Download Disease Transmission

2- Disease
Parasitism
Parasitism:
______________________________________________________________________
____________________________________________________________________
Types of parasites
1) _________________________:
a) Live on outer surface of host
b) Termed an ___________________
2) ______________________:
a) Live internally in the host
b) Termed an _______________________
3) _________________: A parasite unable to live or reproduce without the host
4) ____________________: An organism that can live or reproduce without a host
5) ___________________: A parasite that completes its entire life cycle on the host
6) _____________________: Parasites that come into contact with its host only for
certain intervals in order to feed
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Disease
1) Defined: ___________________________________________________________
2) Types:
a) Direct damage
b) Indirect damage
Direct pathogenesis
1) Direct feeding:
a) Acariasis: ___________________________________
b) Myiasis: __________________________________________
2) Envenomization: _____________________________________________________
a) _________:
i)
Ticks:
(1) Associated with blood feeding
(2) Minimizes host response during feeding
(3) ____________________________________________________
ii)
Blood feeding insects with toxic saliva:
(1) Not known
(2) No adaptive advantage
b) ______________________________________:
i)
ii)
Toxin (venom) injected via mouthparts to paralyze prey or as defense
Examples:
(1) Spiders
(2) Centipedes
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c) _______________________:
i)
Scorpions
ii)
Function for prey immobilization and defense
d) _______________________________:
i)
Hymenoptera only
ii)
Modified ovipositor
iii)
Function for prey immobilization and defense
e) _________________________________________:
f)
i)
Larvae of some Lepidoptera
ii)
Setae (hairs) that penetrate the skin and release toxins
iii)
Termed: ________________________
_______________________________:
i)
Arthropods secrete toxic chemicals from specialized glands
ii)
Examples:
(1) Whipscorpions
(2) Blister beetles
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3) Allergens
a)
Antigens:
i)
___________________________________________________________
ii)
__________________________________________
iii)
Recognized by receptors on lymphocytes
b) Allergens:
i)
___________________________________________________________
__________________________________________________________
ii)
Types of allergens:
(1) __________________: Salvia of hematophagous (blood sucking) insects
(2) _________________: Skin contact with arthropods or arthropod body
parts causing ________________
(3) _________________: Airborne dust containing arthropod particles
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Infectious Disease
1) The chain of infection: In order for infection and disease to occur in an individual, a
process involving six related components must occur:
a) Etiologic agent
b) Reservoir
c) Portal of exit
d) Mode of transmission
e) Portal of entry
f)
Susceptible host
Etiological Agents
a) Metazoa
b) Protozoa
c) Fungi
d) Bacteria
e) Rickettsia
f)
Viruses
g) Prions
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1) Metazoa:
a) _________________________
b) __________________________
c) Characteristics:
i)
______________________________
ii)
Various shapes, sizes and means of locomotion
d) Biology:
i)
_____________________
ii)
________________________
iii)
_______________________________
e) Diseases:
i)
Anaplasmosis
ii)
Coccidosis
iii)
Trypanosomiasis
iv)
Trichinellosis- intestinal round worm
v)
Hookworms- feces contaminate water and soil
vi)
Schistosomiasis- blood fluke; contaminated water
vii)
Heartworms- nematode; transmitted by mosquitoes
viii)
Tapeworms- nematode; transmitted by fleas
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2) Protoza:
a) ______________________________________________________
b) Diseases:
i)
Malaria- mosquito-borne
ii)
Giardiasis- infection of the upper intestinal tract; diarrhea
iii)
Toxoplasmosis; transmitted to humans by cats and uncooked meat
3) Fungi:
a) Characteristics:
i)
___________________________
ii)
________________________________
b) Diseases:
i)
Histoplasmosis- inhaling dust from soil contaminated with bird droppings
ii)
Candidiasis- transmitted by human contact
(1) Thrush
(2) Vulvovaginitis
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4) Bacteria:
a)
Characteristics:
i)
_____________________
ii)
___________________________
iii)
Reproduce by fission
b) Biology:
i)
___________________________
ii)
___________________________
iii)
_____________________________
c) Some produce spores that produce:
i)
Exotoxins (byproducts of metabolism)
ii)
Endotoxins (produced material, typically for defense)
d) Diseases:
i)
Plague
ii)
Tuberculosis
iii)
Salmonella
iv)
Chlamydia
v)
Gonorrhea
vi)
Tetanus
vii)
Pretussis
viii)
Pneumococcal disease
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5) Rickettsia:
a) ________________________________; share some characteristics of viruses
b) Characteristics (____________________________________________):
i)
Extremely small (~475 nm, similar to viruses)
ii)
Very similar to bacteria except:
(1) Not flagellated
(2) Do not form spores
iii)
Divide like bacteria
iv)
Shape: Rod or coccoid
v)
Pleomorphic (variable in pattern; single, pairs, chains)
c) Biology:
i)
______________________________
ii)
_____________________________________
iii)
Occur chiefly as harmless parasites of arthropods
d) Vectors:
i)
Ticks
ii)
Mites
iii)
Lice
iv)
Fleas
e) Diseases:
i)
Typhus (not typhoid fever)
ii)
Rocky Mountain spotted fever
iii)
Q fever
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1) Viruses:
a) Characteristics:
i)
_____________________________________
ii)
________________________________________
iii)
No cytoplasmic membranes nor cytoplasm
iv)
Consist of:
(1) Protein coat (capsid)
(2) Nucleic acid core (DNA or RNA)
(3) May or may be surrounded by an envelope
b) Arbovirus
i)
Ar: _____________________
ii)
Bo: ___________________________
iii)
Defined:
(1) _____________________________________
(2) __________________________________________________
(3) ______________________________________________
iv)
History:
(1) Arboviruses known:
(a) 1950- 30
(b) 1978- 388
(c) 1985- 504 (115 definite arboviruses; 92 probable; 265 possible)
v)
Classification: Classification based mode of transmission, not morphology
(1) Viral families:
(a) Togaviridae (most here)
(b) Bunyaviridae
(c) Rhabdoviridae
(d) Reoviridae
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2) Prions:
a) _________________________________________
b) Consist of:
i)
