Test 3- RIckettsiales

Question 1

Generals

Answer 1

 Obligate intracellular Gram‐negative bacteria

 Bacteria within arthropods

 Family Anaplasmataceae

 Genus Anaplasma
 Survive in erythrocytes, phagocytes and platelets

 Genus Ehrlichia
 Survive in phagocytic cells

 Genus Neorickettsia
 Survive in macrophages and mononuclear cells

 Family Rickettsiaceae
 Rickettsiae (Survive in vascular epithelium)

 Genera Rickettsia, Wolbachia, Orientia

Question 2

Bacterial reclassification- Not super important

Answer 2

 Reorganized by sequence comparison of 16S rRNA gene

 α‐ Proteobacteria in the genera:  Neorickettsia
 Anaplasma
 Ehrlichia

Question 3

Genus Anaplasma

Answer 3

 Gram negative small coccoid – ellipsoid bacteria

 Live within cytoplasmic vacuoles of myeloid cells, neutrophils and erythrocytes- PROTECTS FROM IMMUNE SYSTEM

 Peripheral blood or tissues of mononuclear phagocyte organs

 May cause anemia, thrombocytopenia, leukopenia

 Single or in morulae (bacterial packets)

 Wright‐Giemsa (bluish purple)

 Anaplasma marginale

 Anaplasma centrale
 Anaplasma ovis
 Anaplasma bovis

Bovine anaplasmosis

 Formerly Ehrlichia bovis  Anaplasma platys

 Formerly Ehrlichia platys

 Anaplasma phagocytophilum
 Formerly Ehrlichia phagocytophilum, E. equi and E. phagocytophila

Question 4

Anaplasma marginale

Answer 4

 Reservoir and transmission

 Infected ruminants

 Wild (deer) and domestic species

 REPORTABLE DISEASES

 All continents
 Biologic transmission with hard ticks

Boophilus microplus

 Boophilus, Dermacentor, Ixodes and Rhipicephalus

 Mechanical transmission (less significant)

 Biting flies, contaminated fomites
 Contaminated instruments

Question 5

Pathogenesis of Bovine Anaplasmosis

Answer 5

 Clinical signs and pathological changes

 Subclinical to peracutely fatal presentations

 Mortalities of ~50% in cattle >3 years of age

 Persistent infection, undulating febrile disease

 Depression, anorexia, fever, anemia and icterus

 Long term carriage occur

ERTHOCYTES-THUS ANEMIA

Question 6

Bovine Anaplasmosis Immune Response

Answer 6

 Immune response
 Humoral and cell‐mediated response

 Antigenic variation present

 Msp2 gene
 Related to chronicity

 Antibody response is also directed to host antigens

 DESTRUCTION OF ERYTHROCYTES

 Immune response can be shared between other Anaplasma

 Anaplasma centrale

 Experimental vaccines are available but are not USDA approved

Question 7

Diagnosis of Bovine Anaplasmosis

Answer 7

 Diagnosis
 Routine blood stains, acridine orange or IFA

 Appear purple structures near periphery of erythrocytes in GIEMSA stains

 Molecular diagnosis

 Serological methods

 Complement fixation, capillary agglutination, ELISA  Useful in detecting subclinical cases

 Treatment and control
 Tetracyclines are pretty effective

 Vaccination and VECTOR CONTROL

Question 8

Answer 8

Anaplasma marginale in bovine erythocytes

Question 9

Anaplasma phagocytophilum

generals

Answer 9

 Human granulocytic anaplasmosis

 Tick borne fever

 Domesticated and wild ruminants

 Equine granulocytic anaplasmosis

dogs and horses

Question 10

Anaplasma phagocytophilium

reservior and transmission

Answer 10

 Reservoir and transmission

 Rodents and wildlife (deer)

 In North America
 East is mainly the white‐footed mouse and the deer tick (Ixodes

scapularis)
 West is mainly the western black‐legged tick (Ixodes pacificus)

Question 11

A. phagocytophilium causes, pathogenesis

Answer 11

 Causes tick‐borne fever primarily in ruminants (EUROPE) and in horses, dogs and humans in North America

