symbiotic relationships
Symbiosis any close relationship between species, and three types are, Mutualism, Commensalism, Parasitism.
symbiosis
the living together in mutually helpful association of two dissimilar organisms
mutualism
a relationship between two species in which both species benefit
commensalism
a relationship in which one species benefits and the other species is neither harmed nor helped
parasitism
the relation between two different kinds of organisms in which one receives benefits from the other by causing damage to it (usually not fatal damage)
symptoms
Subjective indications of disease reported by the patient.- pain, dizziness,itching
syndromes
groups or clusters of related symptoms that are characteristic of a disorder.
signs
Objective evidence of disease observed on physical exams- abnormal pulse,fever,sweating or pallor
incubation period
the period between infection and the appearance of symptoms of the disease
pathogenicity
ability of a pathogen to overcome the defensive powers of a host and to induce disease
fomites
inanimate objects that serve as reservoirs for microbes e.g. contaminated medical equipment
Virulence
Degree of pathogenicity. Extreme harmfulness (as the capacity of a microorganism to cause disease)
Prodromal period
2nd stage:Is a very short period of time when the first signs and symptoms begin to appear.
illness period
3rd stage:-aka: Period of Invasion
-display most symptoms
-org multiplies most rapidly
-highest # of pathogens
-disease most acute
-if immune response overcomes - get better
decline period
4th stage� The signs and symptoms begin to subside � sometimes from sweating from fever / due to break in fever. ? COMMON: "BREAKING FEVER". Secondary infxn's most likely to occur
convalescence period
Last stage when tissue damage is repaired and the patient regains strength; recovering individuals may still transmit pathogens to others
Resident microbiota
remain part of the normal microbiota of a person throughout life. Found in upper respiratory tract, upper digestive tract, lower digestive tract, distal portion of the urethra, and vagina.
Transient microbiota
members of the normal flora that are not always present or are present for only a few days, weeks, or months before disappearing.
Indigenous microbiota
Two types: Resident and Transient microbiota
Axenic
completely free of all detectable microorganisms and parasites
Acquisition of Normal Microbiota
begins to develop during the birthing process. Much of one's normal microbiota established during first month of one's life.
Oppertunistic pathogens
an infectious microorganism that is normally a commensal or does not harm its host but can cause disease when the host's resistance is low. Cause disease when the host's defenses are compromised or when they become established in a part of the body that i
Immune suppression
more vulnerable to disease, 1) decrease in lymphocyte number 2) changes in cytokine response 3) decrease in production of IL12 4) impaired antigen presentation
reservoirs
the sources of a pathogen and a potential source of disease. 3 types; Animal,Nonliving, and Human carriers
Animal reservoir
EX: Salmonella, Rabies
Zoonotic pathogen- disease caused by these pathogens - zoonosis
Some diseases do not seem to affect the animal ,often transmission requires a vector (insect bite) or direct contact with the animal.
Human carriers
People who carry the pathogen but are asymptomatic, can unknowingly transmit it to others
Nonliving reservoir
botulism, tetanus. -soil and water and food. Often due to contamination by feces or urine
Contamination
The mere presence of microbes in or on the body
Infection
Results when the organism has invaded the body's external defenses, multiplied, and become established in the body.
Zoonoses
diseases that occur in animals and can be transmitted to humans 150 known (eg, rabies, lymes, anthrax, ringworm, tapeworm)
Portals of Entry
pathogens gain entry via MUCOUS MEMBRANES; ex. eye, GI tract, Respiratory tract( MOST COMMON SITE of ENTRY), genitourinary tract (most pathogens do this); SKIN is another (follicles, glands, burrowing through skin), PLACENTA, PARENTERAL ROUTE
Parenteral route
delivery of a medication outside of the gastrointestinal tract, typically using needles to inject medications into the circulatory system or tissues.
Mucous Membranes
Provide a hospitable environment for pathogens. Line body cavities open to the environment.
