Meningitis

Meningitis is an inflammation of the meninges. These are the membranes that surround the brain and spinal cord.

In some cases, in addition to the meninges, the inflammation also affects the brain. This is then referred to as meningoencephalitis.

Meningitis can be caused by bacteria, viruses and other disease-causing microbes known as pathogens. Other potential causes include a faulty immune system response, cancer or the side-effects of medication.

The typical symptoms include a high temperature, headache, stiff neck and impaired consciousness. People with the condition often appear dazed or confused.

The symptoms of meningitis depend on the cause of the condition, the age of the person affected and the condition of their immune system.

Typical symptoms are:

• high temperature
• neck stiffness
• headache

In many cases, general symptoms also occur, such as:

• light sensitivity
• nausea and/or vomiting
• diarrhea

Skin changes can provide important information about the pathogens: meningococci bacteria cause bleeding into the skin; while pneumococci bacteria cause blisters.

The inflamed meninges can lead to an increase in pressure in the cranial cavity. This is the cavity around the brain that is formed by the cranial bones. The heightened pressure can lead to impaired consciousness, the failure of certain nerves (cranial nerves) and seizures.

In newborns and small children, the symptoms of meningitis are usually less obvious. They can have either a high or a low temperature. Bulging fontanelles – the soft spots between the cranial bones – may indicate inflammation. Sick children eat and drink less. They may be restless and cannot be settled. Alternatively, they may be unusually sleeping.

In older people, confusion or impaired consciousness can be the main symptom of meningitis.

Meningitis is usually caused by pathogens.

Other triggers such as cancer, autoimmune disorders or taking medication such as non-steroidal anti-inflammatory drugs (NSAIDs) or certain antibiotics are rare.

In most cases, meningitis is caused by viruses. These include, for example:

• enteroviruses: these trigger hand, foot and mouth disease, for instance
• parechoviruses: these cause respiratory and gastrointestinal infections
• Epstein-Barr viruses, the pathogens responsible for glandular fever
• herpes simplex viruses: pathogens of oral and genital herpes
• varicella-zoster viruses: pathogens of chickenpox and shingles
• SARS-CoV-2: pathogen of COVID-19
• arboviruses: these include viruses transmitted by mosquitoes or ticks
• flu, measles and mumps viruses

The condition is sometimes caused by bacterial infections. The most common bacterial pathogens include:

• pneumococci
• meningococci
• group b streptococci
• Haemophilus influenzae
• listeria
• in newborns: the intestinal bacterium Escherichia coli

Less common triggers are infections with staphylococci, tuberculosis bacteria or borrelia bacteria.

Meningitis caused by fungal infections, for example with yeast or mold fungi, primarily affects people with a weakened immune system, such as those with HIV/AIDS.

Meningitis caused by infections with worms or other parasites is rare in Germany.

How do the pathogens get to the meninges?

Many pathogens are transmitted via droplet infection, i.e. when speaking, coughing or sneezing. Infection occurs when these pathogen-containing droplets are inhaled.

The pathogens usually start by settling in other areas of the body, then progress to the meninges in several ways. For example, bacteria often colonize the mucous membranes of the nasopharynx, penetrate blood vessels and reach the meninges via the bloodstream.

In the case of inflammation in the vicinity of the meninges, such as in the middle ear or sinuses, the condition can spread directly to the cerebrospinal fluid (liquor) and the meninges. Cerebrospinal fluid is the medical term for the fluid that surrounds the brain and spinal cord. Viruses can also travel along the nerves to the meninges.

Some viruses, such as the TBE virus or the West Nile virus, are contracted from mosquitoes or ticks. The viruses can enter the bloodstream via a tick or mosquito bite and, from there, also travel to the meninges.

Infants, small children and very elderly people are particularly susceptible to meningitis.

In addition to age, there are also several other factors that increase the risk of meningitis. These include the following:

• chronic underlying conditions such as diabetes mellitus
• immunodeficiency as a result of conditions such as HIV/AIDS or the use of medication that causes immune system deficiency, for example after an organ transplant
• alcohol abuse
• a surgically removed spleen or a spleen with reduced function
• a middle ear infection or sinusitis
• bacterial endocarditis (inflammation of the lining of the heart)

Meningitis is most commonly caused by viruses. In Germany, up to 20 in every 100,000 people contract viral meningitis each year. About half of all meningitis cases are caused by enteroviruses.

