Blood Borne Infections- SA Flashcards
describe ehrlichiosis type and mode of transmission
- 3 species:
-E. canis, ewingii, chaffeensis
-intracellular gram negative bacteria
-E. canis causes canine monocytic ehrlichiosis, worldwide distribution
-ewingii and chaffeensis southern USA, africa
-within family anaplasmataceae - mode of transmission:
-tickborne
describe ehrlichiosis clinical signs
Major clinical signs:
-E. canis: fever, lethargy, inappetance, wt loss, cutaneous/mucosal petechia/ecchymotic hemorrhages!!!, lymphadenomegaly, splenomegaly, uveitis
–cats: fever, lethargy, inappetance, weight loss, hyperesthesia, joint patin
E. ewingii: fever, lethargy, inappetance, polyarthritis
CAN infect and cause disease in humans!
describe cytologic characteristics of ehrlichiosis
form morulae (the organisms themselves) within phagosomes of circulating leukocytes
E. canis: monocytes and macrophages,»_space;lymphocytes
-canine monocytic ehrlichiosis
E. ewingii: granulocytes
-canine granulocytic ehrlichiosis
E. chaffeensis: human monocytic ehrlichiosis
describe canine monocytic ehrlichiosis as caused by E. canis
- acute, subclinical, and chronic phases
- thombocytopenia most commonly seen (1-4 weeks post infection) in >90% of acute infections; usually mild to moderate
-likes to replicate in reticuloendothelial tissue = lymphadenomegaly and splenomegaly - +/- morulae within circulating monocytes in acute infection
- chronic and severe can result in severe monoclonal gammopathy (not neoplastic) (FYI)
describe E. canis diagnosis
- serology:
-IFA: gold standard, but abs only detected 7-28d post infection, so false negative common with acute infection!
-ELISA: (SNAP 4DX)- antibodies, so also false negative with acute; does not distinguish between types of ehrlichia
-western immunoblotting (research primarily)
- PCR: whole blood, helpful for acute infection
- ideal: serology + PCR
-positive serum Ab titer may reflect PREVIOUS exposure vs active infection, so retest 2-3 weeks later and interpret in light of clinical signs!
-high titers do NOT correlate with severity of hyperglobulinemia, disease, or duration of illness
-cross reactivity with E, chaffeensis > E. eqingii, A. phagocytophilum
describe E. canis treatment
- supportive care
- antibiotics!
-doxycycline: high blood, tissue, and IC concentration
-dose: don’t actually know best dose or duration, base on clinical signs and recovery - clinical improvement should be within 24-48 hours
-platelets within ref range within 10-14d post starting treatment - dogs can be reinfected!
-titers decline and become negative within 6-9 months post treatment
describe E. chaffeensis
- experimentally infected dogs: fever, thrombocytopenia, leukopenia
- possible persistent carrier state in dogs (bone marrow, spleen, liver, LN, lungs, kidneys, brain)
-white-tailed deer may also be reservoir hosts in north america - diagnosis:
-serology: detectable ab titers 7-23d post infection, cross reactivity with other ehrlichia spp.
-RT-PCR - treatment: abx: doxycycline
describe E. ewingii
- infected dogs can serve as a reservoir host
-replicates in neutrophils, usually subclinical - acute disease (2-3 weeks post infection): fever, lethargy, anorexia, lameness (neutrophilic polyarthritis), possible neurologic manifestations
- diagnosis:
-morulae prior to serconversion or clin signs
-thrombocytopenia (43%), anemia, mild to moderate neutrophilic leukocytosis with left shift
-serology: abs present approx 1 month post inoculation
–ELISA: cross reacts with other ehrlichia spp.