Parvovirus
not enveloped, not double stranded (smallest DNA virus), B19 virus, aplastic crises or sickle cell disease, slapped cheek rash, erythema infectiousum, hydrops fetalis
Treponema pallidum
syphilis; gram - spirochete; virulent form not cultivatable on artificial medium; acquired sexually, vertically, or by kissing or touching open chancres
Rubivirus
A togavirus that is not transmitted by an arthropod vector. A type of arbovirus that causes Rubella or the German measles, 3 day measles.
Role of Adhesion in Infection
Attachment proteins help; Found on viruses (attachment proteins), Bacteria (adhesions), Ligands
attachment proteins
Virion capsule: regulate movement of the hydrophilic molecules through the plasma membrane. Some transport proteins through channels.
Virion
(virology) a complete viral particle, A complete virus particle that consists of an RNA or DNA core with a protein coat sometimes with an external envelope and that is the extracellular infective form of a virus.
Adhesions
Bacterial adhesion: proteins or glycoproteins found on attachment pili and capsules
Ligands
surface Lipoproteins and glycoproteins that enable bacteria and viruses to bind to complementary receptors on host cells
Biofilm
Pathogens stick together to form a biofilm; a community of microorganisms embedded in a polysaccharide matrix, forming a highly resistant coating on almost any moist surface. example: plaque on teeth
Disease
occurs when invading pathogen alters and disrupts the normal functions of the body
Morbidity
sick; a state of disease
Asymptomatic
Or subclinical, showing no symptoms, but may still have signs of infection
Etiology
study of the cause of a disease
Germ theory of disease
idea that infectious diseases are caused by microorganisms, or germs
Robert Koch
German bacteriologist who isolated the anthrax bacillus and the tubercle bacillus and the cholera bacillus (1843-1910). As a results, he figured out that Vaccines could be beneficial
Koch's postulates
1) Pathogen must be present in all disease cases 2) Isolate pathogen, cultivate in pure culture 3) Inoculate into susceptible animal, initiate disease symptoms 4) Re-isolate pathogen, confirm it's the same pathogen
Exceptions to Koch's postulates
1.sometimes the microorgansim might not be able to be cultured in the lab, 2.some diseases, although they have similar symptoms are caused by different or multiple microorganisms, 3.some microorganisms cause several different disease,4. ethical considerat
Pathogenicity
the ability of an organism to cause disease, represents a genetic component of the pathogen
Virulence
degree of pathogenicity
Virulence Factors
Structures or properties of a microbe that lead to pathologic effects on the host. While some virulance factors are those that enable entry or adhesion, many virulence factors lead directly to damage. Adhesion factors, biofilms, extracellular enzymes, tox
Extracellular enzymes
Enzymes secreted by the Pathogen that act as Virulence Factors and dissolve structural chemicals in the body. amylase, lipase, caseinase, gelatinase
Toxins
poisonous chemicals that harm tissues or trigger host immune responses that cause damage.
Toxemia
the presence of toxins in the blood
Exotoxins
gram positive & negative toxins made of metabolic products secreted from living cell. Protein or short peptide. High toxicity. Cytotoxin, neurotoxin, enterotoxin. Stimulate antitoxin (antibody) production. Botulism, tetanus, Gas gangrene, diptheria, chole
Endotoxins
Toxic substances made of lipids and carbohydrates associated with the outer membrane of Gram-negative bacteria, such as E. coli. Liberated only when the bacterial cell is destroyed. Produce fever. Typhoid fever, UTI, meningcoccal meningitis
Antiphagocytic factors
factors that prevent phagocytosis by the host's phagocytic cells ex: bacterial capsule and antiphagocytic chems
Bacterial capsule
composed of chemicals found in the body, not recognized as foreign; can be slippery, making it difficult for phagocytes to engulf bacteria
Antiphagocytic chemicals
prevent fusion of lysosome and phagocytic vesicles; leukocidins directly destroy phagocytic WBC
Leukocidins
exotoxin that disintegrates neutrophils and macrophages involved in phagocytosis
The disease process
*Stages of Infectious Disease
1.Incubation period- NO S/Sx
-->LAG
2. Prodromal period- vague, general symptoms.
->may not always occur as part of this process)
-->LOG or EXPONENTIAL
3. Illness- most severe S/Sx
-->STATIONARY
4. Decline-declining S/Sx
-->D
incubation period
1st stage of infection: Time between the entry of a pathogen into a reservoir and the onset of clinical signs and symptoms. The pathogen multiplies in numbers during this period.
