8. small animal med- ehrlichiosis and anaplasmosis

what are ehrlichia and anaplasma?

-gram negative bacteria

-obligatory intracellular organisms

-ticke-borne diseases

which cells do ehrlichia and anaplasma prefer to live inside?

leukocytes and platelets

are ticks a true reservoir for ehrlichiosis and anaplasma?

no, they are not true reservoirs (ticks cannot transmit from one generation to the next, they have to bite an infected host to then transmit)

what are the canine diseases of ehrlichiosis?

canine monocytic

canine granulocytic

what are the canine diseases of anaplasmosis?

canine granulocytic

canine thrombocytic

what are the causative agents of canine monocytic ehrlichiosis?

ehrlichia canis

ehrlichia chaffeensis

ehrlichia muris eauclairensis

what is the causative agent of canine granulocytic ehrlichiosis?

ehrlichia ewingii

what is the vector for e. canis, e. chaffeensis, e. ewingii, e. muris eauclairensis?

e. canis: rhipicephalus linnaei

e. chaffeensis: amblyomma americanum

e. ewingii: amblyomma americanum

e. muris eauclairensis: ixodes scapularis

what is the causative agent of canine granulocytic anaplasmosis?

anaplasma phagocytophilum

what is the vector of granulocytic anaplasmosis?

ixodes scapualris and ixodes pacificus

will bite dogs, cats, horses, cows, humans

what is the causative agent of canine thrombocytic anaplasmosis?

anaplasma platys

what is the vector of canine thrombocytic anaplasmosis?

rhiphicephalus sanguineous

how do dogs become infected with monocytic ehrlichiosis?

via ticks:

-transstadial

-need an infected dog

-adult ticks can survive 2years

-ticks can transmit for at least 150 days

when does the acute phase of monocytic ehrlichiosis occur?

8-20 days post-infection

what are the clinical signs of the acute phase of monocytic ehrlichiosis?

lasts 2-4 weeks:

-non-specific signs

-mild thrombocytopenia, anemia, and leukopenia

when does the subclinical phase of monocytic ehrlichiosis occur?

40 days to several years

what are the clinical signs of the subclinical phase of monocytic ehrlichiosis?

usually no signs (if any, may have mild thrombocytopenia)

immunocompetent animals can elminate the organism (or not)- but after eliminating, the animal can/may be re-infected

what are the clinical signs of the chronic phase of monocytic ehrlichiosis?

-vague signs

-organ failure

-severe hematological changes (due to destruction of bone marrow)

what multisystemic signs are associated with monocytic ehrlichiosis?

-lethargy, weight loss

-superficial bleeding (from severe thrombocytopenia)

-lymphadenomegaly, splenomegaly

what neuromuscular signs are associated with monocytic ehrlichiosis?

-meningitis

-intracranial disease

-polymyositis

-polyarthritis

what ocular signs are associated with monocytic ehrlichiosis?

anterior uveitis

chorioretinitis

what other disease processes are associated with monocytic ehrlichiosis?

kidney failure

glomerulonephritis

myocarditis

what hemotologic changes occur in the acute phase of monocytic erhlichiosis?

-lymphocytosis (granular or not)

-thrombocytopenia

-anemia

-leukopenia

what hemotologic changes occur in the sub-acute phase of monocytic erhlichiosis?

thrombocytopenia (relative, not severe)

what hemotologic changes occur in the chronic phase of monocytic erhlichiosis?

severeb pancytopenia

what other laboratory changes (non-hematologic) are associated with monocytic ehrlichiosis?

-hyperglobulinemia (monoclonal or polyclonal)

-proteinuria (from glomerular dz)

-mast cell pleocytosis

how is monocytic ehrlichiosis diagnosed?

-clinical signs + serology

-blood smear (ID of morluae; low sensitivity)

-PCR

what is the challenge with using serology to diagnose monocytic ehrlichiosis?

-all ehrlichia can cross react

-can give false negatives if tested too soon (may take up to 28 days to seroconvert)

-false positives may indicate previous exposure (Ab may persist for over a year)

which diagnostic method is best for diagnosing monocytic ehrlichiosis?

PCR (can identify genus or species)---> ideal for conformation of infection

-especially uncommon species

can result in false-negative if receiving doxycycline (within 24 hrs of testing)

what is the therapy for monocytic ehrlichiosis?

doxycycline: 10mg/kg/day for 21-28 days

-less effective in the chronic phase

what is the prognosis for monocytic ehrlichiosis?

signs and thrombocytopenia improve in 48 hours

-therapy is less effective once in the chronic phase

how is monocytic ehrlichiosis prevented?

absolute tick control

is monocytic ehrlichiosis zoonotic?

e. canis: can infect humans, but may not cause disease

e. chaffeensis and e. muris: yes, zoonotic

how does monocytic ehrlichiosis caused by e. chaffeensis differ from ehrlichiosis caused by e. canis?

e. chaffeensis causes milder disease:

-fever

-anterior uveitis

-lymphadenomegaly

-vomiting

-epistaxis

-lab changes not as severe as e. canis

what are the clinical signs of granulocytic ehrlichiosis (caused by e. ewingii)?

causes a milder disease:

-lameness and joint edema

-no documented deaths

-seasonal (spring to late fall)

-zoonosis

when does granulocytic anaplasmosis occur?

seasonal (related to presence of ticks):

-midwest: may-june, october-november

what age of dogs are usually affected by granulocytic anaplasmosis?

50% of cases occur in dogs 6-8 years old

reactivation with immunosuppression

what are the clinical signs of granulocytic anaplasmosis?

-non-specific: fever, lethargy, anorexia

-musculoskeletal: pain, lameness, limb edema

-neurologic signs

-respiratory: cough, dyspnea

-no bleeding

-no chronic disease

how is granulocytic anaplasmosis diagnosed?

-clinical signs + morulae present in blood (sensitivity 36-100%)

-clinical signs + serology (4 fold increase)

-clinical signs + PCR

how can serology help diagnose granulocytic anaplasmosis?

clinical signs + serology:

-4 fold increase of decrease

-antibodies seen 2-5 days post-morulae

-antibodies persist 8-9 months

-40% of dogs are seronegative at time of presentation)

what is the therapy/prevention for granulocytic anaplasmosis?

similar to ehrlichia canis (doxycycline 10mg/kg/day for 21-28 days)

is granulocytic anaplasmosis zoonotic?

-yes, can cause human granulocytic anaplasmosis

-same vector as lyme disease (co-infection common)

-mortality <1%

-may occur from direct contact with blood

what disease occurs with thrombocytic anaplasmosis?

canine cyclic thrombocytopenia (caused by anaplasma platys)

how is thrombocytic anaplasmosis transmitted?

transovarial transmission in ticks

-may have vertical transmission if acquired during pregnancy

what are the clinical signs of thrombotic anaplasmosis?

-cyclic thrombocytopenia (crisis: 7-10 days in 1-2 weeks intervals)

-fever

-hematochezia

-superficial bleeding

-anterior uveitis

-weight loss

how is thrombocytic anaplasmosis diagnosed?

-ID of organism in platelets

-serology (dot-ELISA)

-PCR

how is thrombocytic anaplasmosis treated/prevented?

similar to e. canis (doxycycline 10mg/kg/day for 21-28 days)

is thrombocytic anaplasmosis zoonotic?

yes, humans can become infected, but unknown if it causes disease in humans