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1、医学英语感染病医学英语感染病termsInfectiology Infection Infectious diseasesInfectiologist Types of pathogensSubcelluarProkaryotic Viruses, prionBacterial, chlamydiae, rickettsiae, mycoplasmasEukaryotic Protozoa, fungi, helminthes, arthropodsprionA prion is an infectious agent composed of protein in a misfolded fo
2、rm Disease:Bovine spongiform encephalopathyMadcow disease(MCD)VirusesThe term virion (plural virions) is also used to refer to a single, stable infective viral particle that is released from the cell and is fully capable of infecting other cells of the same type A virus is a small infectious agent t
3、hat can replicate only inside the living cells of organisms. Bacteria (singular: bacterium)chlamydiaechlamyd-, mantle (a cloak) Chlamydia infectionchlamydia conjunctivitisor trachoma rickettsiaeThe genus Rickettsia is named after H. T. Ricketts (18711910), who studied Rocky Mountain spotted fever, a
4、nd eventually died of typhus after studying that disease. rickets, vitamin D deficiency Disease:spotted fever, typhus and scrub typhus Tick hemolymph cells infected with R. rickettsii. From the CDC.Symptoms of Scrub typhus fever headache muscle pain cough gastrointestinal symptoms hemorrhaging and i
5、ntravascular coagulation. maculopapular rash, eschar（焦痂）, splenomegaly and lymphadenopathies are typical signs. http:/ (fungus) and plasma (formed)SpirochetesyphilisSaddle nose Fungi (singular: fungus)Tinea (=ringworm ) of skinTinea pedisTinea manusTinea crurisGroup of extremely small single cell (u
6、nicellular) or acellular organisms that are found in moist soil or water. They tend to exist as parasites, living off other life forms. Protos (First) and zoon (animal)protozoa (singular: protozoon)helminths are worm-like organisms (Parasitic worms) that live and feed off living hosts, receiving nou
7、rishment and protection while disrupting their hosts nutrient absorption, causing weakness and disease. helminthsHelmins = wormHookworms attached to the intestinal mucosa.arthropods Greek arthron, joint, and pods foot, which together mean jointed feet”Culex MosquitoAedes MosquitoTicksPathogen factor
8、spathogenicityvirulenceis the ability of a pathogen to produce an infectious disease in an organism. The virulence factors of bacteria Methods by which bacteria cause disease AdhesionColonizationInvasionImmune response inhibitorsToxins12345The virulence factors of bacteria Adhesion. Many bacteria mu
9、st first bind to host cell surfaces. Colonization. Some virulent bacteria produce special proteins that allow them to colonize parts of the host body. Invasion. Some virulent bacteria produce proteins that either disrupt host cell membranes or stimulate endocytosis into host cells. These virulence f
10、actors allow the bacteria to enter host cells and facilitate entry into the body across epithelial tissue layers at the body surface. Immune response inhibitors. Many bacteria produce virulence factors that inhibit the hosts immune system defenses. Toxins. Many virulence factors are proteins made by
11、 bacteria that poison host cells and cause tissue damage. Methods by which bacteria cause disease invasionminimum lethal dose (MLD) the smallest amount of toxin that will kill an experimental animal.Minimum infective dosemedian infective dose (ID50) the amount of pathogenic microorganisms that will
12、cause infection in 50 per cent of the test subjects. infective dose that amount of pathogenic organisms that will cause infection in susceptible subjects.Host factorssusceptibilitydispositionImmune systemAntibody, immunoglobulinIceberg concept of infectionInfectious disease spectrum If a large numbe
13、r of individuals are equally exposed to an infectious agent, they do not all respond in the same manner. In fact, there may be a broad range of responses: Some do not become infected at all Some become infected but develop no symptoms Some become infected and develop mild or moderate symptoms Some b
14、ecome infected and develop severe symptoms Some die as a result of their infectionPathogenesis of infectionClinical manifestations of infectious diseasesNon-specificOrgan system-basedFeverAnorexiaFatigueMuscle achesSkin rasha state of physical and/or mental weakness Loss of appetite Mary Mallon was
15、an asymptomatic carrier of typhoid fever. Over the course of her career as a cook, she infected 53 people, three of whom died.Host-Pathogen Interactions: Symbiotic RelationshipsMutualismCommensalismParasitismNeutralismA symbiotic relationship in which both species benefit A symbiotic relationship in
16、 which one organism derives benefit and the other is unharmed A symbiotic relationship in which one species, the parasite, benefits at the expense of the other, the host The state of being neutral; neutrality prefix, a variant of syn- before b, p, and m=Together = Life; living organism airborne infe
17、ction droplet infection vector-borne infection waterborne infection bloodborne infectionMode of infectionSneezing can spread the flu virus to other people. airborne infection one that is contracted by inhalation of microorganisms or spores suspended in air on water droplets or dust particles. drople
18、t infection infection due to inhalation of respiratory pathogens suspended on liquid particles exhaled by someone already infected (droplet nuclei) . vector-borne infection infection caused by microorganisms transmitted from one host to another by a carrier, such as a mosquito, louse, fly, or tick.