Portals of exit
how pathogens leave the host -- many are the same as portals of entry. Skin, respiratory tract, digestive system, urinary and reproductive system
Portals of entry
pathogens gain entry via MUCOUS MEMBRANES; ex. eye, GI tract, respiratory tract, genitourinary tract (most pathogens do this); SKIN is another (follicles, glands, burrowing through skin)
Transmission
the way a disease is spread
Contact transmission
Direct (herpes, rabies), indirect (common cold, teanus, pnuemonia), droplets (whooping cough, strep throat). Spread of disease causing microorganism by directly or indirectly touching the source of the infection or by touching an object or environmental s
Vehicle transmission
Airborn (chickenpox, tuberculosis), Waterborne (Cholera, Campylobacter infxn), Food borne ( Hep A, Staphy, tapeworm). Transfer of microorganisms present on or in contaminated items such as food, water, medications, devices, and equipment. Ex. consumption
Vector transmission
Mechanical (e. coli, salmonella-body of arthropod), Biological (Malaria, RM spotted fever, Lyme disease). A vector is an animal or flying or crawling insect that serves as an intermediate means of transporting the infectious agent
Classification of Infectious Disease
Taxonomic group of causative agent
Body system they affect
longevity and severity
How they are spread to hosts
effect on population (rather than individual)
Acute disease
disease having a rapid onset, severe symptoms, and a short course or duration
Chronic disease
a disease that develops gradually and continues over a long period of time
Latent Disease
any disease in which a pathogen remains inactive for a long period of time before becoming active
Local Disease
Disease affecting only one area of the body, such as foot fungus
Contagious Disease
disease that may be transmitted between individuals, with reference to the organism that causes the disease
Noncommunicable disease
not spread from host to host - caused by microbes normally in body or that reside outside and cause disease when introduced into body
Systemic infection
microbes/ products-infections spread throughout by circulatory or lymphatic system
Focal Infection
infection starts in one place, then moves. (strep in the mouth can move in blood stream and to heart valves[ endocarditis]) Can occur @ dentist(bacteremia)
Primary infection
Acute infection that causes the initial illness
Secondary Infection
caused by opportunistic microbe after primary weakened host
Descriptive Epidemiology
careful tabulation of data concerning a disease, including location and time of case, index case, patient info
Incidence
the number of new cases of a disease in a population during a given period of time.
Prevalence
(epidemiology) the ratio (for a given time period) of the number of occurrences of a disease or event to the number of units at risk in the population
Occurance
evaluated in terms or Frequency and Geographic distribution
analytical Epidemiology
seeks to determine probable cause, mode of transmission, methods of prevention (often retrospective study)
Experimental Epidemiology
begins with a hypothesis about a particular disease; experiments to test the hypothesis are then conducted with a group of people
Exogenous infections
Type of nosocomial infection., patients acquire a pathogen from others (sources are other patients, visitors or hospital personnel)
Endogenous Infections
Type of nosocomial infection. Caused by patients own opportunist among their microflorabiota
Types of nosocomial Infections
UTI (most common, catheters), Lower respiratory (most important, pneumonia, ventilators) , surgical wounds, primary bacteremia, cutaneous, Pseudomembranous colitis
latrogenic infections
Type of nosocomial infection. Results from modern medical procedures -- ex: use of catheters, surgery etc. (Doctor induced)
Common normal Microbiota
Lactobacillus, bacteriocides, clostridium, Staph & Strep, Candida, trichominas (protozoan), Malassezis (fungus), propionbacteria, mycobacterium Corynebacterium-skin
Nosocomial infections
Develop in hospitalized patients secondary to patient's original condition