–false negative with acute illness
-PCR: positive as early as 4 days post inoculation - treatment: doxycycline
-rapid clinical improvement within 24-48 hr
describe anaplasmosis
- 2 species:
-anaplasma platys: canine thrombocytotropic anaplasmosis
-anaplasma phagocytophilum: canine granulocytic anaplasmosis - obligate intracellular gram negative pleomorphic bacteria
-obligate aerobes
-lack cell wall - geographic distribution:
-A. platys: throughout Americas
-A. phagocytophilum: upper midwestern, northeastern, western states
describe anaplasmosis transmission
tick borne!
describe major clinical signs of anaplasmosis
- A. platys: maybe fever, lethargy
- A. phagocytophilum: fever, lethargy, inappetance, lameness (polyarthritis)
- causes human granulocytic anaplasmosis (A. phagocytophilum)
-dogs = sentinels
describe anaplasma phagocytophilum/canine granulocytic anaplasmosis
- tropic for granulocytes (esp neutrophils): forms morulae within them
- tick must be attached 24-48 hours for transmission to occur (prevention is key!)
- mild to moderate, occasionally severe thrombocytopenia (approx 90%)
- +/- other cytopenias - self-limiting in many infected dogs and cats
describe diagnosis and treatment of anaplasma phagocytophilum/canine granulocytic anaplasmosis
diagnosis:
1. morulae within granulocytes as early as 4 days post inoculation
- acute and convalescent serology (titers)/ELISA for antibodies
- PCR for acute infection without morulae
treatment:
1. doxycycline!
-clinical improvement within 24-48 hrs of tx
-platelet counts normalize within 2-14d of treatment initiation
describe anaplasmosis platys/infectious canine cyclic thrombcytopenia (ICCT)
- platelet tropism
-thrombocytopenia +/- mild, nonregenerative anemia
-cycles of thrombocytopenia every 1-2 weeks - diagnosis:
-morulae in platelets 7-19d post infection
-serology: cross reacts with other anaplasma spp
–ELISA: false negative in acute infection
–paired titers
-PCR - treatment: doxycycline!
describe rickettsia rickettsii
- AKA rocky mountain spotted fever
-gram negative obligate IC bacteria
-infect endothelial cells!!!!
-affects humans and dogs
-part of family rickettsiaceae - major clinical signs:
-acute febrile illness
-vasculitis
-vomiting
-ocular signs (retinal hemorrhage, uveitis, episcleral injection)
-lymphadenomegaly
-splenomegaly
-peripheral edema
-cutaneous hyperemia and necrosis
-polyarthritis
-neurologic signs - geographic distribution: north, central, south america (ALL of US)
- most of transmission: ticks, everywhere!
-can also spread cell to cell without rupturing the cell = immune system evasion
describe clinical presentation of rickettsia rickettsii
- young and purebred dogs potentially overrepresented
-english springer spaniels with phosphpfructokinase deficiency
-GSDs - endotheliotropic = disseminated vasculitis
-spreads through lymphatics or directly into bloodstream to small capillaries
-primarily infects endothelial cells, smooth muscles and monocytes can be infected though - primarily an acute disease!
-thrombocytopenia common (vasculitis and immune-mediated platelet destruction)
-get bit get sick quick - diagnosis:
-acute CS + PCR or IHC = active infection
-seroconversion: positive titer only indicates exposure; acute and convalescent titers needed (4-fold change to confirm infection)
-PCR: especially in acute phase: false negatives due to low numbers of organisms, transient circulation, or abx therapy
- treatment:
-should be started before confirmed diagnosis
-doxycycline! 7 days usually adequate
-rapid clinical response (24-48hr)
-possible lifelong immunity to reinfection
describe cytauxzoonosis
- cytauxzoon felis
-hematoprotozoal parasite - two distinct forms:
–nonerythrocytic: schizont
–erythrocytic: piroplasm - bobcat = reservoir host
-arthropod vectors: tick borne - geographic distribution: midwest, south central, southeastern, mid-atlantic states; expanded with expansion of A. anericanum range
-outdoor cats in spring and summer, more prevalent in rural and suburban areas (prevention is key!!) - transmission: feeding of vector ticks
-no human health significance
describe cytauxzoonosis clinical presentation
- clinical disease: 1-3 weeks after infection
-rapid clinical course: death within days - major clinical signs:
-rapidly progressive febrile illness (up to 107F)
-icterus
-pallor
-lymphadenomegaly
-splenomegaly: should NOT be able to feel cat spleen
-hepatomegaly
-seizures
-could be subclinical, but if symptomatic = most likely dead soon
describe diagnosis of cytauxzoonosis
- ID RBC parasites on blood smear!
