Causative agent
- Bacillus anthracis
Differential diagnosis
- Blackleg - Hemorrhagic septicemia
- Clostridium infection - Bloat
- Poisoning - Snake bite
1 . Carcass examination
- Sudden onset and rapidly fatal course
- Dark blood discharges from the natural body
openings and fail to clot
2. History taking
- Herbivore are more susceptible
- Infected by oral ingestion
- Incubation period usually 1-5 days
- Sudden death by septicemia, usually sporadic
outbreak (chronic in swine case)
- No history of vaccination and existence of
injuries
- Outbreak commonly associated with
contaminated area in the past onset
3. Clinical examination
- Death due to septicemia and toxemia
- Sudden death without clinical signs in peracute
cases, only high pyrexia before death
- In swine usually enteritis type and pharyngo
laryngitis type while septic type are not common
4. Blood smear
- Stain with polychrome methylene blue or
Giemsa to examine typical capsulated anthracis
5. Necropsy (usually prohibited)
- Absence of rigor mortis, putrifies quickly
- Edematous and hemorrhagic change in any part
of the body
- Blood exudates from natural orifices
- Splenomegaly with dark, unclotted blood
- Swollen, edematous and hemorrhagic lymph
nodes
- In pig ; edema in laryngo-pharynx, congestion
and hemorrhage in tonsil, hemorrhage with
greatly destroyed and swollen in intestine
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6. Ascoli test
- Precipitation test by heat-extracted and filtrated
antigen
7. Bacterial isolation
- Don't open and remove the carcass before blood
smear examination
- The bacilli are excreted in bloody infected fluid
exuding from openings of the carcass, urine, feces
and saliva during the last stage of the disease
Specimen : blood and organs (spleen etc.)
- Inoculate on blood agar and incubate at 37°C for
24 hr
- Colonies are large, flat, grey, rough, curly tailing at
the edges, non-hemolytic and tenacity
Identification :
- Non-motile, cotton mass like growth at bottom and
supernatant clearity in broth culture
- Positive to string of pearls test
- Positive to gamma bacteriophage test
- Proof of encapsulation by culturing the bacteria on
5-10% serum with/or 0.7% sodium bicarbonate
agar under 10-20% CO2 condition or candle jar or
in 2.5 ml defibrinated horse blood
- Pathogenicity test against experimental animal
8. Experimental animal inoculation
- Mice will die within 24-72 hr after inoculation
with emulsion of specimens collected from carcass
Control and treatment
- Quarantine : dispatch, notice and regulation
- Safety disposal of carcasses by burning or deep
burying
- Strict disinfection, decontamination and disposal
of infected or contaminated materials
- Treat exposed animals with penicillin
- Vaccination of all risk animals and surrounding
animals within a radius of 5 km and re-immunise
annually
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