19、waterborne infection infection by microorganisms transmitted in water.Classification of infections 1Type of the pathogenDegree of involvementBacterial, viral, fungal, parasiticLocal/focal, generalizedManner acquiredCommunity, hospital/nosocomialClassification of infections 2Type of occurrenceEndogen
20、ous vs. exogenousAutoinfection vs. cross-infectionSuperinfection vs. reinfectionsepsisOpportunistic infection an infection caused by an infectious agent that is already present in the body, but has previously been inapparent or dormant. an infection that develops from bacteria normally outside the b
21、ody that have gained access to the body an infection caused by a disease agent that is already present in the body an infection by an organism that does not ordinarily cause disease but becomes pathogenic under certain circumstances (e.g., impaired immune responses). the transmission of a communicab
22、le disease from one person to another because of a poor barrier protection an infection following a previous infection, especially when caused by microorganisms that have become resistant to the antibiotics used earlier a second infection by the same microorganism, either after recovery or during th
23、e original infection 12345678 a bacterial infection in the bloodstream or body tissues Cross-infectionExogenous infectionEndogenous infectionOpportunistic infectionReinfectionSuperinfectionAutoinfection Sepsis Laboratory diagnosis of infectious diseasesGold standard testproceduresMicroscopy and Stai
24、ning proceduresCulture and sensitivitySerologic testStaining procedures Urinalysis and fecalysis Specimen smear (blood, stool) Gram Staining Zeihl-Neelson stain KOH (potassium hydroxide) test for fungiGram Staining Gram stain a staining procedure in which microorganisms are stained with crystal viol
25、et, treated with strong iodine solution, decolorized with ethanol, and counterstained with a contrasting dye; those retaining the stain are gram-positive, and those losing the stain but staining with the counterstain are gram-negative.Zeihl-Neelsen stain The Ziehl-Neelsen stain, also known as the ac
26、id-fast stain, was first described by two German doctors; Franz Ziehl (1859-1926), a bacteriologist and Friedrich Neelsen (1854-1898), a pathologist. It is a special bacteriological stain used to identify acid-fast organisms, mainly Mycobacteria. nSpecimens mounted in 10% KOH and examined directly u
27、nder the microscopeKOH (potassium hydroxide) test for fungiCulture and sensitivitySerologic test any laboratory test involving serologic reactions, especially any such test measuring serum antibody titer.Treatment and preventionMedical treatmentprophylaxisPre- and post-exposurePharmacologicalImmuniz
28、ation antibiotics vaccination local treatment of the wound administration of rabies immunoglobulinPre- and post-exposure prophylaxis A young girl infected with smallpox (1973). Due to the development of the , the disease was officially eradicated in 1979. smallpox vaccineOutline Pathogen Host Pathogenesis of infection Classification of infection Clinical manifestations Laboratory diagnosis of infectious diseases Treatment and preventionLEARN MORE, BE MORE