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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 1 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 2 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 3 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 4 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 5 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 6 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 7 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 8 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 9 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 10 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 11 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 12 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 13 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 14 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 15 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 16 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) ____________________________________________________ 17 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 18 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 19