03/09e Zoonoses Flashcards
What is a zoonosis?
A disease transmitted from vertebrate animals to humans
Can be any pathogenic agent
What is NOT a zoonosis?
Fish and reptile toxins
Allergies to vertebrates
Diseases in which animal-derived food serves as a vehicle (e.g. contaminated meat)
Experimentally-transmitted diseases
What is the definitive life cycle of a pathogen?
Ecologic system transit by an organism from reservoir, vector, and host
The normal life cycle of a pathogen in animals
What is an incidental host?
An organism susceptible to infection but not part of the definitive life cycle
What is an epizootic?
A disease that appears at a rate higher than expected in a given animal population (epidemic)
What is an enzootic?
A disease that is maintained in a population without need for external inputs (endemic)
What are six examples of possible bioterrorism agents that are also zoonoses?
Bacillus anthracis C. botulinum Yersinia pestis Francisella tularensis Hemorrhagic fever viruses Brucella sp.
What are orthozoonoses?
Zoonoses that can be perpetuated by a single vertebrate species
Examples - rabies, brucellosis
What are cyclozoonoses?
Require more than one vertebrate species, but no invertebrate species to be perpetuated
Example - tapeworms
What are metazoonoses?
Require vertebrate and invertebrate species to be perpetuated
Examples - all arboviral infections, plague, rickettsial diseases, schistosomiasis
What are some examples of routes of transmission for zoonoses?
Direct contact - tularemia Contact with animal products such as skins - anthrax Contact with urine - hanta virus Fecal-oral route - salmonella Bites and scratches - rabies Via ectoparasites - Lyme disease Eating undercooked meat and fish Ingestion of milk - mycobacterium Respiratory route - histoplasmosis
What are some factors that contribute to the emergence of zoonoses? Name seven
1) Microbial adaptation and change - influenza, rabies
2) Breakdown of public health measures - brucella, anthrax
3) Climate change - dengue and yellow fevers
4) Human demography and behavior - HIV
5) Agrobusiness - E. coli
6) Land use - yellow fever, Lyme disease
7) International travel - SARS
What are six ways that you might be exposed to animals, and thus zoonoses?
1) Pet ownership
2) Leisure pursuits (hunting, fishing, camping)
3) Occupations (veterinarian, farmer, etc.)
4) Medical research
5) Travel
6) Immigration
What are some factors that influence risk of infection from an animal bite? Name five
1) Type of animal
2) Location of bite
3) Type of wound (puncture vs. crush)
4) Treatment delay
5) Nature of the patient (age, preexisting conditions, immunosuppression)
What are some common bite wound pathogens obtained from dog bites?
Viruses - rabies
Bacteria - Pasturella, Capnocytophaga canimorsus, tularemia
Normal skin flora
What are some common bite wound pathogens obtained from cat bites?
Viruses - rabies
Bacteria - Pasturella, plague, tularemia
Normal skin flora
What human behaviors particularly contribute to the emergence and transmission of zoonoses?
Consumption of bush meat and wildlife
Hunting on wild animal game ranches
Owning exotic wildlife as pets
Translocation of wildlife
What is leptospirosis?
Protean disease
Asymptomatic in most cases
Symptoms are usually mild - fever, myalgia, suffusion, headache
Severe disease - Weil’s disease in 5-10% of symptomatic patients
How is leptospirosis transmitted?
Excreted in animal urine or placentas
Established in soil and water
Can infect humans and other animals through direct contact with animals, through soil/water, or through mucous membranes
What is Q fever?
Infection caused by Coxiella burnetii
Spread by livestock, but is very rare
Causes fever, chills, weight loss, anemia, and endocarditis
What diseases are caused by Bartonella species?
Cat scratch disease
Carrion’s disease
Trench fever
What traditionally human-only infection is now becoming a concern in animals?
MRSA!
