Arthropod-Vector Borne Infectious Diseases in Small Animals Flashcards

1
Q

What are vector-borne diseases caused by?

A

Parasites, bacteria or viruses transmitted by the bite of haematogenous arthropods

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2
Q

What is the purpose of the Pet Travel Scheme (PETS)?

A

To protect individual pets but also UK disease status and requires rabies and tapeworm treatment

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3
Q

What changes have recently been made to the PETS?

A

On 1st Jan 2012 the requirement for compulsory treatment of companion animals for ticks before their entry into the UK was withdrawn

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4
Q

What tick borne diseases may be imported in dogs travelling in from the EU?

A

Babesia canis canis
Babesia gibsoni
Ehrlichia canis

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5
Q

What tick borne diseases are already endemic in the UK?

A

Borrelia burgdorferi

Anaplasma phagocytophilum

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6
Q

Which ticks are already endemic in the UK?

A

Ixodes ricinus

Dermacentor reticulatus

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7
Q

Which tick is brought into the UK on animals?

A

Rhipicephalus sanguineus - not endemic in UK and requires >18C for life cycle, vector for Mediterranean spotted fever

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8
Q

What is babesiosis caused by?

A

Protozoan parasite of RBCs transmitted by ticks

2 main genera are Babesia and Theileria = Piroplasms

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9
Q

What are the most important agents of canine babesiosis?

A

Large babesia = B. canis canis (Europe), B. canis vogeli (Africa, Asia, USA, Europe, Australia), B. canis rossi (S. Africa)
Small babesia = B. gibsoni (Asia, Africa, USA, S. Europe)

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10
Q

What differences exist between the different species of babesia?

A

Vectors and geographical distribution (changing)

Virulence, prognosis and response to treatment

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11
Q

What is the pathogenesis of babesia?

A

Within ticks Babesia is transmitted trans-stadially and trans-ovarially
Sporozoites injected from tick salivary glands, enter circulation and endocytosed by RBCs
Immune-mediated component of pathology
Thrombocytopaenia common but usually not enough to cause bleeding or abnormal coagulation

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12
Q

What are the clinical signs of babesiosis?

A

Those of haemolytic anaemia

Lethargy, depression, inappetence, icterus, splenomegaly, tachycardia, tachypnoea

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13
Q

How is babesia diagnosed?

A

Clinical lab findings - thrombocytopaenia, Coombs +ve
Microscopic identification - low sensitivity
PCR - high sensitivity, species identification possible
Serology - indirect fluorescence Ab test/ELISA

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14
Q

What is the treatment for babesiosis?

A

Antibabesial drug - Imidocarb dipropionate
Large forms = rapid clinical response
Small forms = clinical and pathological cure uncommon, clinical relapses can occur

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15
Q

Which rickettsial diseases are vector borne?

A

Canine Ehrlichia and Anaplasma spp

Small obligate intracellular gram -ve bacteria

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16
Q

Which species infect monocytic cells?

A

Ehrlichia canis

Ehrlichia chaffeensis which causes human form but molecular evidence has been found in canine form

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17
Q

Which species infects thrombocytic cells?

A

Anaplasma platys

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18
Q

Which species infects granulocytic cells?

A

Anaplasma phagocytophilum

Ehrilichia erwingii

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19
Q

What is the incubation period of Ehrlichia canis?

20
Q

What are the acute signs of Ehrlichia canis?

A

Vasculitis and immune destruction causing thrombocytopenia and coagulopathy
Multisystemic signs
Spleen and LN enlargement
CNS/ocular sings

21
Q

What are the two outcomes of acute Ehrlichia canis?

A

Clearing of disease

Sub-clinical carriers

22
Q

What can happen to the sub-clinical carriers of Ehrlichia canis?

A

Recover or become chronically infected

23
Q

What are the signs of chronic Ehrlichia canis infection?

A

Bone marrow destruction causing a pancytopenia

Signs as for acute

24
Q

How is Ehrlichia canis diagnosed?

A

Morulae in monocytes in blood smears or macrophages from tissue aspirates
Thrombocytopaenia/pancytopaenia
IFA/ELISA

25
How is Ehrlichia canis treated?
Tetracyclines/Chloramphenicol for 28 days
26
What are the signs of A. phagocytophilum in dogs?
Mild/moderate thrombocytopaenia Lymphopaenia Mild anaemia Natural chronic infection hasn't been seen Impaired PMN function can predispose to secondary infections
27
What are the clinical signs of Lyme disease in people?
Erythema migrans in 80-90% of cases | Later clinical signs involve skin, nervous/musculoskeletal systems
28
What are the commonest signs of Lyme disease in dogs?
Lethargy, anorexia and pyrexia Inflammatory polyarthritis Lymphadenopathy Protein-losing glomerulonephropathy
29
How is diagnosis of Lyme disease achieved in dogs?
No pathognomonic test Asymptomatic seroconversion common Microscopic/genetic detection often not possible
30
What is the treatment for Lyme disease in dogs?
Doxycycline/amoxicillin
31
What are the characteristics of Leishmania?
Flagellate protozoa Phlebotomus vector - sandflies Reservoir host - dogs
32
What is the life-cycle of Leishmania?
IMAGE
33
What are the key features of pathogenesis of canine leishmaniosis?
Macrophages are target tissues Systemic infection in haemolymphatic organs Parasite persistence can lead to chronic infection Protective immunity mediated by T cells Signs may develop months-years after infection
34
How does host immune response determine clinical outcome?
Th2 predominant = severe non self-limiting disease with high serology, decreased cellular immunity and high parasite load Th1 predominant = clinically healthy but infected self-limiting disease with low serology, predominant cellular immunity, low parasite load
35
What other factors influence variation of clinical outcome?
Endemic/naive situation, 2-4 years and >7 years more susceptible Breed, nutrition, concurrent disease and immunosuppression
36
What are the clinical signs of leishmaniosis?
Weight loss, lethargy, inappetence, skin disease, lymphadenomegaly, splenomegaly, lameness, arthropathy, PU/PD, proteinuria, ocular signs, epistaxis, GI signs, hypergammaglobulinaemia, non-regenerative anaemia or mild thrombocytopaenia, azotaemia
37
How is leishmaniosis diagnosed?
Demonstration of parasite (100% spec, 80% sens) Serology with high Ab titre highly suggestive PCR of bone marrow/LN/spleen/skin Clinicopathological findings - hyperglobulinaemia, decreased albumin:globulin ratio, thrombocytopaenia, non-regenerative anaemia, proteinuria
38
What is the treatment for leishmaniosis?
Meglumine antimoniate + allopurinol (prolonged treatment) and needs importation as not licensed in UK
39
What does Diroflaria immitis cause?
Heartworm | Occupy R side heart and pulmonary arteries
40
What are the clinical signs of D. immitis?
Coughing, dyspnoea, reduced exercise tolerance, R sided heart failure
41
What vector transmits D. immitis?
Mosquito
42
What are the prophylactic treatments for D. immitis?
Selamectin (Stronghold) Milbemycin (Program Plus/Milbemax) Moxidectin (Advocate)
43
What is the treatment for D. immitis infection?
Symptomatic treatment with steroids and treatment of CHF Adulticide therapy using melarsomine Microfilarial therapy using levamisole, ivermectin, milbemycin
44
What is Bartonellosis?
Caused by small gram -ve haemotropic bacteria
45
Which species of Bartonella is most common in cats?
Bartonella henselae most common in cats
46
What is the vector for Bartonella?
Fleas | Ticks?
47
How are zoonotic bartonella infections caused?
Cat scratch disease