The Oregon State Public Health Laboratory says recent fecal samples from some of the nearly 100 people who reported getting ill after visiting Elk Lake Resort in recent weeks have tested positive for Norovirus, officials said Thursday.

Although the drinking water at Elk Lake Resort tested positive for Coliform bacteria, it is now conclusive that E. Coli was not the cause of reported illnesses, according to Deschutes County health officials.

The source of the Norovirus is still unknown, they said, and no new reports of illness occurring after Thursday, July 14 have been reported. The total from before that is close to 100, they said.

Norovirus is a virus that causes acute gastroenteritis in humans. The most common symptoms of acute gastroenteritis are diarrhea, vomiting, and stomach pain.

Norovirus is also described as “Norwalk-like viruses.” Norovirus spreads from person to person through contaminated food or water, and by touching contaminated surfaces. Norovirus is recognized as the leading cause of foodborne-disease outbreaks in the United States. Outbreaks can happen to people of all ages and in a variety of settings.

For the fourth time since mid-May, the Se Princess’s passengers have been sickened by norovirus, a gastrointestinal infection that causes diarrhea, vomiting and stomach pain.

At the end of a 10-day sailing, the ship returned to San Francisco June 29 with 53 of its 2,196 passengers affected by the stomach bug, according to USA Today.

The number of cases wasn’t high enough for the Centers of Disease Control and Prevention to consider the episode an official outbreak. The CDC issues an outbreak alert only when 3 percent of either passengers or crew members become ill; only 2.4 percent of Sea Princess’ passengers were sickened.

A recent norovirus outbreak onboard the Alaska cruise ship Sea Princess sickened more than a hundred passengers.

Princess Cruises says a total of 142 people became ill during the ship’s May 30th-to-June 9th cruise, which visited Juneau, Skagway, Glacier Bay and Ketchikan.

The San Francisco-based ship’s next departure was pushed back while crews disinfected the Sea Princess. Spokeswoman Karen Candy says the delay was just four hours. But it was enough to force route changes.

Sitka gained an unscheduled stop, Juneau saw the ship later than expected and Haines lost a docking.

The Sea Princess carries about 2,000 passengers and 900 crew members during 10-day Inside Passage cruises. Other stops along the route can include Skagway, Tracy Arm and Victoria, British Columbia.

Norovirus, also called Norwalk-like virus, is a common gastrointestinal illness that causes diarrhea and vomiting. Princess Cruises says it followed U.S. Centers for Disease Control protocols in reporting the illness and cleaning the vessel before its latest sailing.

The cruise line says norovirus numbers were also higher than usual during the ship’s two previous trips.

CDC inspected the Sea Princess on May 24th and identified 13 problems, including a leaking pipe at a soup station. However, all the issues were considered minor and the overall health rating was high.

Diana Samuels reports that an outbreak of norovirus has sickened more than two-dozen people at The Sequoias in Portola Valley, an official at the retirement community said Tuesday. Officials have closed the retirement community’s dining room and canceled social activities, said Rick Isaacs, The Sequoias’ skilled nursing administrator. Family members and others are “encouraged not to visit, for the time being,” he said, as staff works to keep the illness from spreading.

Norovirus causes diarrhea, vomiting and stomach pain, and is spread from person to person through contaminated food or water and by touching contaminated services, according to the Centers for Disease Control and Prevention’s website. It is recognized as the leading cause of foodborne-disease outbreaks in the United States, the CDC site says. No more than a dozen people at The Sequoias have been sick at any one time since officials at the retirement community learned of the outbreak mid-last week, Isaacs said.

The Kalamazoo County health department has issued an advisory about a “sharp increase in the number of people ill with norovirus” in the past week.

“We don’t have any numbers” because norovirus cases don’t have to be reported to the health department, said Linda Buzas, Kalamazoo County health director. But “we’re getting lots of calls from lots of different places” reporting a spike.

Norovirus causes nausea, vomiting and/or diarrhea, abdominal cramps and sometimes a low-grade fever. The symptoms last 12 to 48 hours and will go away without treatment.

“More than 90 percent of what people call stomach flu is norovirus,” Buzas said. “It comes on very quickly and leaves quick, but it’s very irritating and will make you very miserable.”

Norovirus is “extremely contagious” — thus, the point of the health alert, Buzas said.

“It spreads very easily, and the big problem is that people don’t stay home long enough,” further spreading the disease, she said.

People with the illness are contagious up to 48 hours after their symptoms subside, and they should stay home from work, school and public gatherings during that time.