 Pathogenesis associated with infection of neutrophils (primary) and eosinophils

 Tick pyemia (Staphylococcus infection) is commonly linked to tick‐borne fever

 Disease is mediated by the host immune response

Question 12

Clinical and Pathological Findings for A. phagocytophilium

Answer 12

 Clinically
 Fever, depression, inappetance, anemia, edema, ataxia,

icterus, drop in milk yield, abortions, and leukopenia

 Immunosuppressive effects

 Pathological findings

 Hepatitis, splenomegaly, arthritis, paracortical hyperplasia in lymph nodes

Question 13

A. phagocytophilium Vaccine and immunoaspects

Answer 13

 Immunological aspects

 Antigenic variability

 Major surface proteins (Msp2)

 Serological cross‐reactivity

 Ehrlichia spp, other Anaplasma spp

.  No vaccines

 Recovery with doxycycline therapy and adequate immune responses and tick control

Question 14

A. phagocytophliium diagnosis

Answer 14

 Laboratory diagnosis
 In GIEMSA or Wright’s stained blood smears

 Appear like membrane‐bound morulae (1‐10 bacteria) within neutrophils of ruminants, dogs, horses and humans

 Has been propagated in tick and human leukemic cell cultures

 Serological methods  IFA, ELISA

 Molecular methods  PCR

Question 15

A. platys

Answer 15

PLATLETS!

 Infectious canine cyclic thrombocytopenia

 Cycles of 1‐2 weeks interval

 Fever, lethargy, pale mucous membranes, petechial hemorrhages, epistaxis, and lymphadenopathy

 Co‐infections with Ehrlichia canis common

 Reservoir and transmission

 Rhipicephalus and Dermacentor ticks

 Laboratory diagnosis

 In GIEMSA stained blood smears
 A. platys in surface of canine platelets

 IFA, PCR

Question 16

Rickettsiae

Answer 16

 Small bacteria (0.5‐1 μm)

 Gram‐negative bacteria

 Better to stain with Gimenez (red), Macchiavello (red) or Giemsa (purple) stains

 Non‐motile bacteria

 Actin hijack inside cells

 Pathogenesis includes

 Enter endothelial cells by endocytosis

 Escape from phagosome and multiply in cytoplasm and nucleus  Associated with invertebrate vectors

 In veterinary medicine

 Rickettsia rickettsii

 Rickettsia felis
 Coxiella burnetii

Rocky mountain spotted fever Typhus group
Q fever

Question 17

Reserviors and Transmission for Rickettsia rickettsii

Answer 17

 Causative agent of Rocky Mountain Spotted Fever

 Reservoir and transmission

 Dogs and people in endemic areas
 Small mammals are though to be the major reservoir

 Carried naturally by ~20 species of ixodid ticks

 Dermacentor andersoni (Wood tick)

Wood tick

 D. variabilis (American dog tick)
 Transovarial and transtadial transmission- CAN GO FROM MOTHER TO EGGS

in ticks exist

American dog tick

 Mainly in Eastern North America  Seasonal incidence

Question 18

Pathogensis of Rickettsia rickettsii

Answer 18

 Tick
 Replicates in epithelium
 Transferred to salivary glands and ovarian tissues

 Vertebrate
 Ticks bites injects bacteria and targets vascular endothelium

 Endocytosed, escape phagosome and multiply in cell cytoplasm and nucleus

 Damage of endothelial cell membranes

 Rickettsial phospholipases and proteases

 Necrosis, vasculitis, hemorrhages, edema, thrombosis and dyspnea

 Rarely fatal but does occur
 Nervous system disturbances (~80% cases in dog)

 Heart and kidney involvement

Question 19

Clinical Signs of Rickettsia rickettssii

Answer 19

 Clinical signs
 High fever, anorexia, vomiting, diarrhea, petechiae or ecchymotic

mucous membranes, edema

 Tenderness over lymph nodes, joints and muscle

 Severe necrosis in extremities in dogs occur (severe fatal disease)

 Marked thrombocytopenia and leukopenia may be present during acute phase

Question 20

Immunological Aspects for Rickettsia rickettssii

Answer 20

 Immunologic aspects
 Auto immune reactions are related to pathogenesis in

late RMSF vascular manifestations
 Humoral and cell‐mediated response occurs

 CMI most important for removal of the pathogen

 No vaccines available for RMSF

Question 21

Lab Diagnosis of Rickettsia rickettiiss

Answer 21

 Culture

 Can be propagated in
 Yolk sacs of chick embryos
 Cell culture (VERO cells, endothelial cell lines)

