Anthrax disease

Anthrax is an infection caused by the bacterium Bacillus anthracis. It can occur in four forms: skin, lungs, intestinal, and injection. Symptoms begin between one day and two months after the infection is contracted. The skin form presents with a small blister with surrounding swelling that often turns into a painless ulcer with a black center. The inhalation form presents with fever, chest pain, and shortness of breath. The intestinal form presents with diarrhea which may contain blood, abdominal pains, and nausea and vomiting. The injection form presents with fever and an abscess at the site of drug injection. Anthrax is spread by contact with the bacterium's spores, which often appear in infectious animal products. Contact is by breathing, eating, or through an area of broken skin. It does not typically spread directly between people. Risk factors include people who work with animals or animal products, travelers, postal workers, and military personnel. Diagnosis can be confirmed based on finding antibodies or the toxin in the blood or by culture of a sample from the infected site. Anthrax vaccination is recommended for people who are at high risk of infection. Immunizing animals against anthrax is recommended in areas where previous infections have occurred. Two months of antibiotics such as ciprofloxacin, levofloxacin, and doxycycline after exposure can also prevent infection. If infection occurs treatment is with antibiotics and possibly antitoxin. The type and number of antibiotics used depends on the type of infection. Antitoxin is recommended for those with widespread infection. Although a rare disease, human anthrax, when it does occur, is most common in Africa and central and southern Asia. It also occurs more regularly in Southern Europe than elsewhere on the continent, and is uncommon in Northern Europe and North America. Globally, at least 2,000 cases occur a year with about two cases a year in the United States. Skin infections represent more than 95% of cases. Without treatment, the risk of death from skin anthrax is 24%. For intestinal infection, the risk of death is 25 to 75%, while respiratory anthrax has a mortality of 50 to 80%, even with treatment. Until the 20th century, anthrax infections killed hundreds of thousands of people and animals each year. Anthrax has been developed as a weapon by a number of countries. In plant-eating animals, infection occurs when they eat or breathe in the spores while grazing. Carnivores may become infected by eating infected animals. Cutaneous anthrax, also known as hide-porter's disease, is when anthrax occurs on the skin. It is the most common form (>90% of anthrax cases). It is also the least dangerous form (low mortality with treatment, 20% mortality without). Cutaneous anthrax presents as a boil-like skin lesion that eventually forms an ulcer with a black center (eschar). The black eschar often shows up as a large, painless, necrotic ulcer (beginning as an irritating and itchy skin lesion or blister that is dark and usually concentrated as a black dot, somewhat resembling bread mold) at the site of infection. In general, cutaneous infections form within the site of spore penetration between two and five days after exposure. Unlike bruises or most other lesions, cutaneous anthrax infections normally do not cause pain. Nearby lymph nodes may become infected, reddened, swollen, and painful. A scab forms over the lesion soon, and falls off in a few weeks. Complete recovery may take longer.Cutaneous anthrax is typically caused when B. anthracis spores enter through cuts on the skin. This form is found most commonly when humans handle infected animals and/or animal products. Cutaneous anthrax is rarely fatal if treated, because the infection area is limited to the skin, preventing the lethal factor, edema factor, and protective antigen from entering and destroying a vital organ. Without treatment, about 20% of cutaneous skin infection cases progress to toxemia and death. Respiratory infection in humans is relatively rare and presents as two stages. It infects the lymph nodes in the chest first, rather than the lungs themselves, a condition called hemorrhagic mediastinitis, causing bloody fluid to accumulate in the chest cavity, therefore causing shortness of breath. The first stage causes cold and flu-like symptoms. Symptoms include fever, shortness of breath, cough, fatigue, and chills. This can last hours to days. Often, many fatalities from inhalational anthrax are when the first stage is mistaken for the cold or flu and the victim does not seek treatment until the second stage, which is 90% fatal. The second (pneumonia) stage occurs when the infection spreads from the lymph nodes to the lungs. Symptoms of the second stage develop suddenly after hours or days of the first stage. Symptoms include high fever, extreme shortness of breath, shock, and rapid death within 48 hours in fatal cases. Historical mortality rates were over 85%, but when treated early (seen in the 2001 anthrax attacks), observed case fatality rate dropped to 45%. Distinguishing pulmonary anthrax from more common causes of respiratory illness is essential to avoiding delays in diagnosis and thereby improving outcomes. An algorithm for this purpose has been developed. Gastrointestinal (GI) infection is most often caused by consuming anthrax-infected meat and is characterized by diarrhea, potentially with blood, abdominal pains, acute inflammation of the intestinal tract, and loss of appetite. Occasional vomiting of blood can occur. Lesions have been found in the intestines and in the mouth and throat. After the bacterium invades the gastrointestinal system, it spreads to the bloodstream and throughout the body, while continuing to make toxins. GI infections can be treated, but usually result in fatality rates of 25% to 60%, depending upon how soon treatment commences. This form of anthrax is the rarest.