Also, the spread of norovirus can be prevented through “excellent hand washing,” the health advisory said.

“It’s really important for people to wash their hands” during a norovirus outbreak, Buzas said.

U.S. health officials say last fall’s outbreak of a stomach virus that swept through pro basketball teams sickened 21 players on 13 teams.

They were infected with the norovirus, highly contagious and known for spreading on cruise ships. The federal researchers didn’t name the teams. But media reports have said players with a stomach bug at the time included four on the Orlando Magic, including star center Dwight Howard.

The virus can spread through the air on the basketball court. But researchers said it more likely was spread by players socializing.

The Centers for Disease Control and Prevention initiated the investigation after reading media reports about player illnesses, and the NBA cooperated, said Dr. Rishi Desai, one of the CDC investigators.

It’s not clear how the outbreak started, but the strain of norovirus was an unusual enough that investigators believe players got it from each other rather than from family members or others, he added.

CDC officials believe that there may have been at least two instances in which an infected team passed it to a healthy team. The CDC recommended that in the future, NBA players sick with the virus should not play or take part in team activities.

Norovirus can cause diarrhea, vomiting and stomach pain. It often spreads through contaminated food or water, but the virus can also move through dried vomit particles spread in the air, Desai said.

The Hawaii Department of Health said a Hale­iwa restaurant linked to 42 cases of suspected norovirus in an outbreak on the North Shore has been scrubbed and is safe, but other eating establishments and food sources are still being investigated.

State Epidemiologist Sarah Park said the owners of Cholo’s Homestyle Mexican II voluntarily shut down the restaurant Tuesday afternoon to do a thorough cleaning and reopened Wednesday.

The restaurant disinfected all surfaces and utensils, under the health inspectors’ supervision, and disposed of a lot of food, she said.

The Health Department confirmed that more than 100 people who became sick after dining at or who were in contact with someone who dined at Kally K’s Steakery & Fishery, 3383 Commercial Way, in Spring Hill between March 6 and 11 were stricken by a norovirus. According to the report, at least one employee of the restaurant tested positive for the virus, which is a leading cause of gastroenteritis. Symptoms can include severe vomiting, diarrhea and weakness that can last one or two days. An investigation was conducted jointly by the Health Department and state Department of Business and Professional Regulation on March 14 after more than 100 complaints had been received. An inspection of the restaurant yielded two violations, one of which was listed as critical: An inspector noted that an employee engaged in food preparation had not washed his or her hands prior to handling food and equipment or when changing gloves. The second violation dealt with cleaned and sanitized equipment, utensils, linens or other items that were not properly stored, according to the DBPR.

Scientists at Ohio State University are working on a new method of vaccine delivery to combat human norovirus, a virus that causes highly contagious vomiting and diarrhea. Using a viral vector approach, with the vesicular stomach virus, researchers injected mice with the vaccine and saw a considerable antibody response, which was 25 times higher than the response from a traditional vaccine.

“So it looks like the virus and acts like the virus, but it’s not, and that is how a vaccine designed with virus-like particles should function,” said Jianrong Li, senior author of the study and an assistant professor at OSU. “The virus-like particles can be continually produced in animals or humans for several weeks and stimulate strong immune responses. That’s the advantage of using VSV.”

The traditional vaccine was created using a baculovirus, which is rod-shaped, instead of the VSV, which is bullet-shaped. And despite the elevated response, Li and his colleagues found no evidence of added strain to the mice–mucosal and fecal tests showed similar responses to both vaccines.

According to Science Daily, Scientists have shown that an experimental vaccine against the human norovirus — the bug behind about 90 percent of highly contagious nonbacterial illnesses that cause diarrhea and vomiting — can generate a strong immune response in mice without appearing to cause the animals any harm.

Using a novel viral vector-based method to grow and deliver the vaccine that has shown promise in other agents designed to fight such infections as HIV and hepatitis C, the researchers are the first to test this vaccine design method’s effectiveness against the human norovirus.

Animals receiving the vaccine developed high levels of antibodies, a robust white blood cell response and an additional immune response in the area of the body most affected by this particular infection — the gastrointestinal system.

The researchers say this study supports the use of viral vector-based techniques as a new way to develop vaccines for human norovirus and other viruses that cannot grow in cell cultures. It also suggests that these Ohio State University scientists could be well on their way to developing a safe vaccine against a highly problematic pathogen that causes millions of gastrointestinal illnesses every year in the United States.

“The mice in our study developed a much higher antibody response to our vaccine candidate than they did to a more traditional vaccine. That’s one of the keys, to have a sustained antibody response, so that when the disease comes along, you can neutralize the virus and protect yourself,” said Jianrong Li, assistant professor of food science and technology at Ohio State and senior author of the study.

