Exam 3: Vector Borne Diseases

what are infectious causes of hemolytic anemia

• Babesia

• mycoplasma

• Ehrlichia

• anaplasma

• Bartonella vinsonii berkoffii

• Leishmania

• Dirofilaria

• sepsis

what species are the large Babesia

• B. canis

• B. vogeli

what are the small species of Babesia

• B. gibsoni

• B. conradae

• B. vulpes

how does B. canis appear in RBC

• large tear dropped shaped organisms

• often in paired

what are the primary tick vectors of Canine babesiosis

• B. canis = Dermatocentor in europe

• B. gibsoni = absent vector in north america

• B.. vogeli = Ripicephalus sanguineus

• B. conradae = TBD

how is Babesiosis transmitted

• tick must be attached for approximately 50hrs before transmission can occur

• other routes include biting such as dog fights, blood transfusion, and transplacental

what is the pathogenesis of Babesiosis

• organisms enter the blood and replicate within RBCS resulting in extra and intravascular hemolysis

• splenomegaly is common

• vasculitis and platelet activation may occur

• immune system is activated but rarely results in clearance of organisms, and many of the clinical signs are probably immune mediated

• should be on the differential list for a dog suspected of IMHA

what are the clinical findings of Babesiosis

• greyhounds and pitbulls overrepresented, younger animals more likely to present with clinical signs but most infections will be subclinical

• most typical presentation is acute fever, anorexia, and depression in a dog with hemolytic anemia

• canis/vogeli= recent stress, splenomegaly, or had a blood transfusion

• gibsoni/conradae= usually an adult dog that has recently been in a fight with a pit bull or cyotes

what are the diagnostic findings for Babesiosis

• CBC= macrocytic, normochromicc regenerative anemia, leukocytosis, tend to have thrombocytopenia

• chemistry= non-specific finding associated with anemia

• UA may present with prteinuria

• PCR> serology

• evaluation of blood smears

how is Babesiosis treated

• supportive care ± blood transfusion

• Imidocarb dipropionate

• primary treatment for canis and vogeli

how is B. gibsoni treated

• Azithromycin

• Atovaquone

• ± Artesundate

• doxycycline-enrofloxacin-metronidazole combination

what is Cytauxzoon felis

• tickborne blood protozoal disease of domestic and exotic cats

• found in lower midwest, south central, southeast

what is the primary tick vector to Cytauxzoonosis

Amblyomma americanum aka Lone Star tick

how is cytauxzoonosis transmitted

• occurs 36-48hrs after exposure to infected tick

• incubation period is 5-20 days so disease is most actve in the spring and summer along with tick activity

what is the pathogenesis of Cytauxzoonosis

• Schizonts develop in macrophages which causes vasculitis and thrombosis of multiple organ systems, especially the lungs

• severe illness is the result of mechanical obstruction to blood flow and multiorgan failure

• late in the disease merozoites will be released that infect RBCs and have signet ring appearance

• hemolytic crisis with shock like state and DIC is often the terminal event and merozoites will be noted as incidental finding

what is the major wildlife reservoir of Cytauxzoonosis

• north american bobcat

what are the clinical findings and typical course of Cytauxzoonosis

• early on may be confused with hemotropic mycoplasmosis, but rapid course of illness differentiates it

• fever, dyspnea, lethargy, anorexia, icterus, dark urine with progression to hypothermia, recumbency, coma, and death over 3-5 days

what are the diagostic findings of cytauxzoonosis

• CBC= normocytic, normochromic non-regenerative anemia, thrombocytopenia, leukopenia with toxic changes

• chemistry= increased bilirubin, increased glucose, increased CPK, AST, ALT activities

• blood smear with singlet ring shaped merozoites in the RBCS

how is Cytauxzoonosis treated

• poorly responsive

• supportive treatment is important with blood transfusions

• Atovaquone and azithromycin is treatment of choice

• Imidocarb 26% survival

how is hemotrophic mycoplasmosis generally defined

• gram negative walless bacteria infecting epicellular portion of erythrocytes

• mycoplasma hemofelis, Candidatus M. hemominutum, Canditatus M. turicensis

• Mycoplasma hemocanis, Candidatus M. hematoparvum

how is hemostrophic mycoplasmosis transmitted

• blood sucking arthropod vectors such as fleas and ticks

• direct spread via fighting

• vertical

• blood transfusions

• parasitemic episodes occur cyclically 1-3 weeks after infection

what is the pathogenesis of Hematogenic mycoplasma

• PCV drops rapidly during bacteremic episode causing mainly extravascular hemolysis and sequestration of RBCs in the spleen

