2024-02-28 12:24:53
Encephalitis: How does brain inflammation occur?
The most common cause of encephalitis is an infection with a pathogen. Various viruses, bacteria, fungi or parasites can penetrate the central nervous system, damage cells there and lead to inflammation.
However, encephalitis can also be caused by an autoimmune disease. In this case, the immune system produces antibodies that attack the cells in the brain, leading to chronic inflammation. Sometimes a cancer, an infection or a vaccine trigger such an autoimmune reaction.
Cause of infectious encephalitis
In 70 percent of cases, the causative agents of infectious encephalitis are viruses.
In Germany, herpes viruses most often trigger encephalitis. Anyone who has been infected with them carries the pathogens in their body for life. They can be reactivated later. In rare cases, the viruses can lead to complications such as encephalitis in immunocompromised people. Sometimes encephalitis occurs during the initial infection with herpes viruses. Newborns can also become infected during birth from their mother and develop encephalitis.
Examples of herpes viruses include:
- Herpes simplex viruses, which cause cold sores, for example
- Varicella-zoster viruses, the pathogens that cause chickenpox and shingles
- Epstein-Barr viruses, which cause Pfeiffer’s glandular fever
- Cytomegaloviruses, with which 60 to 90 percent of all adults are asymptomatically infected, but which can be dangerous for immunocompromised people and newborns
Furthermore, in rare cases, other viruses can also spread to the central nervous system and cause encephalitis as a complication. This includes:
Encephalitis caused by bacteria, fungi and parasites
Bacteria can also cause brain inflammation. This is usually the case when bacterial meningitis spreads to the brain. For example, meningococci, listeria or tuberculosis bacteria can be the cause.
Fungi can lead to encephalitis as part of cryptococcosis. The yeast infection is transmitted through bird droppings and usually affects people who are severely immunocompromised.
The parasites that can lead to inflammation of the brain include protozoa such as Toxoplasma gondii and worms such as the pork tapeworm.
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