Zoonoses

Question 1

• List the animal vector associated with brucellosis

Answer 1

Goats, Sheep, Camels, Pigs, Cattle, Dogs

Question 2

• List the animal vector associated with plague,

Answer 2

Urban Plague-maintained in rat pop. Spread to humans by fleas

Sylvatic Plague-endemic in western USA. Carried by prairie dogs, mice, rabbits, rats.

cats that are allowed to rome free in these areas

Question 3

• List the animal vector associated with tularemia

Answer 3

Francisella tularensis is widespread in nature and has been recovered from more that 100 species of wild animals, at least nine species of domestic animals (cats, dogs and cattle) and 50 species of arthropods. The principle animal host include wild hares, rabbits, voles, mice muskrats, beaver. Certain hard ticks are able to maintain infection from one developmental cycle to the other.

Question 4

• List the animal vector associated with pasteurellosis

Answer 4

cats and dogs

Question 5

• Describe special growth requirements of these pathogens for their recovery in culture.

Answer 5

most require special media and do not gram stain well

Question 6

• Describe the populations at risk for Zoonoses caused by Brucella and list measures used to prevent infection with these pathogens.

Answer 6

Consume unpasteurized dairy products
Contact with infected animals
Abattoirs (slaughterhouse workers)
Veterinarians
Farmers
Laboratory  workers

to prevent: Controlled by immunizing livestock,
Avoid unpasteurized milk and dairy products,
No human vaccine available

Question 7

• Describe the populations at risk for Zoonoses caused by Yersinia and list measures used to prevent infection with these pathogens.

Answer 7

at risk: if travel or live in areas where plague is common and have contact with rodents or cats

Prevention: Avoid contact with dead rodents
Chemoprophylaxis with tetracycline
Rat and flea control measures
Vaccine available for high risk patients

Question 8

• Describe the populations at risk for Zoonoses caused by Francisella and list measures used to prevent infection with these pathogens.

Answer 8

• Bite from an infected tick or deer fly
• Contact with an infected animal
• Contact with a domestic pet (cat) that has caught an infected animal (rabbit)
• Consumption of contaminated meat or water
• Inhalation of infectious aerosol in laboratory or while dealing with infected animal
• Hunters, laboratory workers and people exposed to ticks
• Category A Infectious Agent
• U.S: Arkansas, Oklahoma, Missouri

Prevention: Removes ticks promptly, Avoid contact with dead animals, Live attenuated vaccine available

Question 9

• Describe the populations at risk for Zoonoses caused Pasteurella and list measures used to prevent infection with these pathogens.

Answer 9

people with cat and dog bites

Question 10

• Identify the areas within the USA where plague and tularemia are endemic.

Answer 10

Plague: Arizona, California, Colorado, New Mexico, Oregon

Tularemia: Arkansas, Oklahoma, Missouri

Question 11

• Describe the disease conditions association with infections caused by Brucella species

Answer 11

• Symptoms appear to 2-8 weeks after exposure
• Initial: nonspecific symptoms
Malaise, chills, sweats, fatigue, weakness, myalgias,
• Fever: intermittent / cyclical
Organisms sequestered in granulomas in tissue and bone marrow. Release of orgs into circulation causes reappearance of fever and constitutional symptoms
** “Undulant fever”, “FUO”
• Splenomegaly, lymphadenopathy, hepatomegaly

Question 12

• Describe the disease conditions association with infections caused by Francisella tularensis,

Answer 12

Ulcer may develop at entry site
Organisms may disseminate via the bloodstream
•Fever, chills, malaise 2-5 days after exposure
• Ulceroglandular infections
• Oculoglangular- conjuntivitis
• Typhoidal infection
• Typhoidal infection - Fever, prostration, weight loss
• Pneumonic infection
• Glandular form: adenopathy
• Oropharyngeal form : exudative pharyngitis or tonsillitis

Question 13

• Describe the disease conditions association with infections caused by Pasteurella multocida

Answer 13

• Pain, swelling and serosanguinous
drainage at wound site
• Septic arthritis and osteomyelitis may occur following deep puncture wound
• Serious infections (i.e., fasciitis) requiring wide excisional debridement may occur in compromised hosts (e.g. diabetics)

Question 14

• Describe the disease conditions association with infections caused by Yersinia pestis.

Answer 14

Bubonic
Septicemic
Pneumonic

Question 15

Brucella is what kind of pathogen and what type of immunity determines the bodies recovery?

Answer 15

intracellular pathogen – T cell immunity determines your bodies ability to clear it.

