Zoonoses

Question 1

Define the term ‘zoonoses’

Answer 1

Infections that can pass between living animals and humans where the source of the disease is from the animal

Zoonoses can be caused by virus, bacteria, parasites or fungi

Question 2

Why are diseases like Malaria or Schistosomiasis not classed as zoonoses?

Answer 2

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

Question 3

Give examples of some zoonoses

Answer 3

Salmonella

Campylobacter

Shigella

E.coli

Rabies

Yellow fever

Ebola

Toxoplasma

Ringworm

Question 4

How is rabies diagnosed?

Answer 4

It’s difficult to diagnose

Do PCR of saliva or CSF but often confirmed by post-mortem on brain biopsy

Question 5

Immediately after a bite from a dog or bat etc what should be given?

Answer 5

post-exposure prophylaxis

human rabies = Immunoglobulin (HRIG)

Question 6

What is brucellosis?

Answer 6

It used to be an occupational hazard of farmers, vets, slaughterhouse workers etc

You can get it from unpasteurised milk/cheese

Organisms are excreted in milk, placenta and aborted foetus

It can stay in the body for up to 6 months if chronic

It’s very rare in the UK now

Question 7

Symptoms of acute brucellosis infection (5)

Answer 7

High ‘undulant’ fever
Weakness
Headaches
Drenching sweats
Splenomegaly

Question 8

Treatment of brucellosis

Answer 8

Long acting Doxycycline for 2-3 months + Rifampicin, or + intramuscular gentamicin for first week(s)

Chronic form is difficult to treat

Question 9

Leptospirosis

Answer 9

Different forms

Commonest form now = L.hardjo (cattle)
But in the past it used to be common in NE Scotland fish workers - L. icterohaemorrhagiae was carried by rats in the boats

It penetrates abraded skin or mucous membranes and
cause systemic illness

Question 10

Describe the symptoms of severe Leptospirosis disease

Answer 10

Weil’s disease (Triad of jaundice, AKI, bleeding)

Pulmonary haemorrhage

Question 11

Symptoms of Leptospirosis infection

Answer 11

Undifferentiated fever
Myalgia
Headaches & abdominal pain

Question 12

Diagnosis of Leptospirosis

Answer 12

Microscopic agglutination test (MAT) requires paired sera – not useful in clinical context

ELISA serology - suboptimal

Culture – take at least one week on special media

Question 13

Treatment of leptospirosis

Answer 13

Early treatment

Doxycycline if mild, IV penicillin if severe

Question 14

Lyme Borrelios (Lyme disease)

Answer 14

Vectore - ixodes genus (hard-bodied ticks)

Active above 4 degrees (more common in summer months)

Question 15

What is the classical sign of Lyme disease?

Answer 15

Erythema migrans = an expanding red rash

Can occur 3-90 days after the bite

Can have single or multiple lesions

Question 16

What is a common sign of late stage Lyme disease?

Answer 16

Acrodermatitis chronica atroficans - an uncommon skin condition affecting distal parts of the limbs

Bluish-red discoloration – progresses over months to years to atrophic phase

Peripheral neuropathy common

Question 17

What is a very rare sign of progressed Lyme disease?

Answer 17

Lymphocytoma - a bluish solitary painless nodule

Commonly found on the earlobe or nipple

More common in children

Question 18

Approx 15% of Lyme disease patients develop Neuroborreliosis - what is it?

Answer 18

A neurological manifestation of lyme disease

Causes a triad of facial nerve palsy, radicular pain & lymphocytic meningitis

Onset of symptoms 2-6 weeks after bite

Question 19

How is Lyme Disease diagnosed?

Answer 19

Red rash - clinical finding

Neuroborreliosis - clinical and lab findings - CSF, blood tests

Question 20

Treatment of Lyme Disease

Answer 20

Oral doxycycline or Amoxicillin, or IV ceftriazone