Zoonoses Flashcards
what is the CDC definition of zoonoses
contagious diseases spread between animalss and humans
how are humans involved in the life cycles of zoonotic diseases?
they are accidental hosts, not part of the life cycle
what is a reservoir? do they show signs of infection?
non human species that maintains the infection. may or may not show clinical symptoms
what is a vector?
an organism that transmits the pathogen from reservoir to other animals. not required for transmission
what are three transmission routs of a zoonosis?
contact with infected material from an animal, bite by a vector or eating or drinking infected material
what are five bacterial zoonotic pathogens?
bacillus antracis, francisella tularensis, brucella, yersinia pestis, and bartonella henselae
what is the vector of B anthracis?
no vector usually
what are the vectors of F tularensis?
ticks, mosquitos and deer flies
what are the hosts for b anthracis? what disease does it cause?
cattle and other ungulates. causes anthrax
what is the life cycle of b anthracis?
the cattle inhale spores from the soil that germinate once ingested and ultimately kill the host
how are humans exposed to anthrax?
they are exposed to spores from the environment or contaminated animal products
what are the hosts of yersinia pestis? what are the vectors? what disease does it cause?
rodents
fleas
causes the plague
how is y. pestis transmitted to humans?
most commonly from an infected flea bite or contact with an infected rodent
what are the hosts and vectors of type A tularaemia?
lagomorphs (rabbits and hairs) are the hosts and ticks and flies are the vectors and long term reservoirs
how are patients infected with type A tularaemia?
by the bite of an infected vector or by handling a diseased animal. also can inhale dust or aerasols contaminated during farming or landscaping
what are the hosts of francisella tularensis holarctica? vectors? long term reservoirs?
hares, rabbits and beavers
vectors include mosquitoes, tabanid flies and ticks
ticks are also reservoirs
how are mammals infected by f. tularensis holarctica?
by drinking infected water
how are humans invected with tularemia type B?
by contact with infected host or vectors and by ingestion of infected water
what are the three types of anthrax poisoning?
cutaneous-creates dark sores on the skin
inhalation and GI infection
what is the form of bacillus anthracis?
gram positive rod
what does cutaneous anthrax infection look like?
small sore that develops into a blister and then into a skin ulcer with a black area in the center. it does not hurt but there is edema
what are the GI symptoms of anthrax?
nausea, bloody diarrhea, fever and stomach pain
what are the pulmonary symptoms of anthrax?
cold/flu symptoms. later symptoms include cough, SOB and muscle aches
how is anthrax treated?
with cipro or doxycyclin
what regions do the different tularemia strains inhabit?
type A (more virulent) in US and canada type B (less virulent) in Europe and Asia
what is the morphology and metabolism of tularemia?
aerobic gram negative rod
what is the most common form of tularemia?
ulceroglandular- a skin ulcer appears where the organism entered the body and regional lymph nodes swell
what is glandular tularemia?
no ulcer appears but there is regional lymphadenopathy
what is oculoglandular tularemia?
occurs when bacteria enter through the eye - irritation and inflammation of the eye and swelling of lymph nodes around the ear
what is the most serious form of tularemia?
pneumonic- cough, chest pain and difficulty breathing
how is brucella usually transmitted to humans?
by contact with infected farm animals through conjunctiva or broken skin, ingestion of dairy products and undercooked meat or inhalation of infectious aerosols
how many species of brucella exist? are all of them human pathogens?
- two of them do not infect humans
what are cattle signs of brucella?
third trimester abortions, retained placenta, endometriosis, birth of dead or weak calves and low milk yield
what does human brucella infection look like?
can affect any organs. patients have cyclical fever in acute disease and variable clinical signs
what are six complications of brucella infection?
osteoarticular, hepatosplenomegaly, GI complications, GU involvement, Neuro (depression) and endocarditis (most common cause of death)
how is brucella diagnosed in humans?
isolation of gram negative bacillus from blood and marrow, serum agglutination test, immunofluorescence in clinical specimens and PCR
how is brucella treated?
doxycycline for 6 weeks or longer plus streptomycin for first 14-21 days. gentamicin appears as effective
what is the progmosis of brucella?
patients recover, but it may take a long time and disability is common. 5% of treated cases relapse
what is the incubation period of the plague? what is the history associated?
1-6 days
exposure to rodent, rodent fleas, wild rabbits, sick or dead carnivores or patients with pneumonic plague
what are the different types of plague?
bubonic- rapid onset of fever and lymphadenopathy
pneumonic- high fever, pneumonia and bloody sputum
septicemic- fever, hemorrhagia or thrombosis and progresses to gangrene
what causes the plague? where is it isolated on the patient?
yersinia pestis
isolated from bubo aspirates, blood cultures or speutum culture of pneumonic
what is the treatment for the plague?
parenteral streptomycin is first line, gentamicin if oral therapy is necessary. doxy can also be used
describe the morphology of leptospira
they are small (can’t see with light microscope) with paired axial flagella.
what is the reservoire of leptospira?
pet and livestock. shed in urine
how is leptospira passed to humans?
abraded skin or mucous membrane contact with contaminated water
how does leptospira present?
acute fever followed by mild, self limiting symptoms or severe multiorgan disease
what is phase one of leptospirosis?
incubation is 5-14 days. acutely multiplies in endothelium and toxins are released. mostly cleared with opsonization
what is phase two of leptospirosis?
delayed new or continued growth in organ causing more severe symptoms
what phase two organ dysfunction is caused by leptospirosis?
jaundice, renal failure, hemorrhage, aseptic meningitis, HUS, DIC, TTP and vasculitis
what are the different types of leptospirosis?
icteric- phase 2 comes fast with greater severity and high mortality
anicteric
what history is associated with leptospirosis? what eye findings?
eating and swimming in endemic areas. eye exam has conjunctival redness without exudate and uveitis
how is leptospirosis diagnosed on exam?
can be cultured from urine and seen in darkfield with silver or IF staining. confirm with serology or PanBio dipstick in urine
what are the routine lab findings with leptospirosis?
anemia (DIC), elevated BUN and creatinine, elevated bilirubin and alkaline phosphatase and elevated serum creatine kinase with muscle involvement
what is the treatment for leptospirosis?
penicillin (alt doxy or cephalospirins), hydration and restrict diet for organ damage. may have Jarisch Herxheimer reaction
what disease is caused by bartonella henselae?
cat scratch disease- mostly in younger patient
what are the clinical manifestations of cat scratch disease?
fever, enlarged lymph nodes, papules or pustules at innoculation site.
what is the clinical manifestation of bartonella henselae with immunocompromise?
angiomatosis and peliosis hepatitis (HIV). presents as skin, subcutaneous or bone lesions
what is the treatment of b henselae?
azithromycin with extensive adenopathy
erythromycin or doxy for angiomatosis
gentamicin and ceftriaxone for endocarditis
what is pasteurella multocida associated with?
cat or dog bite. clinically evident within a few hours
what complications arise from p multocida?
cellulitis or abscess, pneumonia, endocarditis, seeding of organs or rare meningitis
what is the morphology of capnocytophagg canimorsus? what is the metabolism and where does it reside?
facultive anaerobic gram negative rod. normal flora of cats and dogs
what is the clinical presentation of c canimorsus?
cellulitis, bacteremia, meningitis, shock and fulminent sepsis
