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Year 3 - infection > Zoonoses > Flashcards

Zoonoses Flashcards

1
Q

what is zoonoses?

A
  • Infections that can pass between living animals and humans
  • The source of the disease is from the animal
  • WHO definition: Infections that are naturally transmitted between vertebrate animals and humans
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2
Q
  • Malaria
  • Schistosomiasis (Snail fever)
  • Oncoceriasis (River Blindness)
  • Elephantiasis (Lymphatic Filariasis)

Are these zoonoses? if so why not?

A

Because even though transmitted from animals, they depend on the human host for part of their life-cycle

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3
Q

What is Anthroponosis?

A

‘Reverse zoonoses’ in that humans are infecting animals

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4
Q

What are examples of Anthroponosis?

A

Influenza (virus affecting birds, pigs)

‘Strep throat’ (bacteria affecting dogs)

Leishmaniasis (parasite affecting dogs e.g.)

Chytridiomycosis (fungus affecting amphibians)

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5
Q

what can Zoonoses be?

A

Can be caused by virus, bacteria, parasites or fungi

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6
Q

Pathogens have developed strategies to ensure their own survival/propagation, how?

A

causing a chronic infection to survive

or have a non-human reservoir

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7
Q

List of zoonoses (partial) - bacteria

A

Salmonella

Campylobacter

Shigella

Anthrax

Brucella

E-coli (verotoxigenic)

Leptospirosis

Plague

Psittacosis (Ornitosis)

Q fever

Tularaemia

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8
Q

List of zoonoses (partial) - viruses

A

Rabies

Avian influenza

Crimean-Congo haemorrhagic fever (CCHF)

Ebola virus disease

Lassa Fever

Rift Valley fever

West Nile Fever

Yellow Fever

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9
Q

List of zoonoses (partial) - parasites

A

Cysticercosis

Echinococcosis

Toxoplasmosis

Trichinellosis

Visceral larva migrans (toxocara)

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10
Q

List of zoonoses (partial) - fungi

A

Dermatophytoses

Sporotrichosis

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11
Q

List of zoonoses (partial) - other (pirons)

A

BSE/CJDV

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12
Q

What are examples of ‘common’ zoonoses in the UK?

A
  • Salmonella
  • Campylobacter
  • Toxoplasma
  • (Psittacosis – Chlamydophila psittaci)
  • (Q-fever - Coxiella Burnetti)
  • Ringworm/dermatophytosis
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13
Q

what are some uncommon zoonoses?

A

• Now rarely seen in UK

Anthrax

Rabies

Bubonic plague

Tularaemia

Acute brucellosis

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14
Q

what are 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”

  • Avian influenza
  • Nipah virus
  • Rabies
  • Brucellosis
  • Monkeypox (shown in picture)
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15
Q

how is rabies transmitted?

A
  • Viral Infection (lyssavirus) transmitted from the bite of an infected animal
  • Wide range of wild animal transmitters:
  • Dogs (97%), bats
  • Also monkeys, foxes, racoons, skunks, wolves, cats

• App. 55000 people, mainly children, die each year

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16
Q

What is the incubation period of rabies in humans?

A

• Incubation period in humans – 2 weeks to several months

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17
Q

How and what effects does rabies cause?

A
  • Rabies virus travels to the 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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18
Q

how do you diagnose rabies?

A

• Diagnosis difficult

  • PCR of saliva or CSF
  • Often confirmed post mortem on brain biopsy
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19
Q

is rabies fatal?

A

• Always fatal if untreated (last death in UK May 2012)

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20
Q

what is the management of rabies?

A

• Immediately after bite give post-exposure prophylaxis

  • human rabies immunoglobulin (HRIG)
  • infiltrated round the bite (if possible)
  • +4 doses of rabies vaccine over 14 days
21
Q

what is brucellosis?

A
  • (Used to be) an occupational hazard of farmers, vets, slaughterhouse workers etc
  • Organisms are excreted in milk, placenta and aborted foetus
22
Q

how are humans infected with brucellosis?

A

a) During milking infected animals
b) During parturition
c) Handling carcasses of infected animals
d) Consumption of unpasteurized dairy products

23
Q

Brucellosis - Risk of _____ in laboratory – warn lab!

A

spread

24
Q

what are the features of brucellosis?

A

Now a rare disease in UK

Brucella - small, gram negative coccobacilli

3 species:

  • Melitensis: most virulent
  • Suis
  • Abortus: least virulent
25
Q

what is the incubation period of brucellosis?

A

• Incubation period 5-30 days (up to 6 months)

26
Q

what are the different presentations of brucellosis?

A

Acute (now very rare in Scotland)

Subacute

Chronic

Subclinical (commonest)

27
Q

what is the acute presentation of brucellosis?

A

lasts 1 - 3 weeks

High ‘undulant’ fever

Weakness, headaches

Drenching sweats

Splenomegaly

28
Q

what is the sub-acute presentation of brucellosis?

A

lasts over 1 month

Fever and joint pains (knee, hip, back SI joints)

29
Q

what is the chronic presentation of brucellosis?

