As hospitals in China are reportedly overwhelmed by a surge of mysterious childhood pneumonia cases, outbreaks are starting to crop up in other countries, including parts of the U.S.
"As of today, the CDC is not seeing anything out of the ordinary related to levels of mycoplasma across the country, but we are watching it closely," Dr. Mandy Cohen, M.D., the director of the Centers for Disease Control and Prevention (CDC), told Fox News contributor Dr. Marc Siegel in an emailed statement on Friday.
Another infectious diseases expert, Dr. Sarah Park, medical director of medical affairs at Karius, a California biotech company, told Fox News Digital that the surge in respiratory illnesses, including cases of pneumonia, is primarily attributed to common pathogens like Mycoplasma pneumoniae, respiratory syncytial virus (RSV), adenoviruses and influenza virus.
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"There is no indication of a novel virus causing these illnesses," said Park, who was formerly with the CDC as an epidemic intelligence service officer.
She has contributed to combating diseases such as bacterial respiratory diseases, West Nile Virus and SARS.
The condition has been described as "white lung syndrome," which is a reference to the appearance of the chest scans that show "diffusely damaged lungs" related to severe cases of pneumonia, Park noted.
What factors are causing the outbreak?
The increase in respiratory illnesses is believed to be due to a combination of factors.
Respiratory illnesses typically surge in the colder months, but this has been compounded by a post-pandemic effect, according to experts.
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"This is the first winter without strict COVID-19 measures, and that has likely led to increased exposure and susceptibility to common respiratory infections," Park said.
"Prolonged lockdowns and other COVID-19 containment measures have limited people's exposure to common pathogens, potentially reducing population immunity levels."
While Park called the outbreaks "concerning," she said there is "no current indication that it represents a novel pathogen or a threat on the scale of a new pandemic."
She added, "Most of the reported pathogens are well-known and typically manageable."
Where are the outbreaks occurring?
In China, ProMED, the global digital disease surveillance system, reported that the country’s hospitals — primarily in Beijing — have become "overwhelmed with sick children" as a result of the pneumonia outbreak.
The Netherlands has also seen a surge. During the week of Nov. 13-19, there were 103 pneumonia cases for every 100,000 children between the ages of 5 and 14, according to the Netherlands Institute for Health Services Research (NIVEL).
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Some areas in the U.S. have also reported outbreaks or upticks in cases, including the states of Ohio and Massachusetts.
"Similar patterns of increased respiratory illnesses have been observed in other countries, including the U.S., after the lifting of COVID-19 restrictions," Park told Fox News Digital.
"Prolonged lockdowns and other COVID-19 containment measures have limited people's exposure to common pathogens, potentially reducing population immunity levels."
"However, the specific mix of pathogens and the severity of outbreaks can vary based on local factors such as population immunity and health care infrastructure."
How is childhood pneumonia treated?
Pneumonia, or "white lung syndrome," is usually treated with a course of antibiotics.
There is some concern about antibiotic resistance, particularly in the case of Mycoplasma pneumoniae infections, Park noted.
"Overuse or misuse of antibiotics can lead to strains that are harder to treat, emphasizing the need for responsible antibiotic prescribing and usage," she said.
In managing the childhood pneumonia outbreaks, Park emphasized the importance of "timely and transparent communication" between countries and international health organizations like the World Health Organization (WHO).
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"This exchange of information is critical for global surveillance and response to infectious diseases," she said.
The ongoing mental and physical impacts of the COVID-19 pandemic and associated restrictions may also play a role in the current health landscape, the expert said.
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"As the global community continues to navigate the aftermath of the COVID-19 pandemic, this situation is a reminder of the need for continued vigilance against respiratory illnesses," she said.
"This includes ongoing research, health care system preparedness, and public health measures."
Fox News medical contributor Dr. Marc Siegel contributed reporting.