Anthrax

Anthrax is a serious infectious disease caused by 

gram-positive, rod-shaped bacteria known as Bacillus anthracis. Anthrax spores are found naturally in soil and infect both wild and domestic animals such as cattle, sheep, goats, antelope, and deer.

Mode of Transmission

•Spread of disease in animals: Animals can get infected when they breathe in or ingest spores in contaminated soil, plants or water.

• Spread of disease in humans: Person to person transmission is very rare. People normally get infected by anthrax bacillus by:

* Inhaling spores

* Eating food or drinking water that is contaminated with spores

* Getting spores in the body through a cut or scrape in the skin

Types of Anthrax

• Cutaneous: Entry of anthrax spores into the skin through a cut or scrape, can lead to cutaneous anthrax. The incubation period for cutaneous anthrax is oneseven days. Skin infection begins as a painless, pruritic papule that resembles an insect bite but within one-two days develops into a vesicle (usually one-three cm in diameter) and then a painless ulcer with a characteristic black necrotic area in the center surrounded by erythema and edema. Systemic symptoms are mild and may include malaise and low-grade fever. There may be regional lymphangitis and lymphadenopathy. Occasionally more severe form of cutaneous anthrax may occur with extensive local oedema, induration and toxaemia.

• Gastrointestinal Anthrax: Gastrointestinal anthrax develops when a person eats raw or undercooked meat from an animal infected with anthrax. There are two clinical forms of gastrointestinal anthrax – 

* Intestinal Anthrax

* Oropharyngeal Anthrax 

• Pulmonary (inhalation): Inhalation anthrax is considered to be the deadliest form of anthrax. Infection usually develops within a week after exposure, but it can take up to two months. Brief prodrome resembling acute viral respiratory illness, followed by rapid onset of hypoxia, dyspnea and high temperature, with X-ray evidence of mediastinal widening. Without treatment, only about 10-15% of patients with inhalation anthrax survive. 

• Injection: This form of anthrax was recently identified in heroin-injecting drug users in northern Europe, with symptoms similar to cutaneous anthrax.

Signs and Symptoms

Cutaneous Anthrax

• A group of small blisters or bumps that may itch 

• Swelling around the sore 

• A painless skin sore (ulcer) with a black center that appears after the small blisters or bumps. Most often the sore will be on the face, neck, arms, or hands

Inhalation Anthrax 

• Fever and chills 

• Chest discomfort 

• Shortness of breath 

• Confusion or dizziness 

• Cough 

• Nausea, vomiting, or stomach pains 

• Headache 

• Sweats (often drenching) 

• Extreme tiredness 

• Body aches

Gastrointestinal Anthrax

• Fever and chills 

• Swelling of neck or neck glands 

• Sore throat 

• Painful swallowing 

• Hoarseness 

• Nausea and vomiting, especially bloody vomiting 

• Diarrhea or bloody diarrhea • Headache 

• Flushing (red face) and red eyes 

• Stomach pain 

• Fainting 

• Massive ascites

• Toxaemia

Injection Anthrax

• Fever and chills 

• A group of small blisters or bumps that may itch, appearing where the drug was injected 

• A painless skin sore with a black center that appears after the blisters or bumps 

• Swelling around the sore 

• Abscesses deep under the skin or in the muscle where the drug was injected

Diagnosis

Presumptive Case Definition 

A case that is compatible with the clinical description AND has an epidemiological link to confirmed or suspected animal cases (bleeding from natural orifices or bloated carcass) OR exposure to contaminated animal products with or without Gram positive spore forming bacilli (1.5 to 3-4μm in size), arranged end to end in chains (bamboo stick appearance).

Laboratory Investigation for Confirmation

A presumptive case with isolation and identification of B. anthracis from relevant samples and identified by colony morphology, microscopy and biochemical test. Gamma phage lysis OR validated PCR (toxin and capsule genes) may be used for final confirmation (validated PCR on direct clinical sample is also acceptable).

Prevention 

Anthrax Vaccine Adsorbed (AVA) approved by FDA for use in routine occupational use (before possible exposure) and post-event emergency use (after possible exposure).