Infectious Dz - Blood Borne 2 Flashcards
What are hemotropic mycoplasmas also known as?
Haemobartonellosis
Where do hemotropic mycoplasmas reside?
on the RBC surface
What causes haemobartonellosis in cats?
Mycoplasma haemofelis, Candidatus mycoplasma haemominutum, and Candidatus mycoplasma turicensus
What is the most pathogenic cause of haemobartonellosis in cats?
Mycoplasma haemofelis
What does Mycoplasma haemofelis cause in immunocompetent cats?
moderate to severe hemolytic anemia
What causes feline infectious anemia?
Mycoplasma haemofelis
What is infection with hemoplasmas associated with in cats (risk factors)?
the male sex, nonpedigree status, and outdoor access
What causes haemobartonellosis in dogs?
Mycoplasma haemocanis and Candidatus mycoplasma haematoparvum
True or False: Clinical disease of Haemobartonellosis is more common in dogs.
False - it is more common in cats
How are hemotropic Mycoplasmas transmitted?
Not entirely known - fleas and other arthropod vectors, biting (blood exchange not just saliva), and blood transfusions
When does anemia occur post infection of Mycoplasma haemofelis?
2-34 days after infection
What occurs in the acute phase of M. haemofelis infection?
Extravascular hemolysis
What causes the anemia in the acute phase of M. haemofelis infection?
It is caused by erythrocyte bound antibodies leading to extravascular hemolysis
If the acute phase of M. haemofelis infection is not treated, what is the mortality rate?
1/3 of cats will die
True or False: Cats can be chronically infected with M. haemofelis even though they have recovered from their illness.
True
What are the clinical signs of M. haemofelis infection?
Lethargy, inappetence, pallor, weakness, weight loss, and dehydration
If anemia develops rapidly in patients with infection of M. haemofelis, what clinical signs will be present?
Vocalize, collapse, neurologic signs, and death
What will a patient show in physical examination when infected with M. haemofelis?
Fever, weakness, pallor, tachypnea, and tachycardia
What will a CBC show in actively infected M. haemofelis patients?
regenerative anemia (reticulocytosis, macrocytosis, nucleated RBCs, polychromasia, hypochromasia) and the blood may autoagglutinate
What will a chemistry show in actively infected M. haemofelis patients?
Increased ALT from hypoxia, mild to moderate hyperbilirubinemia, prerenal azotemia, and hyperproteinemia
What will a UA show in patients with M. haemofelis?
+/- bilirubinuria
How can Haemobartonellosis be diagnosed?
Cytology and PCR
What is the test of choice for diagnosing Haemobartonellosis?
PCR
If a cat tests positive for M. haemominutum or M. turicensus on PCR and has anemia, what should be done next?
You should look for alternate causes of anemia because these agents are unlikely to cause anemia
When should Haemobartonellosis be treated?
When clinical signs and lab abnormalities are consistent with hemoplasmosis
What can be used to treat Haemobartonellosis?
Doxycycline (tx of choice). Marbofloxacin, and Pradofloxacin as well as supportive care
What supportive care should be given to patients with Haemobartonellosis?
IV fluids, blood transfusions, +/- glucocorticoid to suppress associated immune-mediated hemolytic process
How is Haemobartonellosis prevented?
Keep cats indoors, flea and tick control, and screen blood donors
Which of the following should make you question your diagnosis of anemia due to hemotropic Mycoplasma in a 2 YO MC DSH cat?
a. The cats anemia resolved with doxycycline therapy
b. The cat is FeLV/FIV negative
c. The cat lives in a multicat household and none of the other cats are sick
d. The cat’s blood is autoagglutinating
e. Your PCR comes back as positive for M. haemominutum, but negative for M. haemofelis and M. turicensis
e. Your PCR comes back as positive for M. haemominutum, but negative for M. haemofelis and M. turicensis
What structures do Erlichia species create in their infected hosts?
morulae (bacterial cluster) within phagosomes of circulating leukocytes
What does Ehrlichia canis infect and what does it cause?
monocytes causing canine monocytic ehrlichiosis
What does Ehrlichia ewingii infect and what does it cause?
Infects granulocytes causing canine granulocytic ehrlichiosis
What does Ehrlichia chaffeensis infect and what does it cause?
It causes human monocytic ehrlichiosis, dogs are the reservoir for this organism
What transmits E. canis?
