These are a family of viruses that carried primarily by rodents and can be transmitted from rodents to humans.

While human-to-human spread doesn’t happen often, it can cause severe illness when it does occur. Sharjeel Ahmad, MD, a staff physician of infectious disease with OSF HealthCare, says there’s one major health concern to stay aware of.

"In the Americas, hantaviruses cause the hantavirus cardiopulmonary syndrome (HCPS). It's a disease characterized primarily by rapid onset failure of breathing (respiratory failure), and heart problems (cardiovascular shock)," Dr. Ahmad says. "The current strain in the news is the Andes virus strain, which is linked to a cluster of passengers onboard a cruise ship, the MV Hondius, which traveled to Patagonia in South America."

Hantavirus is spread through infectious particles that are aerosolized (spreading throughout the air), infected urine, feces or saliva, especially when the contaminated dust becomes airborne during cleaning. That's why Dr. Ahmad stresses that it’s so important for house cleaners or those who may come across rodents or their droppings to be even more cautious. 

The animal reported to have been the reservoir of the Andes strain was a long-tailed pygmy rice rat, Dr. Ahmad says. It’s a rodent found in rural areas of central and southern Chile and the southern Andean region of Argentina.

The cruise ship itself wasn't the only reason it became a nest for the hantavirus to spread, Dr. Ahmad says. But it was also impacted by how passengers picked it up in the first place.

"It creates a unique convergence of risk factors," he says. "Passengers likely had direct environmental exposure to rodent habitats during an shore excursions where the virus is in the endemic stage. Things like hiking, visiting rural structures and exploring the wilderness where infected rodents may be."

Unlike COVID-19, influenza or other well-known viruses, hantavirus does not spread through brief interactions between people.

There's prolonged exposure between people, and infected individuals share rooms with their friends or family members. Medical access on a cruise ship also becomes a point that makes the situation more difficult. 

"Sharing a bed, kissing, attending social gatherings and spending time in close quarters," are common ways viruses like this spread, Dr. Ahmad points out.  

The incubation period for the Andes strain is very long, anywhere from seven to 49 days. This means that people with the virus could have been exposed on shore and not developed symptoms until days or weeks later. 

One hantavirus case is currently being investigated in Illinois, but it has no connection to the cruise ship outbreak. On Monday, May 18, 2026, the Illinois Department of Public Health (IDPH) reported that the Centers for Disease Control and Prevention (CDC) conducted a confirmatory test on the person which turned out to be negative.

In the U.S., 30-40 cases of hantavirus happen each year, normally in the rural parts of Western and Southwestern America like Utah, Colorado, New Mexico and Arizona. Since surveillance began in 1993, the U.S. has recorded 890 cases. This shows that public burden in America remains very low.

Dr. Ahmad says COVID-19 was much more efficient at spreading through respiratory droplets.

The HCPS mortality rate is high. Dr. Ahmad says it’s roughly 35-40% in the United States for several reasons, including the virus’ ability to rapidly cause severe lung fluid leakage and heart dysfunction leading to respiratory failure and shock within hours. Additionally, there are no specific antiviral treatments or vaccines available for hantavirus. 

"This virus targets the lining of the blood vessels, called the endothelium, and causes them to become leaky. So, you get this fluid, it leaks into the lungs and then the heart dysfunction happens," Dr. Ahmad says. "So, both your lungs and heart are not working well." 

However, he believes that hantavirus cases are likely underreported, and that is why the mortality rate is so high. 

“The treatment is entirely supportive care, including admission to the intensive care unit for careful monitoring, careful fluid management, and medication to support blood pressure and the heart,” Dr. Ahmad adds. “Some people may need a ventilator for respiratory failure. In rare cases, someone severely ill may need extracorporeal membrane oxygenation (ECMO), which is in essence is a heart-lung bypass machine.”

Progression of illness from flu-like symptoms to critical access is very fast, Dr. Ahmad says. "Most of it happens within the first 24 hours." 

The best chance of survival, Dr. Ahmad adds, is catching the disease early and getting treatment as soon as possible. Other tips include:

-       Seal homes and buildings: Close gaps and holes where rodents can enter - around pipes, vents, doors, and foundations.

-       Eliminate food sources: Store food in sealed containers, clean up spills, and secure garbage.

-       Clean safely: Don’t sweep or vacuum rodent droppings dry. Ventilate the area, spray droppings/nesting material with disinfectant or diluted bleach, let it soak, then wipe up with gloves.

