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SA DX & TX I > Exam 3 - Vector-borne Diseases > Flashcards

Exam 3 - Vector-borne Diseases Flashcards

1
Q

when is the overall prevalence of tick infestation highest in the USA?

A

may & June – second peak in October

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2
Q

what replication-incompetent bacteria relies on fleas & ticks to be transmitted?

A

bartonella spp.

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3
Q

what protozoal parasite uses an insect as both vector & definitive host?

A

hepatozoon

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4
Q

what agents are obligate intracellular parasites?

A

ehrlichia, anaplasma, rickettsia spp.

genus borrelia spirochetes

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5
Q

T/F: obligate intracellular parasites can’t survive outside of the host or vector & therefore, aren’t directly contagious

A

true – extremely well-adapted to survive

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6
Q

because you typically can’t culture obligate intracellular pathogens to diagnose them, what tests are used instead?

A

serology or molecular diagnostics

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7
Q

how are infections caused by obligate intracellular parasites treated?

A

must get drugs into the cells to kill the pathogen – or prevent the transmission in the first place

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8
Q

general tick-borne syndrome involves what agents?

A

ehrlichia, rickettsia, anaplasma, & borrelia

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9
Q

what is the common presentation of general tick-borne syndrome?

A

tick was attached for 48 hours or more – clinical signs appear 7-21 days later

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10
Q

what are the common initial signs associated with general tick-borne syndrome?

A

fever, lethargy, lameness, shifting leg lameness, polyarthritis, polymyositis, acute thrombocytopenia, & may wax/wane in severity

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11
Q

acute signs associated with general tick-borne syndrome are generally rapidly responsive to what antibiotic?

A

doxycycline

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12
Q

why is shifting leg lameness seen in animals with general tick-borne syndrome?

A

muscle stiffness, soreness, or pain from systemic inflammatory disease or just achiness

true neutrophilic polyarthritis – may be reactive to systemic inflammatory disease or may be direct spread within connective tissues

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13
Q

what 3 mechanisms are associated with acute thrombocytopenia in animals with general tick-borne syndrome?

A
  1. increased consumption – fever, inflammatory cascade during bacteremia/parasitemia, vasculitis
  2. concurrent immune-mediated destruction in some cases – could be specific or bystander
  3. impaired function also likely – bleeding occurs at platelet counts higher than typically seen with spontaneous bleeding
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14
Q

T/F: anemia is a common feature of general tick-borne syndrome

A

false – but when present, anemia of chronic inflammatory disease & is non-regenerative

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15
Q

what major clinical syndromes are associated with vector-borne diseases in humans?

A

spotted fever group, STAR, tick-borne relapsing fever (borrelia turicatae), r. typhi, & r. prowazekii

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16
Q

what is the primary vector of rickettsia rickettsii?

A

dermacentor species

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17
Q

what are the possible reservoirs for rickettsia rickettsii?

A

dermacentor, small mammals, rodents, & birds

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18
Q

where is the highest seropositivity of dogs with rickettsia rickettsii?

A

eastern time zones

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19
Q

where are human cases of rocky mountain spotted fever most prevalent?

A

southeast united states

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20
Q

rickettsia rickettsii causes clinical disease in what species?

A

dogs & people

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21
Q

what are the target cells of r. rickettsii?

A

vascular endothelial cells – ‘spotted’ appearance

typically, mild thrombocytopenia – likely immune-mediated or secondary to vasculitis

diffuse vasculitis often progresses to DIC

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22
Q

what is the prognosis of rocky mountain spotted fever?

A

acute disease only!!!

dead or better in days to weeks – extremely rapidly treatment responsive

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23
Q

T/F: in rocky mountain spotted fever, exposure-induced immunity is protective for 3 years or more

A

true

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24
Q

what ticks transmit ehrlichia canis?

A

r. sanguineus & d. variabilis

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25
Q

what serves as the reservoir for e. canis?

