Tuberculosis

Tuberculosis

Introduction

Communicable diseases are also known as infectious or transmissible diseases. These consist of clear clinically recognized illness, which is caused due to infection, existence and development of pathogenic biological agents within an individual host organism. In a given host, communicable diseases may be asymptomatic in certain instances. Infectious pathogens consist of protozoa, bacteria, viruses, fungi, aberrant proteins and multicellular parasites known as prions. The cause of disease epidemics are these pathogens, as no communicable epidemic occurs without pathogen.

Discussion

Communicable diseases are also known as "contagious" because they can easily be transferred by contact with a person of that illness or their secretions (e.g., influenza). Therefore, a contagious disease is a category of communicable disease which is particularly infective or can easily be transferred. Other kinds of communicable diseases with further specialized infection routes, such as vector or sexual transmission, are commonly not regarded as "contagious," and often do not need medical isolation also known as quarantine of victims. However, this specialized usage of the term contagious and contagious disease (easily transferrable) is not always respected in common use.

Among the nearly unlimited kinds of micro-organisms, only few can cause disease in healthy people. Communicable disease are the outcome of the interaction between some pathogens and the ramparts of the infected hosts. The emergence and intensity of disease coming from any pathogen, is dependent on whether the pathogen is able to damage the host as well as whether the host is able to resist the pathogen. Clinicians therefore categorise communicable micro-organisms as per the condition of host resistance, which can either be opportunistic pathogens or primary pathogens:

Primary pathogens can cause disease as a consequence of their activity or presence in the host which is healthy and normal, and their inherent virulence, which means the intensity of disease they can inflict,is partly, a mandatory result of their requirement to spread and regenerate. Most of the usual basic pathogens of humans only cause infections in themselves, however several severe diseases are as a result of organisms which are acquired from the environment or from which non-human hosts are infected.

Opportunistic pathogens are those organisms which cause a communicable disease in a host with depressed defense. Opportunistic disease can occur because microbes that are normally in contact with the host, for example pathogenic bacteria or fungi in the gastrointestinal or the upper respiratory tract, and they may also be caused from microbes taken from other hosts or from the environment as a consequence of traumatic introduction. An opportunistic disease needs the resistance of hosts to be impaired, which may happen as a consequence of genetic defects, exposure to antimicrobial drugs orimmunosuppressive chemicals, exposure to ionizing radiation, or as a consequence of a communicable disease with immunosuppressive activity, for example malaria . Primary pathogens may also cause more intense disease in a host with depressed defense than would commonly happen in an immunosufficient host.[1]

A way to prove that a particular disease is "contagious”, is to satisfy Koch's postulates, which requires that the communicable agents be determined only in patients and not in healthy controls, and that patients who diminish the agent also develop the disease. These postulates were first used in ...