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Children who suffer from a cough for weeks could be suffering from a form of walking pneumonia that is on the rise in the U.S. this year, and they may need different antibiotic therapy to treat it, infectious disease experts say.

“It’s been on our radar since early summer when we saw a notable increase in the number of children with pneumonia who appeared to have this particular 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-area pediatricians contacted him to ask why so many children cough in the summer. These doctors wanted advice, he says, because their preferred antibiotic for pneumonia – amoxicillin – didn’t seem to work in these cases.

Pneumonia is caused by tiny Mycoplasma pneumoniae bacteria and cases are rising sharply this year, particularly among preschool-aged children, according to the U.S. Centers for Disease Control and Prevention, which sent out a bulletin last week saying alerted parents and doctors to the increase.

Mycoplasma pneumonia is the latest entry To A growing list of lung infections is keeping doctors busy this fall. Cases of whooping cough, or pertussis, which also causes a persistent cough, are five times more common than this time last year, and respiratory syncytial virus (RSV) is also on the rise in parts of the United States.

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 common, if slow, method of testing for bacterial infections.

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

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

According to the CDC, it is important to be aware of the mycoplasma trend because first-line pediatric antibiotics such as amoxicillin and penicillin do not kill this type of bacteria. However, the infection can usually be treated well with other antibiotics such as azithromycin.

According to the CDC, which monitors discharge data from a network of hospitals as well as test results from commercial laboratories, the number of children ages 2 to 4 who were treated in the emergency room for pneumonia and tested positive for mycoplasma increased from 1 % in April 2024 to 7.2% in early October, an increase of seven times. Diagnoses in older children doubled over the same period, rising from 3.6% to 7.4%.

The CDC said the number of mycoplasma cases appeared to have peaked in mid-August but remains high. Creech said he expects them to remain high for another month or so and then ease 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 each reported an increase in this type of pneumonia in children.

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

First, the number of mycoplasma infections is back to pre-Covid-19 pandemic levels.

“It seems very dramatic now, but it is more because almost everything else collapsed during the peak of the Covid pandemic,” Weinberg said. “But the actual statewide rates are quite similar to those before 2019.”

The second reason is that most infections are cyclical and therefore some years are worse than others. Doctors tend to see increases in mycoplasma pneumonia every three to seven years as people lose their immunity to the virus, Creech said.

“Sometimes you just have a bad year and don’t notice it for a while, now we get it more,” Weinberg said. If there are a lot of cases after there weren’t many, the surge could 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 could be that this infection is simply occurring more frequently.

Mycoplasma pneumoniae are bacteria that spread through respiratory droplets. People catch them when they are near another person’s coughing and sneezing, the CDC said. Because of this, this type of pneumonia spreads easily in crowded areas such as schools, college dorms, and nursing homes.

These bacteria are also tricky because they remain in the body for a while – one to four weeks – before they make a person sick. When symptoms appear, a person usually has little memory of what they may have experienced.

Mycoplasma infections fairly commonly begin with a headache, sore throat, low fever, and chills. People often feel bad but still manage, hence the term “walking pneumonia.”

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

Not everyone who gets a mycoplasma infection needs treatment. Weinberg says up to 75% of children and young adults get over it without therapy.

However, sometimes the infection worsens pre-existing conditions such as asthma and leads to serious illness.

In rare cases, these germs can migrate 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 accurately reflect the extent of the increase in cases among young children.