Rickettsia, Orientia, Ehrlichia, Anaplasma and Coxiella

Question 1

Rickettsia rickettsii causes what disease

Answer 1

Rocky Mountain Spotted Fever

Question 2

characteristics of Rickettsia, Orientia, Ehrlichia, Anaplasma and Coxiella

Answer 2

• Small rods
• Gram negative (don’t stain well ) (Giemsa)
• Typical morphology of a gram-negative -LPS, peptidoglycan missing in some
• No flagella

Question 3

Growth and metabolism of Rickettsia, Orientia, Ehrlichia, Anaplasma and Coxiella

Answer 3

Division occurs through binary fission
Growth is slow 8-10 h
Obligate intracellular pathogens

Use host ATP, coenzyme A, nicotinamide adenine dinucleotide and available amino acids

Question 4

how do bacteria enter the host

Answer 4

Bacteria enter by endocytosis:
Energy-requiring
Bacteria initially in a membrane-bound vesicle

Question 5

where do the bacteria replicate

Answer 5

either:
1. *Cytoplasmic vesicle (membrane-bound)
Phagosome (Ehrlichia, Anaplasma)
Phagolysosome-like vesicle (Coxiella)

2. *Cytoplasm
   (Rickettsia, Orientia)

Question 6

lysosome fusion has what effects on : Ehrlichia, Anaplasma and coxiella

Answer 6

Ehrlichia, Anaplasma: Killed if lysosomes fuse with phagosome, Prevents lysosomal fusion

Coxiella: CCV (Coxiella-containing vesicle) Phagosome fuses with endosomes
Requires low pH for growth
Delayed lysosomal fusion

Question 7

symptoms of RMSF

Answer 7

High fever and severe headache
Rash ( Macular rash, initially involving the extremities may become petechial later on) , mental confusion, and myalgia (sore muscles)

Incubation period : 2 to 7 days, but may be upwards of two weeks

Question 8

RMSF epidemiology

Answer 8

Transmitted by hard tick vectors
Associated with exposure to wooded areas where ticks exist – more common in summer months

most common in North Carolina and Oklahoma

Question 9

treatment of RMSF

Answer 9

** Tetracyclines, fluoroquinolones
Chloramphenicol: higher relapse
Delayed treatment: increased likelihood of death
10-25% mortality if untreated

Question 10

Prevention of RMSF

Answer 10

No vaccine
• Avoidance or reduction of tick contact
	Transmission requires 24-48 h exposure
• Control is virtually impossible
	 Non-feeding ticks survive as long as 4 years

Question 11

R. rickettsii is what kind of pathogen

Answer 11

• Intracellular, replicates in cytoplasm and spreads via actin polymerization
• Most common rickettsial pathogen in US

Question 12

Rickettsialpox is caused by

Answer 12

Rickettsia akari

Question 13

Rickettsialpox: phase 1

Answer 13

Phase 1: Firm red papule at the site of the bite
Develops into vesicle, then a black eschar
Bacteria spread

Question 14

Rickettsialpox: phase 2

Answer 14

Phase 2: 9-14 days: high fever, severe headache, chills/sweats, myalgias, photophobia, vesicular rash develops

Self-limiting after 1 week; no deaths have been reported

Question 15

Rickettsialpox is spread by

Answer 15

Vector is bloodsucking mites, found on mice
Transovarian transmission occurs
Northern USA, Russia, Africa, and Korea

Question 16

Transovarial transmission

Answer 16

when arthropods transmit disease-causing bacteria from parent arthropod to offspring arthropod. It allows the disease to remain in the host for generations

Question 17

Epidemic typhus is caused by

Answer 17

Rickettsia prowazekii

Question 18

epidemic typhus symptoms

Answer 18

Fever, headache and myalgias begin 1 to 2 weeks after exposure

Maculopapular rash
Flat red area covered with bumps
First on the trunk** and then spreads to the extremities

more fatal in pts over 40 y/o

Question 19

maculopapular rash

Answer 19

• is a type of rash characterized by a flat, red area on the skin that is covered with small confluent bumps.

The term “maculopapular” is a compound: macules are small, flat discolored spots on the surface of the skin; and papules are small, raised bumps. It is also described as erythematous, or red.

