Meningitis risk factors: who is more likely

What meningitis is

Meningitis is inflammation (swelling) of the lining of the brain and spinal cord. Many things can cause it: viral, bacterial and fungal infections, parasites, ameba, injuries, cancer and certain drugs. Bacterial and viral meningitis are more common than the other types (CDC).

Viral meningitis is the most common type. Most people get better on their own without treatment, but it can be very serious (CDC). Bacterial meningitis is rare but can be deadly (MedlinePlus); death can occur in a few hours, and people who recover can have permanent disabilities (CDC).

Meningitis and meningococcal disease are not the same thing. Meningococcal disease is any illness caused by the bacteria Neisseria meningitidis, and it can, but does not always, include meningitis (CDC).

Who is more likely to get it

Anyone can get meningitis, but it is more common in people with weak immune systems (MedlinePlus). CDC names these risk factors.

Bacterial meningitis

• Age. Some causes are more likely to affect certain age groups: newborns, babies and young children, teens and young adults, and older adults each have their own most likely bacteria (CDC).
• Certain medical conditions. Certain medical conditions, medications and surgical procedures raise the risk, including having a weakened immune system, having a cerebrospinal fluid leak, and not having a spleen (CDC).
• Group settings. Infectious diseases tend to spread where large groups of people gather. For example, college campuses have reported outbreaks of meningococcal disease (CDC).
• Travel. Travelers may be at increased risk for meningococcal disease during the annual Hajj and Umrah pilgrimage, and in sub-Saharan Africa during the dry season. Travelers should also avoid being with people known to have tuberculosis (TB) in crowded, enclosed spaces (CDC).
• Pregnancy. Being pregnant increases the risk of a Listeria infection, one of the bacteria that can cause meningitis. Some foods are more likely to contain Listeria than others (CDC).

Viral meningitis

• Age. Children younger than 5 years old are at increased risk. Babies younger than 1 month old are most likely to have severe illness if they get it (CDC).
• A weakened immune system. People with a weakened immune system are at increased risk of getting viral meningitis and of severe illness. Diseases, some medicines (such as chemotherapy) and a recent organ or bone marrow transplant can weaken the immune system (CDC).

Close contacts of someone with viral meningitis can catch the virus that made that person sick, but they are not likely to develop meningitis (CDC).

Common causes

Leading US causes of bacterial meningitis include Streptococcus pneumoniae, group B Streptococcus, E. coli, Haemophilus influenzae, Neisseria meningitidis and Listeria monocytogenes; the TB germ is a less common cause (CDC). Pneumococcal and meningococcal infections are the most common causes of bacterial meningitis (MedlinePlus).

Many viruses can cause viral meningitis. Non-polio enteroviruses are the most common; others include arboviruses such as West Nile virus, herpesviruses (including the varicella-zoster virus that causes chickenpox and shingles), influenza, lymphocytic choriomeningitis virus, measles and mumps (CDC).

Signs

Common symptoms are fever, headache and stiff neck. There are often other symptoms, such as nausea, vomiting, eyes being more sensitive to light, and confusion (CDC).

Newborns and babies may not have the classic symptoms, or they may be hard to notice. Instead, babies may be slow or inactive, be irritable, vomit, feed poorly, have a bulging soft spot on the head, or have abnormal reflexes (CDC).

Complications of bacterial meningitis can include seizures, coma and death, and many of these bacteria are linked with another serious illness, sepsis (CDC). Bacterial meningitis can also cause stroke, hearing loss and brain damage, and harm other organs (MedlinePlus).

Diagnosis and treatment

Tests include blood tests, imaging tests and a spinal tap to test the cerebrospinal fluid (MedlinePlus). Knowing the exact cause matters because treatment differs depending on the cause (CDC).

Bacterial meningitis is treated with antibiotics, and it is important to start as soon as possible (CDC). In most cases there is no specific treatment for viral meningitis; most people with mild viral meningitis get better on their own within 7 to 10 days, while people with severe illness may need hospital care. Antiviral medicine may help when the cause is a virus such as herpesvirus or influenza (CDC).

Lowering your risk

Vaccines. CDC says vaccines are the most effective way to protect against certain types of bacterial meningitis. There are vaccines for 4 types of bacteria that can cause it: Hib, meningococcal and pneumococcal vaccines, which are widely used in the United States, and the BCG vaccine against TB, which is not (CDC). Chickenpox, influenza, measles and mumps, and shingles vaccines protect against some diseases that can lead to viral meningitis (CDC).

Group B strep screening in pregnancy. Pregnant women should talk to their healthcare provider about screening for group B Streptococcus. Those who test positive get antibiotics during labor, which helps prevent passing the bacteria to the baby (CDC).

Preventive antibiotics. Antibiotics can sometimes help prevent illness in people who were around someone with bacterial meningitis. Healthcare providers and health departments decide who should get them (CDC).

Everyday habits. CDC lists these habits to help prevent viral infections (CDC):

• Wash your hands often, especially after changing diapers or using the toilet.
• Avoid close contact, such as touching and shaking hands, with people who are sick.
• Clean and disinfect frequently touched surfaces.
• Stay home when sick and keep sick children out of school.
• Avoid bites from mosquitoes and other insects that carry diseases.
• Avoid contact with wild mice, and take precautions when handling pet rodents such as mice, hamsters or guinea pigs.

Common questions

Is meningitis contagious?

The germs that cause it can spread. Infectious diseases tend to spread where large groups gather, and outbreaks of meningococcal disease have been reported on college campuses (CDC). Close contacts of someone with viral meningitis can catch the virus, but they are not likely to develop meningitis (CDC).

Who is most at risk of meningitis?

It depends on the type. Children younger than 5 are at increased risk of viral meningitis (CDC), and people with a weakened immune system are at increased risk of both bacterial and viral meningitis (CDC) (CDC). Not having a spleen and having a cerebrospinal fluid leak also raise the risk of bacterial meningitis (CDC).

Can a vaccine prevent meningitis?

Vaccines protect against some of the causes. Hib, meningococcal and pneumococcal vaccines protect against certain types of bacterial meningitis (CDC), and chickenpox, influenza, measles and mumps, and shingles vaccines protect against some diseases that can lead to viral meningitis (CDC). See also sepsis risk factors and shingles risk factors.