A

lasts for months or years

Flu-like symptoms, Malaise, Depression, Chronic arthritis

Endocarditis, Epididymo-orchitis, Rarely meningism, Splenomegaly

30
Q

what is the sub-clinical presentation of brucellosis?

A

most common form

50% of exposed have positive serology

31
Q

what is the treatment of brucellosis?

A
  • Long acting Doxycycline for 2-3 months + Rifampicin, or + intramuscular gentamycin for first week(s)
  • Relapses occur due to intracellular organism (5-10%)
  • Chronic form - difficult to treat
  • Add Cotrimoxazole for 2 weeks in CNS disease
32
Q

what is leptospirosis

A
  • Was common in NE Scotland fish workers
  • Due to L. icterohaemorrhagica
  • Described in Fife miners – bitten by rats
  • Flu like symptoms – then jaundice, and renal failure
  • But now L. hardjo (cattle) is commonest form
  • Fever, meningism – no jaundice
  • 11% of dairy workers have positive serology
  • Most have no history of illness
33
Q

how is leptospirosis transmitted?

A

Thin, highly mobile spirochaetes

One of the most widespread Zoonosis

Many reservoir host

Survive in the environment for weeks to months

Penetrate abraded skin or mucous membranes and cause systemic illness

34
Q

how is the epidemiology of leptospirosis changing?

A

Traditionally an occupational disease

Emerging:

Recreational (Borneo Eco Challenge 2000)

Unexplained emergence in Thailand; 30-40.000 cases at end of 1990s

Climate change/disaster associated outbreaks (Typhoon in The Phillippines 2009, Hurricane in Costa Rica 2017)

35
Q

how are humans incidental hosts of leptospirosis?

A

Direct contact with the animal

Contact with environment (water) contaminated with their urine

Incubation 2-30 days (10-14)

36
Q

what are the symptoms of leptospirosis?

A

Undifferented fever; myalgia, headaches & abdominal pain

37
Q

how common is severe disease in leptospirosis?

A

Severe disease in 5-15%

38
Q

how do you diagnose leptospirosis?

A

Think of it!

Fever in a cattle farmer, Exposure to water or rats, The farmer with protracted flu-symptoms is more likely to have leptospirosis than brucellosis

  • Microscopic agglutination test (MAT) requires paired sera - not useful in clinical context
  • ELISA serology - suboptimal
  • PCR?
  • Culture - take at least one week on special media
39
Q

what is the treatment of leptospirosis?

A

• Early treatment:

  • Lack of evidence that antibiotics are effective, but most effective during early phase of disease
  • Doxycycline for mild disease, IV penicillin for severe

0 Steroids do not help

  • Prompt dialysis
  • Mechanical ventilation
40
Q

what is lyme borrelios? (lyme disease)

A
  • Clustering of childhood arthritis in Old Lyme, Connecticut, USA in 1977
  • Burgdorfer found cause in 1982 – hence Borrelia burgdorferi
  • Spirochaete found in wild deer
  • Transmitted by tick, Ixodes ricinus
  • Commonest in summer months
41
Q

what is the vector of lyme disease?

A

tick

42
Q

What is seen in 80-90% of cases of lyme disease?

A

Erythema Migrans (EM)

  • Clinical diagnosis
  • 3-90 days after the bite (7-30)
  • Single or multiple lesions
43
Q

what is ACRODERMATITIS CHRONICA ATROFICANS (ACA)?

A
  • European (B. Afzelii)
  • Elderly people
  • Extensor surfaces of distal extremities
  • Bluish-red discoloration - progresses over months to years to atrophic phase
  • Peripheral neuropathy common

a skin rash indicative of the third or late stage of European Lyme borreliosis

44
Q

what is LYMPHOCYTOMA?

A
  • Bluish solitary painless nodule
  • Earlobe or areola
  • Children > Adults
45
Q

App 15% of patients develop NB, what is it? (neuroborreliosis)

A

• Triad of facial nerve palsy, radicular pain & lymphocytic meningitis

  • Radicular pain (70-85%), migratory, worse at night
  • Cranial neuropathy (app 50%) - facial palsy
  • Onset of symptoms 2-6 (1-12) weeks after bite
  • Preceded by EM in 30-50%
46
Q

what effects does lyme borreliosis in the usa?

A

• Cardiac disorders more common (8 – 10%)

  • Carditis (peri-myocarditis)
  • Heart block

• Arthritis more common - Large joints, often knees

47
Q

what is the diagnosis of lyme disease?

A
  • EM a clinical diagnosis - no lab needed
  • ACA and Lymphocytoma clinical & high serology titres
  • Arthritis - very high serology titres from synovial fluid. PCR
  • NB, clinical + laboratory findings:
  1. Neuro symptoms consistent with LNB (Lyme Neuroborreliosis) & other causes excluded
  2. CSF pleocytosis (WBC in CSF), often lymphocytic
  3. Paired blood and CSF serolgoy
48
Q

what si the treatment of lyme?

A
  • Oral Doxycycline or Amoxicillin, or IV Ceftriaxone
  • Most manifestations treat for 21 days (28 in arthritis or ACA)

Year 3 - infection (14 decks)

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