Zoonoses Flashcards
- List the animal vector associated with brucellosis
Goats, Sheep, Camels, Pigs, Cattle, Dogs
- List the animal vector associated with plague,
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
- List the animal vector associated with tularemia
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.
- List the animal vector associated with pasteurellosis
cats and dogs
- Describe special growth requirements of these pathogens for their recovery in culture.
most require special media and do not gram stain well
- Describe the populations at risk for Zoonoses caused by Brucella and list measures used to prevent infection with these pathogens.
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
- Describe the populations at risk for Zoonoses caused by Yersinia and list measures used to prevent infection with these pathogens.
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
- Describe the populations at risk for Zoonoses caused by Francisella and list measures used to prevent infection with these pathogens.
- 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
- Describe the populations at risk for Zoonoses caused Pasteurella and list measures used to prevent infection with these pathogens.
people with cat and dog bites
- Identify the areas within the USA where plague and tularemia are endemic.
Plague: Arizona, California, Colorado, New Mexico, Oregon
Tularemia: Arkansas, Oklahoma, Missouri
- Describe the disease conditions association with infections caused by Brucella species
• 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
- Describe the disease conditions association with infections caused by Francisella tularensis,
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
- Describe the disease conditions association with infections caused by Pasteurella multocida
- 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)
- Describe the disease conditions association with infections caused by Yersinia pestis.
Bubonic
Septicemic
Pneumonic
Brucella is what kind of pathogen and what type of immunity determines the bodies recovery?
intracellular pathogen – T cell immunity determines your bodies ability to clear it.
- Describe special growth requirements of Brucella for their recovery in culture and diagnosis tools
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
Brucella gram stain
Small coccobacillary Gram negative rod
bacteria are so small it can be difficult to read the shape, look like fine sand
Brucellosis: Treatment
• 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
Tularemia host response
granulomas - intracelluar pathogen requires cell mediated immune response for recovery
Brucellosis host response
small granulomas
- Describe special growth requirements of Tularemia pathogens for their recovery in culture.
- 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
gram stain of Tularemai
Very small gram negative coccobacilli - looks just like brucellosis (tiny sand like)
• poorly staining
Tularemia: Treatment
• Streptomycin, gentamicin, tetracycline or choramphenicol
Pasteurella identifying characteristics
• 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
pateruella treatment
penicillin
Yersinia pestis – characteristics of bulbonic plague
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
Yersinia pestis – characteristics of pneumonic plague
- 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
Yersinia pestis – characteristics of septicemic plague
- 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
When should you suspect plague
In febrile pts. who have been exposed to rodents or other mammals in known epidemic areas of the world.
Yersinia pestis is a member of what group of bacteria
Enterobacteriaceae
Yersina pestis identifying characteristics
- 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
Yersinia pestis - Treatment
- Streptomycin: alternatives include gentamicin, chloramphenicol, and tetracyclines. Penicillin’s and cephalosporin’s are not effective in treating plague
- Susceptibility testing is not recommended
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?
Pasteurella
Which arthropod is the most important vector of tuleremia?
tick (from infected rabits mostly)
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?
Brucella melitensis