A

wild & domestic canids

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26
Q

why is ‘canine monocytotropic ehrlichiosis’ another name for e. canis infections?

A

monocytes/macrophages are the preferred target cells

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27
Q

what are the 3 phases seen with e. canis infections?

A
  1. acute – 2-4 weeks, thrombocytopenia, multisystemic signs
  2. subclinical – months to years to indefinitely (splenic hideout), may remain mildly thrombocytopenic
  3. chronic – pancytopenia
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28
Q

when are specific IgM & IgG antibodies seen in e. canis infections?

A

IgM by 4-7 days post-infection

IgG by 15 days post-infection

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29
Q

T/F: antibodies for e. canis are not protective

A

true

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30
Q

what are some possible vectors for ehrlichia chaffeensis?

A

amblyomma, dermacentor, ixodes, & haemaphysalis

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31
Q

what are some possible reservoirs for ehrlichia chaffeensis?

A

white tail deer, possums, coyotes, raccoons

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32
Q

ehrlichia chaffeensis causes clinical disease in what species?

A

people & dogs

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33
Q

what are the target cells of ehrlichia chaffeensis?

A

monocytes & neutrophils – perhaps more uveitis seen, milder than e. canis but similar disease

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34
Q

what is the only proven vector of ehrlichia ewingii?

A

amblyomma americanum

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35
Q

what is the reservoir of ehrlichia ewingii?

A

white tailed deer

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36
Q

ehrlichia ewingii causes disease in what species?

A

dogs & people

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37
Q

what is another name for ‘ehrlichia ewingii’?

A

canine granulocytotropic ehrlichiosis – target cells are neutrophils & eosinophils

visually looks like a. phagocytophilum

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38
Q

where is anaplasma phagocytophilum especially common?

A

northern midwest USA

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39
Q

what tick species transmits anaplasma phagocytophilum?

A

ixodes

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40
Q

what are the reservoirs of anaplasma phagocytophilum?

A

small mammals & deer

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41
Q

anaplasma phagocytophilum causes clinical infection in what species?

A

dogs, horses, & people

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42
Q

what is the target cell of anaplasma phagocytophilum?

A

neutrophils

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43
Q

what are the common clinical abnormalities of an animal with anaplasma phagocytophilum?

A

acute illness with notable lameness – muscular pain and/or neutrophilic polyarthritis

typically, low platelets & low eosinophils

antibody titers persist but don’t protect against re-infection

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44
Q

what is the suspected vector of anaplasma platys?

A

r. sanguineus

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45
Q

anaplasma platys causes clinical disease in what species?

A

dogs

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46
Q

what disease does anaplasma platys cause?

A

infectious cyclic thrombocytopenia – 1–2-week cycle of platelet parasitism, clearance & drop in count (<20K)

only 1% of platelets are parasitized – platelet clearance must include immune-mediated component

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47
Q

what ticks transmit borrelia burgdorferi?

A

ixodes species & amblyomma

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48
Q

why is it important to know borrelia burgdorferi has many reservoirs?

A

many reservoirs mean ticks can become infected as larvae, nymphs, or adults

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49
Q

what reservoirs are important for larvae & nymphs when considering borrelia burgdorferi? what about adults?

A

rodents, small mammals, lizards

adults – deer, large mammals, & lizards

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50
Q

borrelia burgdorferi causes clinical disease in what species as hosts of adult ticks?

A

dogs & people

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51
Q

how is the lifecycle of ixodes tick species different in the south from the north?

A

we have lizards who are cold blooded & can’t amplify disease well, so lower prevalence of lyme

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52
Q

in endemic areas of b. burgdorferi, many dogs & people are exposed, but there are few clinical cases of disease – why?

A

takes&raquo_space; 24 hours to infect after tick attachment & also likely natural host resistance

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53
Q

what are the clinical signs of b. burgdorferi infections?

A

direct migration through connective tissues

fever, malaise, polyarthritis, typically acute, self-limiting but some poorly understood chronic immune-mediated complications leading to severe protein-losing nephropathy in certain dogs

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54
Q

how is b. burgdorferi treated?

