How does someone catch meningitis?
Most cases of meningitis occur alone, and the risk of a second, related case is usually very small. It is rare to “catch” meningitis from someone who has the disease.
- The bacteria that can cause meningitis commonly live in the back of the nose or throat. This is called carriage.
- In most cases this carriage is harmless and can help us develop natural immunity.
- Around 10% of the population carry meningococcal bacteria (one of the most common causes of bacterial meningitis) in the back of their throat at any one time.
- Only occasionally do these bacteria defeat the body’s defences and break through the lining at the back of the throat.
- The bacteria can then travel in the bloodstream to infect the meninges, causing meningitis, or while in the bloodstream they can cause septicaemia.
- The bacteria are passed from person to person by coughing, sneezing and intimate kissing.
Viral Meningitis
- Because many different viruses can cause meningitis, the way in which the virus is spread will depend on its type.
- Enteroviruses (one of the most common causes of viral meningitis) are carried harmlessly in the intestines of both children and adults, and carriage of these viruses helps us to build up natural immunity to infection.
- Spread of these viruses is common and they can be passed from person to person by coughing, sneezing and on unwashed hands.
- Practicing good hygiene, such as washing hands after going to the toilet, will help to prevent the spread of viruses that are passed in faeces.
Who is at risk of catching meningitis?
Meningitis and septicaemia can affect anyone, but certain factors can increase the risk. People sometimes ask “how do you catch meningitis?” or “is meningitis contagious?” – the following information helps to answer these questions.
Risk factors
Age
Babies and young children are at increased risk because their immune systems are not fully developed. Vaccines given as part of the UK childhood immunisation schedule will provide protection against some, but not all, causes of meningitis in babies and toddlers.
Teenagers and young adults are at increased risk of meningitis and septicaemia caused by meningococcal bacteria. These bacteria are the most common cause of meningitis in the UK, and are carried in the back of the throat of about one in 10 people. This carriage is usually harmless, but occasionally leads to meningitis and septicaemia. Teenagers and young adults are more likely to carry these bacteria, and are also more likely to spread them to others. The risk of disease is greatest in first year university students living in shared accommodation. The MenACWY vaccine, offered at around 14 years of age, provides protection against some, but not all, strains of meningococcal bacteria.
Older adults are also at increased risk of some types of meningitis. A pneumococcal vaccine is offered to people over 65 years of age.
Medical conditions
Medical conditions or treatments that affect the immune system can increase the risk of meningitis and septicaemia.
- Complement deficiency
Complement is the term used to describe a group of proteins that are critically important in the immune system. Each protein has a different function and they work together to help the body fight infection. Complement deficiencies are rare, but in some cases they can put people at increased risk of meningococcal disease.
- Immunosuppressant drugs and cancer treatment
Immunosuppressant drugs are used to treat inflammatory conditions such as rheumatoid arthritis and Crohn’s disease, or to prevent rejection of an organ transplant. They work by “dampening” the immune system. People who take this type of medication are at increased risk of infections, including meningitis.
Drugs used to treat cancer can also affect the immune system and increase the risk of infections.
Travel
Some bacteria that cause meningitis are more prevalent in certain areas of the world. The risk of meningitis caused by other organisms such as parasites is also increased in some countries. If you are travelling abroad, advice about increased risk and prevention of meningitis can be found at https://travelhealthpro.org.uk/
The risk of meningococcal disease is greatest in the “meningitis belt” of sub-Saharan Africa. This area stretches from Senegal to Ethiopia and experiences epidemics of disease in the dry season. Warm, dusty winds damage the linings of the nose and throat making it easier for meningococcal bacteria to invade the body and cause disease. The MenACWY vaccine is recommended prior to travelling to this area.
Large outbreaks of meningococcal disease have also been linked to the Hajj pilgrimage. As a result of this, proof of up to date vaccination with the MenACWY vaccine is a compulsory requirement for entry into Saudi Arabia for pilgrims.
Environment
Environmental factors such as exposure to cigarette smoke or living in poorly ventilated, crowded conditions can increase the risk of meningitis.
Contact with a case
Most cases of meningitis occur alone, and the risk of a second, related case is usually very small. It is rare to “catch” meningitis from someone who has the disease.
However, when there is a case of meningococcal disease, there is a slightly increased risk of illness in close contacts of that case. Close contacts include family and household members, and intimate kissing contacts. It is the responsibility of the public health team to trace close contacts and assess their risk. Antibiotics and, in some cases, vaccines may be offered to close contacts to reduce the risk of further transmission.
