Synonyms: asymptomatic infection, infection lacking symptoms
German: Stumme Infektion
1 Definition
A silent infection is an infection that does not manifest as a disease. This means that there are no symptoms throughout the course of the infection. This is most common for healthy individuals that have a strong immune system. In this case the infection with a pathogen leads to immunity. This process is referred to as occult immunization.
2 Classification
Silent infections are classified as follows:
- Subclinical infection: During this infection the immune system is stronger and thus prevents the outbreak of the disease.
- Persistent infection: This type of infection is marked by the indefinite survival of the pathogen within the host. When, for several reasons, only few or only ineffective new pathogens are produced the infections maintain to be asymptomatic. However, in case of a weakened immune system (i.e. stress) clinical symptoms can present. A persistent infection can be further subdivided:
- tolerated infection: This type of infection is often acquired intrauterine. The pathogen continues to reproduce in the ordinary way but is excreted regularly.
- latent infection: Here the pathogen and immune system are in a balance. In case the pathogen becomes stronger or the immune system weaker the disease will manifest. Conversely a weaker pathogen or stronger immune system might lead to the eradication of the pathogen.
- occult / masked infection: This is an infection which cannot be shown using direct or indirect testing.
