04a: Zoonotic Bacteria

Question 1

Zoonotic diseases are transmitted from (X) to humans (directly/indirectly) via (Y).

Answer 1

X = animals

Directly or indirectly (Y = vectors like insects/mites)

Question 2

Two most common zoonotic diseases in U.S.

Answer 2

1. Lyme disease

2. RMSF

Question 3

T/F: Diagnosis of zoonotic diseases is typically presumptive, based on clinical presentation and patient history.

Answer 3

True - lab tests take too long

Question 4

Rickettsia organisms cause which diseases? What’s the cell shape and gram reaction?

Answer 4

RMSF, Epidemic and Endemic Typhus

Rods; gram-negative

Question 5

Major virulence factors of Rickettsia.

Answer 5

1. Intracellular growth (obligate intracellular parasite!)

2. Endotoxin

Question 6

Transmission of Rickettsia rickettsii to humans is via (X) vector and mammalian reservoirs are (Y).

Answer 6

X = dog tick (arthropod) bites
Y = dogs/rodents

Question 7

List the common clinical findings of Rickettsia.

Answer 7

Flu-like symptoms:

1. HIGH fever/chills
2. Myalgia, prostration (weakness)
3. Severe headache

Question 8

List the specific clinical findings of Rickettsia rickettsii infection, aka (X) disease.

Answer 8

X = RMSF

Rash that starts on hands/feet (including palms/soles) and extends centrally; macular then progresses to petechiae.

Question 9

T/F: RMSF can be fatal if not treated within a month of symptom onset.

Answer 9

False - within 8 days of symptom onset!

Question 10

(X) is the causative agent for RMSF (Rocky Mountain Spotted Fever).

Answer 10

X = Rickettsia rickettsii

Question 11

(X) is the causative agent for Epidemic Typhus.

Answer 11

X = Rickettsia prowazekii

Question 12

Transmission of Rickettsia prowazekii to humans is via (X) vector and mammalian reservoirs are (Y).

Answer 12

X = lice
Y = humans

Question 13

T/F: Epidemic Typhus is not a real problem in the U.S.

Answer 13

True - in areas of poverty or refugee camps

Question 14

List the specific clinical findings of Rickettsia prowazekii infection, aka (X) disease.

Answer 14

X = Epidemic Typhus

Maculopapular rash (starts at trunk about 1 week after flu-like symptom onset); spreads peripherally (spares face, palms/soles) and becomes petechial

Question 15

(X) is the causative agent for Endemic Typhus.

Answer 15

X = Rickettsia typhi

Question 16

Transmission of Rickettsia typhi to humans is via (X) vector and mammalian reservoirs are (Y).

Answer 16

X = flea
Y = rodents

Question 17

T/F: Endemic Typhus is not a real problem in the U.S.

Answer 17

True - typically in travelers from Africa, Asia, South Europe

Question 18

T/F: Endemic and Epidemic Typhus have nearly identical clinical presentation.

Answer 18

False

Question 19

List the specific clinical findings of Rickettsia typhi infection, aka (X) disease.

Answer 19

X = Endemic Typhus

1. Potential rash development
2. GI/respiratory involvement; CNS involvement (45% of pts)

Question 20

T/F: Endemic Typhus can be fatal if not treated within a month of symptom onset.

Answer 20

False - uncomplicated course with full recovery; especially mild in children

Question 21

List first and second choice treatment for Rickettsial disease.

Answer 21

1. Tetracyclines (doxycyline)

2. Chloramphenicol

Question 22

Coxiella burnetii is a gram-(pos/neg) bacteria with which shape? Infection is associated with which disease?

Answer 22

Gram-neg
Coccobacillus;
Q Fever

Question 23

T/F: Coxiella burnetii is obligate intracellular parasite.

Answer 23

True

Question 24

Transmission of Coxiella burnetii to humans is via (X) vector and mammalian reservoirs are (Y).

Answer 24

X = no vector; via inhaling aerosolized material contaminated with urine, feces, placental tissue (or via drinking unpast. milk)
Y = cattle, sheep, goats

Question 25

T/F: 80% of Coxiella burnetii infections are asymptomatic.

Answer 25

False - about 50%

Question 26

Acute Q fever presents with (X) symptoms and, if untreated, usually progresses to:

Answer 26

X = flu-like (NO RASH) | Recovery (even without antibiotics); can take few months

Question 27

About 30-50% of patients with Q fever develop (X) and some even develop (Y).

Answer 27

``` X = pneumonia Y = hepatitis ```

Question 28

Small portion (5%) of patients develop chronic Q fever and present with (X), which has (Y)% mortality if untreated.

Answer 28

``` X = endocarditis Y = 40 ```

Question 29

T/F: Q fever isn't an important disease in the U.S.

Answer 29

False

Question 30

T/F: There are no vaccines available for Rickettsia or Coxiella burnetii.

