Anthrax
Anthrax is an acute infectious disease caused by the spore-forming bacterium Bacillus anthracis. Anthrax most commonly occurs in wild and domestic lower vertebrates (cattle, sheep, goats, camels, antelopes, and other herbivores), but it can also occur in humansAnthrax is most common in agricultural regions where it occurs in animals. These include South and Central America, Southern and Eastern Europe, Asia, Africa, the Caribbean, and the Middle East. When anthrax affects humans, it is usually due to an occupational exposure to infected animals or their products
Transmission
Anthrax infection can occur in three forms: 1- cutanous (skin): by handling products from infected animals 2-inhalation: by inhaling anthrax spores from contaminated animal products. 3- gastrointestinal: by eating undercooked meat from infected animals. B. anthracis spores can live in the soil for many years.incubation periods:
symptoms usually occur within 7 days. Although incubation periods up to 60 days are possible Cutaneous: Most (about 95%) anthrax infections occur when the bacterial spore enters a cut or abrasion on the skin, such as when handling contaminated wool, hides, leather or hair products (especially goat hair) of infected animalsSkin infection begins as a raised itchy bump that resembles an insect bite but within 1-2 days develops into a vesicle and then a painless ulcer, usually 1-3 cm in diameter, with a characteristic black necrotic (dying) area in the center. Odema or swelling of the surrounding tissues may develop and lymph glands in the adjacent area may swell
About 20% of untreated cases of cutaneous anthrax will result in death. Deaths are rare with appropriate antimicrobial therapy.
Inhalation: Initial symptoms may resemble a common cold. After several days, the symptoms may progress to severe breathing problems and shock. Inhalation anthrax is usually fatal, and even with aggressive antibiotic and supportive therapy 45% of inhalation anthrax cases were fatal.
Intestinal: The intestinal disease form of anthrax may follow the consumption of contaminated meat and is characterized by an acute inflammation of the intestinal tract. Initial signs include: nausea, loss of appetite, vomiting, fever are followed by abdominal pain, vomiting of blood severe diarrhea.
Symptoms may also include lesions and soreness in the throat, difficulty swallowing, marked swelling of the neck and regional lymph glands. Intestinal anthrax results in death in 25% to 60% of cases.
Detection of the DNA or antigens of the bacteria, and detection of antibodies in the blood of suspected cases, are important tools for diagnosis because positive culture is unlikely after antibiotic treatment has been started
Susceptibility: There is some evidence of in apparent infection among people in frequent contact with infectious agent ,second attacks can occur but reports are rare .
Where is anthrax usually found? Anthrax can be found globally. It is more common in developing countries or countries without veterinary public health programs. Certain regions of the world (South and Central America, Southern and Eastern Europe, Asia, Africa, the Caribbean, and the Middle East) report more anthrax in animals than others.
Methods of Control: Preventive measures : a) Immunization : In countries where anthrax is common and vaccination levels of animal herds are low, humans should *avoid contact with livestock and animal products and* avoid eating meat that has not been properly slaughtered and cooked. Also, *an anthrax vaccine has been licensed for use in humans. The vaccine is reported to be 93% effective in protecting against anthrax.
b)Educate employees who handle potentially contaminated articles about modes of anthrax transmission, care of the skin abrasions and personal cleanliness . c) Control dust and properly ventilate work area. Vaporized formaldehyde has been used for disinfection of work places contaminated with B. Anthracis . d) Wash, disinfect or sterilize hair, wool, and bone meal or other feed of animal origin prior to processing
e) Do not sell the hides of animals exposed to anthrax . f) Immunize and annually re immunize all domestic animals at risk , treat symptomatic animal with penicillin or tetracycline , immunize then after cessation of treatment. g) Do not necropsy the animal , if performed , autoclave, incinerate or chemically disinfect all instrument or materials used .
B- Control of patient,contacts and the immediate envirument: 1) report to local health authority , also report to agriculture authority . Even a single case of human anthrax especially of the inhalation type. 2) Isolation :standard precaution for the duration of illness for cutaneous and inhalation anthrax . Antibiotherapy sterilizes skin lesion within 24 hours, but the lesion progress to ulceration, sloughing , and resolution .
3) Concurrent disinfection: a 0.05% hypochlorite solution is sporicidal, hydrogen peroxide, peracetic acid or glutaraldehyde may be alternative , ethylen oxide and cobalt irradiation have been used. Anthrax spores are killed by boiling (100 C or 212 F) for 30 minutes (the actual reported time is considerably less). Spores require steam.
Antibiotics should be given to unvaccinated individuals exposed to inhalation anthrax. Penicillin, tetracyclines and fluoroquinolones are effective if administered before the onset of lymphatic spread or septicemia, estimated to be about 24 hours. Antibiotic treatment is also known to lessen the severity of disease in individuals who acquire anthrax through the skin. Inhalation anthrax was formerly thought to be nearly 100% fatal despite antibiotic treatment, particularly if treatment is started after symptoms appear.