Rhipicephalus sanguineus Just know ticks
What transmits E. ewingii and E. chaffeensis?
Ambylomma americanum Just know ticks
How do ticks pick up E. canis?
Tick larvae or nymphs acquire infection when they feed on infected dogs and it is transmitted transstadially within the tick
What classifications of disease does Canine Monocytic Ehrlichiosis present as?
Acute, subclinical, and chronic
When does acute Canine Monocytic Ehrlichiosis present?
Within 1-4 weeks post infection
What mechanisms are important in disease pathogenesis of acute Canine Monocytic Ehrlichiosis?
immune-mediated mechanisms
What clinical signs are associated with acute Canine Monocytic Ehrlichiosis (CME)?
Lethargy, inappetence, fever, weight loss, lymphadenopathy, splenomegaly, petechial/ecchymotic hemorrhages, neurologic signs
What causes the lymphadenopathy and splenomegaly in acute CME cases?
The replication of E. canis in reticuloendothelial tissues
What causes the petechial ecchymotic hemorrhages in acute CME cases?
thrombocytopenia and platelet dysfunction from immune-mediated platelet attack
What happens in subclinical cases of CME?
The organism is sequestered in the spleen allowing it to avoid host immune system via antigenic variation
What CBC changes are associated with subclinical CME?
Only platelet counts may be subnormal
What disease process is associated with chronic CME?
pancytopenia
What clinical signs are associated with chronic CME?
Fever, lethargy, inappetance, bleeding tendencies, weight loss, and vision change
What will you find on a PE of a patient with ehrlichiosis?
lethargy, fever, peripheral lymphadenopathy, splenomegaly, mucosal petechial hemorrhages, epistaxis, neurological signs, ocular abnormalities, and thin and muscle atrophy in chronic ehrlichiosis
What will you find on CBC in acute cases of CME?
thrombocytopenia and non regenerative anemia (Reticulocytosis, microcytosis, normocytic, normochromia)
What will you find on CBC in chronic cases of CME?
Pancytopenia with nonregenerative anemia and thrombocytopenia
What will you find on a chemistry in patients with CME?
hypoalbuminemia, hyperglobulinemia (usually polyclonal), +/- elevated ALT and ALP
What irregularity may you seen on a UA in patients with CME?
+/- proteinuria
How is CME diagnosed?
Serology (IFA or ELISA snap test) and PCR
True or False: Positive initial serum antibody titer reflects active ehrlichial disease.
False - it may reflect previous exposure and not ehrlichial disease so it is important to retest 3-4 weeks later to demonstrate seroconversion
What do you do if you find incidental Ehrlichia positive in a dog you were just testing for heartworm?
Thorough PE and lab testing to look for signs of CME Only a positive SNAP plus clinical signs supports an ehrlichia diagnosis
What if a sick dog tests positive for Ehrlichia on a SNAP 4Dx test?
Perform quantitative serologic testing so a titer can be obtained as a baseline for acute and convalescent serologic testing
What stage of disease is PCR better than serology in diagnosing Ehrlichia?
It is more sensitive for early diagnosis of CME than serology in acute disease cases because there is not enough time for antibody production for serology to detect
When is serology better than PCR in diagnosing Ehrlichia?
In chronic CME because there are low circulating organism numbers
What ‘test’ is very important in diagnosing Ehrlichia?
Resolution of clinical signs in response to therapy
What is the treatment of choice for CME?
Doxycycline and supportive cares as needed
How quick does improvement occur once treatment has started in patients with acute CME?
in 24-48 hours
Do dogs with chronic CME always respond to treatment?
Dogs with severe chronic CME may not respond to treatment or cytopenias may resolve over several months
How is CME prevented?
avoid tick infested areas, remove ticks early if infected with ticks, ectoparasiticides, and screen blood donors
Bear is a 4 YO MC Flatcoat retriever that has presented for acute epistaxis. He recently moved to Iowa from Puerto Rico. On PE you discovered epistaxis and a mild fever of 103.0 F. He has thrombocytopenia, a PCV of 27%, and he has 20,000 reticulocytes (low). He is 4Dx Ehrlichia SNAP positive. What do you want to do next for Bear?
a. Start treating with doxycycline
b. Euthanize because Ehrlichia has a terrible prognosis
c. Send of a tick panel for Ehrlichia PCR and serology, and to look for other co-infections
d. Transfuse with pRBCs because he is anemic
a and c
What is the reservoir for E. ewingii?
