Why meningitis strikes teens

The reason why meningitis seems to strike during the teen years may be that teens' bodies are more likely to carry a chemical that fuels the growth of the bacteria that cause meningitis, according to a new study.

In the study, the researchers discovered that the bacteria species that causes meningitis, Neisseria meningitidis, contains a cluster of genes that allows it to use a compound called propionic acid for growth. Propionic acid, in turn, is generated by other bacteria that become more common in the human body during adolescence, said James Moir, a researcher at the University of York in England and one of the researchers on the study.

Meningitis is a swelling or inflammation of the membranes that cover the brain and spinal cord (which are called the meninges). When bacteria cause this swelling, the condition is known as bacterial meningitis. Causes of bacterial meningitis can vary depending on a person's age, according to the Centers for Disease Control and Prevention.

Neisseria meningitidis is a common cause of bacterial meningitisamong teens and young adults, and infection often happens when the bacteria from a respiratory infection enter the bloodstream. About 10 percent of people carry Neisseria meningitidis in their nose and throats without having symptoms, and such "colonization" peaks in the late teen years, the researchers said. [7 Absolutely Horrible Head Infections]

The increase in Neisseria meningitidis in teens' noses and throats is often attributed to the increase in social interaction and close contact in this age group (such as living in a college dorm), the researchers said.

While there is "no doubt" that this explanation is true, the new study provides another explanation for why colonization with Neisseria meningitidis varies with age, the researchers said.

The study was first published online June 27 in the journal Molecular Microbiology.

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