Dr. Ahmad says it’s additionally important to keep this illness in mind if you’re traveling somewhere where Hantavirus is in the endemic (native to, or constantly present) stage, like Patagonia, and take common sense measures to prevent exposure.

Infectious disease specialists understand this virus well, Dr. Ahmad reassures, which is why he does not believe there is any chance of a pandemic from this hantavirus strain. 

"Stay informed, avoid panic and focus on practical prevention," he recommends. 

As of May 18, 2026, there were 41 people across the U.S. being monitored for hantavirus. Over the prior weekend, a person in Canada who was on the cruise ship was reported to test positive for the virus.

The CDC is working with state and federal partners to monitor passengers who were on the affected cruise ship. Certain sick patients have been treated at the Nebraska Biocontainment Unit in Omaha and Emory University Hospital in Atlanta. The two patients being monitored in Atlanta were discharged on Friday, May 15 from the hospital’s Serious Communicable Disease Unit. They have now been moved to the Nebraska Biocontainment Unit to join the 16 others.

The World Health Organization (WHO) Director-General, Tedros Adhanom Ghebreyesus, continues to say the risk to the global population remains low.

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Before vaccines, nearly every child in the United States caught the virus. Today, however, public health experts emphasize that while natural immunity does occur after infection, the risks of measles are far too high when compared to the protection offered by the measles, mumps and rubella (MMR) vaccine.

Early 2025 data show rising cases in the U.S., a reminder that measles still spreads quickly wherever vaccination rates dip.

Natural immunity and the role of vaccines

“Natural immunity is wonderful. It's part of the evolution of the human body that has taken all our exposures and creates a memory for them, so that we can protect ourselves in the future. Vaccines augment (improve) that. There are some infections that an individual doesn't have to go through, or are so severe to go through, that receiving a vaccine is more valuable,” says Doug Kasper, MD, infectious disease specialist with OSF HealthCare.

He notes that measles is one of those infections.

“Measles is highly infective and has potential complications in our child population. The key with measles is that the vaccine is so effective at preventing infection. It's unanimously beneficial to receive and has been that way for a long time in the United States.”

For older generations who remember having measles as kids, it can be easy to assume it wasn’t serious. But modern evidence paints a different picture: measles can lead to pneumonia, hospitalization, brain inflammation, long-term complications and death – even in healthy children.

Why measles vaccination remains essential for kids

“Fortunately, measles vaccination remains part of the normal pediatric vaccine schedule. It's something that would be discussed with the parent regarding their child at a standard visit,” Dr. Kasper says. “We strongly recommend all children receive all their childhood vaccinations, which includes the measles, mumps and rubella (MMR) vaccine. The timing of that vaccine begins at one year of age, but it can sometimes be given earlier if there is a local outbreak of measles in the community.”

MMR vaccination rates need to remain extremely high, typically above 95%, to prevent outbreaks. However, declining vaccination rates across parts of the Americas have caused concern. The Pan American Health Organization recently warned that the region may lose its measles elimination status without urgent action.

Vaccines build a “library” of protection

The goal of vaccination isn’t to replace the body’s defenses – it’s to strengthen them.

“In the hospital, we tend to see people that get sicker, so that's what we focus our efforts on. But a lot of medicine is done outside of the hospital, and that is preventive medicine,” Dr. Kasper says. “So, the strategy with vaccine is to try not to get sick or try to get less sick than you would've. Use the utility of the vaccine, along with natural immunity, to build up your individual reservoir as much as possible to protect you in the future.”

This “reservoir” or “library” of immunity is especially important with a virus as contagious as measles, which can linger in the air for hours and infect up to 90% of unprotected people who are exposed.

Localized outbreaks are driving current cases

While measles is not widespread across the U.S., localized outbreaks continue to occur in communities where vaccination rates have dropped. Public health departments monitor these cases closely and respond with tools such as:

• Rapid case investigations
• Community education
• Mobile vaccination units
• Early MMR vaccination for children who qualify

Without high vaccination coverage, these small outbreaks can grow quickly. That’s why maintaining strong MMR rates is essential – to protect children, prevent community spread and preserve decades of progress toward measles elimination.

For more information on measles symptoms and long-term risks, visit the OSF Newsroom.

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What is Norovirus? 

"Norovirus is a viral infection, most people refer to it as the stomach flu. But it's a distinctly different virus than influenza," says Doug Kasper, MD, an infectious disease specialist with OSF HealthCare. "It's acquired by contact, meaning you touch it. Then it gets from outside your body, usually in through your mouth, and then into your GI (gastrointestinal) system."

