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Flashcards in Zoonoses Deck (41)
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1
Q

What are 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

2
Q

Why aren’t the likes of malaria and schistosomiasis zoonoses?

A

Because they depend on the human host for part of their life cycle

3
Q

What is the word for reverse zoonoses?

A

Anthroponosis - humans are infecting animals

4
Q

Give examples of anthroponosis

A

Influenza

Strep throat

Leishmaniasis

Chytridiomycosis

5
Q

What percentage of the 1415 pathogens that infect humans are zoonotic?

A

61%

6
Q

What strategies can zoonoses use to ensure their own survival/propagation?

A

Can cause a chronic infection to survive

Non-human reservoir

7
Q

Give three examples of bacterial zoonoses

A

Salmonella

Campylobacter

Anthrax

8
Q

Give three examples of viral zoonoses

A

Rabies

Avian influenza

Ebola virus disease

9
Q

Give three examples of parasitical zoonoses

A

Toxoplasmosis

Cysticercosis

Echinococcosis

10
Q

Give examples of fungal zoonoses?

A

Dermatophytoses

Sporotrichosis

11
Q

What are the common Zoonoses in the UK

A
  • Salmonella
  • Campylobacter
  • Toxoplasma
  • (Psittacosis – Chlamydophila psittaci)
  • (Q-fever - Coxiella Burnetti)
  • Ringworm/dermatophytosis
12
Q

Uncommon zoonoses include

A

•Now rarely seen in UK

Anthrax

Rabies

Bubonic plague

Tularaemia

Acute brucellosis

13
Q

What is an 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

So it is newly recognised, or newly evolved, or has recently increased incidence or expansion in geographical host or vector range

14
Q

What are examples of emerging zoonoses?

A
  • Avian influenza
  • Nipah virus
  • Rabies
  • Brucellosis
  • Monkeypox
15
Q

What is the most likely transmitter of rabies?

A

–Dogs (97%), bats

–Also monkeys, foxes, racoons, skunks, wolves, cats

16
Q

How many people die each year from rabies?

A

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

17
Q

What is the incubation period of rabies?

A

2 weeks to several months

18
Q

How does the rabies virus travel to the brain?

A

Travels to the brain via peripheral nerves

19
Q

What are the clinical features of rabies?

A

•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
20
Q

How do you diagnose rabies?

A

•Diagnosis difficult

  • PCR of saliva or CSF
  • Often confirmed post mortem on brain biopsy
21
Q

What is the prognosis of rabies?

A

Always fatal if untreated

22
Q

What is post exposure prophylaxis 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

23
Q

Who is more exposed to brucellosis?

A

Used to be an occupational hazard of farmers, vets, slaughterhouses workers etc

24
Q

Where are brucellosis organisms excreted?

A

Excreted in milk, placenta and aborted foetus

Humans are infected:

During milking infected animals

During parturition

Handling carcasses of infected animals

Consumption of unpasteurized dairy products

25
Q

What type of bacteria are brucella?

A

Small gram negative coccobacilli

Examples include melitensis, suis, abortus

26
Q

What is the incubation period for brucellosis?

A

5-30 days (up to 6 months)

27
Q

What is the actue presentation of brucellosis?

A

Lasts 1-3 weeks

High ‘undulant’ fever

Weakness, headaches

Drenching sweats

Splenomegaly

28
Q

What is the subacute presentation of brucellosis?

A

Lasts over 1 month

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

29
Q

What is 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 subclinical presentation of brucellosis?

A

Most common form - 50% of exposed have positive serology

31
Q

What is the treatment for 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 the hostorical cause of leptospirosis?

A

Due to L icterohaemorrhagica historically

Common in NE scotland amongst fish workers - also described in mine workers who were bitten by rats

Now L. hardjo is the commonest form (cattle - dairy workers commonly have positive serology)

33
Q

What are the symptoms of L.Icterhaemorrhagica and L.Hardjo?

A

L. Icterhaemorrhagica = flu like symptoms - then jaundice and renal failure

L. Hardjo - fever, meningism and no jaundice

34
Q

What type of organism is leptospirosis?

A

Thin highly mobile spirochaetes

One of the most widespread Zoonosis

Many reservoir host, survive in the environment for weeks to months

35
Q

How does leptospirosis enter the body?

A

Penetrates abraded skin or mucous membranes and cause systemic illness

Direct contact with the animal

Contact with environment (water) contaminated with their urine

Incubation 2-30 days (10-14)

36
Q

What are the signs and symptoms of leptospirosis?

A

Undifferentiated fever, myalgia, headaches and abdominal pain

Severe disease in 5-15 %:

Weil’s disease (triad of jaundice, AKI and bleeding)

Pulmonary haemorrhage

Case fatality 5-40%, over 50% in pulmonary haemorrhage

37
Q

A farmer with protracted flu-like symptoms is more likely to have?

Brucellosis or leptospirosis?

A

The farmer with protracted flu-symptoms is more likely to have leptospirosis than brucellosis

38
Q

What is the mode of transmission for Lyme Borellios?

A

Spirochaete found in wild deer

Transmitted by tick, Ixodes ricinus (europe)

The Ixodes genus is the vector

39
Q

What are the signs and symptoms of lymes?

A

Erythema migrans

80-90% of cases, 3-90 days after the bite

Single or multiple lesions

Acrodematitis chronica atroficans - extensor surfaces of distal extremities, bluish red discolouration - progresses over months to years to atrophic phase, peripheral neuropathy is common

Lymphocytoma - bluish solitary painless nodule, earlobe or aerola, more common in children than adults

Neuroborelliosis (NB)

15% of patients develop this

Triad of facial nerve palsy, radicular pain (migratory and worse at night) and lymphocytic meningitis

Onset of symptoms 2-6 weeks after bits

Preceeded by EM

Lyme borreliosis - USA

cardiac disorders are more common (carditis and heart block)

Arthritis is more common (large joints, often knees)

40
Q

What is the diagnosis of Lymes disease?

A

EM = clinical diagnosis

Acrodermatitis chronica atroficans = clinical and high serology titres

Arthritis = very high serolgy titres from synovial fluid - PCR

NB - clinical and laboratory findings

  1. Neuro symptoms consistent with LNB & other causes excluded
  2. CSF pleocytosis (WBC in CSF), often lymphocytic
  3. Paired blood and CSF serolgoy

ELISA if Lymes disease is suspected but there is no Eryhtema migrans

Immunoblot test if there is positive ELISA or symptoms remain after 12 weeks even if there is a negative ELISA

41
Q

What is the treatment for LYMES?

A

Oral doxycycline or amoxicillin or IV ceftriaxone

Most manifestations treat for 21 days (28 in arthritis or ACA)

Treatment of Neuroborriellosis is with parenteral beta lactam antibiotics for 2-4 weeks, cephalosporins may be superior to penicillin in this situation.