 Basic facts about infectious disease theory
Added: 12/20/2005 |
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In medicine infectious diseases are often called or communicable diseases or the ones caused by a biological agent (virus, bacterium or parasite), as opposed to chemical (intoxication) or physical (burns) causes. One of the important terms in the infectious disease theory is basic reproductive rate - a number of secondary infections in the host organism. This metric is rather useful and important because it helps to determine whether the person is infected or not.
For many years (even since ancient times) physicians and scientists have known that a wide range of diseases are transmissible. However, because of the idiosyncratic and subtle ways in which various infections are likely to travel, the early-modern physicians believed that the responsible particles should be much smaller than our usual cells (which is correct) and bit closer in their sizes to atoms (which isn't correct). Scientists of the past were wondering whether the bacteria which often seen in infections were the real cause or only one of the side-effects.
The study of the infectious disease theory is pretty interesting because the etiologies of the majority of these diseases are evident and known, namely damage by an invader. According to infectious disease theory, if the mentioned invaders can be killed, the illness can be arrested.
Nowadays, only a number of crooks and fools insist that microorganisms cause diseases. In reality the microbe is only seldom the whole story or the disease cause. The majority of modern infectious agents are so-called "opportunists" (or "secondary invaders" such as bacteria, parasites or viruses).
Thus, according to the modern infectious disease theory the infectious disease can be caused either by any of the biological agents, as opposed to physical or chemical causes. The field of infectious diseases theory occupies itself with the diagnosis and infection's therapy. Any infectious disease has its agent, mode and transmission mode (called vector). One of the best examples for you is malaria mainly caused by the parasite called Plasmodium falciparum. This parasite doesn't do harm to humans unless Anopheles mosquito (the vector) introduces the mentioned parasite into the person's bloodstream. As a matter of fact, the vector is not always of biological nature. Lots of infectious diseases can be transmitted by droplets entering the surrounding air (for example, tuberculosis and cold).
Speaking about infectious disease theory, it's important to pay attention to the basic reproductive rate. This rate is also sometimes called the intrinsic rate of reproduction. It is considered to be the number of secondary infections appearing after the introduction of one single infectious organism into the entirely susceptible population. The mentioned metric helps medical experts in determination of the disease spread through the population. Basic reproductive rate is known to be influenced by a number of factors which include the duration of affected people infectivity, the severity degree of the infection affected the human body and the number of susceptible people who have close contacts with the infected ones.
The overview of the infectious disease theory wouldn't be complete if we didn't pay attention to the top infectious disease killers. These are HIV (or AIDS), tuberculosis and malaria. One of the important tools of studying the infectious diseases in population is epidemiology. It is very helpful in determining if the disease's outbreak is sporadic, endemic, epidemic or pandemic.
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