Norovirus, a gross stomach bug, appears to be hitting NYC. Good ... - Gothamist
Stomach illness is rising in New York City. The number of New Yorkers visiting hospital emergency rooms due to vomiting or diarrhea has risen about 50% from December to mid-February, according to the city health department's EpiQuery data portal.
The most likely culprit is norovirus, a common intestinal germ that spreads easily through food and person-to-person contact. But city, state and federal officials can't say for sure.
Health experts said that's because norovirus is poorly tracked, even though it's estimated to cause billions of dollars in annual economic losses nationally due to missed work and school.
The federal government doesn't require hospitals and health departments to report norovirus cases, even though it is a primary cause of diarrhea and vomiting illness. As a result, norovirus isn't monitored as comprehensively as other widespread viruses. Hesitation to seek medical care for the disease's unpleasant symptoms, combined with fairly limited lab testing, lead experts to suggest that official statistics from health agencies dramatically undercount how many people actually get sick.
Despite the absence of a federal requirement for norovirus tracking, the city's health department requires laboratories in the city to report positive norovirus test results, said spokesperson Patrick Gallahue. The agency also requires providers to "report clusters or outbreaks of GI [gastrointestinal] illness, which can include those caused by norovirus," he said.
We are in the midst of peak norovirus season.
The health department also asks 53 emergency rooms across boroughs to report incidents of severe vomiting and diarrhea. ER visits due to vomiting increased from about 2,400 in the first week of December to 3,700 in the second week of February, while diarrhea-related visits increased from 1,400 in December to 2,100 in February.
This city data gives some insight into what's happening in ZIP codes — but it isn't specific to norovirus and a lot of things can cause stomach problems. Likewise, the Northeast U.S. has reported an increase in positive norovirus tests over recent weeks, according to the Centers for Disease Control and Prevention. But this region stretches from Maine to Pennsylvania, offering little clarity on what's happening in individual states, cities and neighborhoods.
The COVID-19 pandemic served as a reminder of why it's important to detect outbreaks as they happen. In this situation, people could take extra simple precautions, such as remembering to wash their hands if they're aware that a germ like norovirus is thriving.
A three-dimensional (3D) illustration, Based on electron microscopic imagery, provides a graphical representation of a single norovirus particle.
CDC/Jessica A. Allen/Alissa Eckert, MS
Such caution is warranted during norovirus outbreaks, especially for young children and older adults. The CDC estimated that norovirus causes up to 465,000 emergency department visits and 100,000 hospitalizations each year, and some of those cases may be fatal.
"It's just an incredibly successful virus" when it comes to infecting people, said Dr. Christine Moe, an expert on foodborne and waterborne diseases at Emory University.
Exposure to fewer than 100 norovirus particles can cause an infection. Norovirus can spread through direct contact with an infected person's fecal matter or vomit — or surfaces, food and water contaminated by those substances. Alcohol-based hand sanitizers don't work against norovirus, Moe said, so handwashing with soap and water or disinfecting with bleach is necessary to stop its spread.
The increase in diarrhea and vomiting among New Yorkers visiting hospital ERs can likely be attributed to norovirus, Moe said. Outbreaks "with a lot of vomiting" are typically caused by this virus as opposed to other stomach bugs, she noted.
Alcohol-based hand sanitizers don't work against norovirus, so handwashing with soap and water or disinfecting with bleach is necessary.
National monitoring systems in the U.S. and the U.K. have similarly pointed to a norovirus surge this winter, said Dr. Bruce Y. Lee, professor of health policy and management at CUNY. In 2016, Lee and his colleagues published a study estimating that norovirus leads to about $4.2 billion in health care costs and over $60 billion in indirect societal costs around the world, every year.
"Norovirus needs to be taken more seriously," Lee said, because of its rapid spread and ability to cause worse gastrointestinal symptoms than other stomach germs. These factors can lead to intense outbreaks in workplaces, schools and other settings, he added.
Why norovirus is poorly tracked
Lee said that for a norovirus case to be logged in a public health database, three things need to happen: First, a patient needs to seek medical care. Next, the doctor "has to actually test and confirm the case." Finally, the test result must be reported to a public health authority.
"There are three chain links that can be easily broken, and in most cases probably are when it comes to norovirus," Lee said.
Unlike some other foodborne diseases, the CDC doesn't require doctors to report norovirus cases to local or federal health departments, said Kate Grusich, a spokesperson for the agency. The CDC's norovirus data "reflects a sample reporting of outbreaks or clusters, or reports from selected laboratories," she said.
