Anthrax

Anthrax
(splenic fever, charbon, wool sorters disease,

malignant carbuncle )
Dr. Krishna Khadka

Assistant Professsor
M.V.Sc (Veterinary Pathology)
IAAS, Paklihawa Campus
INTRODUCTION
• Anthrax is a peracute , acute disease characterized
by septicaemia and sudden death accompanied by
the exudation of tarry blood from the body orifices
of the carcass , absence of rigor mortis and extensive
enlargement of spleen.
• Anthrax is worldwide in distribution.
• ZOONOTIC DISEASE
Cause
Bacillus anthracis
Capsulated, Gram-positive, rodshaped bacillus,
produces spores
However, spores are not formed until it has been
exposed to air and live for long outside.
Has two virulent factors(capsule(pDg) and triple
toxin)
Predisposing factors
• Ph (Alkaline pH: reserve the organism, acidic soil : destroy the
organism)
• Wet soil: stagnant water spores are concentrated and suspended.
• Major source of infection: contaminated bone meal, pasture and

fodder grown on infected soil, blood and other discharges from
infected animals.
Economic impact
• Severe economic loss
• High mortality
• Reduce milk yield
• Expenses during prevention and control
Host affected
• Mainly a disease of herbivorous animals, but may
affect a wide variety of species, including humans.
• Most susceptible :Cattle, sheep and goats
• Slightly more resistant :horses and mules.
• Pigs, dogs, cats are even more resistant.
Transmission
• Ingestion or inhalation of spores or vegetative forms
of the organism
• Entry of the organism through the broken skin.
• Animal waste and product like bone meal, wool,
bristles and hides also can cause infection causing
wool sorters disease.
• Infected excretion and secretions from animals.
• Mechanical transmission through Tabanid fly bite.
PATHOGENESIS
Infection through ingestion of the spores or opening
Genmination of spore
Localized multiplication
Spread by lymphatics to lymph nodes and further to blood stream
Septicaemia
• The bacteria possesses both capsule and exotoxin.
• Due to presence of capsule phagocytic cells become unable to destroy
them.
• The exotoxin is lethal in nature, it causes edema and tissue damage. The
exotoxin has 3 components:
1. Edema factor (EF) or factor I is adenyl cyclase which causes increase
in cellular c-AMP level that causes electrolyte and fluid loss.
2. Protective antigen (PA) or factor II is a fragment of exotoxin and has
anti-phagocytic activity.
3. Lethal factor (LF) or factor III stimulates macrophages for production
of oxidizing radicals and cytokines. Mainly ILl and TNF- (x, which induce
shock and death.
Symptoms
Cattle and sheep(highly susceptible)
• disease occurs either in the peracute or the acute form.
• Sudden Death is the first premoniory indication of the presence of disease.
• Fever up to 107° F with signs of muscle tremor, dyspnoea, depression,
weakness, congestion of mucous membrane.
• Animal collapses and die due to terminal convulsions.
• Most animals so affected die within a few hours, or a day.
• After death, bloody discharges from body orifices: nostrils, mouth, anus,
vulva .
• Occasional subcutaneous swellings.
Acute form:
• IP: 1-2 weeks
• Course of the disease is about 48 hrs.
• Fever, severe depression, listlessness, congestion and hemorrhage of
mucous membrane, increased heart rate and rapid respiration.
• Mouth breathing due to oxygen hunger.
• Abortion, decrease in milk yield, blood stained milk, diarrhoea, local
edema of tongue and throat, sternum, flank occur.
anthrax-infected bovine carcass. Note the marked bloating. Bacteria in body fluids
exuded from orifices after death
An anthrax-infected bovine carcass. The head is covered by a plastic bag and the
body by a plastic sheet
Zoonosis
• Fatal disease of human beings.
• Agent of Bio-terrorism and listed as category A
disease by OIE.
• Occupational hazard: by inhalation of spores in
wool sorter in wool industry while sorting in
wool and processing of hides (leather industry).
Macroscopic lesions
• Post mortem examination of animals suspected for anthrax should not be
conducted.
• Unclotted tarry colored blood oozes out through natural orifices.
• Oedematous and haemorrhagic changes in any part of the body, particularly
in serous membranes.
• Spleen: enlarged and engorged with dark, unclotted blood.
• Lymph nodes: swollen, oedematous, and sometimes haemorrhagic.
• Haemorrhages and swelling may occur in the intestinal tract, Liver, and
kidneys.
• Pigs: oedema and haemorrhages are seen in the pharynx and cervical lymph
nodes.
• In cases of longer duration, lymph nodes become enlarged and solid, with
yellowish foci surrounded by fibrous connective tissue.
Microscopic Findings
• Large rod-shaped organisms can be
demonstrated in the smears or tissue sections.
• Degenerative and necrotic changes in kidneys
and liver.
• Haemorrhage in spleen and accumulation of
blood in red pulp of kidney
A photomicrograph of Bacillus anthracis bacteria using Gram’s stain technique
Diagnosis
• Symptoms and necropsy findings.
• Isolation and identification of organism.
• Haematological and blood chemistry
examination should not conducted because of
risk for humans.
• Microscopic examination smear: Square ended blue bacilli
chain with metachromatic pink capsule after staining with
polychrome methylene blue stain is called “McFadyean’s
reaction”.
• In early stage ;bacilli may not be present in blood so culture
can be done or fluid can be injected into guinea pigs would
give proper diagnosis.
• Fluorescent antibody technique.
• Gelatin stab culture: Growth resembles “inverted fir tree

appearance”
• Nutrient agar media: 5 % blood agar show “Medusa head

colonies”
• Ascolis test: To demonstrate the antigen in severely decayed

carcass and the skin . The tube containing positive
serum(antibody) is overlayed with suspected
sample(antigen) develops a white precipitation ring at the
junction of the two liquids in positive case.
Differential Diagnosis
– Blackleg
-Lightening strike
-Malignant edema
– Bacillary haemoglobinurea
-Hypomagnesemia
– Hemorrhagic speticemia.

Anthrax

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Anthrax

(splenic fever, charbon, wool sorters disease,

Dr. Krishna Khadka

• Anthrax is worldwide in distribution.

• Wet soil: stagnant water spores are concentrated and suspended.

• Major source of infection: contaminated bone meal, pasture and

Spread by lymphatics to lymph nodes and further to blood stream

• Gelatin stab culture: Growth resembles “inverted fir tree

• Nutrient agar media: 5 % blood agar show “Medusa head

• Ascolis test: To demonstrate the antigen in severely decayed

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