Microorganisms constitute 70 percent of the biomass on Planet Earth.
Comparatively few species are adapted to colonize human surfaces and form a complex Meta-Organism with manyfold mutual benefits.
Occasionally, microorganisms may overcome the barriers of the skin and mucosal surfaces and may multiply locally or in multiple sites inside the body. This process is called infection.
Infections can be caused by bacteria, viruses, parasites, helminths, and fungi.
Immediately after infection, numerous defense mechanisms of the immune system are activated to combat replication of the microbes.
There is a balance between microorganism and human defense mechanisms, which may lead to either asymptomatic infection or result in a wide spectrum of symptoms from mild to severe disease and even death.
The most important factors in the diagnosis of infectious diseases are a careful history, physical examination and the appropriate collection of body fluids and tissues.
Laboratory diagnosis requires between 2 and 72 hours.
Wherever possible, antibiotics should only be used when sufficient evidence of efficacy is available. Then, however, they should be used as early as possible and in high doses.
In addition to everyday hygiene measures, vaccination is the most effective measure to prevent infectious diseases.
Current attitude to deferral of cellular therapy or non‐transplant chemotherapy due to SARS‐CoV‐2 asymptomatic infection: survey of Infectious Diseases Working Party EBMT
