KANSAS CITY, Kan. (WDAF/NEXSTAR) — Respiratory infections caused by a bacteria known as Mycoplasma pneumoniae have been increasing in recent months, leading to widespread cases of a condition known as “walking pneumonia,” according to the CDC. Infections resulting in "walking pneumonia" are generally less severe than pneumonia, with many patients going their daily routines without initially realizing they have it. Symptoms also start out mild in the first week before getting progressively worse; they include a cough, sore throat, headache, and/or fever. "People with pneumonia caused by M. pneumoniae can seem better than expected for someone with a lung infection," the CDC writes. "With mild symptoms, people may not stay home or in bed. Thus, the phrase 'walking pneumonia' was coined." STD epidemic slows as new syphilis and gonorrhea cases fall in US In October, the CDC wrote that since late spring, the number of infections caused by walking pneumonia has been increasing, especially among young children. In fact, the CDC is seeing more cases nationally than it has since the pandemic began in early 2020. The exact number of cases is hard to determine, as "walking pneumonia" isn't a condition that is required to be reported to public health departments. The CDC does, however, have data from the National Syndromic Surveillance Program (NSSP), which collects patient information and diagnoses from emergency departments across the country. NSSP data isn't available publicly, but the CDC has confirmed that several Health and Human Services (HHS) regions are reporting higher case numbers than others. Specifically, the "highest levels" were reported in HHS Regions 2, 6, and 7, which cover: New Jersey, New York, Puerto Rico, and the Virgin Islands (Region 2) Arkansas, Louisiana, New Mexico, Oklahoma, and Texas (Region 6) Iowa, Kansas, Missouri, and Nebraska (Region 7) While still increasing, the lowest increases were reported in HHS regions 8, 9, and 10, which include: Colorado, Montana, North Dakota, South Dakota, Utah, and Wyoming (Region 8) Arizona, California, Hawaii, Nevada, American Samoa, Commonwealth of the Northern Mariana Islands, Federated States of Micronesia, Guam, Marshall Islands, and Republic of Palau (Region 9) Alaska, Idaho, Oregon, and Washington (Region 10) "It’s important to note that while the National Syndromic Surveillance Program collects data from the vast majority of emergency departments, it isn’t 100%, so there may be regions of the country with more or less reporting," the CDC said. Doctors at a Kansas City hospital told Nexstar's WDAF that kids are among the most at-risk. “Every three to four years immunity to mycoplasma waxes and wanes. Now the immunity has waned and we’re seeing more kids clustered together, so we’re seeing a higher rate of walking pneumonia in children especially," Dr. Shawn Sood, a pediatric intensivist at KU Health, said. "Last year I feel like RSV was higher, two years prior COVID, and now we're facing more mycoplasma cases," he added. Sood explained that since symptoms start with a minor cough or sore throat, infected kids go to school and spread it, not realizing they're sick. "Walking pneumonia" is also a bacterial infection and not a virus, so there's no vaccine. "If your child's having this lingering cough, sore throat, or fever have them checked out," Sood urged. James Balmer, a music teacher who spoke with WDAF, is currently recovering from his own 10- to 12-day bout with the illness. He's noticed many of his elementary students coming down with respiratory illnesses over the last month. "You'll see one or two [students] out for two or three days," Balmer said. When asked if he wished parents would keep sick kids at home, he quickly replied that he did. E. coli cases climb in McDonald’s outbreak tied to slivered onions Milder cases of M. pneumoniae infection usually clear up on their own, the CDC says, but antibiotics may be used to treat the infections in some cases. The bacteria is naturally resistant to some antibiotics, so "judicious use" is recommended. "Over-the-counter medicines can help you feel better while you're recovering," the CDC says. If more severe cases of M. pneumoniae infection are left untreated, they can lead to permanent lung damage, or in rare cases, neurological issues like seizures or a wobbly walk., Sood said. "We've also seen kids who had untreated walking pneumonia with severe respiratory symptoms," said Sood, who added that "a lot" of these kids have asthma, or have required a ventilator. Several children were in the KU Health's UCI with respiratory illnesses at the time Sood spoke with WDAF. He expects cases to only increase as kids spend more time indoors during the winter months, especially with holiday break coming up and families traveling. Children who are suspected to be sick with M. pneumoniae infection should be taken to their pediatrician immediately, he said.