A

antibiotics – very responsive

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55
Q

what is the disease process of lyme nephritis?

A

severe membranoproliferative glomerulonephritis causing severe proteinuria that is associated with lyme seropositivity

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56
Q

T/F: lyme nephritis is a direct result of lyme infection

A

false – it is an immune-mediated disease

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57
Q

what major clinical signs are associated with r. rickettsii?

A

high fever, acute severe illness, & often petechiae

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58
Q

what major clinical signs are associated with a. phagocytophilum?

A

often subclinical, can show fever, lethargy, & shifting leg lameness

59
Q

what major clinical signs are associated with e. canis (acute)?

A

fever, acute moderate illness, shifting leg lameness, & rare petechiae

60
Q

what major clinical signs are associated with b. burgdorferi?

A

often subclinical, delayed, can have a fever, shifting leg lameness, no human target lesions!!

61
Q

what is the primary reservoir & definitive host of hepatozoon americanum?

A

a. maculatum

62
Q

what is the accidental host of hepatozoon americanum? how does transmission occur in this fashion?

A

dog is the accidental host – dog must eat the tick for transmission to occur

63
Q

what is the pathogenesis of hepatozoon americanum?

A

sporozoites escape gi tract into blood/lymphatics & travel in unidentified host where it then lodges in skeletal & cardiac muscle causing cysts

cystic structures either go dormant or become merozoites

64
Q

what can be seen on histopathology in hepatozoon americanum infections? what about a blood smear?

A

cysts easily seen on histopathology

merozoites occasionally seen in circulation

65
Q

hepatozoon americanum causes clinical disease in what species?

A

dogs only

66
Q

what clinical signs would cause suspicion of hepatozoon americanum infections?

A

cachexia, progressive wasting illness, painful gait, mucopurulent ocular discharge, outrageous leukocytosis, & periosteal reaction

67
Q

what species of bartonella uses fleas as a vector?

A

b. henselae

68
Q

what species of bartonella uses ticks as a vector?

A

b. vinsonii subspecies berkhoffi

69
Q

b. henselae is adapted to what species?

A

cats - rarely makes them sick

70
Q

b. vinsonii subspecies berkhoffi is adapted to what species?

A

coyotes – occasionally makes dogs sick

71
Q

T/F: each species of bartonella is highly adapted to a preferential mammalian host in which they cause a long lasting intra-erythrocytic bacteremia

A

true

72
Q

what are the 4 koch postulates?

A
  1. microorganism must be found in abundance of all organisms suffering from the disease but should not be found in healthy organisms
  2. microorganism must be isolated from a diseased organism & grown in pure culture
  3. cultured microorganism should cause disease when introduced into a healthy organism
  4. microorganism must be re-isolated from the inoculated, diseased experimental host & identified as being identical to the original specific causative agent
73
Q

why are bartonella species considered to be the ideal parasite?

A

various species coadapted with hosts & vectors over evolutionary time

stimulates minimal immune attack

persists in relatively low but stable numbers inside RBCs

causes minimal disease in host

readily transmitted by common routes or blood

features that make it difficult for science & medicine to detect

74
Q

what are the target cells of bartonella species in mammalian hosts?

A

RBCs & endothelial cells

75
Q

bartonella species cause clinical disease in what species?

A

dogs, cats, & people

76
Q

what clinical signs are associated with bartonella infections?

A

pyogranulomatous lymphadenitis, peliosis/vasculoproliferative lesions, endocarditis/meningitis/encephalitis/retinitis/recurrent fever

77
Q

what is the pathogenesis of babesia?

A

direct hemolysis causing a profound anemia, mild thrombocytopenia, & potential for severe systemic disease

78
Q

what tick transmits b. canis?

A

rhipicephalus, dermacentor

79
Q

what babesia is the classic strain? what is its appearance?