Fewer than one in every 100,000 people contract bacterial meningitis each year in Germany. The most common bacterial pathogens are pneumococci and meningococci. Meningococcal infections primarily affect infants and one-year-olds.

In countries with a moderate climate like Germany, meningococci infections typically peak at the beginning of the year.

The progression and symptoms of meningitis depend on the cause of the condition, the age of the person affected and the condition of their immune system.

Inflammation triggered by viruses or taking medication usually results in mild cases that go away of their own accord within 2 to 3 weeks without any special treatment.

On the other hand, cases of bacterial meningitis can sometimes start very suddenly, rapidly deteriorate and quickly result in fatality. They can also be accompanied by severe complications of bacterial infection such as blood poisoning (sepsis) and can cause serious brain damage, for example, due to elevated pressure on the brain.

Serious cases of meningitis can lead to long-term effects such as the loss of individual brain and nerve functions, hearing loss or cognitive impairment. Behavioral disorders, movement disorders and seizures are also possible long-term effects.

Vaccinations that prevent meningitis exist against several of its pathogens. These include vaccinations against pneumococci, Haemophilus influenzae, meningococci, measles, mumps and chickenpox. In Germany, these are part of the childhood vaccinations recommended by the Standing Committee on Vaccination (Ständige Impfkommission – STIKO). 

Meningococcal meningitis can be caused by various bacterial subtypes (serogroups). For children, vaccination against serogroup B is recommended from the age of 2 months. Vaccination against serogroup C is recommended once the child has reached the age of 1 year. People with an increased risk of developing meningitis can also be vaccinated against serogroups A, C, W and Y.

Close contacts of people with meningococcal meningitis should take preventative antibiotics.

The quickest possible diagnosis is important for preventing serious cases of meningitis.

As there are many different causes, doctors use targeted questions to try and isolate possible triggers. These include questions about:

• living conditions: for example, whether people live in shared accommodation
• vaccinations that have been received
• indications of immune deficiency due to a chronic condition or taking medication
• alcohol consumption
• sex life
• contact with animals
• recent travel and operations

In most cases, a blood sample is then taken. The blood can provide evidence of the inflammation and, in the case of bacteria, often also the pathogen.

The detection of inflammation and often also the pathogens responsible in the patient’s cerebrospinal fluid (liquor) is essential for diagnosis. A lumbar puncture is used for this purpose. This involves inserting a special needle into the lower back and taking a sample of cerebrospinal fluid from the spinal canal. This is the fluid surrounding the brain and spinal cord. In the event of impaired consciousness, the doctor must arrange a computed tomography (CT) or magnetic resonance imaging (MRI) scan of the brain prior to the lumbar puncture to check whether there is increased pressure on the brain. This is essential because a lumbar puncture is dangerous in such cases.

Depending on the outlook, other tests and investigations are also required, such as:

• throat swabs and stool specimens
• an electroencephalography (EEG) to measure the electrical activity of the brain
• imaging of the blood vessels in the brain (angiography)

Bacterial meningitis needs to be treated with effective antibiotics as quickly as possible. Otherwise, it risks developing into a serious or even fatal case. The antibiotics are administered intravenously in a hospital.

If bacterial meningitis is suspected, doctors will start treatment with several antibiotics immediately, even if the results of the laboratory tests are not yet available.

If the condition has been caused by pneumococci, anti-inflammatory cortisone can prevent complications. Cortisone suppresses the body’s inflammatory response, which is triggered by the pathogens. If meningococcal meningitis affects the auditory nerve, cortisone treatment may also be beneficial.

If a viral infection caused by herpes is suspected, preventive medication to target herpes viruses can be administered. This medication can then be stopped if laboratory testing excludes herpes viruses as a cause. 

Once the pathogen responsible has been identified, the meningitis can be treated in a targeted manner. If no bacteria or herpes viruses have been detected, the only treatment is to alleviate the symptoms. In such cases, patients are generally administered painkillers and medication that regulate the fluid balance in the body.