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M. tuberculosis is able to reproduce inside the macrophage and will eventually kill the immune cell. The primary site of infection in the lungs, known as the Ghon focus, is generally located in either the upper part of the lower lobe, or the lower part of the upper lobe. [13] Tuberculosis of the lungs may also occur via infection from the blood ...
Viruses, however, use a completely different mechanism to cause disease. Upon entry into the host, they can do one of two things. Many times, viral pathogens enter the lytic cycle; this is when the virus inserts its DNA or RNA into the host cell, replicates, and eventually causes the cell to lyse, releasing more viruses into the environment.
The Wells-Riley model is a simple model of the airborne transmission of infectious diseases, [1] [2] developed by William F. Wells and Richard L. Riley for tuberculosis [3] and measles.
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 ...
Mycobacterium tuberculosis (M. tb), also known as Koch's bacillus, is a species of pathogenic bacteria in the family Mycobacteriaceae and the causative agent of tuberculosis. [1] [2] First discovered in 1882 by Robert Koch, M. tuberculosis has an unusual, waxy coating on its cell surface primarily due to the presence of mycolic acid.
The terms "intrinsic incubation period" and "extrinsic incubation period" are used in vector-borne diseases.The intrinsic incubation period is the time taken by an organism to complete its development in the definitive host.
To enter the cells, proteins on the surface of the virus interact with proteins of the cell. Attachment, or adsorption, occurs between the viral particle and the host cell membrane. A hole forms in the cell membrane, then the virus particle or its genetic contents are released into the host cell, where replication of the viral genome may commence.
The sylvatic cycle, also enzootic or sylvatic transmission cycle, is a portion of the natural transmission cycle of a pathogen. Sylvatic refers to the occurrence of a subject in or affecting wild animals. The sylvatic cycle is the fraction of the pathogen population's lifespan spent cycling between wild animals and vectors. Humans are usually ...