 33‐35°C with a generation time of ~9h

 Need to have glutamate as nutrient

 Serological methods
 Immunofluorescence and ELISA commonly used

 Mainly detect circulating IgG
 Negative or low titers can be present early in the diseases

 Laboratory diagnosis

 Molecular diagnosis- Have to bx hemorrage sites because you can’t just pull blood
 PCR is now widely used and accepted  Very sensitive and specific
 Limitations of PCR

Question 22

Treatment and Control of Ricketsia Rickettsii

Answer 22

 Treatment and Control
 Susceptible to chloramphenicol, fluoroquinolones and

tetracyclines

 Dogs need aggressive supportive therapy and possibly steroids

 NEED TICK CONTROL

Question 23

Coxiella burnetii

Answer 23

Reservoir

 Worldwide

 Survives in environment
 Different from other related rickettsiae

 Have a endospore‐like growth phase

 Can be disseminated by airborne route - DOES NOT NEED A VECTOR

 Natural hosts and vectors include

 ~125 mammalian species
 Arthropods

 Ticks, mites, fleas, lice and flies

 Environmental persistence

Question 24

Transmission of Coxiella burnetti

Answer 24

 Transmission
 Human cases of Q‐fever can be traced to

 Sheep, cattle and goats
 Direct or via unpasteurized milk products, feces, sperm and

reproductive discharges
 Wind can carry “spore like stages”

 BIO‐WEAPON, REPORTABLE

 In humans

 Subclinical influenza like occupational diseases

 Farmers, abattoir workers, veterinarians

 Endocarditis in chronic presentations

Question 25

Pathogenesis of C. burnetti

Answer 25

 Mildly affected animals can have latent infection ** Persist particularly in lactating mammary gland and pregnant uterus** _ Shedding of bacteria occurs during pregnancy_  Activated during parturition  Sporadic aborts occur  Pathological changes  Severe vasculitis, placentitis, splenomegaly, mild hepatitis, fever **ENDOTHELIUM and RESPIRATORY**

Question 26

Immunologic Aspects of C. burnetti

Answer 26

 Vaccine is available in some countries for at risk people  Uses the avirulent phase II  Has altered LPS and are killed by macrophages  Whole cell killed vaccine to researchers  Coxevac (France) vaccine for small ruminants  Phase I vaccine containing inactivated C. burnetii strain Nine Mile  Two antigenic phases, Phase 1 and Phase 2  Phase 2 antibodies are indicative of acute infection Antibodies to Phase 1 indicative of chronic infection

Question 27

Lab Diagnosis of C. burnetti

Answer 27

 Tissue stains  Gimenez, Giemsa, modified Ziehl Neelsen  Doesn’t differentiate between Coxiella and Chlamydophila psittaci  Isolation in cell culture or embryonated eggs  Serological methods  IFA, ELISA and others  Molecular diagnosis  PCR

Question 28

Treatment and Control of C. burnetti

Answer 28

Treatment and Control  Major challenge  Antimicrobials are not effective in the acidic phagosome where C. burnetii resides ** Need to add alkalinizing agents**  Chloroquine + Tetracycline  Chloramphenicol, clarithromycin, enrofloxacin and trimethoprim‐sulfa

Question 29

Ehrlichiae

Answer 29

 White blood cell obligate intracellular bacteria  Multiply within membrane‐lined intracytoplasmic vesicles

Question 30

Ehrlichiae canis

Answer 30

Reservoir and transmission  Agent of **CANINE MONOCYTIC EHRLICHIOSIS**  Only few cases of human monocytic ehrlichiosis due to E. canis  Brown dog tick (Rhipicephalus sanguineus)  Obtain the bacteria from infected dogs only during acute diseases (~2 weeks)  Dog can remain infected for years, despite therapy  Puppies and particular breeds are more susceptible  All continents (except Australia, low to no cases)  Tropical and subtropical latitudes

