Zoonoses Flashcards
1
Q
definition
A
- diseases and infections which are naturally transmitted between vertebrate animals and humans under natural conditions
- any type of organism included
- directly transmitted from animals to people, or indirectly through the environment or vectors
- human population is not part of life cycle, accidental insertion that is often dead end host
- reservoir is non-human animal species that maintains infections
2
Q
vector
A
- transmits pathogen from reservoir to other animals
- can also be reservoir itself
- not all zoonotic diseases require a vector, some direct from animal to human
3
Q
spectrum of disease
A
-broad death from rabies severe illness from the plague chronic illness from Q fever mild illness from psittacosis
4
Q
transmission
A
- routes varry
- contact with saliva, blood, urine, or feces of an infected animal
- bite by a tick, mosquito, fly
- eating or drinking something unsafe- unpasteurized milk, undercooked meat, unwashed fruits and veggies
5
Q
bacterial zoonotic pathogens
A
- bacillus anthracis-no vector
- francisella tularensis- tick, mosquito, deer flies
- brucella species- no vector
- yersinia pestis- fleas
- bartonella henselae- fleas ?ticks
6
Q
bacillus anthracis
A
- gram pos rod
- bacteria shed at death from hemorrhage from nose, mouth or anus
- sporulizes on contact with O2, then infect humans or cow
- can also be vectored by a biting fly, but not common
- 3 types- cutaneous, inhalation, GI
- GPR on culture of lesion
- treat with cipro, doxy
7
Q
cutaneous anthrax
A
- small sore that develops into a blister (eschar)
- blister develops into skin ulcer with a black area in the middles
- significant edema
- blister and ulcer do not hurt
8
Q
GI anthrax
A
-nausea, loss of appetite, bloody diarrhea, fever, followed by bad stomach pain
9
Q
inhalation anthrax
A
- cold or flu symptoms and can include a sore throat, mild fever, and muscle aches
- later sx include cough, chest discomfort, SOB, tiredness and muscle aches
10
Q
francisella tularemia
A
- aerobic gram neg rod
- type a and b (for beaver!)
- a more virulent and in US/Canada. B less virulent and in europe
- both spread through direct contact or through vector (flea, tick, fly)
- 5 types- ulceroglandular, glandular, oculoglandular, oropharyngeal, pneumonic
- can acquire by inhaling dust/aerosols contaminated with bacteria- farming/landscaping
11
Q
ulceroglandular tularemia
A
- most common form and usually occurs following a tick or deer fly bite or after handing of an infected animal
- A skin ulcer appears at the site where the organism entered the body.
- The ulcer is accompanied by swelling of regional lymph glands, usually in the armpit or groin.
- glandular is similar but without ulcer
12
Q
oculoglandular tularemia
A
- occurs when the bacteria enter through the eye usually when a person is butchering an infected animal and touches his eyes
- Symptoms include irritation and inflammation of eye and swelling of lymph glands in front of the ear.
13
Q
oropharyngeal
A
- results from eating or drinking contaminated food or water.
- Patients with orophyangeal tularemia may have sore throat, mouth ulcers, tonsillitis, and swelling of lymph glands in the neck.
14
Q
pneumonic
A
- most serious form of tularemia.
- Symptoms include cough, chest pain, and difficulty breathing.
- This form results from breathing dusts or aerosols containing the organism.
15
Q
Brucella
A
- usually transmitted to humans by contact with infected farm animals
- lots of different types
16
Q
cattle signs for Brucella
A
- third trimester abortions with B abortus
- retained placenta- once expelled will have a leathery appearance
- endometritis
- birth of dead or weak calves
- low milk yield
17
Q
brucella transmission to humans
A
- contact of conjunctiva or broken skin with infected tissues
- blood, urine, vaginal discharges, aborted fetuses, placentas
- ingestion- raw milk/unpasteurized dairy products, rarely through undercooked meat
- inhalation of infectious aerosols- pens, stables, slaughterhouses
18
Q
brucella human disease
A
- can affect any organ or organ system
- patients have cyclical fever in acute disease
- variability in acute clinical signs- headache, weakness, arthralgia, depression, weight loss, fatigue, liver dysfunction
- osteoarticular complications-20-60% of cases-arthritis, spondylitis, osteomyelitis
- HSM- 33%
- GI complications- 2-20%
- GU involvement- 6-8%- orchitis and epididymitis
- neuro- depression, mental fatigue- 305%
- cardiovascular- 1-3%, endocarditis
- chronic is hard to define- length, type and response to trt variable, localized infection
- blood donations of infected persons should not be accepted
- treated with doxy for 6 weeks plus streptomycin for first 14-21 days
- doxy +gentamicin probably as effective
19
Q
diagnosis of brucella
A
- isolation of organism in culture
- gram ned bacillus
- blood, bone marrow, other tissues
- serum agglutination test, titer over 1:160
- immunofluorescence
- PCR
20
Q
prognosis of brucella
A
- recovery is common
- may last days, months, years
- disability is often pronounced
- about 5-8% of cases relapse
- case fatality rate <2%
21
Q
plague
A
- sylvatic cycle and urban cycle
- transmitted through direct contact with rodents or through flea vector
- once pneumonic in people can spread to other people
- caused by gram neg bacterium yersinia pestis
- can be isolated from bubo aspirates, blood cultures, or sputum culture if pneumonic
- parenteral antibiotic therapy with streptomycin is recommended 1st line, gentamicin alt, or doxy if limited to oral
22
Q
clinical presentation of the plague
A
- incubation period 1-6 days
