Rickettsia

Lecture 18

Rickettsiales

The order ____________ is composed of two families:

* Anaplasmataceae
* Rickettsiaceae

anaplasmataceae

The order Rickettsiales is composed of two families:

* ______________
* Rickettsiaceae

rickettsiaceae

The order Rickettsiales is composed of two families:

* Anaplasmataceae
* _________________

small, pleomorphic, negative

Bacteria belonging to the order Rickettsiales are

* (SMALL/LARGE)
* (PLEOMORPHIC/UNIFORM)
* Gram-(POSITIVE/NEGATIVE)

true

(TRUE/FALSE): Rickettsia are obligate intracellular bacteria.

false

(TRUE/FALSE): Rickettsiales bacteria can be cultured on agar plates.

embryonated

Rickettsiales bacteria need to be cultured in

* yolk sac of _____________ eggs
* tissue culture cell lines

tissue culture

Rickettsiales bacteria need to be cultured in

* yolk sac of embryonated eggs
* __________ __________ cell lines

true

(TRUE/FALSE): Rickettsiales bacteria can be stained with Romanowsky based stains.

erythrocytes, endothelial cells

When looking for Rickettsiales bacteria on microscopy, you’re looking for infected ____________ or __________ _______

viruses, bacteria

Rickettsiales characteristics make them a sort of “intermediate” between ___________(obligate intracellular organisms) and __________ (use oxygen, susceptible to antibacterial drugs, possess cell walls),

orientia

There are two genera in the family Rickettsiaceae

* ________
* Rickettsia

Rickettsia

There are two genera in the family Rickettsiaceae

* Orientia
* _________

bite, feces

Infection with Rickettsiaceae occurs through arthropod ______ or arthropod _______ inoculation/inhalation.

reservoirs, arthropod

Rodents and small mammals act as _______ for Rickettsiaceae, while ____________ hosts transmit infection.

spotted fever, typhus

Genus Rickettsia can be broken into two groups

* ________ _______ group
* _________ group

Rickettsia

Genus ___________ can be broken into two groups

* Spotted Fever group
* Typhus group

true

(TRUE/FALSE): All diseases caused by genus Rickettsia can infect humans.

Rocky mountain spotted fever

R. rickettsii causes (ROCKY MOUNTAIN SPOTTED FEVER/CAT FLEA TYPHUS-LIKE INFECTION/MURINE TYPHUS)

cat flea typhus-like infection

R. felis causes (ROCKY MOUNTAIN SPOTTED FEVER/CAT FLEA TYPHUS-LIKE INFECTION/MURINE TYPHUS)

murine typhus

R. typhi causes (ROCKY MOUNTAIN SPOTTED FEVER/CAT FLEA TYPHUS-LIKE INFECTION/MURINE TYPHUS)

f

Cat fleas transmit

a. R. rickettsii

b. R. felis

c. R. typhi

d. all of the above

e. a + b

f. b + c

g. a + c

c

Rat fleas transmit

a. R. rickettsii

b. R. felis

c. R. typhi

d. all of the above

e. a + b

f. b + c

g. a + c

a

Ticks transmit

a. R. rickettsii

b. R. felis

c. R. typhi

d. all of the above

e. a + b

f. b + c

g. a + c

rickettsii

R. ____________ is transmitted by Dermacentor andersoni and Dermacentor variabilis.

rickettsemia

In the sylvatic cycle, rodents and small mammals develop high ____________ - making them important reservoirs of Rickettsia.

sylvatic

In the __________ cycle, rodents and small mammals develop high rickettsemia - making them important reservoirs of Rickettsia.

humans

Rocky Mountain Spotted Fever affects a range of hosts

* Small mammals/rodents
* sylvatic cycle
* Dogs and __________
* domestic cycle

dogs

Rocky Mountain Spotted Fever affects a range of hosts

* Small mammals/rodents
* sylvatic cycle
* ________ and humans
* domestic cycle

rickettsia rickettsii

This map shows the range of ticks that carry ___________ ____________, the agent of Rocky Mountain Spotted Fever.

Rocky mountain spotted fever

This map shows the range of ticks that carry Rickettsia rickettsii, the agent of:

rocky mountain spotted fever

Pathogenicity of ______ _______ ______ ______


1. endothelial cell damage
2. vasculitis
3. platelet activation
4. thrombocytopenia
5. DIC
6. necrosis

endothelial, vasculitis

Pathogenicity of Rocky Mountain Spotted Fever


1. __________ cell damage
2. __________
3. platelet activation
4. thrombocytopenia
5. DIC
6. necrosis

platelet, thrombocytopenia

Pathogenicity of Rocky Mountain Spotted Fever


1. endothelial cell damage
2. vasculitis
3. _________ activation
4. _________________
5. DIC
6. necrosis

DIC

Pathogenicity of Rocky Mountain Spotted Fever


1. endothelial cell damage
2. vasculitis
3. platelet activation
4. thrombocytopenia
5. ____
6. necrosis

necrosis

Pathogenicity of Rocky Mountain Spotted Fever


1. endothelial cell damage
2. vasculitis
3. platelet activation
4. thrombocytopenia
5. DIC
6. _________

rickettsia ricketsii

This flow chart outlines progression of disease caused by what bacteria?

rocky mountain spotted fever

A 4-year-old MN Brittany presents to your clinic in Idaho after a week-long hunting trip. He has a fever, depression, anorexia, SQ edema, petechiated mucosa, and myalgia. Owner reports removing a few ticks from his head and neck.

