Final Exam Flashcards
Zoonoses
Diseases/infections naturally transmitted between animals and humans
Anthropozoonosis
Animal to human infection
-Rabies, brucellosis, cat scratch disease
Zooanthroponosis
Human to animal infection
- Tuberculosis to elephants, influenza to ferrets
What are zoonoses NOT
- Poisoning/envenomation by animals/insects
- Bites, kicks, or scratches by animals
- Allergies to animals
- Anthroponoses (diseases that people get from other people)
Where might zoonoses occur?
- Farm sites: close contact w/ livestock & their by products (milk, placenta)
- Animal processing facilities: slaughterhouses and processing plants
- Forestry/outdoors: wildlife habitat for professional or recreational reasons
- Recreation: contact with pets or wildlife
- Laboratories/clinics: handle specimens, tissues, carcasses
- Emergencies: catastrophes, refugees, temporarily living in crowded or high stress situations
Agent
Organism causing the disease
- Can act alone or in concert with other organisms
- Transient or persistent
Reservoir
“Carrier”; source of persistence in nature and infection in new hosts
- May/may not have symptoms
- Sometimes, may be environment itself
Amplifier
“intermediate host”
- High levels of agent replication
- Often in closer human contact than a reservoir
- Asymptomatic infections in many cases, but not always
- Most commonly associated with vector-borne diseases
Dead-end host
- Agent does not replicate to the level of necessary for further transmission
- Asymptomatic infections in many cases, but in some cases severe disease is possible
- Often associated with vector-borne diseases
Common bacterial zoonotic agents
Anthrax, brucellosis, lepto, plague, Q fever
Common viral zoonotic agents
COVID-19, influenza, monkeypox, rabies, west nile virus
Common fungal zoonotic agents
Dermatophytes, histoplasma, basidiobolus
Common prion zoonotic agents
Mad Cow Disease (BSE)
Common parasitic zoonotic agents
Protozoal: Toxoplasma, giardia
Helminths: Baylisascaris, trichinella
Arthropods: scabies
Dogs/Cats reservoir diseases
Rabies, roundworms, ringworm, cat scratch disease
Livestock reservoir diseases
Salmonella, E. coli, brucellosis, Q fever
Birds/Poultry reservoir diseases
Avian influenza, chlamydiosis, cryptococcus
Reptiles, fish, amphibians reservoir diseases
Salmonella, mycobacterium
Wildlife reservoir species
Rabies, hantavirus, plague, tularemia
Routes of zoonotic disease transmission
Direct contact: infected tissue, bite wounds, body fluids
Indirect contact: fomites, aerosol
Foodborne: contaminated food/water
Vectorborne: rodents, mosquitoes, fleas, ticks
“SIR” model of pathogenesis
Susceptible —(incubation period)—> Infected/symptomatic —–> Recovered, removed, or dead (immune, carriers, or remain susceptible)
*transmission = IR
How many nationally notifiable zoonotic diseases?
25
Notifiable zoonotic diseases
Reportable disease vary by locality
- National vs state
Examples: yersinia pestis (plague), rabies, bacillus antracis, myobacterium bovis, VEE
What is the cost of zoonotic diseases?
Cost to human health
- Lost productivity, loss of life due to disease
Economic costs
- Direct/indirect costs of prophylaxis & tx
- Cost of import/export restrictions
- Loss of trade and tourism
Traditional health management
Focuses on tx of sick animals
- Called to the farm to treat sick animals; directed at medical treatment, less towards protection
Herd Health Management (HHM) Approach
Optimizes HEALTH, WELFARE, PRODUCTION through systematic analysis of relevant DATA and through REGULAR objective observations of the ANIMALS and their ENVIRONMENT. INFORMED, TIMELY decisions are made to adjust and improve herd management over time
Where is the focus in HHM approach?
