Aseptic meningitis is an inflammation of the protective membranes surrounding the brain and spinal cord, known as the meninges. While the condition itself is not contagious, the organisms that cause it are frequently transmissible between people. The core distinction is that a person cannot “catch” the meningitis, which is the body’s inflammatory reaction, but they can contract the underlying infectious agent, which is often a virus. Viral infections account for the vast majority of cases, meaning that while the condition is usually less severe than bacterial meningitis, its source is often easily spread.
What “Aseptic” Means: Identifying the Primary Causes
The term “aseptic” is a medical classification that refers to a negative result on standard bacterial cultures of the cerebrospinal fluid (CSF). This negative result rules out the presence of common pyogenic bacteria, which cause the highly severe form of the disease known as bacterial meningitis. Physicians confirm the condition by analyzing the cerebrospinal fluid, obtained through a lumbar puncture, which typically shows an elevated white blood cell count, known as pleocytosis, without bacterial growth on routine testing.
Viruses are the most common cause of aseptic meningitis, specifically a group known as non-polio enteroviruses, which account for a high percentage of cases where a pathogen is identified. These small RNA viruses, which include Coxsackieviruses and Echoviruses, are particularly prevalent during the summer and fall months. While many people infected with an enterovirus experience no symptoms or only a mild, flu-like illness, a small fraction of individuals develop meningitis as a complication.
Other viral agents, such as the mumps virus, measles virus, varicella-zoster virus (which causes chickenpox and shingles), and herpes simplex virus, can also trigger aseptic meningitis. Fungi and parasites represent less common infectious causes. These agents are typically not spread from person to person.
Transmission Routes for Contagious Triggers
For the viral causes of aseptic meningitis, particularly enteroviruses, the primary route of spread is fecal-oral. This means the virus is shed in the stool of an infected person and can be inadvertently ingested by another. This often occurs when hand hygiene is insufficient, such as after using the toilet or changing a diaper, and then touching the mouth or face. Young children, especially those who are not fully toilet-trained, are frequently the source of transmission in a community setting.
Respiratory secretions also play a role in spreading the infection, allowing transmission through close personal contact with an infected individual. When an infected person coughs or sneezes, the virus can be expelled in droplets and inhaled by others nearby. The viruses can also survive on surfaces for days, creating another potential pathway for indirect spread if a contaminated object is touched and then the mouth or nose is contacted.
A person is often contagious before symptoms of the resulting illness even appear, and they may continue to shed the virus after recovery. Specifically, enteroviruses can be found in a person’s stool for several weeks after the onset of symptoms, even though respiratory shedding usually lasts for a week or less.
Non-Infectious Triggers and Prevention Strategies
Not all cases of aseptic meningitis result from an infectious agent, as the inflammation can also be a reaction to non-contagious factors. Certain medications, such as nonsteroidal anti-inflammatory drugs (NSAIDs) or specific antibiotics, are known to induce this condition, referred to as drug-induced aseptic meningitis. Autoimmune disorders like systemic lupus erythematosus (SLE) can also cause inflammation of the meninges, as can certain types of cancer that spread to the central nervous system.
Since the majority of cases are caused by transmissible viruses, prevention efforts focus on interrupting the pathways of viral spread. Rigorous hand hygiene is the most effective defense, requiring frequent and thorough washing, especially after using the restroom, changing diapers, or before eating. Avoiding close contact, such as kissing or sharing eating utensils, with people who are sick helps limit the exchange of respiratory droplets and saliva. It is also important to practice proper sanitization of frequently touched surfaces, including doorknobs and countertops, as viruses can persist on these objects. Vaccination against certain viruses indirectly prevents cases of aseptic meningitis by eliminating the viral trigger, such as the measles, mumps, and rubella (MMR) vaccine.