Your top differentials are canine ehrlichiosis and what other tick-borne disease?

Dermacentor andersoni

A 4-year-old MN Brittany presents to your clinic in Idaho after a week-long hunting trip. He has a fever, depression, anorexia, SQ edema, petechiated mucosa, and myalgia. Owner reports removing a few ticks from his head and neck.

The patient is diagnosed with Rocky Mountain Spotted Fever. What species of tick are you suspicious of as the vector?

Dermacentor variabilis

A 3-year-old F Rhodesian Ridgeback presents to your clinic in North Carolina after a week-long hunting trip. She has a fever, depression, anorexia, SQ edema, petechiated mucosa, and myalgia. Owner reports removing a few ticks from her head and neck.

The patient is diagnosed with Rocky Mountain Spotted Fever. What species of tick are you suspicious of as the vector?

Ctenocephalides felis

Cat flea typhus-like illness is caused by R. felis. The vector is believed to be ________________ ____________.

typhus-like illness

Cat Flea ____________ __________ involves two cycles:

* Opossums and fleas
* sylvatic cycle
* Cats and fleas
* domestic cycle

opossums, cats

Cat Flea Typhus-like illness involves two cycles:

* __________ and fleas
* sylvatic cycle
* _______ and fleas
* domestic cycle

non-specific

People affected by Cat Flea Typhus-like illness often have ____________ signs such as cutaneous flea bite reactions, fever, hyperesthesia, and myalgia, but also develop a more diagnostic maculopapular rash.

maculopapular rash

People affected by Cat Flea Typhus-like illness often have non-specific signs such as cutaneous flea bite reactions, fever, hyperesthesia, and myalgia, but also develop a more diagnostic _____________ ________.

typhi

R. _______ is spread by cat and rat fleas. Exposure occurs after inoculation of infected flea feces into a flea bite wound.

inoculation

R. typhi is spread by cat and rat fleas. Exposure occurs after ___________ of infected flea feces into a flea bite wound.

flea bite

R. typhi is spread by cat and rat fleas. Exposure occurs after inoculation of infected flea feces into a ______ _____ wound.

eschar

People affected by Murine typhus can be identified by the presence of __________ and lymphadenomegaly.

eschar

Stages of __________ - an important and early clinical feature of some rickettsial diseases.

Murine typhus

An owner brings her 6-year-old MN DSH into your clinic in southern Texas. She’s concerned about how itchy her cat has been lately. During the consult you note a lesion on her arm (pictured). What zoonotic bacterial infection are you concerned about?

Ctenocephalides felis

An owner brings her 2-year-old FS Bengal into your southern California clinic. She’s concerned about how itchy her cat has been lately. During the consult you note a lesion on her arm (pictured). What insect vector are you looking for?

cutaneous

Primary clinical signs of rickettsia are often __________ in human infections

serology

Rickettsial disease diagnosis

* clinical signs
* history of flea/tick exposure
* __________
* ELISA
* IFI
* Agglutination
* culture and isolation
* requires BSL 3 lab
* PCR
* may be negative on host
* useful on reservoirs and vectors

3

Rickettsial disease diagnosis

* clinical signs
* history of flea/tick exposure
* serology
* culture and isolation
* requires BSL __ lab
* PCR
* may be negative on host
* useful on reservoirs and vectors

host, reservoirs

Rickettsial disease diagnosis

* clinical signs
* history of flea/tick exposure
* serology
* culture and isolation
* requires BSL 3 lab
* PCR
* may be negative on _______
* useful on __________ and vectors

true

(TRUE/FALSE): Antibiotics are effective in treating Rickettsial diseases.

vector

Prevention of Rickettsial diseases mostly involves ________ control

serology

__________ is often used in diagnosis of Rickettsial diseases, but there is often cross-reactivity between species of the typhus group and SFG.

Rickettsiaceae, Anaplasmataceae

_____________ parasitize endothelial cells while ________________ parasitize leukocytes, erythrocytes, and platelets in addition to endothelial cells.

endothelial

Both Rickettsiaceae and Anaplasmataceae parasitize __________ cells.

