Anthrax - notifiable disease

Cause and characteristics of bacillus?

• appearance

• Oxygen requirement

• Found in??

• Spore formers

• Large gram +ve rods

• Aerobic / facultative anaerobes

• Ubiquitous

What are the three spiecies of bacillus

• licheniformis

• Cereus

• Anthracis

What does b.licheniformis cause

Abortion in cattle and sheep

What does b.cereus cause

Mastitis in cattle

food poisoning in humans

What does b.anthracis cause

Anthrax - most animal, humans not birds / reptiles

What does anthrax cause disease in? From worst to least

Consequence?

If it zoonotic? What is important about the spores?

• Obligate pathogen. Cattle/sheep/goat most , horses and pigs/carnivores

• Often fatal

• Zoonotic and notifiable

• Resistant spores

Virulence determinants of b.anthracis?

• poly-D-glutamic acid capsule

• Protective antigen

• Oedema factor

• Lethal factor

How does the protective antigen work in b.anthracis

• binds to target cell

• Cleaver by host serum protease

• Anchor for oedema factor and lethal factor

What does oedema factor in b.anthracis do?

Causes oedema and prevent leukocyte activity

What does lethal factor do in b.anthracis

Increased vascular permeability and kills macrophages

How does the poly-D-glutamic acid capsule protect b.anthracis?

Resists antibodies , complement and phagocytes

How do humans get cutaneous anthrax?

• spores form soil, meat, blood, milk , fescues, hides, hair

How do horses and pigs get cutaneous anthrax? How does this occur?

Spores from soil

• spores enter wounds, germinate, multiply and release toxins

How does cutaneous anthrax present?

Painless lesion, very dark crust (local oedema and haemorrhage)

How do horses, ruminant , pigs and carnivores get septicaemic anthrax ?

• horses/ruminant - from soil

• Pigs/carnivores - from protein supplements , carcasses

How do humans get septicaemic anthrax?

• humane inhale spore (woolsorters disease)

What happens when septicaemic anthrax enters the body?

Where does the bacteria spread to?

• spores germinate , multiply , release toxins

• Oedematous focus - oral/GIT or RT

• Bacteria spread to lymphatics and blood

What is the result of septicaemic anthrax? (6)

• bacteria use up oxygen

• Septicaemia : toxaemia

• Capillary thrombosis : haemorrhage

• Fluid loss from blood vessels : pulmonary oedema

• Circulatory collapse

• DEATH

Clinical signs of selticeamic anthrax? Before death

• increased resp and heart rate

• Fever

• Very dark tar like blood oozes from all orifices

Clinical signs of septicaemic anthrax? After death

• dark blood around orifices

• Incomplete rigour mortis

Incubation period of septicaemic anthrax?

1-14 days

How does an onset of septicaemic anthrax in ruminants present?

• Peracute

• rapid onset of signs

• Death in 1-2 hours

How does an onset of septicaemic anthrax in humans/horses present?

• acute

• Slightly slower onset of signs , death in 24hrs

How does an onset of septicaemic anthrax in pigs/carnivores present?

• subacute

• Oedema of face, throat, neck

• Invasion of blood

What is anthrax associated with today?

• disturbed soil

• Ponds / mole hills / ditches

What do you do when anthrax is found?

(Anthrax order 1991)

1. Inform APHA - apply property restrictions

2. Take blood / oedematous fluid sample by syringe

3. Prepare and stain smear (mcfadyeans stain)

4. Inform APHA of result

5. Inform local council if +ve

6. Send swab + 2 air dried smears to APHA

7. No post Morton - burn body

8. Clean up - burn bedding, formaldehyde

9. Monitor area

What is done in at risk animal and further suspect/confirmed cases in living animals

• cull

• Treat with antibiotics

• Treat with antitoxin

• Vaccinate