Norovirus symptoms and concerns

"Symptoms usually come on very quickly. Roughly a day or two after exposure, the person will notice gastrointestinal symptoms like nausea, abdominal pain, bloating pain, gas and diarrhea," Dr. Kasper says. "Most people that don't have an immuno-compromised history, the symptoms will pass in 2-3 days. It can be a much bigger problem in people who are chronically ill. It leads to dehydration and low food intake. So, if someone is more vulnerable or they have underlying GI issues like Chron's disease, ulcerative colitis, it can cause more profuse symptoms."

Concern for reinfection 

"One of the main issues with Norovirus, is that everybody is susceptible to it. There is no vaccine and there is no significant immunity that is generated by infection," Dr. Kasper says. "Which also means you can be reinfected shortly after you've had infection."

Neutralize Norovirus at the source

"Because people get so sick and they're using the same bathroom, where they're all in the same area, you really have to neutralize Norovirus at the source. Because otherwise people will just reinfect each other over and over again," Dr. Kasper says. 

Dr. Kasper emphasizes that alcohol hand gels do not kill Norovirus. Washing your hands with soap and water and practicing good hand hygiene is extremely important.

For cleaning the contaminated areas and surfaces, use bleach-based products. You must clean bathrooms, common living areas and food preparation counters, Dr. Kasper adds. The Centers for Disease Control and Prevention (CDC) recommend leaving the bleach disinfectant on the affected area for five minutes. Then clean the whole area again with soap and hot water, followed by washing any dirty laundry, taking out the trash, and once again washing your hands.

The CDC reports that 685 million total cases of acute gastroenteritis (which leads to vomiting and diarrhea) comes from Norovirus. 200 million of those cases come from kids under 5 years of age, normally peaking in January.

Clean all products the person would've touched while they have Norovirus. Norovirus is "durable," Dr. Kasper says. It can last on surfaces for up to a few days.

Where Norovirus is most common

"We see this a lot in school-aged children, daycares, nursing homes and assisted living facilities where many people are congregating," Dr. Kasper says. "The main issue with Norovirus becomes environmental cleaning and hand hygiene."

Dr. Kasper adds that spikes are typically seen when kids go back to school in the fall or early winter.

“Kids share meals at lunch, or they touch each other through play when they're sick," Dr. Kasper says. "With older adults, especially if they're living in their home, it's less likely because they're just not around that many people or touching things throughout the day."

How food preparation can increase Norovirus spread

"It's not the actual food; it's the person preparing the food. What we worry about with Norovirus is the hand hygiene of the worker. Whether it's at a cafeteria or a restaurant, or even at the home," Dr. Kasper says. "To get infected with Norovirus, the person has to ingest it. It's not a skin infection, so most of the time we put our hands to our mouth, it's when we're eating. So, if somebody is preparing food, and the food becomes contaminated, you acquire it by touching or ingesting the contaminated food. But it's not coming from the food primarily, it's coming from the person who prepares the food."

Norovirus is highly transmissible 

"You need a very small amount of virus, very few copies, for somebody to become infected," Dr. Kasper says. "With any virus, there's a certain amount the person has to acquire to trigger an infection. So, it's not one copy, but Norovirus is on the end of the spectrum where you need many fewer copies to generate infection."

Why Norovirus is dangerous for immunocompromised people

"The immune system is what clears Norovirus. So, somebody who has an intact immune system, although they'll get sick and it'll be very unpleasant, generally they will get better within a period of days," Dr. Kasper says. "Somebody who is immunocompromised, whether it's through having a transplant or medication steroids, they can really struggle to clear Norovirus for a longer period of time. What really builds up is the fluid loss leads to dehydration and possible electrolyte loss that leads to other complications. Then anorexia can occur when you're not hungry to eat. That can compound for somebody that is in a frailer state to begin with."

Most senior living communities have specific cleaning guidelines they’re expected to follow by government agencies. Schools follow different guidelines, Dr. Kasper says, but a lot of the guidance is based on using industrial-based cleaners to try and stop the spread of illnesses.

Norovirus is reported in outbreaks, not a specific number of cases, because the virus spreads so fast and can affect a large amount of people in a smaller space. “When contact happens, infection is likely to occur,” Dr. Kasper adds.

Norovirus is common and not unexpected, Dr. Kasper says. There are no new strains that come out like we see in the flu or COVID-19. The need for communication on the virus is simply to bring awareness to cleaning habits and to give advice on how to keep others safe. 

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Now health professionals are warning the public about a number of health concerns that can come with sitting on the toilet too long and scrolling on your cell phone. 

