week 1

Question 1

what is Infectious Disease?
how is it transmitted
what is an infectious agent
what is infection

Answer 1

Illness caused by a specific agent or toxic product
1) transmitted person to person, animal or reservoir
by direct or indirect contact
2)Infectious agent - organism that is capable of causing an infectious dz
3) infection- entrance and development of an infectious agent in a host

Question 2

when/how does ID occur?

Answer 2

when the IA and host defenses are out of balance.

factors for this include: an overabundance of infecting agents, virulence factors, inadequacy of the immune response

Question 3

IA (infectious agents) include?

Answer 3

worms
protists
yeast and filamentous fungi
bacteria
viruses
prions

Question 4

explain the dilution effect hypothesis

Answer 4

linear relationship: increase in population = increased diversity= decrease in disease

Question 5

details about bacteria

Answer 5

prokaryotes
divide by binary fission
cell wall that contains peptidoglycan
most have single chromosome
classified by shape (cocci, bacilli, spirochetes)

Question 6

details about helminths

Answer 6

worms
multicellular
eukaryotic
produce eggs that are passed in excretions/secretions
(about 2 billion infected w/ soil-transmitted helminths…ie hookworm, whipworm, roundworm)
effects …malabsorption of nutrients and impaired cognitive/physical development.

Question 7

details about protists

Answer 7

single celled organisms
eukaryotic
many have life cycle that includes multiple organisms
(trypanosoma)

Question 8

details about yeasts

Answer 8

eukaryotic
less complex
divide by budding

Question 9

details about filamentous fungi

Answer 9

eukaryotic

divide by mitosis

Question 10

details about Viruses

Answer 10

non-living
obligate intracellular parasites
DNA or RNA
difficult ot treat
oncoviruses (viruses capable of causing cancer)

Question 11

details about prions

Answer 11

infectious protien
NO GENETIC MATERIAL
PrP - dz causing form can conver normal cellular protein
examples include:
scrapie (sheep)
bovine spongiform encephalopathy (cattle)
variant creutzfeldt jakob dz (humans)
sporadic fatal insomnia (humans)
chronic wasting dz (deer/elk)

Question 12

(mode of transmission) list types of direct penetration and example of a dz transmitted

Answer 12

trauma- rabies virus
needle stick- hep b virus
arthropod bite- malaria
sexual transmission- HIV
transplacental- t. pallidum
organism directed - hookworm

Question 13

virus modes of transmission (and example of dz’s contracted via mode)

Answer 13

ingestion- vibrio cholera, giardia, polliovirus

inhalation - mycobacterium tuberculosis, Cryptococcus neoformans, influenza virus

Question 14

Types of Immunity and explaination of each

Answer 14

Innate Immunity- Phagocytic cells, complement, physical barriers, inflammation, cytokines

Adaptive Immunity- antibody, T-cell responses, antigen specific

Question 15

define emerging infection

Answer 15

emerging infection is one that is newly recognized AS OCCURING IN HUMANS
newly appearing in A DIFFERENT POPULATION than previously affected
is newly affecting MANY MORE INDIVIDUALS
has EVOLVED NEW ATTRIBUTES

Question 16

factors that contribute to emerging infections

9 with examples

Answer 16

1) discovery of new IA of a known dz (H. pylori)
2) evolution of IA ( high mutation rate or horizontal gene transfer in bacteria)
3) Urbanization (slums, poor sanitation)
4) Movement of populations (migration, movement of military, international travel (SARS, west nile, Marburg virus))
5) Clearance of rainforest for farming (hemorrahagic fevers in S. Am.)
6) Natural Disasters (cholera Haiti, Plague India)
7) Climate - Sin Nombre virus 1993
8) Decreased vaccination ( measles, mumps)
9) Increase number of immunocompromised (late stage AIDS)

Question 17

give medical name for Syphilis

Answer 17

Treponema pallidum

Question 18

Name the 4 subspecies of Syphilis

Answer 18

T. pallidum subspecies pallidum
T. pallidum ssp. endemicum
T. pallidum ssp.petenue
T. pallidum ssp. carateum (T. carateum)

Question 19

what are the organism characteristics and transmission methods of syphilis?

Answer 19

characteristics: Microaerophilic, spiral shaped, cannot be grown in vitro
Transmission: direct penetration (sexually and transplacentally)