Li co-authored the study with Yuanmei Ma, a graduate student in food science and technology. The research appears in the current issue of the Journal of Virology.

The Centers for Disease Control and Prevention estimates that more than 21 million cases of acute gastroenteritis — characterized by diarrhea, vomiting and stomach pain — each year are caused by norovirus infection. Human norovirus is transmitted primarily through fecal-oral contact, either through contaminated food or water or direct person-to-person spread. This virus is famous for being so contagious that as few as 10 viral particles may be enough to cause symptoms. No vaccine or anti-viral drug is currently available for human norovirus.

That kind of pathogenic power makes the virus a high priority for vaccine developers, said Li, who also serves on Ohio State’s environmental health sciences faculty. But the process is complicated by two primary problems: The virus cannot grow in cell cultures, and no small animal models exist to mimic the infection.

Without the ability to grow the norovirus in cell cultures, the researchers instead inserted a human norovirus capsid gene — capsid refers to the virus’s outer shell — into a specific location on the genome of a different virus. This process creates what is known as a recombinant virus — a new viral strain formed by recombining genetic material from other viruses.

The viral host for this vaccine candidate is called vesicular stomatitis virus, or VSV, a bullet-shaped virus that has been an attractive vector for vaccine designers, Li said. The resulting recombinant viral vector functions as both the vehicle to deliver the vaccine as well as the agent that produces virus-like particles that mimic the human norovirus itself.

In this work, vaccination with the recombinant virus caused the norovirus capsid particles to grow continuously in animals, triggering a specific immune response. When the scientists tested these particles for their antigenic potential to look like foreign intruders in the body, the particles were neutralized by antibodies specifically designed to fight the human norovirus.

“So it looks like the virus and acts like the virus, but it’s not, and that is how a vaccine designed with virus-like particles should function,” Li said. “The virus-like particles can be continually produced in animals or humans for several weeks and stimulate strong immune responses. That’s the advantage of using VSV.”

Li said the VSV-based recombinant is also considered a powerful application because it can essentially be used as a bioreactor to facilitate large-scale production of these specific virus-like particles. In addition, it saves time: The viral vector developed virus-like particles within two days.

For comparison purposes in this study, Li and Ma also created a more traditional vaccine candidate by inserting a human norovirus gene into a different type of virus: a baculovirus, which is rod-shaped. It took six days for these viruses to grow enough to be used as a vaccine candidate, and the production level was comparatively low.

The scientists then conducted an animal study to observe what kind of immune response the VSV-based norovirus vaccine candidate could generate. Mice received either the VSV-based vaccine or various types of control substances for comparison, including one group that received the vaccine created with the more traditional technique. The substances were given orally or through the nose.

Weekly blood samples showed that two weeks after receiving the vaccines, the mice given the VSV-based norovirus vaccine had developed and sustained a high level of antibodies against the human norovirus — about 25 times higher levels of antibodies than those induced by the traditionally prepared vaccine candidate.

“This might be the most important advantage of the VSV-based norovirus vaccine candidate: It prepares a high concentration of norovirus-specific antibodies that can assist with virus detection, disease diagnosis and therapy,” Li said.

In addition, the mice vaccinated with VSV-based vaccine generated a T cell immune response that was two times higher than the T cell response produced in mice receiving the traditional vaccine candidate. The immune response involving T cells, a type of white blood cell, plays an important role in efficient clearance of norovirus infection.

Li said the mucosal immune response — that involving areas covered by mucous membranes — was similar in the two vaccine types the mice received. The scientists tested fecal samples and vaginal antibody levels in the mice, and found the levels comparable between the groups of mice receiving the two different types of vaccine.

VSV is known to infect animals, especially cattle and pigs. Human infection with VSV is very rare. The VSV-based norovirus vaccine led to minimal weight loss but caused no symptoms of illness in mice. This showed that the virus strain was attenuated, or had lost its ability to spread, because of the additional gene inserted into its genome, Li explained.

Because mice will not develop traditional norovirus symptoms, this study did not involve a test of the vaccine against the pathogen itself. Li said his further research plans include enhancing the vaccine candidate by inserting additional genes into VSV along with the human norovirus gene, which is expected to make the vaccine more potent but still safe. And he then hopes to test the vaccine candidate in a larger animal model, such as so-called germ-free pigs, animals that have never been exposed to any pathogens. These animals develop diarrhea in response to norovirus infection, as do humans.