ID Exam 2: Zoonotics

Question 1

Bartonella Henselase

Answer 1

Gram negative
Silver stain
Cat scratch fever (painful axillary lymphadenopathy - immunocompetent)
Bacillary angiomatosis (raised red vascular lesions - immunocompromised – HIV)
BA: doxy
CSF or BA: macrolides

Question 2

Brucella

Answer 2

Gram negative
Barn animals = reservoir, unpasteurized dairy
Facultative intracellular (open gate)
Undulating fever
Hepatosplenomegaly (RE system infection)
Osteomyelitis
Tx: doxy, rifampin

Question 3

Francisella tularensis

Answer 3

Gram negative coccobacilli
Facultative intracellular (open gate), need cystiene
Phase variation
Genotypes: A1 (eastern US), A1b = fatal cases
Rabbits are main reservoir (dermacenter ticks can transmit)
Can be aerosolized (report to CDC)
NO person to person spread
Path: ulcer, lymph spread, RE system, caseating granuloma
Tx: AG

Question 4

Pasteurella Multocida

Answer 4

Cats and dogs
Osteomyelitis, nec fas
Catalase positive, oxidase positive, encapsulated
SGA, bipolar staining (safety pin staining)
Tx: PCN

Question 5

Rickettsial diseases

Answer 5

Poor gram staining (neg), coccibacillary
Stain with Giemsa
Obligate intracellular -> needs NAD+ and CoA (small genome, no LPS or aminoglycan, acquire cholesterol from host)
Transmission via arthropods
Targets endothelial cells (blood vessels)
Weil-Felix medium
HA, fever, vasculitis
Tx: doxy

Question 6

Rickettsia rickettsii

Answer 6

Dermacentor tick
Palms and sole rash, spread centrally (2-14d incubation)
HA, fever, myalgias, vasculitis

Question 7

Rickettsia prowzekii

Answer 7

Spread by louse
Rash start centrally, spread out, spares palms/soles
Myalgias, PNA, encephalitis/coma

Question 8

Modes of transmission

Answer 8

Cutaneous contact (bites)
Arthropod vector
Inhale
Ingest

Question 9

Types of plague

Answer 9

Bubonic: LNA, 60-90% mortality
Septicemic: Multiorgan invasion, little evidence of dz, death in 24 hours (probably ingestion for route)
Pneumonic: Lung infection, highly infectious, 100% mortality

Question 10

Virulence factors of yersinia

Answer 10

Plasmid encoded: VW antigens, T3SS, coagulase/fibrinogen

Chr encoded: Fe acquisition, attachement/invasion, endotoxin

Question 11

Francisella tularensis presentations/types

Answer 11

Glandular 
Oculoglandular
Pharyngeal
Typhoidal
Pulmonary

Question 12

Erythemia chronicum migrans

Answer 12

Bulls eye rash

Detects collagen and migrates along bundles

Question 13

Erythemia chronicum migrans

Answer 13

Bulls eye rash

Detects collagen and migrates along bundles

Question 14

Rickettsia typhi

Answer 14

Flea transmission, endemic responsible

epidemic = lice

Question 15

Rickettsia typhi

Answer 15

Flea transmission, endemic responsible

epidemic = lice

Question 16

Scrub typhus rickettsia group

Answer 16

Rash often missing, eschar present

Chiggers

Question 17

Ehrlichia and Anaplasmosis

Answer 17

Obligate intracellular
Infect phagocytic cells
Multiply inside vaccules (mulberry inclusions)
Fever, HA, malase, WITHOUT rash
Elevated liver enzymes
Leukopenia, thrombocytopenia
Ehr = monocytes, tetra
Ana = granulocytes, doxy

Question 18

Viral zoonotic transmission

Answer 18

Animals to humans (no human to human): rabies, sin nombre, west nile
Animals to humans (some human to human): ebola, marburg, nipah, monkeypox
Animals to humans (and human to human): flu, SARS, HIV, yellow, dengue, zika, chikungunya

Question 19

Rabies virus (rhabdovirus)

Answer 19

Do not need to be reported, underreported
Immunization and PEP (rabies Ig)
Bullet shaped, non-seg
Each host harbors unique variant

Question 20

Rabies: two forms

Answer 20

Furious (encephalitic): Difficultly swallowing, hydrophobia, hypersalivation, halliucination, CNS death

Paralytic form: Lack of furious features, quadraplegia, multiple organ failure, death

Question 21

Rabies PEP

Answer 21

Soapy water
Human rabies Ig: area of wound
Vaccine: different site (day 0,3,7,14)

Question 22

Hantavirus

Answer 22

3 segments, -RNA
Aerosolized rat urine, host doesn’t show dz
Hemorrhagic fever with renal syndrome
Hantavirus pulmonary syndrome

Question 23

Hantavirus pulmonary syndrome

Answer 23

Prodrome: Fever, chills, myalgia
Severe leg/back pain
NO COUGH
Low platelet, neutrophilia, elevated LDH and AST

Question 24

Ebola vaccine

Answer 24

Tested during recent outbreak
Immediate vaccination group = 100% protection
Rhabdovirus with ebola glycoprotein

Question 25

Long term consequences ebola

Answer 25

People do recover but can develop eye/joint problems

Ebola can persist in eye, semen, amniotic fluid, CNS

Question 26

Humans as host for arborviruses

Answer 26

Usually dead end hosts: west nile, St. Louis, eastern/northern/venusalia/japanese

Exceptions (human-mosquito-human transmission): 
Dengue
Yellow
Zika
Chikungunya

Virus must replicate in mosquito, eventually in salivary gland and transmitted at next bite

Question 27

Arborviruses outcomes

Answer 27

Usually asx. (except chikungunya)
Febrile illness - most mild
Neuro dz
MSK dz
Hemorrhagic fever (loss of platelet fxn)
Congenital dz (Zika)

Question 28

3 classes of arborviruses

Answer 28

Bunyaviridae
Flaviviridae
Togaviridae

Question 29

Dengue serotypes and syndromes

Answer 29

Serotypes 1-4 (all emerged separately)
Human-mosquito-human cycle maintains
Fever: acute, febrile, HA, pain, rash
Hemorrhagic fever, shock: thrombocytopenia, capillary leakage, liver damage
Risk factor: second infection with DIFFERENT serotype -> more likely to get DHF/DSS disease

Question 30

Antibody mediate enhancement of infection

Answer 30

Hypothesis for dengue severe infection
Subacute, non-neutralizing abx bind but don’t neutralize disease
Larger, more severe immune response
Can be mediated by maternal antibodies as well

Question 31

Complications of dengue vaccine

Dengavaxia

Answer 31

Need to protect against all 4 serotypes
Concern about waning immunity enhancing disease

Current working vaccine uses yellow fever vaccine and replaces with dengue proteins
Undergoing long term safety analysis
Seronegative at vaccination may be at high risk for hospitalization

Question 32

Chikungunya virus

Answer 32

Togavirus

Joint/muscle pain, progression to chronic MSK pain

Question 33

Zika virus: congenital syndrome

Answer 33

Most severe if 1st trimester
Sexually transmissible??
Microcephaly but also:
CNS injury, growth restriction, ocular abnormalities, placental insufficency

Question 34

Epidemologic features of arborviruses in US: age groups

Answer 34

Neuroinvasive charateristics:
WNV: elderly (July-Sept), bird host
St. Louis: elderly
La Crosse: young