Anthrax

(Credit: Wikipedia) Skin reaction to anthrax

Anthrax is an acute disease caused by the bacterium Bacillus anthracis. Most forms of the disease are lethal, and it affects mostly animals. It is contagious and can be transmitted through contact or consumption of infected meat. Effective vaccines against anthrax are available, and some forms of the disease respond well to antibiotic treatment.

Like many other members of the genus Bacillus, B. anthracis can form dormant endospores (often referred to as "spores" for short, but not to be confused with fungal spores) that are able to survive in harsh conditions for decades or even centuries. Such spores can be found on all continents, even Antarctica. When spores are inhaled, ingested, or come into contact with a skin lesion on a host, they may become reactivated and multiply rapidly.

Anthrax commonly infects wild and domesticated herbivorous mammals that ingest or inhale the spores while grazing. Ingestion is thought to be the most common route by which herbivores contract anthrax. Carnivores living in the same environment may become infected by consuming infected animals. Diseased animals can spread anthrax to humans, either by direct contact (e.g., inoculation of infected blood to broken skin) or by consumption of a diseased animal's flesh.

Anthrax does not spread directly from one infected animal or person to another; rather, it is spread by spores. These spores can be transported by clothing or shoes. The body of an animal that had active anthrax at the time of death can also be a source of anthrax spores. Owing to the hardiness of anthrax spores, and their ease of production in vitro, they are extraordinarily well suited to use (in powdered and aerosol form) as biological weapons. Such weaponization has been accomplished in the past by at least five state bioweapons programs — those of the United Kingdom, Japan, the United States, Russia, and Iraq — and has been attempted by several others.

Until the 20th century, anthrax infections killed hundreds of thousands of animals and people worldwide each year. French scientist Louis Pasteur developed the first effective vaccine for anthrax in 1881. Anthrax is especially rare in dogs and cats, as is evidenced by a single reported case in the United States in 2001.

Anthrax outbreaks occur in some wild animal populations with some regularity. The disease is more common in countries without widespread veterinary or human public health programs. In the 21st century, anthrax is still a problem in less developed countries. An outbreak of anthrax in humans who had eaten meat from a dead carabao was reported in Cagayan Province in the Philippines in early 2010, with over 400 cases of illness and at least two fatalities.

B. anthracis bacterial spores are soil-borne. Because of their long lifespan, spores are present globally and remain at the burial sites of animals killed by anthrax for many decades. Disturbed grave sites of infected animals have caused reinfection over 70 years after the animal's interment.

Signs and symptoms

Pulmonary

Respiratory infection in humans is relatively rare and initially presents with cold or flu-like symptoms for several days, followed by pneumonia and severe (and often fatal) respiratory collapse. 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.

A lethal infection is reported to result from inhalation of about 10,000–20,000 spores, though this dose varies among host species. As with all diseases, a wide variation in susceptibility is presumed, with evidence indicating some people may die from much lower exposures; little documented evidence is available to verify the exact or average number of spores needed for infection. Inhalational anthrax is also known as woolsorters' or ragpickers' disease. These professions were more susceptible to the disease due to their exposure to infected animal products. Other practices associated with exposure include the slicing up of animal horns for the manufacture of buttons, the handling of hair bristles used for the manufacturing of brushes, and the handling of animal skins. Whether these animal skins came from animals that died of the disease or from animals that had simply lain on ground with spores on it is unknown.

Gastrointestinal

Gastrointestinal (GI) infection in humans is most often caused by consuming anthrax-infected meat and is characterized by serious GI difficulty, vomiting of blood, severe diarrhea, acute inflammation of the intestinal tract, and loss of appetite. Lesions have been found in the intestines and in the mouth and throat. After the bacterium invades the bowel system, it spreads through the bloodstream throughout the body, while also 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 form. In the United States, only two official cases have occurred, the first reported in 1942 by the CDC and the second reported in 2010 that was treated at the Massachusetts General Hospital. It is the only known case of survival from GI anthrax in the United States. An outbreak of anthrax among people who had eaten meat from a dead carabao was reported in Cagayan Province in the Philippines in early 2010, with over 400 cases of illness and at least two fatalities.

Source: https://en.wikipedia.org/wiki/Anthrax