A

b. canis vogeli - larger, single or paired, piriform shape

80
Q

what animals are predisposed to b. canis vogeli?

A

greyhounds & splenectomized dogs

81
Q

what animals are predisposed to b. gibsoni?

A

pitbulls & splenectomized dogs

82
Q

what is the newer strain of babesia?

A

b. gibsoni - smaller, usually single, pleomorphic in appearance

83
Q

how is b. gibsoni transmitted?

A

suspected transplacental & blood to blood transmission

84
Q

what is seen on this blood smear?

A

b. canis vogeli

85
Q

what is seen on this blood smear?

A

b. gibsoni

86
Q

T/F: immunosuppression (splenectomized patients) can exacerbate clinical presentation of babesia

A

true - if spleen is present, likely to be enlarged

87
Q

what babesia strains usually cause a mild, chronic, insidious usually extravascular hemolysis?

A

b. canis strains in the US & b. gibsoni

88
Q

what babesia strains usually cause a peracute severe intravascular hemolysis?

A

b. canis in africa & b. gibsoni in USA

89
Q

what are the presumed vectors & transmission of hemotropic mycoplasma species?

A

flea in cats & tick in dogs are presumed - direct blood to blood contact may also be a source of transmission

90
Q

what are the hemotropic mycoplasma species in dogs & cats?

A

mycoplasma hemofelis in cats

mycoplasma hemocanis in dogs

91
Q

what disease do hemotropic mycoplasma species cause in dogs & cats?

A

hemolytic anemia in cats & splenectomized dogs that may be severe or cyclic in times of stress/pregnancy

92
Q

what is the definitive host & main vector of cytauxzoon felis?

A

a. americanum - definitive host & main vector

93
Q

what is the reservoir host of cytauxzoon felis in the midwest & east US?

A

bobcat

94
Q

what is the incubation period of c. felis?

A

2 weeks

95
Q

what is the terminal phase of disease associated with cytauxzoon felis?

A

survivors develop piroplasms in RBCs causing hemolysis

96
Q

what is the pathogenesis of cytauxzoon felis?

A

sporozoites invade mononuclear cells in circulation where they undergo schizogony where large numbers of schizonts are produced

bloated, infected cells clog capillaries & result in multi-organ failure & death

97
Q

what agent is seen on this histopath sample?

A

cytauxzoon felis

98
Q

when would you do a muscle biopsy for a presumed vector-borne disease?

A

hepatozoon infections - to visualize cysts on muscle bopsy or circulating gamonts in neutrophils

99
Q

what is seen on this muscle biopsy?

A

hepatozoon cyst

100
Q

what is seen in the neutrophils?

A

gamonts of hepatozoon

101
Q

what disease would you use IFA detection for organisms in skin lesions?

A

rocky mountain spotted fever

102
Q

what disease would you enrich a sample by growth on insect media, and then perform a PCR?

A

bartonella species

103
Q

what is the therapy used for treating ‘challenging’ hepatozoon?

A

triple therapy - TMS, clindamycin, & pyrimethamine for the first 14 days & coccidiostat for life

104
Q

what is the therapy for bartonella infections?

A

long-term doxycycline, enrofloxacin, azithromycin, & rifampin

105
Q

what therapy is used to treat babesia canis?

A

imidocarb

106
Q

what therapy is used to treat babesia gibsoni?

A

azithromycin/atovaquone

107
Q

what therapy is used to treat cytauxzoon felis?

A

azithromycin/atovaquone

108
Q

flea preventatives protect animals from what agents?

A

bartonella & mycoplasma

109
Q

tick preventatives protect animals from what agents?

A

rickettsia, ehrlichia, anaplasma, babesia - kills the ticks before engorgement & transmission

110
Q

not eating raw salmon prevents what disease?

A

neorickettsia

111
Q

no eating ticks helps prevent what disease?

A

hepatozoon

112
Q

no fighting with pitbulls prevents what disease?

A

babesia gibsoni

113
Q

what lyme vaccine is available for dogs?

