According to the U.S. Centers for Disease Control and Prevention, cases of bacterial pneumonia in young children are increasing.

Pneumonia, a common lung infection, can be caused by several causes including bacteria, viruses, fungi and parasites. However, the CDC says cases caused by the bacterium Mycoplasma pneumoniae have “increased since late spring and remain high” over the past six months, particularly affecting children.

Additional cases caused by M. pneumoniae in younger children are particularly “notable,” the CDC said in an Oct. 18 statement.

According to the CDC, cases have increased from about 1% to more than 7% among 2- to 4-year-olds and from about 3% to more than 7% among older children ages 5 to 17.

“That may not seem like much,” said Dr. ABC News Medical Contributor Darien Sutton on “Good Morning America” ​​about the rise in cases. “But we’re at the beginning of this viral season, so we don’t yet know what to expect.”

Why should parents worry about pneumonia caused by M. pneumoniae?

According to the CDC, cases of M. pneumoniae infections most commonly occur in children between the ages of 5 and 17 and young adults.

“Walking pneumonia can be caused by a variety of things, but in pediatrics it's most commonly caused by this bacteria called mycoplasma,” Sutton said, later adding that it can take up to six weeks for this type of pneumonia to progress recovered.

What are the symptoms of bacterial pneumonia caused by M. pneumoniae?

M. pneumoniae can damage the lining of the respiratory tract, including the throat, trachea, and lungs.

Symptoms of an M. pneumoniae infection are similar to those of a chest cold and can include fever, cough and sore throat, but in some cases can also result in what is known as “walking pneumonia,” in which symptoms appear mild.

In children younger than 5 years, M. pneumoniae infections may cause different symptoms than the chest cold symptoms that may occur in older children and adults. This includes:

• Diarrhea
• Sneeze
• Sore throat
• Stuffy or runny nose
• Vomit
• Watery eyes
• Panting

“Any child under 5 is also susceptible to what are called non-specific symptoms, which can easily mimic other types of infections and are different from what we see in this older population,” said Dr. Jade Cobern, pediatrician and member of the ABC News Medical Department. “In this younger age group, it can be common for these children to have really general symptoms that may not be respiratory related at all.”

If someone has a severe case, they may need to be hospitalized. Symptoms of more serious infections include worsening of asthma, new development of asthma, severe pneumonia, or encephalitis (inflammation of the brain).

“This type of infection can start very slowly and symptoms can last longer than other types of pneumonia. And if kids have symptoms that really aren't getting better, if they're having any difficulty breathing, they need to be seen right away,” Cobern said.

What are common pneumonia symptoms in children?

Other types of pneumonia may have similar or slightly different symptoms than cases of pneumonia caused by M. pneumoniae. This includes:

• Chest pain when breathing or coughing
• Altered mental status (confusion)
• Cough
• tiredness (fatigue)
• Fever or chills
• Nausea, vomiting or diarrhea
• shortness of breath

How does an M. pneumoniae infection spread?

An infection with M. pneumoniae can be contagious. When a sick person coughs or sneezes, bacteria in the respiratory droplets can be exhaled and another person can inhale the bacteria.

What is the treatment for bacterial pneumonia caused by M. pneumoniae?

Some people with M. pneumoniae infections can recover on their own, and over-the-counter medications can provide symptom relief.

However, others may require medication, such as certain antibiotics called macrolides.

M. pneumonia is naturally resistant to some antibiotics commonly used to treat other types of bacterial pneumonia.

How can infections with M. pneumoniae be prevented?

The CDC recommends practicing good hygiene to prevent bacterial pneumonia infections, including washing hands and covering coughs and sneezes.

“This is an infectious, contagious organism, so you want to make sure you wear a mask and wash your hands,” Sutton said. “But if you are at risk – for example, young children under 2, adults over 65, or people with weakened immune systems – you will want to get checked because you may be a candidate for antibiotics to treat your infection.”