On prevention
- Based on the identification of risk factors for disease
Role of State Department of Agriculture:
- Animal health & welfare regulations
- Classifying reportable diseases
- Animal import/export requirements
AZ State Vet: Dr. Ryan Wolker
Role of USDA/APHIS
- CVO: Dr. Rosemary Sifford
- Area veterinarian in Charge (AVIC)
- Animal health and welfare regulations
- Classifying reportable diseases
- Animal import/export requirements
Role of World Organization for Animal Health
- Director: Dr. Monique Eloit
- Sets disease prevention & control standards
- Serves as point of contact for disease occurrence
- Ensures members have access to all the tools necessary to respond to disease threats
- Foster a One Health approach across borders
Agroterrorism
“Deliberate introduction of animal/plant disease”
- Generate fear, economic loss, or undermining social stability
Departments/agencies responsible for protection: Homeland, APHIS, FSIS, ARS
Likely agroterrorism agents
- Newcastle disease, rift valley fever, highly pathogenic avian flu
- WOAH List A
Emerging infection
New or newly identified pathogen or syndrome, or one that has resulted in new manifestation of an infectious disease
Examples: 1982 Borrelia burgdorferi (Lyme); 2019 COVID-19
Re-emerging infection
Previously identified or known pathogen that is increasing in incidence, expanding to new geographical areas, or affecting new populations or species
Ex: omicron variant; Rabies, TB
Genetic & biological disease emergence
- Microbial adaptation and change
- Host susceptibility to infection
Physical environment disease emergence
- Climate and weather
- Urbanization and land use
Ecological disease emergence
- Changing ecosystems
- Human demographics and behavior
Social, political, economic disease emergence
- International travel and commerce
- Technology and industry
- Breakdown of public health measures
- Poverty and social inequality
- Lack of political will
- War and famine
- Intent to harm
Hotspots of Potential Elevated Risk for Diseases
Hantavirus, Plague = Western US
Chikungunya, Dengue Fever = Central US
Malaria = Northern South America
Hemorrhagic Fever = SE Asia
Cholera, Malaria, Rift Valley Fever = Eastern Africa
How many people will be living in urban areas by 2030?
60% compared to 47% in 2000
True or False: Diseases spread more due to (international) travel.
True
Ex: neuroinvasive disease in 2000 = NY; in 2003 spread across most of the US
How much has life expectancy increased in the 20th century?
30 years
Factors promoting zoonoses transmission
- Frequent contact (people-animal, animal-animal, vector expansion, habitat loss/overlap)
- Animal husbandry and health (nontraditional pets, intensive production sys)
- Personal hygiene
** Globalization: increased domestic and international travel (people, animals, products)
Strategies for mitigating future disease emergence
- Novel vaccines & delivery systems
- Address antimicrobial resistance as a national priority
- Grow One Health practitioners & research teams
- Build predictive capability
- Reduce effects of poverty and inequality
Human focused - High Risk groups
Recognize Immunocompromised/high risk:
- HIV/AIDS, chemo, chronic disease
- Elderly
- Pregnant women
- Children
- Frequent travelers
Discuss occupation: livestock producers/ stockmen, vets, zookeepers, lab techs etc.
Prevention strategies - humans
- Good hygiene
- PPE/Barrier precautions
- Food preparation
Prevention strategies - animals
- Control programs (vaccinations, wellness exams)
- Screening and treatment (parasites etc.)
Site specific prevention strategies
- Public settings: childcare/schools, pet stores
- Health care facilities (therapy animals): vaccinated, healthy, free of parasites etc.
- Vet clinics: handwashing, PPE, infection control, attention to bites/scratch prevention
**HANDWASHING!!
Most important aspect of coordinating with Human HCPs
Reporting!
- Refer clients suspected, communicate directly with HCPs
Primary causes of immunodeficiency
Congenital acquisition
- manifested by recurrent or persistent infections of developmental delay
Secondary causes of immunodeficiency
Immune system damaged later in life:
- Age, malnutrition, infection/disease, medical treatments
Immunocompromised children, elderly, pregnant women
- Under 5 are at greater risk
- 13% > 65 years
- Pregnant women experience immune changes
Immunocompromised HIV/AIDS, chronically diseased, long-term medical tx
- 1.1 mil positive HIV/AIDS in US
- Cancer and diabetes
- Cancer chemotherapies, anti-inflammatory drugs
Pet selection
- Young animals are more likely to be infected
- Consider those that don’t bite/scratch
- High risk species (reptiles, some birds, non-human primates, exotics, wildlife)
Human-animal contact
- Routine care: raw meat, fecal contact, reptile habitats
- Animal bites: children
Important zoonoses for immunocompromised clients
- Bartonella henselae “cat scratch disease”
- Toxoplasma gondii “toxoplasmosis”
- staphylococcus aureus “MRSA”
- Chlamydophila psittaci “avian chlamydiosis”
- Myobacterium spp. “TB, leprosy”
- Lymphocytic choriomeningitis virsus
Preventing zoonotic disease in immunocompromised client
- Urge consultation with HCP
- Discuss human implications of zoonotic dx
- Guidance topics: pet care, animal bite avoidance, food prep etc.
