Flashcards in Arthropod-bourne infectious disease 1 Deck (59):
1
What tick borne pathogens my be importe in dogs travelling from EU
NON ENDEMIC to UK: babesia canis canis, babesia gibsoni, ehrlichia canis
ENDEMIC TO UK: borrelia burgdorferi, anaplasma phagocytophilum
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Which ticks are present in Europe?
- Ixodes ricin us: widespread
- Dermacentor reticularis: more restricted distribution
- Rhipicephalus sanguineus : life cycle requires temp > 18 degrees, not endemic in UK, intro from dogs travelling from EU, establish in houses / kennels here, vector for Mediterranean spotted fever (rickettsia conorii), carries babesia and ehrlichia
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What are babesia and theileria?
Piroplasms
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Most important agents of canine babesiosis
- LARGE BABESIA: b. Canis canis, B canis vogeli and B. Canis Rossi
- SMALL BABESIA: b. Gibsoni
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How do different babesia spp vary?
- size
- vectors
- geo distribution
- Virulence
- prognosis
- response to tx
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Babesia pathogens sis
- within ticks transmitted trans-stadially and trans-ovarially
- sporophytes injected from tick salivary glands
- enter circulation, endocytosed by RBC
- IM component of pathology
- TP common (but usually doesn't cause bleeding or abnormal coagulation)
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Which babesia spp are zoonotic?
- b.microti - rodent reservoir
- b. Divergent - cattle reservoir
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CS - babesiosis
- those of haemolytic anaemia
- lethargy, depression, inappetance
- icterus
- splenomegaly
- tachycardia and tachypnoea
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Babesia - diagnosis
1 clinical laboratory findings: non-specific, TP common, many dogs are Coombs positive / auto agglutinate
2. Microscope identification : low sensitivity so must use another test to verify
3. PCR : high sensitivity, broad range babesia PCR, spp id possible using species specific PCR / sequencing
4. Serology: usually IFA or ELISA
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Babesia - tx
- antibabesia drug : Imidiocarb dipropronate
- LARGE BABESIA: rapid clinical response
- SMALL FORMS : clinical and parasitological cure uncommon, clinical relapses may occur
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What type of bacteria are rickettsia?
Small obligate intracellular gram negative
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Which rickettsia infect monocytes?
- ehrlichia canis
- ehrlichia Chaffeensis: causes human monocytes ehrlichiosis, transmitted by ambylomma americanum, molecular evidence canine infections
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Which rickettsial parasite infects thrombocytes?
Anaplasma platys
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Which ricketssia infects granulocytes?
- anaplasma phagocytophilum
- ehrlichia erwingii
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Incubation time - ehrlichia canis
1-3 weeks
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Acute CS - ehrlichia canis
- vascular is and immune destruction leading to thrombocytopenia and cpagulopathy
- multi systemic signs
- spleen and LN enlargement
- CNS / ocular signs
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Chronic - CS - ehrlichia canis
- BM destruction leading to pancytopaenia
- signs as for acute
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Species infected by ehrlichia canis
Dogs and wild canids only
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Diagnosis - ehrlichia canis
- modular in blood smears or macrophages from tissue as pirates (spleen, lung, LN)
- thrombocytopenia / pancytopaenia
- IFA/ELISA
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Tx/ prevention - Ehrlichia canis
-tx: TCs for 28d/ chloramphenicol
- no vaccine
- chemo prophylaxis
- tick control
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Anaplasma phagocytophilum - CS
- mild/ moderate TP
- lymphopaenia
- mild anaemia
- naturL chronic infection has not been seen
- impaired PMn function can predispose to secondary infection
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A. Phagocytophilum in cats?
Very rarely
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A.phagocytophilum - zoonotic?
Yes but unclear if infected domestic animals pose zoonotic risk. May have role as sentinels
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What is Borrelia burgdorferi sensu lato associated with?
Lyme borreliosis
25
Hosts - borrelia
Humans, dogs incidental host (sylvatic tick- wildlife cycle)
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What are the Borrelia pathogenic genospecies?
- b.afzelli (skin complications)
- b. Garinii (Neuro complications)
- b.burgdorferi sensu stricto ( the only pathogenic spp in USA, present in some parts of. Europe and can cause Neuro / arthritic complications)
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What is the most prevalent tick- transmit infection in temperate areas of Europe, USA and Asia?
