Anthrax Testing

Anthrax is a serious bacterial disease caused by Bacillus Anthracis. It occurs naturally in soil and can infect livestock and wild animals when they inhale spores  or eat or drink spores in contaminated soil, plants or water. Humans usually become ill after contacting infected animals or contaminated animal products. Routes of transmission include inhalation of anthrax spores, eating food containing spores, drinking water contaminated with spores, or embedding spores in a skin lesion. 

Anthrax can enter the body through the skin, respiratory tract or gastrointestinal system. The route of infection determines the clinical disease. Cutaneous anthrax occurs when anthrax spores enter a skin lesion. It usually occurs when a person handles infected animals or contaminated products like wool, hides, or hair. Lesions most commonly occur on the head, neck, forearms, and hands. Cutaneous anthrax can causes blisters or black sores with prominent swelling. 

Inhalation anthrax occurs when a person breathes in spores. People working in wool mills, slaughterhouses, and tanneries are at highest risk of infection. Infection starts in the mediastinal lymph nodes and then spreads throughout the body. Patients typically have fever, chills, sweating, chest pain, cough, and shortness of breath. It is the most deadly form of anthrax. 

Gastrointestinal anthrax can happen when a person eats raw or undercooked meat from an infected animal. It can infect the throat, esophagus, stomach and intestines. Symptoms include fever, chills , lymphadenopathy, sore throat, pain with swallowing, nausea, vomiting, diarrhea, hematemesis, and hematochezia. 

Welder’s anthrax is a more recently described disease that occurs in welders and metalworkers. It is caused by a Bacillus species other than B. anthracis that produces a toxin. It results in rapidly progressive pneumonia and can be fatal. 

Injection anthrax has been reported in heroin users in northern Europe. It is similar to cutaneous anthrax and causes abscesses deep in the skin or muscle where the drug was injected. 

Anthrax is a reportable disease in all U.S. states and territories. Anthrax cases must be reported to state and territorial jurisdictions when identified by a healthcare provider, hospital, or laboratory. Specific requirements vary by jurisdiction.

Anthrax infections can be confirmed by measuring anthrax LF toxin in blood, pleural, and ascites fluid. Biopsies can be tested for anthrax by culture and RT-PCR.  Patient samples should be collected prior to starting antibiotics. 

Plasma is the preferred specimen for anthrax lethal factor toxin testing. Samples can be collected from zero to 18 days after expected exposure or the onset of symptoms. Blood should be collected in a lavender-top tube (EDTA). 

A full thickness biopsy of a papule or vesicle, including adjacent skin, can be used to diagnose cutaneous anthrax. This biopsy should be taken preferably before the patient has started antibiotic treatment. Skin lesions can also be swabbed for culture and RT-PCR. 

A bronchial or pleural biopsy should be obtained for patients with symptoms of inhalation anthrax. If the biopsy samples are formalin-fixed, they should be shipped to CDC at room temperature. Do not freeze. If the biopsy samples are fresh-frozen, they should be stored at -70°C and shipped to CDC using dry ice. Pleural fluid can also be tested by RT-PCR and for LF toxin. 

Gastrointestinal anthrax can be diagnosed by collecting swabs for culture and RT-PCR from the oropharyngeal cavity and the rectum. Ascites fluid can also be tested by RT-PCR and for LF toxin.