Answer 30

False - ANIMAL vaccines for Coxiella burnetii exist

Question 31

Ehrlichia chaffeensis is the causative agent for (X) disease. It is gram-(pos/neg) and has which shape?

Answer 31

X = Human monocytic ehrlichiosis (HME) | Gram-neg, short rods ** NO pepditoglycan or LPS!

Question 32

T/F: Ehrlichia chaffeensis and Anaplasma phagocytophilum are obligate intracellular parasites.

Answer 32

True

Question 33

Transmission of Ehrlichia chaffeensis to humans is via (X) vector and mammalian reservoirs are (Y).

Answer 33

``` X = Lone Star Tick Y = humans ```

Question 34

A significant portion (50-90%) of patients with (X) zoonotic disease(s) present with leukopenia, thrombocytopenia, and elevated (Y).

Answer 34

``` X = HME (Human Monocytic Ehrlichiosis) and HGA (Human Granulocytic Anaplasmosis) Y = aminotransferases ```

Question 35

T/F: HME (Human Monocytic Ehrlichiosis) and HGA (Human Granulocytic Anaplasmosis) are rash-free.

Answer 35

False - 30% of patients with HME may present with rash

Question 36

T/F: HME (Human Monocytic Ehrlichiosis) and HGA (Human Granulocytic Anaplasmosis) are both treated with doxycycline.

Answer 36

True

Question 37

T/F: HME (Human Monocytic Ehrlichiosis) and HGA (Human Granulocytic Anaplasmosis) can be prevented via vaccination.

Answer 37

False - no vaccines; remain tick-free

Question 38

Anaplasma phagocytophilum is the causative agent for (X) disease. It is gram-(pos/neg) and has which shape?

Answer 38

X = Human granulocytic anaplasmosis (HGA) | Gram-neg, short rods ** NO pepditoglycan or LPS!

Question 39

T/F: Ehrlichia chaffeensis and Anaplasma phagocytophilum are not problematic in the U.S.

Answer 39

False

Question 40

(X) zoonotic bacteria form morulae during (intra/extra)-cellular replication.

Answer 40

X = Erhlichia (in monocytes) and Anaplasma (in granulocytes); Intracellular (within phagosomes)

Question 41

Zoonotic bac: About (X)% of patients with HME require hospitalization. And (Y)% of patients with HGA.

Answer 41

X = Y = 50

Question 42

T/F: Mortality rates from Erhlichia and Anaplasma infections (HME/HGA) are virtually negligible.

Answer 42

False.. HME: 2-3% HGA: about 1%

Question 43

T/F: Erhlichia and Anaplasma infections are more prevalent in young children, under 1 y.o.

Answer 43

False - among elderly

Question 44

Transmission of Anaplasma phagocytophilum to humans is via (X) vector and mammalian reservoirs are (Y).

Answer 44

``` X = Ixodes scapularis tick Y = humans, horses, dogs ```

Question 45

Causative agent for Lyme is (X). It's gram-(pos/neg) and what shape?

Answer 45

X = Borrelia burgdorferi Spirochete! No gram stain (seen in silver or Giemsa stains or darkfield microscopy) Irregular, loosely coiled

Question 46

Borrelia burgdorferi is transmitted to humans via (X) vector and the mammalian reservoir is (Y).

Answer 46

``` X = ticks (esp. Ixodes scapularis) Y = white-footed mouse (and to lesser extent white-tailed deer) ```

Question 47

Early, localized Lyme infection may have which clinical presentation?

Answer 47

1. Erythema migrans (80% of time), which is painless, circular/bullseye rash 2. Potential flu-like symptoms

Question 48

Early, disseminated Lyme infection may have which clinical presentation?

Answer 48

1. CV (carditis with AV block) | 2. CNS (meningoencephalitis, cranial neuropathies - Bell's Palsy, radiculitis, peripheral neuropathy)

Question 49

Late, disseminated Lyme infection may have which clinical presentation?

Answer 49

Arthritis (esp knee) and maybe subtle lyme encephalopathy or polyneuropathy

Question 50

T/F: All stages of Lyme are diagnosed via clinical presentation/patient history and serological tests.

Answer 50

False - serological tests not for classic erythema migrans (early, localized Lyme)

Question 51

First step of Lyme serological test is (X), to detect (Y).

Answer 51

``` X = ELISA Y = anti-B. burgdorferi Ab ```

Question 52

Second step of Lyme serological test is (X), to detect (Y).

Answer 52

``` X = Western blot Y = IgM and IgG against specific B. burgdorferi Ag ```

Question 53

Stage 1/mild Lyme treated with:

Answer 53

Oral doxycycline or ampicillin (short course)

Question 54

Late stage (severe), invasive Lyme treated with:

Answer 54

Ceftriaxone