Should immunocompromised clients keep their pets?
In most cases yes:
- High risk: more susceptible to pathogens, disease may be more virulent, affected person likely to transmit to others
- Benefits: decrease depression, anxiety, BP, medical visits, pain perception; increases activity, socialization, happiness, confidence etc.
Prevention zoonotic disease in pets
Diet: reputable commercial diet
Vet care: yearly exams, UTD on vax, deworming etc.
Grooming/flea control: keep environments clean
What is tularemia?
Occurs year-round, comes from rabbits, common in children during summer
Tularemia in AZ
Circulates naturally among rabbits and rodents: usually found in areas above 3000 ft
Tularemia agent
Considered a potential bioterrorism weapon (can be aerosolized)
Francisella tularensis (gram neg)
Tularemia epidemiology
- Period of communicability: not directly transmitted from person-person, drainage is potentially dangerous; flies & ticks
- Susceptibility & resistance: all ages; long-term immunity follows
Tularemia clinical diagnosis
- Supported by evidence/hx of tick or deerfly bite, exposure to contaminated water
- Flu like symptoms
- Differential diagnosis is plague
Clinical forms of tularemia
- Ulceroglandular: most common; cutaneous ulcer
- Glandular: no ulcer
- Oculoglandular: bacteria enter eye
- Oropharyngeal: eating/drinking contaminated
- Pneumonic: most serious form
- Typhoidal: ‘catch all’
Tularemia reservoirs
Type A infections from rabbits/ticks (A II strains are localized to western US)
Tularemia mode of transmission
- Bites of arthropods
- Contaminated water/food
- Inhalation of dust
- Contaminated pelt and paws of animals
Etc
Tularemia treatments
- Antibiotics: streptomycin, doxy etc.
- Lasts 10-21 days
Tularemia testing
Report all confirmed, probable, and suspect cases to AZDA within 4 hours
Tularemia prevention
Note any change in the behavior of your pets (especially rodents, rabbits, and hares) or livestock
What is Rocky Mountain Spotted Fever (RMSF)?
Most severe disease caused by a tick in the US
Notifiable to CDC
About 5-10% cases fatal w/ tx
RMSF in AZ
Most cases in the US
Majority is due to roaming dogs and lots of ticks
RMSF causative agents and epidemiology
Caused by Rickettsia rickettsii
- transmitted through bite of infected tick
Invaded endothelial cells of venules/capillaries
RMSF clinical signs
- Nonspecific symptoms initially
- 60% of cases have some type of rash (uncommon in AZ RMSF cases)
- Late stage: necrosis, abd pain, vomiting, etc.
- Lab findings: hypoalbuminemia, moderate leukocytosis, thrombocytopenia
RMSF diagnosis
- Gold standard: IFA w/ R. rickettsii antigen
- PCR testing
RMSF treatment
- Antibiotic: Doxy
- Mortality directly related to incorrect treatment, delayed diagnosis or both
RMSF prevention
- Prevent RMSF in dogs: prevent tick attachment/remove ticks
- Applications fo acaricidal tx
What is chagas?
- Primary domestic reservoir = dogs
- Infection is lifelong if untreated
Chagas in AZ
Up to half of ‘kissing bugs’ collected and tested positive
Chagas causative organism
Transmitted to animals and people by insect vectors
Chagas transmission to humans
- Vector-borne
- Congenital
- Control in the US focused on the non vector-borne methods
Chagas clinical signs and epidemiology
Acute: nonspecific fever, swelling of eyelids
Chronic: decades to lifetime; 20-30% develop cardiac or GI complications
Chagas diagnosis
Acute: can find trypomastigotes in blood or CSF
Chronic: serologic testing
Chagas treatment and monitoring
- Antiparasitic treatment to kill parasite
- Symptomatic treatment
- Monitor heart rate via heart tracing test
Chagas in dogs and emidemiology
Similar to humans
- Diagnostic differential for dogs with heart problems
Outdoor work/housing lifestyles
High densities of dogs in confined areas
Chagas prevention
Vector control
Traditional flea and tick repellants do not repel kissing bugs
What is onchocerca lupi?
