Zoonoses

Question 1

What is zoonoses?

Answer 1

Infections that are naturally transmitted between vertebrate animals and humans

Question 2

What is not a zoonose? And why?

Answer 2

Malaria Schistosomiasis (Snail fever) Oncoceriasis (River Blindness) Elephantiasis (Lymphatic Filariasis) - Because even though transmitted from animals, they depend on the human host for part of their life-cycle

Question 3

What is a anthroponosis? Give some examples.

Answer 3

‘Reverse zoonoses’ in that humans are infecting animals - Influenza (virus affecting birds, pigs) - ‘Strep throat’ (bacteria affecting dogs)

Question 4

Of the current pathogens affecting humans, what percentage are zoonotic?

Answer 4

It is likely that most modern infectious diseases originated in animal Of the 1415 pathogens currently known to affect humans, 61% are zoonotic

Question 5

What can cause zoonoses?

Answer 5

Can be caused by virus, bacteria, parasites or fungi - Where pathogens have developed strategies to ensure their own survival

Question 6

What are common zoonoses in the UK?

Answer 6

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

Question 7

What are some emerging zoonoses in the UK?

Answer 7

• Avian influenza
• Nipah virus
• Rabies

Question 8

What is rabies infection?

Answer 8

Viral Infection (lyssavirus) transmitted from the bite of an infected animal

Question 9

What animals transmit it?

Answer 9

Dogs (97%), bats

Question 10

How many people die from rabies each year?

Answer 10

App. 55000 people, mainly children, die each year

Question 11

What is the incubation period of rabies?

Answer 11

2 weeks to several months

Question 12

What is the transmission of Rabies in the body and what effect does this have?

Answer 12

Travels to the brain via the peripheral nerves

It causes an acute encephalitis: malaise, headache and fever

• Progresses to mania, lethargy and coma
• Over production of tears and saliva
• Unable to swallow
• Death by resp failure

Question 13

How is diagnosis of Rabies carried out?

Answer 13

PCR of saliva or CSF

• Often confirmed post mortem on brain biopsy

Question 14

What is the prognosis of rabies?

Answer 14

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

Question 15

What is the immediate treatment of rabies?

Answer 15

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

Question 16

Outline brucellosis.

Answer 16

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

Humans infected when: during partirition, handling carcasses of dead animals, during milking of infected animals

Question 17

How common is brucellosis?

Answer 17

v rare

Question 18

What is the incubation period of brucellosis?

Answer 18

•5-30 days (up to 6 months)

Question 19

What are the symptoms of brucellosis?

Answer 19

• Acute (now very rare in Scotland)
• Subacute
• Chronic
• Subclinical (commonest)

Question 20

How do we treat brucellosis?

Answer 20

• 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

Question 21

Outline leptospirosis.

Answer 21

Infection that was common in NE scotland fish workers.

Infection associated with rats but now more commonly cattle.

In severe cases aka weil’s disease!!

Question 22

What are the symptoms of leptospirosis?

Answer 22

Flu like symptoms – then jaundice, and renal failure

Undifferented fever; myalgia, headaches & abdominal pain

Question 23

What is the mode of transmission of leptospirosis?

Answer 23

Animal urine

Question 24

How does leptospirosis access the body?

Answer 24

Penetrate abraded skin or

mucous membranes and

cause systemic illness

Question 25

How do human’s host leptospirosis?

Answer 25

Humans are incidental hosts

• Direct contact with the animal
• Contact with environment (water) contaminated with their urine
• Incubation 2-30 days (10-14)

Question 26

How can we diagnose leptospirosis?

Answer 26

Think of it!

• 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 27

How can we treat leptospirosis?

Answer 27

–Lack of evidence that antibiotics are effective, but most effective during early phase of disease

–Doxycycline for mild disease, IV penicillin for severe

–Steroids do not help

**Prompt dialysis is necessary**

Question 28

What is the vector for lyme borrelios (lyme’s disease)?

Answer 28

the little buggars - ticks [Ixodes genus]

Question 29

When is lyme borrelios most common?

Answer 29

Summer months

Question 30

What is the features of lymes?

Answer 30

Red circular rash around the site of bite. Rash may migrate along dermatome.

Question 31

If a patient presents one day after tick bite with a rash, is it lyme’s?

Answer 31

No, lymes rash will only present 3-90 days after the bite.

Question 32

How is lyme’s diagnosed?

Answer 32

Clinical diagnosis – no lab needed

NB, clinical + 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

Question 33

How is lyme’s disease treated?

Answer 33

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