Question 31

Ehrlichiae canis Pathogenesis

Answer 31

monocytes live longer, so it can be CHRONIC subclinical infections usually

Question 32

Acute and Chronic Diseases of E. canis

Answer 32

 Acute diseases  Fever, malaise, depression, inappetance, weight loss, pale mucous membranes, lymphadenopathy, epistaxis  Thrombocytopenia, leukopenia and anemia (pancytopenia)  Chronic diseases  Dyspnea, enlargement of spleen, lymph nodes and liver  Polyarthritis, CNS disturbances and pulmonary infiltration  Secondary infections

Question 33

E. canis Immunological aspects

Answer 33

 Immunological aspects  Progression to the latent and chronic occurs mainly in dogs with genetic predisposition and possibly impaired cell‐ mediated immunity  Latent infections may reside in spleen, liver, bone marrow  Not known at this time  Cellular and humoral immune‐mediated response to infected mononuclear cells and platelets contribute to:  Blood cell destruction  Bone marrow depression  Polyarthritis  Uveitis  Immune complex deposition possible

Question 34

Lab Diagnosis of E. canis

Answer 34

 Laboratory diagnosis  Giemsa‐stained smears of buffy coat  Colonies (morulae) less than 4 μm in diameter are demonstrable  Scarce and found mainly during acute stage  Canine cell lines can be used for culture and isolation  Serology  IFA  Molecular  PCR

Question 35

E. chaffeenis

Answer 35

E. chaffeensis ** Human monocytic ehrlichiosis**  Closely related to E. canis  Its vector is Dermacentor variabilis (American dog tick)  Mammalian reservoir is the deer

Question 36

E. ewingii

Answer 36

E. ewingii  Agent of canine granulocytic ehrlichiosis  Amblyoma americanum _(Lone star tick)_  Mainly in central North America  Similar disease to A. phagocytophilum infection

Question 37

Treatment and Control of E. canis, ewingii and chaffeenis

Answer 37

 Treatment and Control  Tetracyclines and imidocarb dipropionate  Mainly in acute cases  Less so in advanced cases  Doxycycline and steroids  Late‐stage monocytic ehrlichiosis  POOR PROGNOSIS PREVENTION  Tick control

Question 38

African heartwater

Answer 38

Ehrlichia ruminantium causative agent ** REPORTABLE DISEASE**  Mainly in ruminants in Africa and parts of the Caribbean  Passed only by parenteral introduction to the blood  Tick vector is Amblyomma spp.  Replicates in reticuloendothelial cells  Macrophages, endothelial cells, and neutrophils

Question 39

Pathogenesis of African heartwater

Answer 39

CS; edema, and likes to go to pericardium can see NS signs

Question 40

Acute, Subclinical, and Percute CS of African Heartwater

Answer 40

_ Peracute form_  Fever of several hours  Collapse and death under convulsion _ Acute form- Very common_  Fever followed by neurological signs  Hyperexitability, muscle tremors, ataxia, deficit in conscious proprioception, head pressing, coma and seizures  Death within 2‐10 days  Mortality 6‐80% _ Subclinical form is also described_  Hydropericardium, hydrothorax, congestion  Splenomegaly and extensive hemorrhages

Question 41

Pathological Findings of African heartwater

Answer 41

Widespread vasculitis with effusion  Epithelial and endothelial hemorrhages  _Pericardial effusion_ and encephalitis can occur  Enlarged spleen, liver and lymph nodes  Bone marrow depression

Question 42

What is one of the findings on necropsy from african heartwater?

Answer 42

hemorraghic lesions in muliple organs

Question 43

Immunological and Lab diagnosis of E. ruminantium

Answer 43

 Immunologic aspects  Some cattle breeds and newborns appear to be resistant  In surviving cattle, cell‐mediated immunity persists for up to 5 years (unless a different isolate)  Laboratory diagnosis  Demonstration of agent in Giemsa‐stained smears  Molecular and serological diagnosis

Question 44

Treatment and Prevention of E. ruminantium

Answer 44

Treatment  Tetracycline Effective if early during diseases presentations  Prevention Tick control and vaccination are important  Young calves and lambs are vaccinated with virulent bacteria  Older cattle infected & immediately treated

