MICROPARA BACTERIA AND DISEASE

• Disease – result of an undesirable relationship between the host and the pathogen, marked by interruption in the normal functioning of a body part or parts.
• Infection – invasion of the body by pathogenic microorganisms. The term is not synonymous with disease.
• Symbiosis – prolonged and close interaction between organisms of different species.
• Mutualism – a form of symbiosis in which both organisms benefit from the relationship.
• Commensalism– a form of symbiosis in which one organism benefits from another organism without causing harm to it.
• Parasitism– a form of symbiosis where one organism benefits from another organism and at the same time causes harm to the other.
• Pathogenicity– ability of an organism to produce disease. An organism that can produce disease in humans is said to be pathogenic
• Virulence – describes the degree of pathogenicity of an organism or the degree to which an organism can produce disease.
• Contamination– presence of unwanted materials(chemical, biological, or radiological) where they should not be or at concentrations above the normal. The presence of these substances may not necessarily lead to harm.
• Pollution – presence of contaminants that can cause adverse biological effects to humans and communities. All pollutants are contaminants but not all contaminants are pollutants.
• Bacteremia – presence of bacteria in the blood.
• Septicemia – presence of actively multiplying bacteria in the blood, usually from a source of infection. The condition is called sepsis.
• Pyemia – presence of pus producing bacteria in the bloodstream.
• Viremia – presence of viruses in the blood.
• Toxemia – presence of toxins in the blood.
• A disease that is spread from one host to another, either directly or indirectly, is called a communicable disease.
• If the disease is easily and rapidly spread from one person to another, then it is classified as a contagious disease (e.g., measles and chickenpox).
• If the infection results in the death of the patient over a short period of time, it is called a fulminant infection. An example is meningococcemia where a patient may die hours after confinement in the hospital.
• A non communicable disease is one that is not spread from one person to another. It is usually caused by organisms that normally inhabit the body and produce disease only occasionally or by organisms that produce disease only when introduced into the body such as Clostridium tetani, the agent that causes tetanus. It produces disease only when it enters the body through breaks in the skin.
• An infection is said to be exogenous if the source of the infectious agent is from outside the body. For example, cholera is an exogenous infection because the causative agent enters the body through ingestion of contaminated water.
• Hospital acquired infections or nosocomial infections can also be considered as exogenous infections where the offending organism was obtained from the hospital environment during the period of confinement of the patient in the hospital.
• endogenous infection is one where the source of the causative

  organism is from inside the body. Escherichia coli is part of the normal flora of the colon that can enter the urinary tract via the urethra, especially in women, due to its close proximity to the anal orifice.
• A disease that occurs occasionallyis called a sporadic disease.
• If the disease is constantly present in a population at low levels, then it is called an endemic disease. Malaria is said to be endemic in Palawan while schistosomiasisis considered endemic in Leyte.
• If a great number of people in a given locality develop an infectious disease in a relatively short period of time, it is called an epidemic. Influenza is an example of a disease that can cause epidemics.
• If a disease has a worldwide occurrence or involves at least three regions in the world, it is said to be a pandemic. Influenza, especially due to influenza A, SARS, and AIDS are examples of disease that can cause pandemics.
• An acute disease is one that develops rapidly but lasts for only a short period of time. An example is the common cold.
• If the disease develops more slowly and occursfor long periods of

  time, it is called a chronic disease. A good example of this is tuberculosis.
• Hepatitis B infection is an example of a disease that can have either an acute form or a chronic form.
• A latent disease is one in which the causative organism remains inactive for a time but can become active again and produce symptoms of the disease.
• A localized infection is one in which the invading organisms are limited to a relatively small area of the body. Boils and abscesses are examples of localized infections.
• A systemic infections or generalized infection is one where the causative organisms or their products are spread throughout the body through blood or lymph.
• In some cases, the causative agents of a localized infection may enter a blood or lymphatic vessel, spread to specific parts of the body and become confined to specific areas. This is called a focal infection. Focal infections can arise from infections in areas such as the teeth, tonsils, or sinuses.
• A primary infection is an acute infection that causes the initial illness, while a secondary infection is one which is caused by opportunistic pathogens after the primary infection has weakened the body’s defenses. Secondary infections are common in patients whose immune system have been compromised by another disease
• A subclinical or inapparent infection is one that

  does not cause noticeable illness.