The incubation period is the time between infection with a pathogen and the onset of the first symptoms. During the incubation period, the pathogens multiply and the patient’s body produces antibodies. How long this phase drags on depends on the infection and the patient’s constitution.
What is the incubation period?
The incubation period is the time between infection with a pathogen and the onset of the first symptoms. Infectiology deals with the treatment and study of viral and bacterial infections as well as fungal infections. Incubation is known from this medical field. The term incubation is derived from the Latin term “incubare” and means “to incubate”. In relation to an infection, the incubation period is the time span between contact with a pathogen and the outbreak of the disease. Depending on the particular disease and the patient’s constitution, this period can range from hours to several years or decades. During the incubation period, the pathogens multiply in the body and spread throughout the organism. The term virulence is used to describe the extent of the ability to make an organism ill. The latency period of toxins must be distinguished from the incubation period. In principle, latency and incubation are the same phase. However, the latency period occurs after exposure to contaminants and corresponds to the clinically symptom-free interval between contact with the contaminant and the first symptoms. Both pathogens and contaminants are called noxious agents. Non-microbiological noxae have a latency period. For microbiological noxae, the incubation period applies.
Function and task
At the beginning of an infection is the immigration of pathogens. This immigration of pathogens usually goes unnoticed. The pathogens can enter the organism by different routes. Aerogenic infection is also known as droplet infection and allows the pathogens to migrate with the air. In alimentary infection or smear infection, the pathogens enter the body with food. In contact or parenteral infection, they enter the body without passing through the gastrointestinal tract. Somewhat better known is sexual contact infection via sexual intercourse. Transmissive infection occurs via natural vehicles such as mosquitoes, ticks, or flies, and diaplacental infection is referred to when the pathogen is transmitted between the mother and an unborn child. Possible routes of infection include the skin, mucous membranes, intestines, and wounds such as bites, stings, and cuts. With the immigration of the pathogens, the incubation period begins. The pathogens multiply locally at the point of entry. They are not yet in the bloodstream. They do not reach their target organs until they enter the bloodstream. This second step of the infection, like the entry of the pathogens, counts as part of the incubation period. Depending on the temperament and virulence of pathogens, it can take hours, weeks or years from the time of entry until the first symptoms are observed. With the first symptoms, medicine speaks of the disease outbreak and thus the end of the incubation period. During the symptom-free phase, the immune system registers the antigens and produces antibodies to fight the antigen. The incubation period is thus a phase of maximum activity for the immune system and does not necessarily lead to the outbreak of the infection. The patient’s organism may develop immunity to the disease with the incubation period or may already have immunity due to a previous infection or vaccination. In the case of immunity, the incubation period is not followed by an outbreak of the disease. The patient’s immune system successfully renders the pathogens harmless.
Diseases and ailments
The incubation period plays a role for all microbiological noxious agents and infections and thus affects viral, bacterial, and parasitic diseases. Some infectious diseases are limited to specific organ systems. Others affect multiple organ systems. For example, poliovirus has a relatively short incubation period. The pathogens enter through the gastrointestinal tract and multiply there in the lymphoid tissue. After two weeks, nonspecific symptoms such as fever appear. The incubation period ends with the onset of paralysis. Unlike poliovirus, rabies is transmitted by bites.The localization of the bite determines the incubation period. The pathogens multiply at the site of the bite and migrate from there along peripheral nerves to the brain. The further their path along the nerves, the longer the incubation period. If there is an outbreak of the disease after the incubation period, the immune system has failed at producing immunity. Nonetheless, immunity may exist at the next infection with the pathogen in question. Antibodies develop from B lymphocytes after contact with an antigen. This form of immune response is called the humoral immune response and is thus distinguished from the innate immune response. In patients with immunodeficiency, insufficient antibodies are formed during the incubation period. Immune deficiencies can occur in the context of stress. Poor nutrition, lack of exercise and lack of sleep can also promote immune deficiencies. Disease-related immune deficiencies are present, for example, in HIV infections. The same applies to malignant tumors and aggressive treatments such as chemotherapy. Drugs, alcohol and nicotine are also considered risk factors for acquired immune deficiency. People who have had their spleen removed are also more susceptible to bacterial infections. The immune response changes with age physiology. Therefore, the incubation period may be significantly shorter in older people than in younger people.
