Zoonoses I

Question 1

pathogens shared with animals count for what percentage of infections in human

Answer 1

greater than 60%

Question 2

zoonoses pathogen classes

Answer 2

helminths: taenia solium
protozoa: toxoplasma gondii
bacterial: campylobacter jejuni
virus: influenza
prions: BSE and v CJD

Question 3

how does a zoonosis become an epidemic

Answer 3

interaction between pathogen, vector, host

Question 4

the worst route of transmission of zoonoses and why it is such a problem

Answer 4

inhalation because pulmonary symptoms tend to be the deadliest

Question 5

causative agent of anthrax and characteristics of this agent

Answer 5

bacillus anthracis

large, box-car, gram negative rod, aerobic and spore forming

Question 6

is person to person transmission common in anthrax

Answer 6

no

Question 7

virulence factor of anthrax

Answer 7

toxins and its polypeptide capsule (poly-D-glutamic acid)

Question 8

toxins in anthrax

Answer 8

three proteins on large plasmid pXO1: lethal factor (LF), edema factor (EF), and protective antigen (PA) make up the toxins

PA + EF = edema toxin
PA + LF = lethal toxin

Question 9

what is so significant about the capsule of anthrax

Answer 9

it is an amino acid capsule made from three genes (CapA, CapB, CapC) from plasmid pXO2 - only one serotype

Question 10

function of the virulence factors of anthrax

Answer 10

• capsule - inhibits phagocytosis of replicating cells
• edema toxin - cAMP allows accumulation of fluid in tissue
• lethal toxin - stimulates macs to release TNFalpha, IL-1B and other inflammatory toxins
• both toxins inhibit host innate immunity

Question 11

what is the pathogenesis of cutaneous anthrax

Answer 11

begins at primary site of infection as papule then progresses through vesicular stage to a depressed black necrotic ulcer called eschar

without antibiotics there is an increased chance from 1% to 20% chance of death

Question 12

clinical manifestation of anthrax

Answer 12

cutaneous - least life threatening
septicemic - higher mortality
pulmonary - highest mortality –> “wool sorter disease”

Question 13

clinical manifestation of inhalation anthrax

Answer 13

flu like symptoms so myalgia, fatigue, fever but then they get dyspnea and hypoxia

half of people get meningitis

Question 14

diagnosis of anthrax

Answer 14

culture or biopsy then do PCR

Question 15

agent that causes brucellosis and its characteristics

Answer 15

brucella

gram neg non motile short rod that is facultatively intracellular hence requires complex artificial media in vitro

Question 16

4 types of brucella found in human and animals they are found in

Answer 16

b. melitensis - goats, sheep, camel
b. abortus - cattle
b. suis - pig
b. canis - dog

Question 17

reservoir of brucella and its transmission to humans

Answer 17

animals make milk, their urine, feces

drinking the milk, access through skin breaks, mucosal membrane, aerosols, splashes

organism is killed by pasteurization

Question 18

pathogenesis of brucella

Answer 18

• once skin or mucosal membrane is penetrated it is carried to lymphatics by PMNs
• cells multiply within mac by inhibiting phagosome lysosome fusion
• humoral response ineffective since hidden inside macs
• T cell response required but if it fails it multiplies within RES
• waves of bacteria from these sites are released –> recurrent infections

Question 19

symptoms in acute infection with brucellosis

Answer 19

• brucella melitensis is most severe
• brucella suis causes abscess formation
• sweating, high fever, swinging fever, headaches, scrotal pain
• lymphadenopathy and splenomegaly

Question 20

symptoms in chronic infection with brucellosis

Answer 20

night fever, sacro ileitis, weight loss, depression

Question 21

how do you diagnose brucellosis

Answer 21

blood culture which show brucella melitensis most of the time

Question 22

epidemiology of leptospirosis

Answer 22

• leptospira interrogans is most common

- shed in rat urine/rodent urine

Question 23

characteristics of leptospira interrogans

Answer 23

tight spiral
sensitive to heat, drying, and most chemicals
enters host by penetrating skin or mucous membrane

Question 24

disease that one can acquire from leptospira interrogans and its description

Answer 24

weils disease and it is leptospira multiplying and damaging endothelium of small blood vessels

Question 25

where can leptospira be isolated

Answer 25

blood and CSF then later on in disease it can be isolated in urine

Question 26

clinical feature of leptospirosis

Answer 26

conjunctival congestion, viral like meningitis, icteric symptoms, and pulmonary ARDS

Question 27

how is leptospirosis diagnosed

Answer 27

increased PMNs, liver enzymes rise, viral pattern of meningitis, decreased platelets,

serology and PCR

Question 28

pathogen in tularemia aka rabbit fever and its characteristics

Answer 28

francisella tularensis

gram neg short rods that is nutritionally fastidious because it is facultative

Question 29

agar used for tularemia

Answer 29

cysteine glucose blood agar

Question 30

pathogens that use thayer martin

Answer 30

both tularemia and neisseria gonorrhea

Question 31

animals and vectors associated with tularemia

Answer 31

rabbits and ticks

Question 32

clinical manifestations of tularemia

Answer 32

ulcero-glandular (from injection - lowest mortality)
typhoidal (from ingestion - higher mortality)
pneumonia (from inhalation - highest mortality)

Question 33

what should be seen on serodiagnosis of tularemia

Answer 33

1:40 to 1:320 in 1 to 2 weeks

Question 34

treatment of tularemia

Answer 34

aminoglycoside