He Disease periodic pathogen Refers to the time when a pathogen or disease enters the host without the body still having symptoms.
In this period cellular, tissue and organic changes are carried out. When a disease can be transmitted, the pathogenic period begins at the time when the pathogen penetrates to establish itself in an organism.
Flu virus
The pathogenic stage is characterized by being present in the environment, just after the human being is affected. Here, there is an interaction between the pathogen, the host, and the environment.
In the pathogenic period the subclinical and clinical manifestations of a particular disease begin to appear. For these reasons, it can be said that the pathogenic period is the disease as such. Initially, the ratio of the host agent is given in a subclinical plane.
Later, symptoms that depend on the host and the degree of aggressiveness of the agent will begin to manifest; Typically the disease picture.
It can be said that this period culminates in the end of the symptoms referring to the clinical picture, either because the disease was terminated because it was cured or because death occurred in the development of the pathological process.
The pathogenic period is divided into the incubation period or the latency period
Incubation period
The incubation period is the time between exposure to a pathogenic organism, chemical, or radiation, until symptoms and signs are apparent.
In a typical infectious disease, the incubation period refers to the period it takes for multiple organisms to reach an amount sufficient to produce symptoms in the host.
For example, a person may be the carrier of a disease, such as strep throat, without exhibiting any symptoms. Depending on the disease this person may or may not be contagious during the incubation period.
During this period, an infection is subclinical. When talking about viral infections, the virus replicates in latency. If a disease is infectious, it begins at the time of infection by the infectious agent; Can be manifested with a special serological marker, or with a particular symptom.
The intrinsic period of incubation refers to the time it takes an organism to complete its development within its definitive host.
For its part, the extrinsic incubation period is the time it takes an organism to complete its development within its immediate host.
Factors that determine the specific incubation period depend on multiple factors including: the dose of the infectious agent, the route of inoculation, the frequency of replication of the infectious agent and the immune response and / or sensitivity of the host.
Examples of incubation periods in humans
Due to inter-individual variation, the incubation period is always expressed as a range. When possible, it is best to express it in percentiles, although this information is not always available.
In many conditions, incubation periods are longer in adults than in infants or children.
- Cellulitis: between zero and one day.
- Colera: between 0.5 and 4.5 days.
- Common cold: between one and three days.
- HIV: between two to three weeks, months, or longer.
- Tetanus: between seven and 21 days.
- Rabies: between seven and 14 days.
- Smallpox: between nine and 21 days.
Virus latency period
When a disease belongs to the category of degenerative, it can be referred to as a latency period. This means that their evolution is slow, occurring over months or even years.
Viral latency is the ability of a pathogenic virus to remain dormant (dormant) within a cell, denoted as the lysogenic part of the viral life cycle.
It can be said that latency is the period between exposure until the first adverse effects appear.
Many scientists define the latency period as the time span between exposure to a pathogen or cause of disease, and the time at which symptomatic disease appears.
If a disease manifests with the appearance of a symptom, it can be said that the latency period is the same as the incubation period. The incubation period is usually used for infectious diseases.
A latent viral infection is a persistent type of viral infection that differs from a chronic viral infection. Latency is the stage in which certain virus life cycles, after the initial infection, stop propagating their viral particles.
However, the viral genome is not completely eradicated. The result of this is that the virus can be reactivated and continue to produce large amounts of viral genome without the host being affected by new external virus.
This is denoted as the lytic cycle of the viral life cycle and stays within the host indefinitely. Viral latency should not be confused with clinical latency during the incubation period, as the virus is not in dormancy.
Examples of disease latency
An example of a latency period for a disease may be cancer and leukemia. It is estimated that this disease has a latency period of about five years before the onset of leukemia and that it can take an additional 20 years until malignant tumors appear.
The latency period in cancer is also defined as the time that elapses between exposure to a carcinogen (such as radiation or a virus) and the time the symptoms appear.
It should be noted that diseases with long periods of latency make it difficult to detect it.
Short latencies, related to acute exposures can be expressed in seconds, minutes or hours. Chronic exposures, on the other hand, have long latencies, days or months.
References
- Natural history of disease. Retrieved from wikipedia.org
- Incubation period. Retrieved from wikipedia.org
- Virus latency. Retrieved from wikipedia.org
- The latency period in RNQB (2017). Recovered from cbrn.es.