An emerging zoonosis in the US
Concentrated in southwestern states
Onchocerca lupi organism and epidemiology
- Filarial nematode
- Embedded in ocular nodules and granulomatous masses of infected dogs
Onchocerca lupi clinical diagnosis
- Eyes, joints, upper servical spine masses
- Most infected dogs are asymptomatic
Onchocerca lupi treatment
No evidence-based protocols for treatment
- If possible, surgical excision of periocular nodules and cysts
Other southwestern zoonoses (rodent-borne)
Hantavirus & Plague
Bacterial diseases
Salmonellosis, chlamydiosis, mycobacteriosis, rat bite fever
Parasitic diseases
Rat lungworm, encphalitozoonosis
Viral diseases
Influenzas, Herpesviruses, Coronaviruses
Salmonellosis etiology/exposure
Etiologic agent: Salmonella spp.; gram neg
Exposure root: infectious food-borne pathogen; reptiles, birds, sugar gliders, hedgehogs, rodents
Salmonellosis in humans/animals
Clinical signs: A-rare, asymptomatic; P- headache, fever, nausea, vomiting, diarrhea
Diagnostics: culture, pcr, serology
Treatments: treat exotics if they have symptoms; supportive care
Chlamydiosis etiology/exposure
- Chlamydia psittaci
- Direct/indirect contact; contaminated bedding, dust, dander; aerosolized and ingested feces
Chlamydiosis human/animals
A: conjunctivitis, granulomas, respiratory disease
P: flu-like, ketatoconjunctivits, pneumonia
- PCR, culture, serology (high false pos)
- Birds: doxy
**Reportable disease in AZ
Mycobacteriosis etiology/exposure
Mycobacteria spp. (tuberculosis reportable)
- direct contact w/ contaminated water
- aerosol of infectious material
Mycobacteriosis humans/animals
A: weight loss, anorexia, respiratory discharge, appetite loss, cough
H: cutaneous, pulmonary disease, weight loss
- Culture, PCR, biopsy, routine testing, TB skin test
-Tx: may need sx, prolonged antibiotics, combo of drugs over several months
Rat bite fever etiology/exposure
Streptobacillus moniliformis; Spirilum minus
- bite wounds/scratches
Rat bite fever humans/animals
Rats: asymptomatic, otitis, pneumonia
H: flu-like, petechial rash
- screening PCR, culture
Tx: immediate disinfection of bite; antibiotic
Avian influenza etiology/expsoure
Influenza A – enveloped RNA virus
- occurs worldwide, broad host range, mainly fecal-oral/fecal-cloacal transmission
Avian flu humans/animals
Both: respiratory, GI, nervous systems
- Highly pathogenic avian flue reportable
- Serology, PCR, viral isolation
Tx: no specific, disinfection
Human flu (seen in ferrets)
Human flu type A and B
- Human to ferret transmission
- Primarily upper respiratory disease
- Treat supportively
Human herpesvirus etiology/exposure
Herpesvirus 1/2; zooanthroponotic (reverse)
- worldwide, direct contact w/ infected people
Human herpes humans/animals
H: blisters/ulcers around oral cavity/genitalia
A: GI signs, oral ulcers, Peracure encephalitis
- Sample vesicles: serology, PCR, histopath, virus isolation
Tx: antiviral agents, supportive care
Definitive host
Final host; parasite becomes sexually mature
Intermediate host
a necessary host in which a parasite passes one or more of its asexual stages
Paratenic host
potential intermediate host that serves until definitive host is reached; no development occurs; may/may not be needed to complete parasite life cycle
Accidental host
one that accidentally harbors an organism that is not ordinarily part of the parasite life cycle; may cause severe disease in this host
Rat lungworm etiology/exposure
Angiostrongylus cantonensis
Def host: rats
Inter host: snails/slugs
Para host: crabs, shrimp, amphibians
Affects: primates, marsupials, horses, dogs, tawny frogmouths, armadillo etc.
