We call pathogens, organisms that are capable of causing disease in a host. Some bacteria, for example, can cause disease in humans, and they are therefore a pathogen. Besides bacteria, we can mention as pathogens: fungi, protozoa and virus.
→ Pathogenicity
To cthe ability of a pathogen to cause changes in infected host organisms is called pathogenicity. There are organisms with great pathogenicity, that is, they produce symptoms in practically all those infected. This is the case of measles. It is noteworthy, however, that there are organisms with low pathogenicity, that is, they cause severe symptoms in a few infected.
→ Virulence
THE Virulence, in turn, is the the pathogen's ability to damage the host organism, that is, virulence refers to the intensity and severity of diseases caused by pathogens. A pathogen with high virulence is responsible for causing the death of many patients, as occurs with anger, for example. Low virulence, on the other hand, usually produces signs and symptoms of little concern.
A highly virulence pathogen has several strategies that ensure success in the infectious process. The presence of capsules, antimicrobial resistance and the ability to cause structural and biochemical changes in host cells are examples of important factors related to the virulence of some species of bacteria.
→ Classification of pathogens
Pathogens can be classified into two groups:
Primary pathogen: It is one that will cause disease in the body, even if the individual is healthy. As an example of a primary pathogenic microorganism we can mention the bacterium Mycobacterium tuberculosis, which causes tuberculosis, and the hepatitis and flu viruses.
Opportunistic pathogen: It is one that can be found normally in the body, but does not cause any harm in healthy individuals. The organism will only be infected and will have the disease when there are low immune defenses. As an example of opportunistic pathogenic microorganisms we can cite the Staphylococcus aureus which can cause pneumonia, boils, and septicemia (serious, life-threatening general infection).
By Ma. Vanessa dos Santos
Source: Brazil School - https://brasilescola.uol.com.br/o-que-e/biologia/o-que-e-patogeno.htm