-piroplasms shaped as signet rings within RBCs
-distinguish from M. hameofelis: epicellular cocci/rods/rings - PCR: may remain positive in recovered cats
- cytology:
-schizonts within mononuclear cells
-schizont-laden macrophages on FNA (LN, spleen, liver)
serology not mentioned bc some animals die before the body has a chance to make Abs :(
describe treatment of cytauxzoonosis
- supportive intensive care
-IVF
-RBC transfusion for severe anemia
–heparin for clot formation associated with DIC but CAREFUL if already bleeding - antiprotozoal therapy:
-imidocarb: may lack efficacy (26% survival rate)
-atovaquone and azithromycin: improved survival rate compare to imidocarb (60% survival rate) - no vaccine, preventing tick bite is key!!
describe hemotropic mycoplasms
- gram neg, obligate epierythrocytic bacteria, wall-less, non-acid fast, not culturable!
-formerly haemobartonella and epierythrozoon - includes:
-dogs: M. haemocanis, candidatus mycoplasma haemotoparvum
cats: M. haemofelis, candidatus mycoplasma haemominitum, candidatus mycoplasma turicensis
- geographic distribution: worldwide
describe mode of transmission, major clinical signs, and zoonotic capability of hemotropic mycoplasms
modes of transmission:
1. tickborne
2. other arthropods: fleas, mosquitoes
3. biting/aggressive interactions
4. vertical transmission
5. ingestion/injection of infected blood (blood transfusions)
major clinical signs:
-fever, lethargy, inappetance, weakness, pallor, dehydration
possible zoonotic infections (potentially)
describe hemotropic mycoplasmas in cats
- M. haemofelis
-candidatus mycoplasma haemominutum
-candidatus mycoplasma turicensis
(candidatus = new and incompletely described) - blood film: small, dark blue-staining rods, cocci, or slightly larger ring forms
-Candidatus M. haemominutum- rarely seen in blood films (tiny)
-may see loss of normal RBC appearance and shape
- exact prevalence difficult to determine
- clinical disease most associated with M. haemofelis: severe hemolytic anemia, macrocytic, hypochromic, regenerative (but pronounced reticulocytosis not always evident)
-positive Coombs (esp cold agglutinins); autoagglutination in the acute phase
-FIV/FeLV positive (predisposes)
describe M. haemofelis
- clinical signs within 2-34 days post infection
- anemia lasting 18-30 days
- M. haemofelis blood organism numbers fluctuate greatly
- chronic infection not usually associated with significant anemia
describe candidatus M. haemominutum
- no clinical illness or significant anemia
-carrier status common - occasional reports of only recognizable cause of anemia in some naturally infected cats (co-infection usually required)
- risk factors:
-older age
-outdoor exposure
-cutaneous SCC
-stomatitis
-FIV and/or FeLV +
plus C. M. tericensis: moderate to severe hemolytic anemia
describe hemotropic mycoplasmas in dogs (M. haemocanis)
- experimental transmission via tick
- blood transfusions can cause infection
- prepatent period: 1-2d to 2+ weeks
-some with rapidly progressive anemia and death within approx 1 month post infection
-sone with gradual anemia with repetitive parasitemic episodes - hemolytic anemia: +/- positive coomb’s test
- approx 1-2 months required fr HCT to drop to minimum and 1-2 months to recovery
- splenectomy in dogs almost always required for dogs to become clinical!
