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An infectious disease agent can be transmitted in two ways: as horizontal disease agent transmission from one individual to another in the same generation (peers in the same age group) [3] by either direct contact (licking, touching, biting), or indirect contact through air – cough or sneeze (vectors or fomites that allow the transmission of the agent causing the disease without physical ...
The following outline is provided as an overview of and topical guide to concepts related to infectious diseases in humans.. Infection – transmission, entry/invasion after evading/overcoming defense, establishment, and replication of disease-causing microscopic organisms (pathogens) inside a host organism, and the reaction of host tissues to them and to the toxins they produce.
Infectious aerosols may stay suspended in air currents long enough to travel for considerable distances; sneezes, for example, can easily project infectious droplets for dozens of feet (ten or more meters). [12] Airborne pathogens or allergens typically enter the body via the nose, throat, sinuses and lungs. Inhalation of these pathogens ...
The body has defence mechanisms that enable it to resist microbial invasion of its tissues and give it a natural immunity or innate resistance against many microorganisms. Pathogenic bacteria are specially adapted and endowed with mechanisms for overcoming the normal body defences, and can invade parts of the body, such as the blood, where ...
Bacteria in the culture on the right are resistant to most of the antibiotics. In addition to drugs being specific to a certain kind of organism (bacteria, fungi, etc.), some drugs are specific to a certain genus or species of organism, and will not work on other organisms. Because of this specificity, medical microbiologists must consider the ...
Pathogens include bacteria, fungi, protozoa, parasitic worms (helminths), and viruses. Each of these different types of organisms can then be further classified as a pathogen based on its mode of transmission. This includes the following: food borne, airborne, waterborne, blood-borne, and vector-borne.
Exogenous bacteria are microorganisms introduced to closed biological systems from the external world. [citation needed] They exist in aquatic and terrestrial environments, as well as the atmosphere. Microorganisms in the external environment have existed on Earth for 3.5 billion years. [1] Exogenous bacteria can be either benign or pathogenic.
Microbiology (from Ancient Greek μῑκρος (mīkros) ' small ' βίος (bíos) ' life ' and -λογία () ' study of ') is the scientific study of microorganisms, those being of unicellular (single-celled), multicellular (consisting of complex cells), or acellular (lacking cells).