Zoonoses Flashcards

1
Q

What is zoonoses?

A

Infections that are naturally transmitted between vertebrate animals and humans (source is the animal)

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2
Q

Are diseases that are transmitted from animals but depend on human host for part of their life cycle zoonoses?

A

No, such as

  • Malaria
  • Schistosomiasis (Snail fever)
  • Oncoceriasis (river blindness)
  • Elephantiasis (lymphatic filariasis)
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3
Q

What is antroponosis?

A

Infections that are naturally transmitted between humans and animals (source is the human)

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4
Q

What are some examples of antrhoponosis?

A
  • Influenza (virus affecting birds, pigs)
  • Strep throat (bacteria affecting dogs)
  • Leishmaniasis (parasite affecting dogs)
  • Chytridiomycosis (fungus affecting amphibians)
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5
Q

What are some methods pathogens have developed to ensure their survival?

A
  • Causing a chronic infection to survive
  • Or having a non-human reservoir
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6
Q

What are some common zoonoses in the UK?

A
  • Salmonella
  • Campylobacter
  • Toxoplasma
  • (Psittacosis – Chlamydophila psittaci)
  • (Q-fever - Coxiella Burnetti)
  • Ringworm/dermatophytosis
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7
Q

What are some uncomon zoonoses in the UK?

A
  • Anthrax
  • Rabies
  • Bubonic plague
  • Tularaemia
  • Acute brucellosis
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8
Q

What is the definition of emerging zoonoses?

A

A zoonosis that is newly recognized or newly evolved, or that has occurred previously but shows an increase in incidence or expansion in geographical, host or vector range

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9
Q

What are some examples of emerging zoonoses?

A
  • Avian influenza
  • Nipah virus
  • Rabies
  • Brucellosis
  • Monkeypox
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10
Q

What viral infection causes rabies?

A

Lyssavirus

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11
Q

How is rabies transmitted?

A

Wide range of wild animal transmitters (bite):

  • Dogs (97%), bats
  • Also monkeys, foxes, racoons, skunks, wolves, cats
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12
Q

What is the presentation of rabies?

A
  • Travels to brain via peripheral nerves
  • Causes an acute encephalitis
    • Malaise, headache & fever
    • Progressing to mania, lethargy & coma
    • Over production of saliva & tears
    • Unable to swallow & ‘hydrophobia’
    • Death by respiratory failure
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13
Q

How is rabies diagnosed?

A
  • PCR of saliva or CSF
  • Often confirmed post mortem on brain biopsy
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14
Q

What is the prognosis of rabies if untreated?

A

Always fatal

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15
Q

What is the treatment for rabies?

A
  • Human rabies immunoglobulin (HRIG)
  • Infiltrated round the bite (if possible)
  • +4 doses of rabies vaccine over 14 days
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16
Q

How do humans get infected by brucellosis?

A
  • During milking infected animals
  • During parturition
  • Handling carcasses of infected animals
  • Consumption of unpasteurised dairy products
17
Q

Where are brucellosis organisms excreted?

A

Organisms are excreted in milk, placenta and aborted foetus

18
Q

What bacteria is responsible for brucellosis?

A

Bacteria responsible is Brucella, small gram negative coccobacilli

19
Q

What are the 3 species of brucella from most virulent to least?

A

1) Melitensis
2) Suis
3) Abortus

20
Q

What is the presentation of brucellosis?

A
  • Acute (now very rare in Scotland)
    • Lasts 1-3 weeks
    • High ‘undulant’ fever
    • Weakness, headaches
    • Drenching sweats
    • Splenomegaly
  • Subacute
    • Lasts over 1 month
    • Fever and joint pains (knee, hip, back SI joints)
  • Chronic
    • Lasts for months or years
    • Flu like symptoms, malaise, depression, chronic arthritis
    • Endocarditis, epididymo-orchitis, rarely menignism, plenomegaly
  • Subclinical (commonest)
21
Q

What is the treatment for brucellosis?

A
  • Long acting doxycycline for 2-3 months and rifampicin or +intramuscular gentamycin for first week
  • Relapses occur due to intracellular organism (5-10%)
  • Chronic form is difficult to treat
  • Add cotrimoxazole for 2 weeks in CNS disease
22
Q

What causes leptospirosis?

A

Thin, highly mobile spirochaetes

23
Q

How is leptospirosis transmitted to humans?

A

Penetrate abraded skin or mucous membranes and cause systemic illness

Traditionally an occupational disease, 10% of dairy farmers have

How transmitted to humans:

  • Direct contact with infected animal
24
Q

What are the main species of leptospriosis?

A
  • L. Hardjo (most common)
    • From cattle
    • Fever, meningism – no jaundice
  • L. Icterohaemorrhagica
    • From rats
    • Flu like symptoms, then jaundice and renal failure
25
Q

What is the presentation of leptospirosis?

A
  • L. Hardjo (most common)
    • From cattle
    • Fever, meningism – no jaundice
  • L. Icterohaemorrhagica
    • From rats
    • Flu like symptoms, then jaundice and renal failure
  • General
    • Undifferented fever
    • Myalgia
    • Headaches
    • Abdominal pain
26
Q

Leptospirosis can lead to severe disease in 5-15%, what are examples?

A
  • Weil’s disease (triad of jaundice, AKI and bleeding)
  • Pulmonary haemorrhage (PH)
27
Q

How is leptospirosis diagnosed?

A
  • Microscopic agglutination test (MAT), but requires paired sera so not useful in clinical context
  • ELISA serology, is suboptimal
  • PCR?
  • Culture, takes at least 1 week on special media
28
Q

What is the treatment for leptospirosis?

A
  • Early treatment important
  • Lack of evidence antibiotics are effective but most effective during early phase of disease
    • Doxycycline for mild disease
    • IV penicillin for severe disease
    • Steroids do not help
  • Prompt dialysis
  • Mechanical ventilation
29
Q

What causes lyme borrelios?

A

Borrelia burgdorferi is the cause, found in wild deer

30
Q

What is lyme borrelios transmitted by?

A

Transmitted by ticks (Ixodes ricinus), which is the vector:

  • I. Ricinus (Europe)
  • I. Scapularis/pacificus (N. America)
  • I. Persulcatus (Asia)
  • Active when >4oC and humid
31
Q

What is the presentation of lyme borrelios?

A
  • Erythema migrans (EM)
    • 80-90% of cases)
    • Single or multiple lesions
  • Acrodermatitis chronica atroficans (ACA)
    • Affects extensor surfaces of distal extremities
    • Bluish-red decolourisation
    • Peripheral neuropathy common
  • Lymphocytoma
    • Bluish solitary painless nodule
    • Earlobe or areola
    • Children > adults
  • Neuroborreliosis (NB)
    • Triad of facial nerve palsy, radicular pain and lymphocytic meningitis
    • Preceded by EM in 30-50% of cases
  • Cardiac disorders
    • Carditis
    • Heart block
  • Arthritis
32
Q

How is lyme borrelios diagnosed?

A
  • EM is a clinical diagnosis, no lab needed
  • ACA and lymphocytoma clinical and high serology titres
  • Arthritis very high serology titres from synovial fluid, PCR
  • Usually clinical and lab findings
      1. Neuro symptoms consistent with LNB and other causes excluded
      1. CSF pleocytosis (WBC in CSF)
      1. Paired blood and CSF serology
33
Q

What does EM stand for?

A

Erythema migrans

34
Q

What does ACA stand for?

A

Acrodermatitis chronica atroficans

35
Q

What is the treatment for lyme borrelios?

A
  • Oral doxycycline or amoxicillin or IV ceftriaxone