Rat lungworm humans/animals
- Primarily neurologic signs
- diagnosis difficult, hx is helpful, eosinophilia
Tx: many recover w/o tx, anthelmintics/supportive care if heavy burden
Encephalitozoonosis etiology/exposure
Encephalitozoon cuniculi
- rabbits, rodents, carnivores, primates, birds
- commonly shed in rabbit urine
Encephalitozoonosis humans/animals
Rabbits: latent
H: neurologic signs, diarrhea, hepatitis, nephritis, spores
- urine antibody levels, CSF analysis, histopathology, serologic testing
Tx: quiet environment for neuro cases; benzimidazoles help decrease clinical signs
Managing Zoonotic Disease Outbreak
- Identify triggers
- Notify stakeholders
- Isolate the animal
- waste management
- report to authorities (if appropriate)
- treatment/animal management
How do rats/mice act as disease vectors?
Disease reservoirs: hosts that rarely transmit disease directly to humans (vector required)
Disease carriers: hosts can directly transmit to humans
Why do rats/mice serve as effective disease vectors?
“Synanthopic” species: important human competitors for food
Rodent-borne bacterial zoonoses
Plague, tularemia, lepto, murine typhus
Plague
- Yersinia pestis
- Rodents are reservoir
- Found in mountain west of US
- Sym: enlarged lymph nodes
- Transmission: Fleas
- Prevention: avoiding contact w/ reservoirs and fleas
Tularemia
- Francisella tularensis
- Rodents directly to humans, or mechanical via insects
- Found in midwest river valleys of US
- Enlarged lymph nodes
- direct contact w/ rodents as carriers; or ticks/flies as reservoirs (aerosolization)
- Prevention: avoid contact, limit exposure
Leptospirosis
- Leptospira interrogans
- Flu-like symptoms (jaundice, polyuria)
- Globally = tropical areas; US = around bodies of water
- Direct contact w/ urine
- Prevention: avoid contact w/ urine; treat water in endemic areas
Murine typhus
- Rickettsia typhi
- Mostly in Texas , Cali, Hawaii
- Flu-like symptoms
- Fleas feeding on reservoir species/humans
- Prevention: hygiene; rodent//flea control
Rodent-borne viral zoonoses
Hantavirus, Mpox
Hantavirus
- Bunyaviridae
- Rodents are carriers
- Most seen in mountain west in US
- Flu-like symptoms (severe)
- Aerosolization of rodent urine/feces
- Prevention: avoid aerosolization
Mpox
- Poxviridae
- Rodents are carriers
- Prior to 2022, almost all cases West Africa
- Pox lesions on hands/genitals; rodents: oculonasal discharge, pox lesions
- Handling affectsed rodents/primates, close contact
- Prevention: smallpox vaccination
Integrated Pest Management
- Categorize problems
- Set action points
- Identify specific problem species
- Understand lifecycle/behavior
- Monitor for evidence of species/problems
* Seek solutions that focus preventing problems
Pest management of rodents
Eliminate food sources and routes of entry
Pest management of insects
- Remove potential breeding grounds
- Biological control
Anthrax in animals
- Bacillus anthracis (found in soil)
- Reportable in all state
- Primarily ruminants
- Control: vaccination, quarantine, proper carcass disposal
Anthrax in humans
- Contact with infected tissues/animal products
- Inhalation, ingestion, contact w/ skin wounds
- Control of importation of meat/animal products (hides)
Bovine TB
- Mycobacterium bovis
- Mainly cattle
- Transmission by respiratory route/ingestion
- Control: routine testing
Humans: mycobacterium tuberculosis; similar to bovine
Brucellosis
- 5/9 Brucella species affect humans
- B. melitensis (small ruminants) –> B. suis (pigs) –> B. abortus (cattle) –> B. canis
- Contact with infected animals
- Vaccination for cattle; testing/culling
Humans: melitensis; training on livestock handling
Cryptosporidiosis
- Cryptosporidium (coccidian parasite)
- Dairy calves and lambs
- Ingestion of oocysts; causes diarrhea
- Ensure passive transfer of immunity
Humans: C. hominis/parvum; outbreaks in daycares, swimming pools, potable water; hygiene, PPE
Q fever
- Coxiella burnetii
- Sheep, goats, and cattle (causes abortions)
- Bacteria shed in birth products, urine, feces, and milk of infected animals
- Humans: breathing in contaminated dust; avoid contact with animal
*Notifiable disease
Contagious ectherma (Orf)
- (Para)poxvirus
- Sheep and goats
- Usually self-limiting
- Commercial vaccine
Humans: contamination of wounds - PPE
How do insects act as disease vectors?