- more commonyl forms chains on surface of RBCs, can see small cocci, rods, rings
- candidatus mycoplasma haematoparvum: novel, small hemoplasma
describe diagnosis of hemotropic mycoplasma
- direct cytologic exam
-stained blood smears: approx 50% accurate in the acute phase - PCR based assays: highly sensitive
-can have subclinical carrier state
-interpret positive results in light of clinical signs - culture is unsuccessful!
describe therapy and prevention of hemotropic mycoplasmas
- supportive care
- antimicrobial therapy:
-does not predictably clear organism from body!!
-doxycycline, marbofloxacin, pradofloxacin and enrofloxacin are second line drugs - clinical improvement within 2-3 days of starting treatment
- prevention!
-flea/tick preventative
-screen blood donors (PCR preferred)
describe canine babesiosis
- intraerythrocytic protozoan parasite
- many species
- geo distrib: worldwide
- major clin signs:
-lethargy, pallor, splenomegaly, subclinical
-no human health concerns
describe babesiosis transmission
- B. canis (vogeli): brown dog tick, most common in southern US, greyhounds!!!
- B. gibsoni:
-NON VECTOR transmission most common: dog fighting wounds!!!!
-or transplacental
describe babesia in greyhouds and APBTs
greyhounds: B. canis
-reported rates of positive carriers: 20-60%
-risk considered low for clinical disease, but increases in a kennel situation
-IMPORTANT: know the seropositive status of adopted greyhounds
pit bull terriers: B. gibsoni
-most cases reported in US in this breed
-if another dog breed is positive for B. gibsoni, important to ask if they’ve been in a fight with an APBT- history is important!
describe pathogenesis of canine babesiosis
- infected RBCs have parasite antigens on their surface, inducing host-opsonizing antibodies to remove infected erythrocytes via mono-nuclear phagocyte system
- hosts develop anti-RBC membrane antibodies against self antigens, resulting in immune-mediated anemia
- thrombocytopenia occurs due to consumption of platelets +/- immune-mediated
- HEMOLYTIC ANEMIA and THROMBOCYTOPENIA
-anemia initially mild, normocytic, normochromic
-then macrocytic, hypochromic, and regenerative - a splenectomy makes the parasitemia and anemia more severe
describe diagnosis of babesiosis
- microscopic identification:
-large spp. 3-5 um in length: B. canis, vogeli, rossi
-small spp. 1-3 um in length: B. gibsoni, conradae, vulpes - serologic testing:
-IFA
-convalescent titers - nucleic acid-based detection
-PCR: required for accurate species ID - parasite visualization:
-capillary blood: ear tip or nail bed
-negative slide exam does not rule it out! poor sensitivity - there is NO perfect test!
describe treatment of babesiosis
- imidocarb diproprionate
-side effects: pain, autonomic signs
-likely curative for B. canis, vogeli, rossi
-reduces morbidity and mortality for B. gibsoni: does NOT cure! - atovaquone and azithromycin combination therapy
-more effective treatment for B. gibsoni, conradae
-use liquid suspension of atovaquone - clindamycin, metronidazole, and doxocycline combination therapy
-for B. gibsoni if fail atovaquone/azithromycin for a minimum of 3 months, with uncertain efficacy
describe tularemia
- francisella tularensis: gram negative coccobacillus, facultatis intracellular bacteria, aerobia
- mode of transmission: inoculation, skin/mucosal contact, aerosol inhalation, ingestions, vector transmission
- major vectors:
-ticks
-biting flies - geographic distribution: norther hemisphere, virulent strains prevalent in USA
- major clinical signs: fever, lethargy, lymphadenopathy, SC abscesses, splenomegaly, hepatomegaly, GI
- young adult cats and dogs; cats more susceptible
- DO NOT CULTURE; REPORTABLE; WILL INFECT HUMAN
