Zoonotic Infections

Question 1

what is a zoonotic disease

Answer 1

a disease in which initial acquisition comes from an animal, either directly, indirectly (contaminated food, water, unpasteurized milk), or via a vector

Question 2

brucella sp - physiology and structure

Answer 2

*gram negative coccobacilli
*facultative intracellular
*aerobe
*requires chocolate agar with CO2 for culture

Question 3

brucella sp - virulence

Answer 3

*facultative intracellular (survives in macrophages)
*inhibits myeloperoxidase-peroxide system
*spread through LYMPHATICS

Question 4

brucella sp - pathophysiology

Answer 4

*usually ingested (unpasteurized milk or soft cheese) but can be direct inoculation
*host response is GRANULOMATOUS

Question 5

Brucella melitensis - animal host

Answer 5

goats

Question 6

Brucella abortus - animal host

Answer 6

cows

Question 7

Brucella suis - animal host

Answer 7

pigs

Question 8

Brucella canis - animal host

Answer 8

dogs

Question 9

where does brucella infection have the highest incidence

Answer 9

Mongolia & Turkey
(middle east, north africa, mediterranean)

Question 10

brucellosis - clinical presentation

Answer 10

fever
malaise/fatigue
headaches
HEPATOSPLENOMEGALY
lymphadenopathy

Question 11

brucella - control measures

Answer 11

*pasteurize milk and cheese
*vaccinate food-producing animals

Question 12

tularemia - agent

Answer 12

Franciscella tularensis
*gram negative coccobacillus
*aerobic
*facultative intracellular
*highly virulent

Question 13

tularemia - reservoir and vectors

Answer 13

*reservoir = mammalian animals
*vectors = rabbits, ticks, deer flies

Question 14

tularemia - transmission

Answer 14

inhalation, ingestion, or other contact with infected animals (ex. slaughtering a rabbit)

Question 15

tularemia - clinical features

Answer 15

*ulceroglandular tularemia: fever, chills, ulcerated skin lesion, painful regional lymphadenopathy
*can lead to really severe septic shock (low BP, organ dysfunction)

Question 16

tularemia - control measures

Answer 16

*education of hunters (wear gloves and wash hands)
*avoid reservoirs and vectors of infection
*there is a vaccine but rarely used

Question 17

Q fever - agent

Answer 17

*Coxiella brunettia (a proteobacteria)
*strict obligate intracellular pathogen
*short pleomorphic rod
*survives in macrophages (thus primary site of infection)
*disseminates through LYMPHATICS

Question 18

Q fever (C. brunetti) - virulence factors

Answer 18

1. phase I antigen (cellular entry and attachment; highly infectious)
2. phase II antigen (more virulent, but not infectious)

Question 19

Q fever - epidemiology

Answer 19

*acquired form ungulate (hoofed) animals [cattle, sheep, goats, etc]
*often acquired during assisting with birthing or placenta contact
*AEROSOL transmission
*more prevalence in Europe (France)

Question 20

Q fever - clinical presentation

Answer 20

*flu-like s/s with fever, headache, malaise
*can cause PNEUMONIA and HEPATITIS

Question 21

Q fever - diagnosis

Answer 21

serology: antibodies against both phase I and phase II antigens

Question 22

plague - agent

Answer 22

*yersinia pestis
*gram negative coccobacillus
*SAFETY PIN STAINING

Question 23

plague (yersinia pestis) - virulence factors

Answer 23

type III secretion system (T3SS): facilitates uptake and survival in the macrophage

Question 24

plague - reservoir & transmission

Answer 24

*reservoir = mammals & rodents or their fleas
*transmission = direct contact with infected animals (PRAIRIE DOGS, squirrels, cats) or airborne from infected person

Question 25

plague - clinical syndromes

Answer 25

*short incubation period (1-7 days) *syndromes: bubonic, septicemic, pneumonic, etc

Question 26

plague - symptoms

Answer 26

-sudden onset of fever, shortness of breath, hemoptysis, chest pain -GI symptoms common -high mortality

Question 27

plague - control

Answer 27

*rodent and flea control *antibiotic prophylaxis of contacts or infected individuals or exposures

Question 28

anthrax - agent

Answer 28

*Bacillus anthracis *gram positive, spore-forming bacillus

Question 29

what is the major concern with anthrax

Answer 29

use as a bioterrorism agent

Question 30

anthrax (Bacillus anthracis) - reservoir & transmission

Answer 30

*reservoir = herbivores (cattle, goats, sheep); capable of surviving in environment for long periods of time *transmission = contact, ingestion, or inhalation *contaminated HIDES are common source of infection

Question 31

anthrax - 3 clinical presentations

Answer 31

1. cutaneous (spore in skin; causes ulcer) 2. intestinal 3. pulmonary (severe; inhalation; into macrophages and spread through lymphatics)

Question 32

anthrax - virulence factors

Answer 32

1) edema toxin (ATP -> cAMP -> leaky capillaries -> edema) 2) lethal toxin (inflammation & cell death) *protective factor helps protect these toxins from degradation by human proteases

Question 33

what disease is associated with MEDIASTINAL WIDENING in a patient in septic shock

Answer 33

ANTHRAX (pulmonary/inhalational anthrax)

Question 34

anthrax - treatment and prophylaxis

Answer 34

ciprofloxacin is recommended

Question 35

cat scratch fever - agent

Answer 35

*Bartonella henselae *probably the most common zoonotic infection in the US

Question 36

cat scratch fever - clinical presentation

Answer 36

*fever with **papule at inoculation site *regional adenopathy** *comes from bite, lick, or scratch of a cat (usually outdoor kittens)

Question 37

pasteurella multocida

Answer 37

*facultative anaerobic gram negative coccobacilli *commensals in oropharynx of dogs and cats (bite = think ab this)

Question 38

pasteurella multocida - virulence factors

Answer 38

capsule and endotoxin

Question 39

pasteurella multocida - common risk factors

Answer 39

iron storage disease or liver disease

Question 40

pasteurella multocida - 3 types of infections

Answer 40

1. animal bite 2. pneumonia 3. systemic infection with septic shock

Question 41

rabies - agent

Answer 41

*Lyssavirus (a rhabdovirus) *bullet shaped

Question 42

rabies - transmission

Answer 42

saliva of infected mammal, usually a bite

Question 43

rabies - most frequent source in india

Answer 43

dog bite

Question 44

rabies - most frequent source in US

Answer 44

bats

Question 45

rabies - pathophysiology

Answer 45

inoculation at site of bite and reaches CNS through retrograde trafficking of virus through peripheral nerve