Anaplasmataceae

Obligate intracellular aerobes lacking a glycolytic pathway and cell wall.

glycolytic, cell wall

Anaplasmataceae are obligate intracellular aerobes lacking a _____________ pathway and _______ ______.

hematopoietic

Anaplasmataceae inhabit ___________ cells of mammalian hosts.

morula

The thick black line is pointing to a __________, a cluster of bacteria commonly seen in Anaplasmataceae infections.

canine monocytic ehrlichiosis

A 5-year-old M medium-sized mixed-breed dog presents to your clinic in early June for nasal discharge. The owner removed a Brown Dog Tick (Rhipicephalus sanguineus) from him and is upset he hadn’t yet restarted flea/tick prevention.

The patient has a fever, generalized lymphadenopathy, and splenomegaly. Bloodwork shows thrombocytopenia and the following is seen on peripheral blood smear.

What condition are you concerned for?

anaplasma phagocytophilum

_____________ ______________ is the causative agent of granulocytic anaplasmosis that infects neutrophils (+/- eosinophils). It encapsulates a few species of bacteria formerly classified as separate - E. equi, E. phagocytophilia, and the HGE agent in humans.

granulocytic anaplasmosis

Anaplasma phagocytophilum is the causative agent of __________ ___________ that infects neutrophils (+/- eosinophils). It encapsulates a few species of bacteria formerly classified as separate - E. equi, E. phagocytophilia, and the HGE agent in humans.

migratory birds

Anaplasma phagocytophilum is known to be amplified by

phagocytophilum

A. _______________ is known to be amplified by migratory birds.

ixodes ticks

The vectors of Anaplasma phagocytophilum.

neutrophils

Anaplasma phagocytophilum impairs phagocytosis and bactericidal activities of _____________.

granulocytic

Clinical signs of ______________ anaplasmosis include fever and lethargy in both humans and domestic species, with additional signs of musculoskeletal pain and headache in humans.

musculoskeletal pain

Clinical signs of granulocytic anaplasmosis include fever and lethargy in both humans and domestic species, with additional signs of ___________ _________ and headache in humans.

granulocytic anaplasmosis

Differential diagnoses for a dog presenting with fever and lethargy after a bite from an Ixodes tick

* __________ ____________
* Lyme disease

Lyme disease

Differential diagnoses for a dog presenting with fever and lethargy after a bite from an Ixodes tick

* Granulocytic anaplasmosis
* _______ _________

True

(TRUE/FALSE): Granulocytic anaplasmosis can be self-limiting in humans and dogs.

DIC

Horses infected with granulocytic anaplasmosis can die rapidly due to ______.

Horses

_______ infected with Anaplasma phagocytophilum can suffer

* mild or subclinical limb edema
* ataxia
* DIC

edema, ataxia

Horses infected with Anaplasma phagocytophilum can suffer

* mild or subclinical limb ______
* _______
* DIC

Anaplasma platys

Causative agent of Canine Cyclic Thrombocytopenia. Transmitted by Rhipicephalus sanguineus.

Rhipicephalus sanguineus

Anaplasma platys causes Canine Cyclic Thrombocytopenia. It is transmitted by

true

(TRUE/FALSE): Dogs affected by canine cyclic thrombocytopenia are often asymptomatic.

platelets

Anaplasma platys enters _________, resulting in the formation of a morula.

1-2

Parasitemias and subsequent thrombocytopenic episodes caused by A. platys recur at ______ *(range)* week intervals

platys

Although many dogs infected with A. _____ are asymptomatic, acute infections can manifest as fever, petechia, and ecchymosis.

petechia

Although many dogs infected with A. platys are asymptomatic, acute infections can manifest as fever, ________, and ecchymosis.

ecchymosis

Although many dogs infected with A. platys are asymptomatic, acute infections can manifest as fever, petechia, and ____________.

anaplasma marginale

Causative agent of Bovine anaplasmosis. Transmitted by ticks, flies, and blood-contaminated fomites

false

(TRUE/FALSE): Bovine anaplasmosis is associated with age immunity.

true

(TRUE/FALSE): Bovine anaplasmosis is associated with reverse age immunity.

50

Mortality rate in naïve adult cattle infected with Bovine Anaplasmosis can reach ___%

adult

Mortality rate in naïve _________ cattle infected with Bovine Anaplasmosis can reach 50%

bovine anaplasmosis

Control measures for _________ ____________ are aimed at

* testing and removing carrier animals
* minimizing stress
* vaccination

carrier

Control measures for Bovine Anaplasmosis are aimed at

* testing and removing ________ animals
* minimizing stress
* vaccination

stress

Control measures for Bovine Anaplasmosis are aimed at

* testing and removing carrier animals
* minimizing ___________
* vaccination

vaccination

Control measures for Bovine Anaplasmosis are aimed at

* testing and removing carrier animals
* minimizing stress
* ____________

endemic

In areas where Anaplasma marginale is __________, some livestock management involve infecting all young animals so they are resistant to infection later in life.

Ehrlichia canis

_________ _______ is spread via Rhipicephalus sanguineus (the brown dog tick). Replication occurs in vacuoles which offer protection from the immune system.