Many people have gotten into the habit of taking their phone into the bathroom with them and scrolling TikTok or Instagram while they do their business. 

Kaylin Heinz, an infection preventionist registered nurse at OSF HealthCare, recommends making the mental decision to not even take your phone with you. 

A simple flush doesn't get rid of the nastiness that is common in the restroom. Especially with bathrooms that have showers and bathtubs in them. 

The moisture in the room can lead to bacteria, fungi and virus growth, not just inside the toilet, but on all bathroom surfaces. 

Heinz calls these a “breeding ground” for germs. 

“With sitting and scrolling, you're sitting there for long periods. Your hands are probably dirty before you go to the bathroom, because you're typically not washing your hands before you go to the bathroom. Then when you're sitting on the toilet, you're probably setting your phone down on a surface area that has germs," Heinz says. "Then you'll wash your hands, which you'll typically think your hands are clean, but they're not. Then you wash your hands and pick up the phone that was on the surface with germs, and now your hands are dirty again. And you're picking up the germs, taking them elsewhere, and spreading them to other people.”

Does your toothbrush hang out on the bathroom counter? You might want to rethink that. 

Heinz says if it's not put away safely, it likely has fecal matter on it. 

Another tip, she says, is to close the lid before flushing. It helps keep the germs inside and not aerosolize across the room.

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The newest tool for protecting our littlest population is now available in the United States. 

The respiratory syncytial virus (RSV) vaccine was initially approved in summer 2023 for adults 60 and older, quickly followed by a recommendation by the U.S. Food and Drug Administration (FDA) for pregnant women. The goal of vaccinating pregnant women would be to pass on RSV antibodies from mom to baby.

"(Pregnant women should get the vaccine) somewhere between 32-36 weeks of pregnancy. As long as they receive the vaccine and give birth two weeks after or more after getting the vaccine, the baby should be having good protection for their first year of life,” says Kinnera Are, DO, a pediatrician with OSF HealthCare.

When is RSV season?

Dr. Are says RSV season normally starts in October, goes through the winter, and wraps up in March or April.

"We are expecting to see it this year, but hopefully not as bad as it has been the last couple of years,” Dr. Are adds.

What babies are eligible?

Infants eight months and younger are eligible for the RSV vaccine, along with older infants who have serious medical conditions like chronic lung disease and heart conditions.

"Some infants at higher risk are eligible to get the vaccine for their second RSV season. So, the second year October through March. Some things that would put them at higher risk if infants have chronic lung disease and prematurity and needed oxygen or medications within the last six months. Otherwise, we can offer it during that second season to infants from American Indian heritage or Alaskan Native heritage,” Dr. Area says. “Severely immunocompromised infants are eligible for that second season, and infants with cystic fibrosis who have issues with their lungs. Or if they're very small and are having issues with growth, they may also be eligible." 

How to protect infants and others from RSV

Ways to protect infants from RSV are on par with other respiratory illnesses.

-          Stay away from sick individuals

-          Keep kids home if sick (fever, runny nose)

-          Prioritize good sleep

-          Focus on good eating habits, hydration

-          Wash your hands

"RSV will show symptoms like most other respiratory illnesses. So, you may start off with congestion and runny nose, maybe a fever or a cough," Dr. Are says. “RSV, especially in the infant age group, tends to affect the lungs a little bit more than older kids. So, you may see more of that cough or congestion that's not coming out.”

Days 3-5 are usually the worst

"Any respiratory illness, but especially RSV, is worse between days three and five. Based on where the infant is when they come in, we'll guide them to see if they're getting better or do we expect it to get worse before it gets better,” Dr. Are says.

When it’s time to go to the emergency department

“Two things that would make me tell someone they need to go to the emergency room; One, if the infant is having respiratory distress like breathing really fast, having trouble breathing or having a lot of wheezing that is not getting better and it's very persistent," Dr. Are says. “You can give us a call (at the pediatrics office) but we'll probably recommend you go to the emergency room. The other thing is dehydration. Severe hydration can be shown in no wet diapers for eight hours and no urine output for eight hours. That's a sign they probably need some IV fluids and need to go to the emergency room for care.”

If a pregnant mother didn’t get the RSV vaccine, your child’s pediatrician will ask if they want the baby to get the vaccine in the first few visits.

Normally, symptoms can be managed at home. Antibiotics aren’t prescribed, since RSV is a virus, but sometimes the virus can cause a secondary bacterial infection like pneumonia, which could call for antibiotics. You can use a nasal suction tool to keep the baby’s nose and airways clean, which is especially important when they’re eating or sleeping.

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