INDIANAPOLIS  - The new year is beginning with a new rise in illnesses. One of the biggest viruses going around is Norovirus, or a stomach bug that is referred to by some as the ‘winter vomiting bug.’ According to the most recent CDC data, Norovirus cases are up at least 30% since the end of November. “You talk with a lot of people and they will tell you they are seeing a lot more of it in the community,” said Dr. John Christenson, the associate medical director of infection prevention at Riley Hospital for Children. “This is the perfect storm. All kinds of different things show up at this time of the year."  Respiratory illnesses like influenza and RSV are also on the rise. According to the Indiana Department of Health, flu activity in the state has now reached the “high” threshold.  “We know we are on the rise,” Christenson said. “You just look at our numbers from week to week... this is the worst time of the year for all kinds of respiratory infections but also for norovirus.” The main reason for the rise is due to the time of year and how these viruses spread. “We see this surge every year,” Christenson said. “The so-called ‘respiratory season’ is generally in the colder months. There are many different reasons but I think the number one reason is the viruses tend to persist in the air as aerosols for longer because of the humidity and the cooler temperatures.” When you combine that with all the holiday parties people just went to, as well as more people staying indoors for the colder months, it becomes a lot more problematic. “No question. This is the worst time of the year," Christenson said. "These viruses will survive on surfaces for long periods of time, Norovirus in particular, RSV, influenza… Norovirus is one of those viruses that you only need probably one infectious particle for you to get infected with it." The good news is most cases don't need care outside of the home. For Norovirus, the most important thing to remember is to stay hydrated. If the sickness doesn’t seem to be getting better, that’s when a trip to the doctor’s office may be necessary. “If they are vomiting and the vomiting is out of control then they need to have someone see them,” he said. As for respiratory illnesses like the flu or RSV, they can spread quickly in school settings. Parents should seek extra medical attention if their child is having breathing problems. “In some cases, they think their child is having difficulty breathing, they should take them to urgent care or the emergency department,” he said. The most important thing to do to prevent these kinds of illnesses is to take extra precautions. That includes thoroughly washing your hands for at least 20 seconds, cleaning and disinfecting commonly used surfaces like your kitchen table, and staying away from people who may be sick.  For more prevention tips for Norovirus, click here. For more prevention tips for respiratory illnesses, click here.