• PCV rises rapidly at the end of the episode

• repeated episodes result in immune mediated damage to erythrocytes and more severe disease

• without treatment 1/3 cats will die from progressive anemia

• dogs rarely get clinical signs unless dog has no spleen

what are the clinical findings of hemocentric mycoplasma

• usually vague and related to anemia

• anorexia, depression, weakness

• pale mucous membranes

• weight loss

• icterus but is not consistent

how does hemocentric mycoplasa present on clin path

• anemia that is usually regenerative, macrocytic and hypochronic

• organisms may be obvious but disappear

• Coombs’ + test of agglutination may be present for the presnce of antibodies

• WBC normal to high

• platelets usually normal

how is hemotrophic mycoplasmosis diagnosed

• blood smear evidence though bacteremia waxes and wanes

• PCR

• IFA stainting

how is hemotrophic mycoplasma treated

• supportive care as needed, fluids, potassium, blood if anemia is severe

• antimicrobial therapy

• immunosuppressive therapy in severely affected cats where immune mediated hemolysis is likely a significant part of the pathogenesis = prednisolone

what is the primary tick vector for lyme disease

• blacklegged ticks I. scapularis and I. pacificus

what is the pathogenesis of lyme disease

• tick bite → decrease in OspA and increase in OspC and migration to tick salivary glands

• host infection OspC mediates invasion

• persistence = VlsE variability prevents antibody recognition

• immune respinse = inflammation, tissue damage, immune evasion

what is the clinical relevance of the outer surface proteins of lyme disease

• VlsE is the target for C6 peptide used in serologic testing

• OspA used in early vaccines

• understanding Osp dynamics aids in diagnostic interpretation

how is lyme disease transmitted

• tick must be attached for approximately 50 hrs before transmission can occur

what are the clinical findings of lyme disease

• retrievers are overrepresented

• younger animals are more likely to show clinical signs bit seroprevalence is high

• acute fever, anorexia, and depression in a dog with shifting leg lameness, joint swelling, and lymphadenopathy

what are chronic clinical syndromes associated with Lyme disease

• chronic non-erosive polyarthritis

• lyme nephropathy- PLN due to immune mediated GN and lyme ag-ab complex deposition

• meningitis

what are diagnostic findings of lyme disease

• CBC non-specific, leukocytosis and tend not to have thrombocytopenia

• proteinura may be seen and may be an early sign of Lyme nephropathy (most are not)

• C6 antibdy titer test does not cross react with vaccination titer OspA

how is Lyme disease treated

• only symptomatic dogs = Doxycycline or Amoxicillin for 30 days

• prevent with tick control and vaccination

what is the importance of lyme disease in public heath

= dogs can serve as sentinels for infections in humans, but are not a source of infection

what is the transmission of Hepatozoonosis

• Amblyomma maculatum, gulf coast tick

• dog ingests the tick, not the typical other way

what is the pathogenesis of Hepatozoonosis

• sporozoites travel to muscles where they develop into meronts and form cysts

• as cysts rupture a pyogranulomatous inflammatory myositis ensures and merozoites are released

• gamonts develop within leukocytes where they can travel to other muscles

• cycles over long periods causing waxing and waneing and progressively worsening disease

• secondary glomerulonephritis and amylodisos

what are the clinical findings of hepatozoonosis

• fever with stiffness and reluctance to move

• pain that accomapnies the myositis

• mucopurulent ocular discharge

• chronic weight loss

• PU/PD occasionally seen secondary to renal disease associated with glomerulonephrosis or amyloid deposition in glomeruli

• most dogs maintain a good appetite

what are diagnostic findings of Hepatozoonosis

• CBC= marked leukocytosis is most consistent finding, normochromic, normocytic nonregenerative anemia, thrombocytosis

• chemistry = increased ALP activity, hypoalbuminemia, hypoglycemia

• proteinuria is common

how is hepatoxoonosis diagnosed with a smear

• gamonts may be noted in neutrophils but may be difficult to find

  • PCR

  • muscle biopsy

how is hepatozoonosis treated

• pain and fever is treated with NSAIDs

• combination of clindamycin, triethprin-sulfa, pyrimethamine

• relapse is common, but Decoquinate hhas been shown to reduce