_____________________________________
c) ______________________________________________
d) ____________________________________________
e) Diseases:
i)
CWD: chronic wasting disease of deer and elk
ii)
BSR: bovine spongiform encephalopathy (mad cow disease)
iii)
CJD: Creutzfeld-Jacob disease of human
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Indirect agents of disease
Disease Transmission
2) Transmission: _______________________________________________________
3) Vector:
__________________________________________________________________
____________________________________________________
4)
Microbial pathogens most often transmitted:
a) _______________
b) _________________
c) ____________________
d) ______________________
e) ________________________________
5) Transmission methods:
a) Mechanical
b) Biological
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Mechanical transmission
(Passive transmission)
1) ___________________________________________________________________
__________________________________________________________________
2) ___________________________________________________________________
__________________________________________________________________
3) Subsequent feedings take place within minutes for successful transmission
4) Types of mechanical transmission:
a) ______________________:
i)
Disease agent picked up directly on vector’s body
ii)
Examples: Salmonella on legs of cockroaches and house fly
b) Internal surfaces:
i)
____________________:
(1) Disease agent transferred via regurgitation
(2) Examples: Bacteria in house fly vomit
ii)
__________________________:
(1) Disease agent picked up by vector and passes through with feces
(2) Example: Bacteria passed through house flies
iii)
____________________:
(1) Parasite introduced into host tissue via the vector’s mouthparts
(2) Parasite is sucked-up but not multiplied or change in the vector
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Biological transmission
1) ___________________________________________________________________
___________________________________________________________________
2) ___________________________________________________________________
_________________________________________________________________
3) ____________________________:Time required during which the pathogen must
proliferate and/or develop in the arthropod vector
4) ___________________________: Time required for the organism to develop and
produce disease after injection into a new host
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Biological Horizontal disease transmission
1) Disease agent is transmitted between one host individual and another; Not
necessarily the same species; Three types:
a) __________________________________________:
i)
Pathogen increases in number (increased titer) without undergoing
developmental changes within the body of the arthropod
ii)
Example: Equine encephalitis
(1) Virus multiplies in the body of mosquitoes, concentrating in the salivary
glands
(2) Virus injected when the mosquito feeds on another host
b) ___________________________________________:
i)
Pathogen undergoes an essential part of its developmental cycle in the
body of the arthropod without increasing in numbers
ii)
Example: Heartworms in dogs
(1) Mosquito sucks microfiliariae during feeding
(2) Develops into infective stages within the malpigian tubules
(3) Infective larvae migrate to the proboscis to infect another host
c) _____________________________________________:
i)
There is both an increase in number and developmental changes of the
pathogen in the body of the arthropod vector.
ii)
Example: cattle fever (babesiosis)
iii)
The pathogen undergoes an essential change and increase in numbers
within the body of tick
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Biological vertical disease transmission
1) __________________________________________:
a) A highly specialized type of biological disease transmission
b) The pathogen is passed from one generation of arthropod to the next via the egg
through the infected ovaries of the female
c) Occurs in a number of arthropods including mosquitoes and ticks
2) _____________________________________:
a) Immature stage of the arthropod feeds on an infected host
b) Obtains pathogen
c) Transmits pathogen to an uninfected host during a subsequent stage of its
developmental cycle
d) Occurs primarily in ticks
Hosts
1) _____________________:
a) One or more hosts or vectors that serve to harbor a pathogen, usually over an
extended period of time.
b) Typically do not show any symptoms of infection
2) ________________: Usually shows overt, clinical signs of disease and tend to
maintain the pathogen for shorter duration
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Disease Outbreaks
1) ____________: That branch of medicine that deals with epidemic outbreaks
a) Applied ecology of a disease
b) Consider all factors of the natural history of the disease
2) _______________: Diseases in animals at more or less a constant level year to year
3) _________________: Diseases at unusually high level in animals
4) _______________: Diseases in humans that smolder at more or less a constant
level year to year
5) ________________: Diseases at unusually high level in humans
6) ________________: Diseases that occur over countries or continents
7) Epidemiology & entomology:
a) ___________________________________________
b) _________________________________
c) __________________
d) ____________________________________________________
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Disease factors
1) Every organism can be represented as a set of all spatio-temporal points it occupies
in a given system
2) Disease is limited to the intersection of the “sets” of factors involved
3) __________________________:
a) Generally genetic disorders
b) Involves only the individual
c) Gene frequency is the only parameter determining their prevalence
4) __________________________:
a) Host and causal agent (pathogen)
b) Parasite is contained within the host
c) The disease is an intersection between the pathogen and the host
d) The epidemiology of the infection is explained by the host ecology
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5) ________________________:
a) Host, pathogen, vector
b) Transmission involves a vector between two hosts of the same species
c) Epidemiology explained by host ecology and vector ecology
6) _________________________:
a) Host A, host B, vector, pathogen
b) Parasite shared by two or more different vertebrate hosts
c) Epidemiology:
i)
Consider ecology of:
(1) Vector
(2) Vertebrate host A
(3) Vertebrate host B
ii)
Complexity increases factorially with each additional host species
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