Anthrax overview and Definition

It is an infectious disease caused by the bacterium Bacillus anthracis.The bacterium is found commonly in soil and commonly it affects the domestic and wild animals around the world.

Peoples tends to get the anthrax when they come in contact with the soil or contaminated animals.

The disease does not spread by human to human contact.

Animals come in to contact with the bacteria when they inhale them.Animals sucha as cattle.goats,antelope,deer are commonly affected with the anthrax bacilli.There are four types of anthrax:






Bacillus anthracis is used as an biological weapon(bioterrorism).

Structure of Anthrax

It is an gram positive spore forming bacteria.

In culture the bacilli shows end to end and end of the bacilli shows truncated appearance,concave, and swollen and this gives the chain of bacilli a drum stick appearance.

It is capsid made of D glutamic acid which prevents the bacteria from phagocytosis mechanism by the host cell.


They show spore formation.they are formed in culture or soil which favours the growth of the bacteria.it is facilitated by nitrogen content in the soil,pH greater than 6,temperature greater than 15 degree,and presence of sodium chloride.

Duckering:A procedure used to reduce the spores in a wool below critical infection level.in thismethod 2% formaldehyde is used at 30-40◦c for 20 minutes and it results in disinfection of the wool.


B.antracis is a non motile spore forming gram positive bacterium. The spores of B. anthracis, which can remain dormant in the environment for decades, are the infectious form, but vegetative B. anthracis rarely causes disease.spore introduced through the skin leads to cutaneous anthrax.those introduced through the GIT lead to gastrointestinal anthrax. and those introduced through the lungs lead to inhalation anthrax. After entering a human or animal, B. anthracis spores are believed to germinate locally or be transported by phagocytic cells to the lymphatics and regional lymph nodes, where they germinate. Tend to produce the Protective antigen (PA) and edema factor (EF) combine to form edema toxin (ET) and PA and lethal factor (LF) combine to form lethal toxin (LT). After binding to surface receptors, the PA portion of the complexes facilitates translocation of the toxins to the cytosol, in which EF and LF exert their toxic effects .

Clinical signs & symptoms

Cutaneous anthrax:

This is the most common form of anthrax.The symptoms includes-

Small itchy or blisters on the skin surfaces

A painless swollen sore with a black center

Swelling in nearby lymph glands and tissues.

This is the mildest from and can be easily treated.

Gastrointestinal anthrax:

Abdominal pain and swelling


Loss of appetite

Flushing face and red eyes

Nausea and vomiting

Sore throat with difficulty in swallowing

Swelling of the neck and neck glands


Inhalational anthrax:

Initial symptoms

Chest discomfort

Coughing up of the blood

Nausea and vomiting,flu like symptoms

Progressive symptoms:

Low oxygen level

Meningitis and shock

This is the mostly deadly form of anthrax and it is fatal in 80-90% of the cases.

Injection anthrax:

It is more common among the people who inject heroin.

Initial symptoms:

Abscess in and around the injected site

Blisters and bumps,papules around the imjected site


A swollen sore is seen near the injected site.

Progressive form of the disease:


Organ failure


Differential Diagnosis

Skin testing:A sample of fluid from a doubtful lesions or a small tissue sample(biopsy) can be taken and lab sign may be investigated for cutaneous anthrax

Chest xray or computed tomography

Stool testing:it is used in gastrointestinal anthrax

Spinal tap(limbar puncture):The physician inserts the needle into your spunal canal and withdraws small amount of fluid.It is used in the investigation of meningitis caused by the bacterium.


A.Nutrient agar:produce grayish and granular colonies.under lower power microscope it appears as long interlacing chain of bacilli resembling locks of matted air leading to medusa head appearance

B.Selective medium:Knisely’s polymyxin B lysozyme EDT thallous acetate (PLET) agar is an selective medium for isolation of bacillus anthracis.

C.Blood smear:Is isndone with polychrome methylene blue shows encapsulated bacilli(MC Faydean stain)

D.Gelatin Agar:In Gelatin agar it shows inverted fir tree appearance.


Inhalational anthrax has worst prognosi.chance of fatality is approximately 90%.

Other types of anthrax include 40-45% of the fatality rate


Eat the meats that has been properly slaughtered and cooked

Avoid raw contact with animals especially cattle,sheep goat