White-tailed deer
What form of disease does E. ewingii cause?
acute only
Where does E. ewingii replicate?
in the neutrophil delaying neutrophil apoptosis
What clinical signs do patients with E. ewingii infections have?
No signs to fever, lethargy, anorexia, and neutrophilic polyarthritis
How is E. ewingii diagnosed?
4Dx SNAP test or PCR
How is E. ewingii infection treated?
Doxycycline
What causes canine granulocytic anaplasmosis?
Anaplasma phagocytophilum - infects neutrophils
What causes canine thrombocytic anaplasmosis?
Anaplasma platys
What is the pathogenesis of Canine granulocytic anaplasmosis (CGA) infection?
Once transmitted by a tick, it enters the blood stream, attaches to ligands on the surface of neutrophils. It then enters the neutrophils via endocytosis. The organism survives the harsh neutrophil environment by bypassing phagolysosome pathways and dysregulating neutrophil function.
What clinical signs are associated with CGA?
A vast majority have no clinical signs! But some can be a self-limiting febrile illness, lethargy, fever, inappetence, lameness, and sometimes GI signs (vomiting +/- diarrhea)
What will you find on a PE in a patient with CGA?
Fever of up to 106.7 F, lymphadenopathy, splenomegaly, +/- lameness
What will you find on a CBC in patients with CGA?
Thrombocytopenia, mild nonregenerative anemia, and morulae within granulocytes
What will you find on Chemistry in patients with CGA? UA? Synovial fluid analysis?
Chemistry - mild to moderate hypoalbuminemia Urinalysis - proteinuria Synovial fluid analysis - Neutrophilic polyarthritis +/- morulae
How is CGA diagnosed?
Serology (IFA and SNAP 4Dx) and PCR
What test do you want to do when diagnosing CGA early on?
PCR
Do positive results imply CGA is the cause of illness? Negative results?
No Negative results also don’t imply anything because it can be negative in early stages of disease
Since a positive IFA titer can reflect exposure of A. phagocytophilum, what must the results be to indicate Anaplasma is the cause of the disease?
fourfold rise in titer
What is the treatment of choice for CGA?
Doxycycline
What is the prognosis for CGA?
Excellent - in 24-48 hours most dogs clinically improve and platelet counts normalize in 2-14 days
What does A. platys cause?
canine cyclic thrombocytopenia
Are there clinical signs associated with A. platys infections?
No, it causes thrombocytopenia without other clinical signs
How is A. platys infection diagnosed? Treatment?
Diagnosed by seeing morulae in platelets or via PCR Treated with Doxycycline
Do cats get anaplasmosis?
Yes, clinical signs appear similar to those in dogs. It should be considered when more common causes of disease are not apparent
Moses is an 8 YO MC mixed breed dog presented for a sudden onset of lethargy, anorexia, and vomiting. On physical examination you noted he had a fever of 105.8 with prominent mandibular lymph nodes. He is thrombocytopenic and has a morulae located in a granulocyte. The chemistry and UA were WNL. You note that he has splenomegaly on rads. His 4Dx snap test was negative across the board. What are your top differentials based on the morulae in a granulocyte?
E. ewingii and A. phagocytophilum
Moses is an 8 YO MC mixed breed dog presented for a sudden onset of lethargy, anorexia, and vomiting. On physical examination you noted he had a fever of 105.8 with prominent mandibular lymph nodes. He is thrombocytopenic and has a morulae located in a granulocyte. The chemistry and UA were WNL. You note that he has splenomegaly on rads. His 4Dx snap test was negative across the board. Why do you think the snap test was negative?
Too acute an infection to have performed antibodies
Moses is an 8 YO MC mixed breed dog presented for a sudden onset of lethargy, anorexia, and vomiting. On physical examination you noted he had a fever of 105.8 with prominent mandibular lymph nodes. He is thrombocytopenic and has a morulae located in a granulocyte. The chemistry and UA were WNL. You note that he has splenomegaly on rads. His 4Dx snap test was negative across the board. What are your next diagnostic and therapeutic tests?
Baseline and convalescent serology, PCR, and treat with Doxycycline
