n
Crying with minimal tears<\/p>\n<\/div>\n<\/li>\n<\/ul>\n
To protect against norovirus, avoid raw shellfish (especially oysters) and always wash your hands thoroughly with soap and water. Hand sanitizers are often ineffective against this virus, so clean surfaces using EPA-registered disinfectants specifically labeled to kill it.<\/p>\n
This article was originally published on\u00a0NBCNews.com<\/p>\n","protected":false},"excerpt":{"rendered":"
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