Pathology
The study of disease
Etiology
The study of the cause of a disease
Pathogenesis
The development of disease
Infection
Colonization of the body by pathogens
Disease
Abnormal state when the body is not functioning normally. Disease does not always mean caused by an infection (i.e. Cancer)
Transient Microbiota
Present for days, wks, mnths. Normal microbiota that body comes in contact w/on daily basis but does not stay on the body for very long
Normal Microbiota
Permanently colonize the host. Bacteria, fungus, protozoa that naturally live on the body, typically not removed by washing/handwashing
Symbiosis
1) Commensalism: 1 organism benefits, other is unaffected
2) Mutualism: both organisms benefit (Ex: E. coli in the gut)
3) Parasitism: 1 organism benefits at the expense of the other
Opportunistic Pathogens
Some normal microbiota are opportunistic pathogens. Humans live w/them commensally or mutually but they can turn pathogenic and parasitic under certain circumstances
- Ex: MSRA on healthcare workers
Normal Microbiota Functions
Protect host by –
Koch’s Postulates
Used to prove cause of an infectious disease. Some pathogens can cause several diseases. Some pathogens only cause disease in humans
Koch’s Postulates Limitations
Symptom
Change in body fxn that is felt by a patient as result of disease, cannot be measure
- headaches, fatigue, stomach ache
Sign
Change in body that can be measured or observed as result of disease
- rash, fever, elevated white blood cell count
Syndrome
Signs + Symptoms
Communicable disease
Disease spread from one host to another
- flu
Contagious disease
Disease easily spread from one host to another
- chicken pox
Noncommunicable disease
Disease not transmitted from one host to another
- cancer
Incidence
Fraction of a population that contracts a disease during a specific time
Prevalence
Fraction of a population having a specific disease at a given time
- If a rapidly-cured disease, incidence and prevalence rates usually the same, but if not then prevalence rate usually higher
Sporadic disease
Disease that occurs occasionally in a population
- chicken pox
Endemic disease
Disease constantly present in a population
- head cold
Epidemic disease
Disease acquired by many hosts in a given area in a short time
- Ebola in Africa
Pandemic disease
Worldwide epidemic, reached more than 1 continent
- Zika virus