Question 45

Generals for Neorickettsia

Answer 45

 Small, non‐motile, coccoid, intracytoplasmic  Found within vacuoles of monocytes, macrophages and enterocytes  Gram‐negative bacteria  Stain readily with Macchiavello and Giemsa stain  Cannot be cultivated in cell‐free media or chicken embryos  Fluke serve as vectors  All stages within the life cycle of fluke are infectious

Question 46

Salmon posioning disease

Answer 46

 Caused by Neorickettsia helminthoeca in Pacific Northwest coast  Range of the snail intermediate  Elokomin fluke fever is a mild form of salmon poisoning disease  Infects lymphoreticular tissues of canids (LN, Peyers patches)  Target cell are the canine mononuclear cells  Multiplies in cytoplasm, frequently forming multiple morulae and filling the entire cell  Infects dogs after ingestion of fluke (Nanophyetus salmincola)  Neorickettsia helminthoeca is maintained by transovarial passage in the helminth  Found throughout the life cycle of the fluke  INCLUDING FREE‐SWIMMING CERCARIA encysted in salmonid fish

Question 47

Host of salmon posioning and pathogenesis

Answer 47

 Generally only members of family Canidae  Reported in captive polar bears and raccoons

Question 48

Acute diseases - salmon poisioning

Answer 48

 Acute diseases  Fever, depression, dehydration, anorexia, vomiting, weight loss, hemorrhagic diarrhea, and lymphadenopathy  From proliferation of reticuloendothelial components  Case fatality high in untreated dogs  Recovered animals are immune to re‐infection

Question 49

Diagnosis and Prevention of Salmon Poisioning

Answer 49

 Diagnosis  Detection of fluke eggs in feces, history, clinical signs, LOCATION  Organism in lymph node aspirates  Has been propagated in cell culture media  Serology/molecular  IFA, can be unreliable, PCR best  Differential Diagnosis  Canine Parvovirus 2 and canine distemper  Prevention  Not allow dogs to eat raw fish  Sick animals  Supportive care  Control vomiting and diarrhea  Maintain acid‐base balance  Tetracycline, penicillin G, chloramphenicol and sulfonamides  No vaccine

Question 50

Potomac Horse Fever

Answer 50

 Also known as:  Equine monocytic ehrlichiosis  Equine scours  Acute diarrheic illness of equids  Caused by Neorickettsia (Ehrlichia) risticii  Affinity for blood monocytes, tissue macrophages, and intestinal epithelial cells

Question 51

Epidemelogy of Potomac Horse Fever

Answer 51

 Very little is known  US, Canada, South America  Serological Europe, Asia and Australia  Proximity to bodies of water  Seasonal pattern  Mainly summer  Very little is known  US, Canada, South America  Serological Europe, Asia and Australia  Proximity to bodies of water  Seasonal pattern  Mainly summer  Infectious life cycle involves an intermediate snail reservoir and trematode cercaria  Aquatic insects also suspected, mayflies

Question 52

Potomac Horse Fever Clinical Signs

Answer 52

 Primary clinical sign is acute, watery diarrhea  Fever, anorexia, mild colic, depression, dehydration, laminitis and leukopenia  Case fatality is 5‐30%  Enterocyte infection with loss of microvilli and malabsorption of sodium and chloride ions and lack of water resorption  DIARRHEA

Question 53

Dx and Tx of Potomac Horse Fever

Answer 53

 Diagnosis  History  Wright‐stained blood smears  Not reliable  Serology ‐ unreliable  IFA, ELISA  Molecular detection  PCR  Treatment  Available vaccine is questionable  Heterogeneity among isolates  Deficiency in antibody response  IV administration of tetracycline or oxytetracycline early in the course of diseases

Question 54

Aeyptianosis

Answer 54

 Diseases caused by Aegyptianella pullorum  Affects poultry and wild birds  Vector are tick of genus Argus  Present with ruffled feathers, anorexia, diarrhea, anemia and hyperthermia  Lesions include hepatosplenomegaly and punctiform hemorrhages of serosal surfaces  Treatment with tetracyclines  Control of ticks is important

Question 55

Salmoning poisiong and potmac horse fever cause....

Answer 55

GI SIGNS