CNN
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Children who cough for weeks may have a form of walking pneumonia that is on the rise in the U.S. this year, and they may need another course of antibiotics to treat it, infectious disease experts say.

“It’s been on our radar since early summer when we started seeing a noticeable increase in the number of children with pneumonia who appeared to have this specific type of pneumonia,” said Dr. Buddy Creech, a pediatric infectious disease specialist at Vanderbilt University Medical Center.

Creech says that on the same day in August, four Nashville pediatricians contacted him to ask why so many children were coughing during the summer. These doctors wanted advice, he says, because their favorite antibiotic for pneumonia – amoxicillin – didn’t seem to work in these cases.

The pneumonia is caused by tiny Mycoplasma pneumoniae bacteria and cases are increasing this year, especially among preschool-aged children, according to the U.S. Centers for Disease Control and Prevention, which sent a bulletin last week alerting parents and doctors determine the increase.

Mycoplasma pneumonia is the latest entry on a growing list of lung infections is keeping doctors on their toes this fall. Whooping cough, or whooping cough, cases — which also cause prolonged coughing — are five times higher than this time last year, and respiratory syncytial virus, or RSV, is also on the rise in parts of the US.

In the past it was difficult to test for Mycoplasma. It’s not a germ that likes to grow in a petri dish, which is the standard, if slow, way to test for bacterial infections.

Now, Creech says, better diagnostic tests make it easier to detect these bacteria faster and more reliably. With so many germs causing children to cough this fall, it’s critical that doctors use these new tests to make the correct diagnosis, he said.

“This is exactly the time when we need to use these diagnostic tests that can guide treatment,” he said.

Awareness of the Mycoplasma trend is important, the CDC says, because first-line antibiotics for children, such as amoxicillin and penicillin, do not kill these types of bacteria. However, the infection can usually be easily treated with other antibiotics, such as azithromycin.

According to the CDC, which monitors discharge data from a network of hospitals and test results from commercial labs, the number of children ages 2 through 4 seen in emergency rooms for pneumonia who tested positive for Mycoplasma increased from 1% in April 2024 to 7.2% in early October, a sevenfold increase. The number of diagnoses in older children doubled in the same period, from 3.6% to 7.4%.

The CDC said Mycoplasma cases appear to have peaked in mid-August, but are still high. Creech said he expects them to remain high for about another month, then start to taper off later in the fall.

On an X-ray, Mycoplasma infections can give the lungs a cloudy or “white lung” appearance.

Last year, China, Denmark and France all reported increases in this type of pneumonia in children.

The rise in cases is likely due to at least three factors, said Dr. Geoffrey Weinberg, a pediatric infectious disease specialist at the University of Rochester Medical Center.

The first is that Mycoplasma infections are returning to pre-Covid-19 pandemic levels.

“It seems very dramatic now, but it’s more because during the peak of the Covid pandemic, pretty much everything else went down,” Weinberg said. “But the actual national rates are quite similar to what they were before 2019.”

The second reason is that most infections are cyclical, making some years worse than others. Doctors tend to see spikes of Mycoplasma pneumonia every three to seven years as people lose their immunity to the virus, Creech said.

“Sometimes you just have a bad year, combined with not noticing for a while, now we’re getting it more and more,” Weinberg said. If you have a lot of cases when you don’t have many at all, the spike can feel even bigger, he added.

The third reason is that doctors have more advanced tests – called multiplex tests – that can check for multiple types of viruses and bacteria at the same time. So it may be that this infection is only picked up more often.

Mycoplasma pneumoniae are bacteria that travel via respiratory droplets. People catch them when they are near someone else’s coughs and sneezes, according to the CDC. For that reason, this type of pneumonia spreads easily through crowded environments such as schools, college residences, and nursing homes.

These bacteria are also troublesome because they linger in the body for a while – from one to four weeks – before making someone sick. By the time symptoms begin, a person usually has little memory of what he or she has been exposed to.

Mycoplasma infections start out fairly common, with headache, sore throat, low fever and chills. People often feel miserable but can still get by, hence the term “walking pneumonia.”

The cough is usually a dry cough, without mucus. It starts gradually and increases slowly over a period of two to three weeks, becoming almost constant.

Not everyone who gets a Mycoplasma infection needs treatment. Weinberg says that as many as 75% of children and young adults will get over it without any therapy.

However, sometimes the infection will worsen pre-existing conditions such as asthma and make people seriously ill.

In rare cases, these germs can travel outside the lungs. In the central nervous system, they can infect the lining of the brain and spinal cord. The bacteria can also infect the nerves of the eyes, as well as the nerves that control the legs and bladder. These patients may never develop a cough.

CORRECTION: This story has been updated to correctly reflect the magnitude of the increase in cases among young children.