Lyme disease in people
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CS - human Lyme disease
- erythema migrans in 80-90%
- later involves skin, Neuro and msk systems
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Overall mean prevalence of b.burgdorferi in ticks in Europe
12%. Central Europe has highest tick infection rates
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CS - borreliosis in dogs
- co infections common
- lethargy, anorexia and pyrexia
- inflammatory PA
- inflammatory arthritis
- lymphadenopathy
- protein losing glomerulonephropathy
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Dx - borreliosis in dogs
- no pathognomic test
- a symptomatic seroconversion common
- microscopic / genetic detection often not possible
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Tx - borreliosis in dogs
Empirical AB tx (doxycycline - amoxicillin)
33
Describe leishmania
- flagellate Protozoa
- phlebotomous vector
- reservoir host
- non- vector routes of transmission: venereal, blood products, direct contact (skin wounds)
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What is the most important leishmania spp in Europe?
L. Infantum
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Outline canine Leishmaniosis in Europe
- 2.5 million infected in France, Spain, Italy and Portugal
- infection rates 70-90% in some areas (Spanish Balearics)
- prevalence requires PCR and serology
- in North Europe infection generally restricted to dogs travelling from endemic area ( and high sandfly exposure March to November)
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UK dog Leishmaniosis situation
Infected dogs are potential reservoir should incursion of a competent vector occur
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Outline leishmania lifecycle
Promos tigons develop in macrophages - ingested by sandfly rep, infected human/ dog - flagellate amastigote in sandfly - then becomes inoculated into dog/ human
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Pathogenesis - leishmania
- macrophage is target cell
- systemic infection in haemolymphatic organs
- parasite persistence can cause chronic infection
- protective immunity mediated by TC
- signs may develop months to years after infection > 7 years
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What determines leishmania clinical outcome?
- host immune response
- also:
- age (2-4 and >7 more susceptible)
- breed
- nutrition
- concurrent dz
- immunosuppression
40
CS - leishmania
Chronic systemic dz
- usually visceral and cutaneous signs
- waxing and waning
41
Dx - canine leishmania
1. Demonstration of parasite: definitive diagnosis, specificity 100%, sensitivity
42
Tx - canine leishmaniasis
- ANTILEISHMANIAL DRUGS: often give clinical remissions persistent parasite ai, meglumine antimoniate ('glucantime') + allopurinol, prolonged tx, not licensed for use in UK
- consider euthanasia d/t zoonotic risk, especially where endemic
43
Prevention - canine Leishmaniosis
- sandfly avoidance
- topical insecticides: imidacloprid/ permethrin spot on 2d before travel, deltamethrin collars 2 wks before travel
- vaccine available
44
Human Leishmaniosis - CS
- cutaneous
- visceral ( can be fatal)
- mucocutaneous
- self- limiting / sub clinical
45
At risk groups for human Leishmaniosis
Young, immunosuppression, poor
46
Primary route of infection - human leishmania
Sandflies from dogs, also possibly direct contact
47
T/f: human and canine Leishamnia correlated at population level
True
48
Dirofilaria immitis - distribution
- endemic in Europe USA, Australia np but not UK
49
Vector - dirofilaria immitis
Mosquito (>70spp can transmit)
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What does dirofilaria immitis cause?
- heart worm
- occupy RHs heart and PA
- CS: coughing, dyspnoea, decrease exercise tolerance and right sided heart failure
- cats more resistant than dogs but dz can occur
- zoonotic
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PPP - dirofilaria immitis
6 months
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Prophylaxis - dirofilaria immitis
- selamectin (stronghold)
- milbemycin (milbemax)
- moxidectin (advocate)
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Dirofilaria immitis - tx
1. Symtomatic - steroids and tx CHF
2. Adults code - melarsomine
3. Microfilarial - levamisole, ivermectin, milbemycin
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What type of bacteria is bartonella?
Small gram negative haemotropic bacteria. Different host- adapted spp within bartonella
55
What is commonest bartonella in cats?
Bartonella hensellae (also B. Clarridgeiae)
56
Prevalence of bartonella
Widespread - seroprevalence up to 40%. Feline dz reported but unusual.
57
Main relevance of bartonella
Zoonotic potential - causes cat scratch disease. Causes lymphadenomegaly in immunocompetant hosts. Roughly 125 human cases / year in UK. Serological diagnosis but indirect IFA.
58
Why may diagnosis of arthropod borne diseases be complicated?
Long incubation period and aasymptomatic states.
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