Meningitis is caused by the inflammation of the meninges, the protective membranes covering the brain and spinal cord. Unlike viral meningitis, bacterial meningitis can be fatal if left untreated. Many people carry the bacteria without getting sick. However, if the bacteria are able to break through the immune system and travel through the bloodstream, they can infect the brain and create harmful swelling. Bacterial meningitis is most commonly spread in close-contact groups, such as those in grade schools, college campuses, military camps, and corrections facilities.
There are an estimated 1.2 million cases and 135,000 resulting deaths worldwide caused by bacterial meningitis. Incidents most commonly occur during the winter or early spring.
Bacterial meningitis can be transmitted through mouth, nose, and throat secretions. It is not transmitted from sexual contact, including oral sex. The bacteria cannot survive more than a few moments outside the body. Due to this, secretions are mainly contagious as large droplets (such as sneezing in someone’s face or French kissing), rather than from simply having a conversation with an infected person. The bacteria can also be transferred through stool, so it is important for you and your child to wash your hands regularly to avoid infection.
At any time, one in ten people carries the bacteria without ever developing symptoms. Though only a small number of people exposed actually get ill, any person carrying the bacteria can still be contagious until his or her body develops an immune response (a few days to a few months after infection).
Meningitis infection is produced if the bacteria are able to cross the blood-brain barrier. This barrier normally prevents large molecules from entering the cerebrospinal fluid, allowing the brain to continue functioning optimally. Signs of infection will usually appear within the first 3-7 days following exposure. Common symptoms include:
- Sudden onset of fever.
- Stiff neck.
- Nausea or vomiting.
- Increased light sensitivity.
- Altered mental state.
If bacterial meningitis goes untreated, it can result in seizures, coma, or even death. Infants younger than one month old are at a higher risk of contracting bacterial meningitis since their immune systems have not fully developed. Signs of disease in infants may include a bulging of the soft spot on their head or a lack of alertness. If you think you or your infant has bacterial meningitis, contact your doctor immediately.
Blood poisoning, called septicaemia, can also occur from the bacterial infection. This poisoning causes blood vessel leakage so that the body is able to carry less oxygen. Common symptoms include:
- Pale skin.
- Cold hands and feet.
- Rapid breathing.
In extreme situations, septicaemia can also cause the formation of blood clots. Large-scale tissue damage can lead to amputation or kidney failure. About one in five cases of meningococcal septicaemia are fatal, making it more likely to result in death than meningitis.
Meningitis is diagnosed using blood samples or cerebrospinal fluid. An antibiotic is chosen based on the specific type of bacteria that is causing the infection. Antibiotics are used for one to three weeks and can help prevent and reduce the spread of infection. Following immediate hospitalization, the patient will be given oxygen and resuscitation fluids. If the patient has septicaemia, these fluids will allow their blood volume to return to a normal level. The sooner treatment is begun, the greater the chance that it will be effective. Effective treatment can reduce the risk of death to below 15%.
The Centers for Disease Control and Prevention recommends screening for bacterial meningitis during the third trimester of pregnancy (at around 35 to 37 weeks). If any bacteria are found, the woman is given antibiotics to prevent infection of newborns.
Most survivors are left without long-term consequences to the infection. However, some are left with disabilities or problems after treatment. If the meningitis is able to damage nerve cells, the person can be left with epilepsy, learning difficulties, problems with coordination or speech, or a change in behavior. If bacterial poisons damage the inner ear, the survivor can be left with deafness. Therefore, it is important to make sure the patient receives a hearing test within four weeks of treatment. These problems may go away over time, but in some cases can be permanent. Meningococcal meningitis is less likely to produce long-term effects than the other types of bacterial meningitis.
If behavioral changes are not disappearing, it may be helpful for the survivor to talk to a counselor.
The most effective method to prevent infection is vaccination. There are vaccines for the three types of bacterial meningitis:
- Haemophilus influenzae type b (Hib).
The meningococcal vaccine is recommended for college and high school students prior to entering a dorm. It is effective for three to five years but does not protect against all strains of the bacteria. The vaccines are noninfectious, meaning that they can be taken during pregnancy or breastfeeding without harming the infant.
If you have been exposed to someone with meningococcal meningitis, your doctor may recommend antibiotics in order to decrease the risk of getting and spreading infection.
Last Updated May 4 2013.