Mechanical vectors: acting merely as a ‘dirty syringe’ going from host to host
Biological vectors: important stages of the infectious agent’s lifecycle take place in the insect host
Why do insects serve as effective disease vectors?
Many are synanthropic
Rocky Mountain Spotted Fever
- Reckettsia rickettsii
- Gram neg coccobacillus transmitted by Dermacentor/Ixodes ticks
- Rash; vascular damage; non-specific in dogs
Lyme disease
- Rodents are reservoirs; disease transmission is via deer ticks
- New England and upper Midwest
- Flu like; ‘bulls-eye’ rash; shifting leg lameness
- Deer ticks w/ humans and pets; 36-48 hrs
- Tick preventatives; adequate clothing
EEE/WEE
- Togaviruses via Culiseta mosquitoes
- Birds serve as amplifying reservoirs
- 95% asymptomatic
- Horses: neuro disease
Powassan encephalitis
- Mice/other rodents as reservoirs
- via deer ticks and groundhog tick
- New England and upper Midwest
- Rare, flu-like +/- encephalitis in humans
- No symptoms noted in animals
- tick prevention
Colorado Tick Fever
- Squirrels, chipmunks, mice reservoirs
- Via Rocky Mountain wood tick
- Mountain west, extending into western Can.
- Flu like +/- biphasic fever/rash, rarely CNS
- No symptoms in animals
Chagas disease
- Trypanosoma cruzi
- Rodens/small animal reservoirs; ‘kissing bugs’
- Southern states bordering Mexico
- Swelling at infection; fever, fatigue, rash
- Animals: asymptomatic rodents; depression, lethargy dogs
- Can be passed via transfusions/transplants
- Pest management and insecticides
Babesia
- Babesia microti
- Rodents/small animals reservoirs via ticks
- Mostly New England and upper Midwest
- Flu like symptoms, hemolytic anemia
- Animals: rodents asymptomatic, domestics anemia
- Ixodes tick bites; blood transfusions
- Tick prevention
Bartonellosis ‘cat scratch disease’
- Bartonella henselae
- High risk to vets
- Seroprevalence in cats
- Transmission via cats by flea excrement
- To humans: cat scratch/bite, fleas/ticks
- Mild, self-limiting, skin rash, lymph node
- Diagnosis: mostly by history and phys. exam
- Tx: supportive care for humans; treat cats with clinical signs
- Prevention: flea control; avoid bites/scratches
Toxoplasmosis
- Toxoplasma gondii parasite
- Cats definitive host
- Oocysts require O2 and 1-5 days to sporulate
- 4 stage: oocysts, tachyzoites, bradyzoites, tissue cysts
- Cleaning litterbox, predation, mom to fetus
- Cats: fatal disease; uveitis, fever
- Diagnosis: detection of zoites, oocysts in feces
- Tx: Recover with treatment
- H: no or benign symptoms; ocular, encephalitis or congenital
- Prevention: avoid raw meat, wash hands
Larva migrans
- Migration of immature (larval) worms
- Cutaneous: worms species; humans - walking barefoot, unprotected skin
- Visceral: roundworm infection
- Diagnosis: red, raised itchy tracts; serologic test
- Tx: help control symptoms; prevent 2nd bacterial infections; antiparasitics
- Prevention: wear shoes, deworm dogs, cover sandboxes
Dermatophytosis (ringworm)
- Superficial fungal infection
- Microsporum canis (vets most worried)
- Circular rash in humans, red/itchy
- Animals: ‘hair-borne’
- Diagnosis: fungal culture; PCR; Wood’s lamp
- Tx: shortens disease and avoid contagion; systemic antifungal
- Prevention: PPE, be suspicious
