Microbiology

Microbiology Study Guide . Further, when both the organisms benefit each other, the . When one of them causes damage to the other one, the relationship is termed as parasitism . That is why a large number of bacteria that can cause disease are known as parasites. The mechanism that inhibits these organisms is known as antibiosis . The degree or magnitude of the disease known as called virulence . Some pathogenic organisms that do not lead to disease are known as opportunistic organisms. These pathogens may see opportunity and invade the body tissues where the host is compromised. For instance, in patients suffering from AIDS, the organism Pn um cystis carinii may find that the person’s immunity is compromised and may enter the lung tissues of the patient, causing lethal pneumonia. Progress of Disease Periods of Disease Disease results when the pathogen overcomes the body tissues. There are different periods in the development of disease. The first one is the incubation period , which is the lapse of time between exposure of the body tissues to the pathogenic organism and when signs and symptoms of such a reaction become visible. The duration of the incubation period varies from a few minutes to many years, as in case of Creutzfeldt-Jakob disease. The next period is known as the latency period , which denotes the time lapse between the onset of infection and the state of infectiousness. The duration of the incubation period and latent period depends on the nature of disease. For instance, suppose a person is suffering from throat infection and carrying the microbe Streptococcus. If the person does not show any symptoms this could mean that the person may not be infectious in the incubation period. The state of latency can be distinguished between subclinical latency and viral latency. In the case of subclinical latency, the viral infections replicate in an active state, while in viral latency, the virus remains in a dormant state and does not replicate. Disease Patterns A disease develops itself in an individual in different phases and patterns. The first phase is known as the period of incubation. The next phase is known as the prodrome period, which shows mild symptoms or early signs of disease, like aches and fever. The third phase is the period of illness and is when the disease becomes really acute. In this phase, the signs and symptoms of the disease become highly apparent and depend on the unique feature and nature of the disease. The next phase is known as the period of decline . In this stage, the individual begins to feel better and the signs and symptoms of the disease start to subside. The last is the stage of convalescence , in which the person returns to their normal state. Once the disease abates, the immune system of the individual becomes healthy and starts to generate antimicrobes that help the individual attain immunity against pathogens for a long period of time. unaffected it is termed as commensalism relation is known as mutualism

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