- history is suggestive of exposure to rodents, rodent fleas, wild rabbits, sick or dead carnivores, patients with pneumonic plague
- bubonic- rapid onset of fever and painful, swollen, tender lymph nodes- usually inguinal, axillary, or cervical
- pneumonic-high fever, overwhelming pneumonia, cough ,bloody sputum, chills
- septicemic- fever, prostration, hemorrhagic or thrombotic phenomena, progressing to acral gangrene
23
Q
letptospira bacteriology
A
- spirochete
- small diameter means invisible to light microscope
- motile-paired axial flagella, corkscrew motion
- reasonably sturdy, can live outside host for weeks
- pet and livestock reservoirs, shed in urine
- passed to humans by contact with contaminated water- worlds most common zoonosis
- endemic canine leptospirosis is becoming more common in US
24
Q
leptospira pathogenesis
A
- L interrogans- bilious typhoid
- 100-200 in US, half in hawaii
- bacteria from contaminated water (swimming) or food enter abraded skin, mucous membrane, cross into lymphatics and lead to leptospiremia
- no buildup, encodes toxins
- acute febrile illness followed by either more mild, self limiting sx or severe multiorgan involvement
25
leptospira pathogenesis 2
- Normal incubation 5-14 days but variable
- Anicteric leptospirosis: (normal course)
- Phase 1 (acute): leptospira circulate in blood and multiply in blood vessel endothelium
- Vasculitis from leptospiral toxins releases blood into tissues and deprives target tissues of oxygen
- Initial sepsis can kill susceptible hosts, most clear it w/ opsonizing immunoglobulin
- Spirochetes persist in privileged sites for weeks to months afterward
Phase 2: (delayed, immune) New or continued growth of leptospira in organs causes more severe symptoms
Liver: jaundice
Kidneys: renal failure
Lungs: hemorrhage
CNS: aseptic meningitis
Vascular system overall: HUS, DIC, thrombotic (TTP)
Icteric disease- Phase 2 follows phase 1 with less delay and greater severity
26
leptospirosis dx
- acute phase- 5-7 days of high fever, rigor, sudden headache, nausea, anorexia, diarrhea, cough, rash, muscle pain
- delayed/immune phase-1-2 afebrile days, 4-30 days resumed illness with organ specific sx
- conjunctival suffusion
- chest xray for cardiac or lung involvement
- hx-eating and swimming in endemic area
27
leptospira dx in lab
- can sometimes be cultured from patient urine
- can sometimes be seen by darkfield from centrifuged urine or CSF
- confirmation of diagnosis requires serology of paired acute and convalescent sera by CDC
- panbio dipstick is FDA approved
- histology-silver or IF staining of biopsies may reveal leptospires
- anemia from DIC, elevated BUN/Cr
- elevated bili an alkphos
- elevated Cks
28
leptospira trt
- penicillin G, doxy or 3rd gen cephalosporins
- maintain hydration
- organ damage, admission for supportive care, restricted diet
- kidneys usually healthy after recovery
- jarisch herxheimer rxn
29
leptospira prevention
- sanitation-rodent control, use of protective clothing when working with livestock
- vaccination- none useful in US, some countries vaccinate against their local serovars
- prophylaxis- oral doxy for short term exposures
30
bartonella
-carrions disease in peru- fever and blisters
-reservoir unknown
bartonella henselae is cat scratch fever
31
bartonella h
- multitude of manifestations depending on immune status
- if immunocompromised- bacillary angiomatosis
- if fine-asx, cat scratch, meningeoencephalitis, visceral involvement, stellar retinitis, bacteremia, osteomyelitis, pericarditis
- 25,000 cases of cat scratch per year, usually in patients younger than 21
- fleas carry it from cat to cat
- infects kittens and can remain in bloodstream for 1 year, more likely to infect owner
- human transmission through cats or possible fleas
- usually self limited
- if extensive adenopathy- azithromycin 1 time
- bacillary angiomatosis- erythromycin or doxy
- endocarditis-gentamicin and ceftriaxone
32
clinical manifestations of cat scratch in normal immune
- fever, enlarged tender lymph nodes
- 1-2 weeks after exposure
- papule/pustule at inoculation site
- unusual manifestations-granulomatous, conjunctivitis, neuroretinitis, atypical pneumonia, endocarditis
33
clinical manifestations of cat scratch in immunocompromised
- bacillary angiomatosis
- peliosis hepatitis
- HIV patients
- skin, subQ or bone lesions
34
cat bites
- pasteurella multocida
- often clinical evidence of wound infection within a few hours of bite injury, scratch, or lick
- cellulitis or abscesses +/- bacteremia
- occasional cause of pneumonia and endocard
- metastatic seeding of internal organs from bacteremia
- CNS- meningitis, most often in young children or elderly
- cause of rapidly progressive infections similar to group A strep or vibrio
- patient may present within a few hours or cat bite with established severe infection
- dx based on culture
- trt with amoxicillin/cavulanate, ampicillin/sulbactam, penicillin, cipro, levofloxacin, doxy
- first gen cephalo, cloxacillin, erythromycin and clinda not effective
35
dog bites
- capnocytophaga canimorsus
- facultatively anaerobic gram neg rod, part of normal flora
- many pts have hx of dog bite or scratch, less commonly in cats
- cellulitis, bacteremia/sepsis, meningitis and endocarditis
- severe-shock, DIC, acral gangrene, disseminated purpura, renal failire, meningitis and pulm infiltrates
- ***fulminant sepsis following dog >cat bites, particularly in asplenic patients, alcoholics, or immunosuppressed
- trt of mild- amox/claculanate, or clinda, doxy
- severe-penicillin G 2-4 mU q 4hr IV or clinda 600 mg IV q 8hr
- alternative-ceftriaxone 1-2q IV qd, cipro 400 mg IV q12hr or meropenem 1g IV q8hr
- prevention in asplenic patients- amox/clavulanate for 7-10 days
