pathology
study of disease
etiology
study of the cause of disease
pathogenesis
development of disease
infection
colonization of the body by pathogens
disease
an abnormal state in which the body is not functioning normally
Transient Vs. normal microbiota
transient maybe be present for days weeks months. normal microbiota permantly colonoze the host.
Locations of normal flora
eyes, nose and throat(upper respritory system), skin, large intestine, urinary and reproductive systems(lower urethra)
microbial antagonism
competition between microbes
how do normal flora protect host
occupying niches that pathogens might occupy, producing acids, producing bacteriocins
Probiotics
live microbes applied to or ingested into the body, intended to exert a beneficial effect (yogurt)
Koch's postulates
used to determine etiology using pure culture and mice. Isolated, grown in pure culture, identified, injected, isolated, grown, identified.
symptom
any sensation or change in bodily function that is felt by a patient as a result of disease. chills, sore throat, pain, nausea, itching, headache.
sign
a change in a body that can be measured or observed as a result of disease. fever, septicemia, chest sounds, skin eruptions, swollen lymph nodes, tachycardia. etc.
syndrome
a group of symptoms or signs that collectively accompany a disease
communicable disease
a disease that is spread from one host to another, ex. HIV
contagious disease
a disease that is EASILY spread from one host to another ex. cold and measles
noncommunicable disease
a disease that is not transmitted from one host to another. ex: tetanus, gangrene, food poisoning
sporadic disease
Disease that occurs occasionally in a population
endemic disease
diseases that are constantly present in the population (ex. cold)
epidemic disease
Disease acquired by many hosts in a given area in a short time. (ex. flu, malaria)
pandemic disease
Worldwide Epidemic (ex. HIV)
herd immunity
immunity in most of a population
acute disease
symptoms develop rapidly (ex. cold)
chronic disease
disease develops slowly (ex. Hepitits and TB)
Latent Disease
Disease with a period of no symptoms when the patient is inactive. (ex. herpes and shingles)
Local Infection
pathogens limited to a small area of the body (ex. pimple)
Systemic infection
An infection throughout the body (ex. HIV)
Bacteremia
bacteria in the blood
septicemia
growth of bacteria in the blood
toxemia
toxins in the blood
viremia
viruses in the blood
primary infection
Acute infection that causes the initial illness
secondary infection
Opportunistic infection after a primary (predisposing) infection
subclinical disease
no noticeable sings or symptoms (inapparent infection) (ex. hep. A)
predisposing factors
(make the body more susceptible to disease) short urethra in females and UTIs, inherited traits such as sickle cell gene, fatigue, age, lifestyle, chemotherapy, nutrition
reservoir
anything (a person or animal or plant or substance) in which an infectious agent normally lives and multiplies aka. continual sources of infection.
3 reservoirs of infection
human, animal, nonliving
human reservoir
aids, gonorrhea, hepatitis, colds, strep. -carriers may have inapparent infections or latent disease
animal reservoir
rabies, lyme disease, influenza. -about 150 zoonoses may be transmitted to humans
nonliving reservoir
botulism, tatanus. -soil and water
methods of transmission
contact, vehicle, vector
contact transmission
direct- kiss, sex touch
indirect- via fomites(needle, door handle)
droplet-mucous(sneeze)
vehicle transmission
airborne >1m
water
food
vector transmission
mechanical- carries pathogen on feet then lands on you/food. ex. cholera
biological- pathogen reproduces in vector and is transmitted through a bite ex. malaria
may involve antropods- mosquito/tick.
Nosocomial infections
hospital acquired infections
5-15% of all patients aquire nosocomial infections
most common nosocomial infections
UTI- 40%
surgical site infections- 30%
Lower respritory- 20%
common causes of nosocomial infections
25% coagulase-negative staphlococci (89% resistant to antibiotics)
16% s. aureus (80% resistant to antibiotics)
10% enterococcus (29% resistant)
23% gram neg rods (5-32% resistant)
13% c. difficle (none resistant)
How many disease are reported at national level?
63 diseases
Koch's postulate 1
the same pathogen must be present in every case of the disease
koch's postulate 2
the pathogen must be isolated from the diseases host and grown in a pure culture
koch's postulate 3
the pathogen from the pure culture must cause the disease when it is inoculated into a healthy, susceptible lab animal
koch's postulate 4
the pathogen must be isolated from the inoculated animal and must be shown to be the original organism
commensalism
one benefited, other unaffected
mutualism
both benefited
parasitism
one benefited, other affected
incidence
contracts disease during specific time
prevalence
having disease during specific time
Snow
cholera
Semmelweis
Puerperal fever
Nightingale
Typhus
Epidemiology
study of where and when disease occur
morbidity/rate
incidence of a specific notifiable disease/# affected
mortality/rate
deaths from notifiable diseases/# of deaths