A

recombinant osp A - expressed on borrelia in tick, so anti-osp a antibodies in dog blood kill borrelia in tick before transmission

114
Q

what is included in genera; tick-borne disease therapy?

A

doxycycline for: ehrlichia, rickettsia, anaplasma, borrelia, mycoplasma

fluid therapy for fever, prevent dehydration from malaise/anorexia/painful ambulation

consider NSAIDS for fever & joint pain if hydrated

optimal duration of therapy is uncertain because clinical signs improve quickly but not always certain that the pathogen is fully eradicated

115
Q

a 5 y/o lab has a positive 4DX snap test for anaplasma species at the time of his annual exam. What does this mean?

A

positive for antibodies to anaplasma - may not be an ongoing infection, can still treat

116
Q

a 5 y/o lab has a positive 4DX snap test for anaplasma species at the time of his annual exam. What does this mean? How does your answer change if the dog is sick with a fever, shifting leg lameness, & mild thrombocytopenia?

A

give it doxycycline - suggests active problem

117
Q

what agents does a 4DX snap test look for?

A

ehrlichia canis or chaffeensis antibodies

anaplasma phagocytophilum or platys antibodies

borrelia antibodies against C6 antigen

heartworm antigen

118
Q

T/F: RMSF has a high background in endemic areas

A

true

119
Q

T/F: bartonella also has a very high background seropositivity, so most chronic cases were never sick

A

true

120
Q

T/F: in RMSF, there is acute disease only, so convalescent titers rise after recovery

A

true

121
Q

what is serology?

A

study of serum

122
Q

the presence of antibodies in the serum means that the pathogen has been there, but what is unclear?

A

not clear when the animal had the pathogen

not clear if the pathogen made the animal sick then or now

123
Q

T/F: patient side tests for vector-borne diseases don’t reveal the magnitude of disease

A

true

124
Q

what historical or physical examination findings may help you recognize infection with ehrlichia species?

A

*

125
Q

what historical or physical examination findings may help you recognize infection with hepatozoon?

A

*

126
Q

what historical or physical examination findings may help you recognize infection with rickettsia rickettsii?

A

*

127
Q

what is the life cycle of neorickettsia species?

A

n. helminthoeca infects the fluke

fluke infects snail & reproduces

fluke progeny directly penetrate & infect fish

dog eats fish infected with flukes that are infected with n. helminthoeca

128
Q

what is the agent that causes potomac horse fever?

A

neorickettsia risticii

129
Q

what are the target cells of neorickettsia helminthoeca?

A

monocytotropic & enterocytotropic

130
Q

what is the agent that causes salmon poisoning?

A

neorickettsia helminthoeca

131
Q

what is neorickettsia helminthoeca?

A

regionally restricted trematode vectors that are infected with neorickettsia species

132
Q

how is neorickettsia helminthoeca diagnosed?

A

assisted by the presence of trematode ova in feces of a sick dog

133
Q

what is a one-host tick? two-host? three-host?

A

one host - one individual through all life stages

two host - two individuals, +/- 2 species

three host - 3 individuals, up to 3 species

134
Q

what does transstadial mean?

A

between life stages

135
Q

what does transovarial mean?

A

between generations

136
Q

what does ixodid mean?

A

family of all hard ticks

137
Q

what agent has the cell target of platelets?

A

anaplasma platys

138
Q

what is this tick?

A

rhipicephalus sanguineus - brown dog tick

139
Q

what is this tick?

A

rocky mountain wood tick or american dog tick - dermacentor andersoni, d. variabilis

140
Q

what is this tick?

A

‘deer ticks’

141
Q

what is this tick?

A

lone star tick, gulf coast tick - amblyomma americanum, a. maculatum

142
Q

how does the need for a vector impact epidemiology, diagnosis, or treatment of these infections?

A

*

143
Q

what agents are involved in causing general tick-borne syndrome?

A

ehrlichia, rickettsia, anaplasma, & borrelia

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