(CNN)Here's a look at meningitis outbreaks in the United States.
Meningitis is caused by the inflammation of the protective membranes (known as meninges) covering the brain and spinal cord. The inflammation is typically caused by an infection of the fluid surrounding these areas.
Bacterial meningitis is contagious and comes in a number of different strains.
Viral meningitis is less severe and occurs more frequently than bacterial meningitis.
Fungal, viral, parasitic and non-infectious meningitis are not contagious, and do not spread from person to person.
Fungal and parasitic meningitis are rare.
The most common causes of meningitis are viral infections, when a virus travels to the brain after entering the system through the nose or the mouth.
Bacterial meningitis starts with an infection similar to a cold and spreads via respiratory and throat secretions, like saliva and phlegm.
People contract fungal meningitis by inhaling affected spores.
Contamination of food, water and soil can lead to parasitic meningitis.
Non-infectious meningitis can be caused by physical injury, cancer, systemic lupus and certain drugs.
Enteroviruses, the most common cause of viral meningitis, are most often spread from person to person through fecal contamination or through respiratory secretions of an infected person.
Symptoms and Treatment
Symptoms usually present themselves quickly for some types of meningitis and include high fever and chills, mental status changes, nausea and vomiting, sensitivity to light, headaches and a stiff neck.
Bacterial meningitis is treated with antibiotics.
Viral meningitis is treated with bed rest, plenty of fluids and pain medication for body aches.
Fungal meningitis is treated with anti-fungal medications.
Parasitic meningitis is less common, and most cases have proven fatal.
In 2012, a multi-state outbreak of fungal meningitis associated with contaminated steroid injections was linked to the New England Compounding Center (NECC). The outbreak infected 753 people in 20 states, killing 64. This is the deadliest meningitis outbreak in US history.
September 2012 - The CDC and the FDA begin investigating a multi-state outbreak of fungal meningitis.
September 26, 2012 - The NECC recalls three lots of steroid injections associated with the outbreak of fungal meningitis.
October 6, 2012 - The NECC expands its recall to include all of its products.
December 21, 2012 - The NECC files for bankruptcy.
December 2013 - The NECC agrees to a preliminary settlement that would create a $100 million fund for victims of the outbreak.
December 16, 2014 - Fourteen people are indicted in connection with the 2012 outbreak, including two, NECC President Barry Cadden and supervisory pharmacist Glenn Chin, charged with 25 counts of second-degree murder. Other charges include racketeering, conspiracy, mail fraud and the production and sale of both "adulterated" and misbranded drugs.
March 22, 2017 - Cadden is convicted of racketeering, racketeering conspiracy, mail fraud and introduction of misbranded drugs into interstate commerce with the intent to defraud and mislead. He is acquitted of 25 counts of second-degree murder.
June 26, 2017 - Cadden is sentenced to nine years in prison.
January 31, 2018 - Chin is sentenced to eight years in prison.