microbio weiss ppt

growth spurts

driven by technologic advances: invention of tools, agriculture, industry

plateaus

set by birth/death rates – limiting factors: disease, famine, war, birth control

how is the agricultural revolution associated with disease?

crowding - enhanced disease transmission (respiratory), human/animal manure as fertilizer (water/foodborne disease), poor nutrition from primarily grain crops

origin of influenza a

ducks, pigs, wild birds

origin of measles

cattle

origin of smallpox

camels

origin of tuberculosis

ruminants

origin of mumps

mammals, possibly pigs

origin of rotavirus a

domestic herbivores

origin of diphtheria

domestic herbivores

origin of pertussis

mammals

origin of plague and typhus

rodents

origin of cholera

aquatic organisms

origin of hepatitis b

apes

origin of aids

chimpanzees

origin of yellow fever

african primates

origin of dengue fever

old world primates

emerging infectious diseases

diseases that have increased recently or could increase in the near future

zoonotic

transmission to humans from animal reservoir

why is zoonotic transmission from bats high?

ability to fly, body temperature fluctuations, roosting habits, migration, hibernation

human monoclonal antibodies

isolate antibody-producing cells from convalescent individuals, clone and sequence the antibody genes, prepare synthetic human antibodies

cause of death categories

communicable (infectious and parasitic diseases, maternal, perinatal, and nutritional conditions), noncommunicable (chronic), injuries

years of potential life lost (ypll)

assesses "premature“, "preventable“, and "unnecessary" mortality

crude mortality

treats deaths at all ages equally

major causes of death years 1-9

unintentional injuries, cancer, congenital malformation

major causes of death years 10-24

injuries, suicide, homicide, cancer

major causes of death years 65+

heart disease, cancer, chronic lower respiratory disease

what receives low funding

gun violence and falls

what receives high funding

HIV

disability adjusted life years (daly)

number of productive years lost due to ill-health, disability, or early death

disease

a change from general good health, involving disruption of normal structure or functioning of body

disease causes

inadequate nutrition, genetic abnormalities, structural or functional disorders, trauma

infectious agents

prions, viruses, bacteria, fungi (protozoa)

prions

single protein – too small to represent here

viruses

average about 100 nanometers; have few proteins; must commandeer the machinery of the

cells they invade to reproduce

bacteria

sizes vary, but are at least ten times bigger than viruses; single cell organisms, and can reproduce independently

single-celled parasites

at least ten times larger than bacteria

multicellular parasites

so large they can often be seen with the naked eye; tapeworms can be 20 feet long

eubacteria

bacteria of medical importance

archaebacteria

collection of evolutional distinct organisms; primarily found in extreme terrestrial and aquatic environments

where do antibiotics work?

cell wall and cytoplasm

where do antibodies work?

cell-surface

PAMPS - pathogen-associated molecular patterns

conserved structures on microorganisms, genetically encoded to be recognized by the innate immune system, jump-start the immune response, and can cause symptoms of disease in the absence of living bacteria, including the cell wall structures of bacteria

cell wall (peptidoglycan)

protects from environmental stresses, provides strength, maintains bacterial shape, limits penetration of molecules

medical importance of cell wall

protects from some host defenses, role in adherence to host cells

selective toxicity

unique to bacteria, target for many antibiotics

capsule functions

protection from harsh environment, permeability barrier, surface attachment - including host tissues, mutans attaches to teeth and causes tooth decay), capsules are antigenic – can induce protective antibodies that promote engulfment by phagocytes

capsule pathogenicity (survival in host)

encapsulated = virulent; no capsule = avirulent

what does the capsule protect bacteria from

phagocytosis

flagella

rope-like filaments of coiled flagellin

role of motility in pathogenesis

mediates tissue invasion, traverse cellular/extracellular barriers

chemotaxis

swim through intestinal mucus barrier, access intestinal cells

pili

attachment of environmental surfaces, bacterial sex (conjugation), host cells; transformation (uptake of DNA)

