The U.S. Centers for Disease Control and Prevention (CDC) has issued a warning, alerting the public about an unusual surge in cases of walking pneumonia in young children over the past six months.

Mycoplasma pneumoniae (M. pneumoniae) causes respiratory infections that range from mild colds to severe pneumonia. In rare cases, it can lead to serious complications such as asthma attacks, encephalitis (brain swelling), hemolytic anemia, and kidney problems. Since most people with pneumonia caused by this bacteria experience mild symptoms, they often remain active rather than resting at home, leading to the term 'walking pneumonia.

According to the latest CDC report, this year has seen a spike in cases since late spring, particularly among young children, a shift from previous years when most cases were reported in school-aged children and adolescents. The recent surge in cases, particularly among children between the ages of 2 and 4, is "notable" as M. pneumoniae is not typically considered a leading cause of pneumonia in this age group.

"The M. pneumoniae discharge diagnosis data from March 31 through October 5, 2024, show an increase among all age groups across the United States, peaking in August, and remaining high. The increase, however, was highest among children. The percentage grew from 1.0% to 7.2% among children ages 2–4 years and from 3.6% to 7.4% among children ages 5–17 years in that time frame," the CDC stated.

The test positivity rates of M. pneumoniae infections have also gone up since late spring for all age groups, from 0.7% to 3.3%.

It is estimated to cause around 2 million infections annually in the U.S. After a period of reduced incidence during the pandemic, M. pneumoniae infections re-emerged last year.

Common symptoms include fatigue, fever, headache, a gradually worsening cough, and a sore throat. However, younger children may experience different symptoms including diarrhea, sneezing, a sore throat, a stuffy or runny nose, vomiting, and watery eyes.

Since the infection spreads through respiratory droplets when an infected person coughs or sneezes, officials are urging people to follow prevention strategies like regular handwashing and covering coughs and sneezes to help stop the spread of the bacteria.

Meanwhile, the CDC is closely monitoring the rise in infections through various surveillance tools. It is also reaching out to healthcare providers and health departments to raise awareness of the issue and working with them to monitor for antibiotic resistance.

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