In infectious disease …disease can differ from simple infection, which is the invasion of and replication in the body by any of various agents—including bacteria, viruses, fungi, protozoans, and worms—as well as the reaction of tissues to their presence or to the toxins that they produce. When health is not altered, the process… Read More
inflammatory response
In inflammation …organisms to protect them from infection and injury. Its purpose is to localize and eliminate the injurious agent and to remove damaged tissue components so that the body can begin to heal. The response consists of changes in blood flow, an increase in permeability of blood vessels, and the migration… Read More
In neutrophil …neutrophils migrate to areas of infection or tissue injury. The force of attraction that determines the direction in which neutrophils will move is known as chemotaxis and is attributed to substances liberated at sites of tissue damage. Of the many neutrophils circulating outside the bone marrow, half are in the… Read More
In transduction …bacteriophage initiates another cycle of infection. In general transduction, any of the genes of the host cell may be involved in the process; in special transduction, however, only a few specific genes are transduced. It has been exploited as a remarkable molecular biological technique for altering the genetic construction of… Read More
transmission of disease
In disease: Communicable disease Infectious diseases are diseases caused in the host by infection with living, and therefore replicating, microorganisms, such as animal parasites, bacteria, fungi, or viruses. Practically, these two classes of disease are the same, because infectious diseases generally are communicable, or Read More
In disease: Treatment For other infectious diseases there is no specific therapy. There are, for example, very few antiviral chemotherapeutic agents; treatment of viral diseases is mainly directed toward relief of discomfort and pain, and recovery, if it ensues, is largely a matter of an effective cellular immune response mounted… Read More
virus
In virus …was a new kind of infectious agent, which he designated contagium vivum fluidum, meaning that it was a live, reproducing organism that differed from other organisms. Both of these investigators found that a disease of tobacco plants could be transmitted by an agent, later called tobacco mosaic virus, passing through… Read More
In virus: Treatment …as colds caused by rhinoviruses, infections caused by herpesviruses, and benign tumours and warts caused by papillomaviruses. Local administration at the sites of viral infection affords the best results, although injections of large amounts of interferons can be harmful, probably because they tend to inhibit protein synthesis in the host… Read More
manifestation in
abscesses
In abscess …have been broken down by infectious bacteria. An abscess is caused when such bacteria as staphylococci or streptococci gain access to solid tissue (e.g., by means of a small wound on the skin). The toxins released by these multiplying bacteria destroy cells and thus trigger an acute inflammation at the… Read More
adenoids
In adenoids …of mucus tends to carry infectious agents and dust particles inhaled through the nose down to the pharynx, where the epithelium is more resistant. Immune substances, or antibodies, are thought to be formed within the lymphatic tissue, which, combined with phagocytic action, tends to arrest and absorb infectious agents. Read More
burns
In burn: Complications. …reduced the incidence of post-burn infection, but infection remains one of the most serious complications of burns. Burn surgeons often obtain cultures of the burn wound and of sputum and other body secretions; these are examined for signs of infection. Early detection and prompt treatment of infection with antibiotics and… Read More
childhood diseases
In childhood disease and disorder: Infections The newborn infant is subject to the ordinary infections and, in addition, to infection with commonly encountered organisms such as Escherichia coli,Staphylococcus aureus, and group B hemolytic streptococci, which are not usual causes of serious infection in older age groups. Infection may be… Read More
fractured bones
In fracture …is frequently a result of infection. Because healing will not ordinarily take place until an infection is treated, all procedures are aimed at combating infection at the site of injury whenever the possibility exists (as in compound fractures). Failure to heal may also result from severe destruction of bone, disruption… Read More
immune system deficiencies
In immune system disorder: Deficiencies caused by infection Damage to lymphocytes that is inflicted by viruses is common but usually transient. During infectious mononucleosis, for example, the Epstein-Barr virus infects B cells, causing them to express viral antigens. T cells that react against these antigens then attack the B cells, and a… Read More
nervous system