But the absence of a "reportable" requirement means tracking is spotty, providing limited insights into where hotspots are occurring or how intense they might be. Health departments in 14 states report more detailed data to the CDC; New York is not one of them.
According to the CDC, foods that are commonly involved in norovirus outbreaks include leafy greens, fresh fruits and shellfish such as oysters.
AP/Shutterstock
Norovirus surveillance is "pretty poor," said Alexandria Boehm, an environmental engineering professor at Stanford and one of the principal investigators for WastewaterSCAN, an academic project testing wastewater for viruses. It's harder to study than other common viruses because norovirus is difficult to grow in a laboratory, she said. Also, people often find gastrointestinal symptoms embarrassing and opt out of a trip to the doctor's office, which limits case identification.
While the CDC still encourages doctors and health officials to report norovirus outbreaks, it can also be hard to track multiple cases to the same source. This investigation process typically requires taking stool samples from prospective norovirus patients, which is unpopular.
"It's much easier to get a blood sample from someone than to get a stool sample," Moe said.
Boehm recalled a historical example of public health surveillance failing for a similar stomach bug: In 1993, the waterborne parasite cryptosporidium made over 400,000 people sick in Milwaukee.
"The only way that [officials] figured out there was a huge outbreak was that the stores ran out of Pepto-Bismol," she said.
In New York City, the health department identifies potential norovirus outbreaks through reports from doctors' offices, nursing homes, schools and other settings, along with the hospital ER data and 311 complaints. "Once clusters are identified, we investigate," Gallahue said. This involves interviewing patients and coordinating with facilities experiencing outbreaks.
Health experts say improving public awareness of norovirus and increasing access to lab tests can help catch more outbreaks.
Ian Lesogor via Shutterstock
According to the CDC's CaliciNet monitoring program, the entirety of New York state has reported two norovirus outbreaks between September 2022 and the end of January. This is likely an undercount: "probably the tip of the iceberg," Moe said. Meanwhile, although NYC's health department tracks norovirus more comprehensively than other local agencies, its most recent NYC public data on norovirus cases is from 2020.
In response to questions, the state health department merely acknowledged that norovirus is not a reportable communicable disease and recommended that people take basic precautions.
"The department does encourage New Yorkers to take simple steps to protect themselves, their loved ones, and others from becoming ill, such as thorough handwashing, staying home when sick, not drinking untreated water, and cooking shellfish thoroughly before eating them," New York State Department of Health spokesperson Cadence Acquaviva stated via email.
New technologies offer more insight
Norovirus is typically a seasonal virus that most commonly spreads from November to April, according to the CDC. The U.S. as a whole has seen relatively high levels of norovirus both last winter and this year.
"We are in the midst of peak norovirus season," Gallahue said, noting that NYC data has shown similar seasonal trends to the CDC's numbers.
Earlier in the pandemic, safety measures taken for COVID-19 helped to curb the spread of other common viruses, including norovirus, said epidemiologist Alex Davidson on behalf of a team at Kinsa Health, which monitors health indicators through smart thermometers and a symptom-tracking app. The last two years, "as people return to pre-pandemic behaviors and patterns, these illnesses are seeing a resurgence," Davidson said.
The COVID-19 pandemic has also inspired creativity among scientists working to track common viruses. For example, Boehm's WastewaterSCAN expanded its wastewater testing program from coronavirus to add norovirus, influenza, RSV, mpox and HMPV. New York State's wastewater surveillance program has also included norovirus in its upcoming planned expansion, as has a lab at Queens College.
Unlike other diseases tracked by WastewaterSCAN, there isn't a "traditional or accepted clinical data stream" that can be compared to the project's norovirus results, Boehm said. Wastewater surveillance, as well as symptom surveillance from organizations like Kinsa, could provide population-level data on this virus that wasn't available before.
Such monitoring could be particularly valuable at "sentinel sites" like nursing homes or schools, Moe said. But wastewater data from an entire city or county is hard to use for contact tracing outbreaks or revealing how a virus is spreading within communities. But if health officials knew norovirus was spreading at one of these outbreak-prone locations, they could take steps to stop it by recommending people stay home and widespread cleaning.
While new surveillance technologies are developed, improving public awareness of norovirus and increasing access to lab tests can help catch more outbreaks, experts said. With more data, scientists will better be able to understand how many people are affected by the norovirus, and who would benefit most from potential vaccines currently in development.
Comments
Post a Comment