Question 16

• Describe special growth requirements of Brucella for their recovery in culture and diagnosis tools

Answer 16

Blood cultures with extended incubation time
Bone marrow or infected tissue cultures
• growth takes more than 5 days which is the standard growth time
• Slow growing
• Requires enriched media to grow (chocolate agar)

Use serology
Elevated febrile agglutinin titer

Question 17

Brucella gram stain

Answer 17

Small coccobacillary Gram negative rod

bacteria are so small it can be difficult to read the shape, look like fine sand

Question 18

Brucellosis: Treatment

Answer 18

• Because of chronicity of some infections, disease must be treated for a prolonged time
• Treatment involves agents that penetrate and have activity within phagocytic cells
- Oral tetracyclines along with aminoglycosides (e.g., gentamicin, streptomycin)

• Surgical intervention may be necessary in some cases e.g., valve replacement brucella endocarditis

Question 19

Tularemia host response

Answer 19

granulomas - intracelluar pathogen requires cell mediated immune response for recovery

Question 20

Brucellosis host response

Answer 20

small granulomas

Question 21

• Describe special growth requirements of Tularemia pathogens for their recovery in culture.

Answer 21

• Can culture from: Blood, pleural fluids, lymph nodes, wounds, conjunctival swabs, tissue, respiratory tract secretions
• Does not grow on routine media (chocolate agar)
• Requires sulfhydryl compounds for growth
• Requires extended incubation time
• Strict aerobe

Question 22

gram stain of Tularemai

Answer 22

Very small gram negative coccobacilli - looks just like brucellosis (tiny sand like)
• poorly staining

Question 23

Tularemia: Treatment

Answer 23

• Streptomycin, gentamicin, tetracycline or choramphenicol

Question 24

Pasteurella identifying characteristics

Answer 24

• Most common species isolated from humans
Small bipolar Gram negative rods
• Facultative anaerobe
• Grows on blood and chocolate but **NOT MacConkey agar
• Large buttery colonies with 
moth ball odor
• Most species are **Oxidase-POSITIVE 
and Catalase-POSITIVE
• Penicillin-susceptible

Question 25

pateruella treatment

Answer 25

penicillin

Question 26

Yersinia pestis
 -- characteristics of bulbonic plague

Answer 26

Fever and painful bubo 2-7 days after bite Pts. present with sudden onset of fever, chills, weakness, and headache. Within hrs. notice intense pain in anatomic region with buboes, become prostrate and lethargic 80% have + blood cultures 75% mortality if untreated

Question 27

Yersinia pestis
 -- characteristics of pneumonic plague

Answer 27

* Plague bacillus reaches lungs by hematogenous spread or by inhalation of infectious aerosol from plague pt. with cough. * Initially: headache, malaise, fever vomiting, prostration and confusion * Pts. develop cough, chest pain, hemoptysis. *  Sputum usually purulent and contains plague bacillus (Patient highly infectious) * Quickly followed by sepsis and death unless therapy initiated within one day following onset of symptoms

Question 28

Yersinia pestis
 -- characteristics of septicemic plague

Answer 28

* Direct infection of bloodstream by flea bite, or spread of microorganism from LN to blood * High fever, delirium, seizures in children, septic shock, DIC * Black hemorrhagic splotches gave rise to the name “Black Death” * 100% of pts. become septic with + blood cultures * Fatality rate high due to delay in Dx and Tx

Question 29

When should you suspect plague

Answer 29

In febrile pts. who have been exposed to rodents or other mammals in known epidemic areas of the world.

Question 30

Yersinia pestis 
is a member of what group of bacteria

Answer 30

Enterobacteriaceae

Question 31

Yersina pestis identifying characteristics

Answer 31

* oxidase neg., non-motile * Cells small and cocco-bacillary on Gram stain, • bipolar staining - “safety pins” * Colonies slow growing on ordinary media after 48 hrs “fried egg” or “beaten copper” when viewed under stereoscope * Small, pinpoint colonies on MacConkey * Faster growth at 28 C than 37 C

Question 32

Yersinia pestis - Treatment

Answer 32

* Streptomycin: alternatives include gentamicin, chloramphenicol, and tetracyclines. Penicillin's and cephalosporin's are not effective in treating plague * Susceptibility testing is not recommended

Question 33

A 6 Y.O. boy arrives with his mother in ER complaining of pain in right arm where a cat had bit him the previous day. The next morning the boy awoke crying and complaining of pain in his hand. Temp 39 C. Skin over the wound is erythematous. Material from the wound is submitted for culture and Gram stain. The laboratory reports growth of gram-negative coccobacilli. The organisms were faculatatively anaerobic but failed to grow on MacConkey agar. Which organisms is most likely responsible for this infection?

Answer 33

Pasteurella

Question 34

Which arthropod is the most important vector of tuleremia?

Answer 34

tick (from infected rabits mostly)

Question 35

During a military conflict in Somalia, several soldiers develop a febrile illness characterized by abrupt onset of fever with rigors, severe headaches, myalgias, arthralgias, lethargy, photophobia, and coughing. Conjunctival suffusion and a petechial rash develop 4 days into the illness and then fade after 1 to 2 days at the time symptoms wane. Splenomegally and hepatomegaly are also observed. After 1 week, the symptoms recur. Blood cultures are collected during febrile phase and are positive after extended (7 days) incubation with small, faint staining gram-negative coccobacill. What is the likely etiologic agent for this disease?

Answer 35

Brucella melitensis