In nervous system disease: Infections Although the blood-brain barrier protects the nervous system from microorganisms, it may be damaged by bacteria, viruses, fungi, and other organisms. If damage occurs, resistance to infection of the nervous system is decreased. The major classes of inflammatory disease are meningitis and encephalitis Read More
In nervous system disease: Infections Encephalitis, an infection of the brain, may be caused by a number of microorganisms including viruses, bacteria, and fungi. In the Western world, viral encephalitis is the most common type of the disorder; it is typically caused by the herpes simplex virus. Other… Read More
open wounds
In wound: Open wounds …local or general complications from infection. Furthermore, if the break in the skin is large, the resulting exposure of the wounded tissues to the drying and cooling effects of the air may increase the damage caused by the wounding agent itself. Read More
plant diseases
In plant disease: Infectious disease-causing agents Plants are subject to infection by thousands of species from very diverse groups of organisms. Most are microscopic, but a few are macroscopic. The infectious agents, as previously mentioned, are called pathogens and can be grouped as follows: viruses and viroids, bacteria (including mycoplasmas and spiroplasmas, collectively referred to… Read More
respiratory disease
In respiratory disease: Viral infections of the respiratory system A wide variety of viruses are responsible for acute respiratory disease. The common cold—frequently of viral origin—can cause inflammation of the trachea and laryngitis, and such inflammation may extend to involve the lower bronchial tree. After such episodes the Read More
skin disease and disorder
In skin disease: Distribution …environmental agents, fungal or viral infections, and drugs) are among the most common extrinsic determinants of distribution. Environmental influences, such as sunburn and light-sensitive, drug-induced reactions, may also play a major role. Psoriasis and the rare hereditary blistering disorders collectively called epidermolysis bullosa owe their distributions to local trauma; lesions… Read More
In skin disease: Aging and the skin …common skin conditions as fungal infections, excessive dryness, various benign tumours, seborrheic dermatitis, seborrheic warts, solar keratoses, and hirsutism. Many age-related skin disorders previously viewed as inevitable accompaniments of advancing age are now known to be remediable. Read More
spoiled meats
In meat processing: Food-poisoning microorganisms Infection occurs when an organism is ingested by the host, then grows inside the host and causes acute sickness and, in extreme cases, death. Common infectious bacteria capable of causing food poisoning in undercooked or contaminated meats are Salmonella, Escherichia coli, Campylobacter jejuni, and Listeria… Read More
tissue and organ transplants
In transplant: Transplantation and postoperative care …with bacteria that might cause infection. The patient is usually nursed in a separate room, and doctors and nurses entering the room take care to wear masks and wash their hands before touching the patient. The air of the room is purified by filtration. Close relatives are allowed to visit… Read More
prevention and treatment
antibiotics
In antibiotic: Penicillins …penicillins to the treatment of infections caused by gram-negative rods, the broad-spectrum penicillins (ampicillin, amoxicillin, carbenicillin, and ticarcillin) were developed. These penicillins are sensitive to penicillinase, but they are useful in treating urinary tract infections caused by gram-negative rods as well as in treating typhoid and enteric fevers. Read More
In history of medicine: The situation encountered The means to combat infection hovered between antisepsis and asepsis. Instruments and dressings were mostly sterilized by soaking them in dilute carbolic acid (or other antiseptic), and the surgeon often endured a gown freshly wrung out in the same solution. Asepsis gained ground fast, however. It had been born… Read More
antiserum production
In antiserum …in humans, in response to infection, intoxication, or vaccination. Animal and human antiserums can be used in other individuals to confer immunity to a specific disease or to treat bites or stings of venomous animals. Antiserums from animals are most often used, but human antiserums have proved valuable for use… Read More
immunity
In immune system: External barriers to infection The skin and the mucous membrane linings of the respiratory, gastrointestinal, and genitourinary tracts provide the first line of defense against invasion by microbes or parasites. Read More
In immune system: Nonspecific responses to infection The body has a number of nonspecific methods of fighting infection that are called early induced responses. They include the acute-phase response and the inflammation response, which can eliminate infection or hold it in check until specific, acquired immune responses have time to develop.… Read More
immunization
In immunization …discussion focuses on immunization against infectious diseases in vertebrate animals, specifically humans. Read More