sporulation

bacteria form endospores

endospores

highly resistant, dormant structures—to survive harsh environmental conditions

what are spores resistant to killing by

heat (2+ hours boiling), drying, freezing, pH extremes, deterious chemicals, antibiotics, radiation

sterilization procedures

bleach, autoclaving (exposure to high temperature and pressure)

toxicity steps

1. b-component binds to receptors on the host target cell

2. b-component promotes entry and cellular trafficking of toxic a-component

3. a-component causes a specific alteration in the target cell that leads to the dire consequences

cytolytic toxins

cause cell lysis

cytotoxic toxins

cause metabolic alterations

most deathly agents

tetanus and botulinum toxin

diphtheria toxin

inactivates ribosomes, protein synthesis stops, and cell dies

diphtheria

upper respiratory tract infection, transmitted by droplets, leads to airway obstruction, toxic myocarditis and heart failure, and nerve paralysis

cholera toxin

leads to watery diarrhea

tetanus and botulinum toxins

no vesicle fusion, blocks release of neurotransmitters (botulinum blocks release of acetylcholine)

c. tetani

produces tetanus toxin; characterized by uncontrollable muscle contractions; spastic paralysis

c. botulinum

produces botulinum toxin, characterized by flaccid paralysis

virulence

degree of pathogenicity of a microorganism, or how effectively it can cause disease in a host

vaccines

contain agent that represents disease-causing organism that’s often made from weakened/killed forms of microbe that stimulates immune system to recognize it as a threat and destroy it if it encounters it in the future

active immunization

produced by pathogen

naturally acquired = recovery from infection

artificially acquired = vaccination

passive immunization

produced by antibodies or cell from an immune individual

naturally acquired - maternal transfer of immunoglobulin via milk

artificially acquired - immune globulin

toxoids

chemically or genetically inactivated toxins with immunogenicity retained

attenuated pathogens

live agents that induce a protective immune response without causing disease

adjuvants

substances that enhance immune response, ex. alum, Freund’s adjuvant

humoral immunity

antibodies are produced to clear or inactivate toxins or pathogens circulating outside the

cells in our body; activated by extracellular antigens; effective against many bacteria and toxins, some circulating viruses

cellular immunity

t-cells are produced that recognize and kill infected cells or induce inflammatory responses; immunity induced by antigens produced inside cells; effective against viral infection

killed vaccine pros + cons

pros: low-tech, easy to prepare, cheap

cons: toxicity, short-term immunity

attenuated vaccine pros + cons

pros: sustained stimulus, right immunity

cons: reversion to virulence, harmful to immunocompromised

subunit vaccine pros + cons

pros: low toxicity, no reversion

cons: poorly immunogenic, may need adjuvant, expensive

killed (inactivated) vaccine examples

non-viable pathogens
bacterial: pertussis, cholera, plague, typhoid, anthrax

viral: polio, influenza, hepatitis A, rabies, encephalitis virus

subunit vaccine examples

antigenic components

toxoids: inactivated toxins. ex. diphtheria, tetanus

capsules: often conjugated with proteins to improve immunogenicity, ex. H. influenzae (Type B), N. meningitidis, streptococcus pneumoniae (23 capsule types)

bacterial: pertussis

viral: hepatitis B surface antigen, human papillomaviruses

live-attenuated vaccine examples

bacterial: BCG for tuberculosis, tularemia, typhoid fever

viral: polio, measles, mumps, rubella, chicken pox, adenovirus, yellow fever, smallpox, rotavirus, influenza

RNA vaccines

covid-19

herd immunity

transmission is limited, unvaccinated are protected

efficacy

calculated by comparing the number of cases of disease in the vaccinated population vs. a control group in an exposed population

VAERS - vaccine adverse event reporting system

voluntary reporting system for reporting adverse events after vaccination