Question 20

epidemiology of Epidemic typhus

Answer 20

• Present in Central, South America, Africa

* Disease associated with unsanitary conditions; peaks in winter

Question 21

Epidemic typhus vector and resevoir

Answer 21

Transmission by body louse - Organisms are present in the feces of the infected lice (lice die after 2-3 weeks therefore no transvarian transmission)

Reservoirs include humans and flying squirrels

Question 22

treatment of Epidemic typhus

Answer 22

Tetracycline or chloramphenicol

Louse control

Vaccine available for high risk population

Question 23

Brill-Zinsser

Answer 23

aka Recrudescent Typhus or Brill’s disease

Relapse of louse-borne typhus
Appears 10-40 years after the primary attack

Milder and less often fatal
Partial immunity may still be present

Rickettsia persist for many years in the lymph nodes

Humans themselves are thus the reservoir

Question 24

R. prowazekii characteristics

Answer 24

Intracellular, replicates in cytoplasm, no actin polymerization

Question 25

Murine Typhus (Endemic Typhus) is caused by

Answer 25

R. typhi

Question 26

murine typhus vectors and resevoirs

Answer 26

Rat flea, cat flea vectors Rodents are reservoirs 50-100 cases annually in U.S. Found in temperate and subtropical coastal areas (texas, hawaii)

Question 27

murine typhus is treated with

Answer 27

Tetracycline, doxycycline, chloramphenicol

Question 28

murine typhus symptoms

Answer 28

Incubation period 1-2 weeks Abrupt fever, severe headache, chills, myalgia, nausea Rash in 50% of cases—late--maculopapular on trunk

Question 29

Scrub Typhus cause

Answer 29

Orientia tsutsugamushi

Question 30

scrub typhus symptoms

Answer 30

Fever, headache, maculopapular rash after 5 days, lymphadenopathy 50 to 80% develop initial lesion: Necrotic eschar at site of bite

Question 31

scrub typhus epidemiology

Answer 31

Found in the Far East (Southwest Pacific, Southeast Asia, and Japan) Mites are the vectors and reservoir. Passaged to progeny via infected ova.

Question 32

scrub typhus treatment

Answer 32

Fever responds to tetracycline, doxycycline or chloramphenicol Untreated: fever disappears within 2-3 weeks

Question 33

Ehrlichiosis two diseases

Answer 33

Human anaplasmosis (HA): Anaplasma phagocytophilum Ehrlichia ewingii Human monocyte ehrlichiosis (HME)-- Ehrlichia chaffeensis

Question 34

common symptoms of HA and HME

Answer 34

both: flu-like illness, high fever, headache, myalgias. onset 1-2 weeks after tick bite Leukopenia, thrombocytopenia, and elevated serum transaminases develop in majority of patients Mortality low but >50% require hospitalization

Question 35

differences between HA and HME

Answer 35

HME - sometimes late onset rash, primarily monocytes, mononuclear phagocytes HA: granulocytes primarily infected (neutrophils, eosinohils, basophils)

Question 36

common areas of Ehrlichiosis:

Answer 36

Most common in the summer Most common in Midwest, south states HME: Midwest, coastal Atlantic HA: Upper midwest, northeast Atlantic

Question 37

Ehrlichiosis is spread by

Answer 37

Transmitted by ticks: Lone star, western black legged ticks (deer and mice reservoirs) Transovarial transmission inefficient Transmission within about 6 hours

Question 38

Ehrlichiae structure

Answer 38

lack peptidoglycan and LPS 2 morphologic forms: small elementary bodies and larger reticulate bodies. Elementary bodies assemble morulae Prevent lysosomal fusion, Growth until cell lysis

Question 39

Ehrlichiae treatment

Answer 39

Doxycycline should be used Rifampin: pregnant women Chloramphenicol, penicillins, macrolides not effective Vaccines not available

Question 40

Q-Fever is caused by

Answer 40

Coxiella burnetii

Question 41

Q-fever symptoms

Answer 41

• Most human infections are NOT apparent: No rash • A mild, dry, hacking cough and pneumonia sometimes present. • 9 to 20 days: abrupt onset of fever, chills, and headache. • Chronic Q fever: subacute endocarditis Fatalities are rare

Question 42

Q-fever transmission

Answer 42

* Transmission from animals to humans by inhalation of dust * Carried by mammals such as cattle, sheep, and goats * World-wide distribution

Question 43

Q-fever phase 1 and 2

Answer 43

Phase I: intact LPS | Phase II: missing outermost O-antigen of LPS

Question 44

Treatment and prevention of Q-fever

Answer 44

* Tetracycline (doxycycline) or combination for chronic infections * Vaccines have been developed--for unexposed