الثلاثاء , 6 ديسمبر 2016
أخبار عاجلة

anthrax

human anthrax is azoonotic disease usually affecting skin but may involve lungs or gastro intestinal tract the source of human infection is always infected animals- contaminated animal product or enviromental contamination by spores from these sources.  the etiologic agent is bacillus anthracis which is found in vegetative state in man and animal.when exposedto oxygen in air it form spores that are highly resistant to chemical agent and physical changes in the enviroment.spores may remain infective for years .    resevoir hosts are domestic herbivores as cattle sheep -and goat

Anthrax is one of the oldest recorded diseases of grazing animals such as sheep and cattle and is believed to be the mentioned in the in the Anthrax is also mentioned by . Infection of humans can result from contact with infected animal hides, fur, wool (“Woolsorter’s disease”), leather or contaminated soil. Anthrax is now fairly rare in humans, although it still regularly occurs in , such as cattle, wild bufallo, and antelops, in hind-gut fermenters such as  zabres and rhinos , and in other wildlife such as elephants and  linos in certain endemic areas of the world.

Bacillus anthracis bacteria spores are soil-borne and because of their long lifetime, they are still present globally and at animal burial sites of anthrax-killed animals for many decades; spores have been known to have reinfected animals over 70 years after burial sites of anthrax-infected animals were disturbed

Until the twentieth century, anthrax infections killed hundreds and thousands of animals and people each year in Europe, Asia, Africa, Australia, and Southern Vietnam, specifically in the concentration camps during WWI, and North America. French scientist  developed the first effective vaccine for anthrax in 1881. Thanks to over a century of animal vaccination programs, sterilization of raw animal waste materials and anthrax eradication programs in North America, Australia, New Zealand, Russia, Europe and parts of Africa and Asia, anthrax infection is now relatively rare in domestic animals with normally only a few dozen cases reported every year. Anthrax is even rarer in doges and cats: there had only ever been one documented case in dogs in the USA by 2001, although the disease affects livestock. Anthrax typically does not cause disease in carnivores and scavengers, even when these animals consume anthrax-infected carcasses. Anthrax outbreaks do occur in some wild animal populations with some regularity. The disease is more common in developing countries without widespread veterinary or human public health programs.

symptoms based on its site of entry. An infected human will generally be quarantined. However, anthrax does not usually spread from an infected human to a noninfected human. But if the disease is fatal the person’s body and its mass of anthrax bacilli becomes a potential source of infection to others and special precautions should be used to prevent further contamination. Inhalational anthrax, if left untreated until obvious symptoms occur, may be fatal.

Anthrax can be contracted in laboratory accidents or by handling infected animals or their wool or hides. It has also been used in  biological werfar agents and by terrorist to intentionally infect as exemplified by the .

Respiratory infection in humans initially presents with cold or  flu like symptoms for several days, followed by severe (and often fatal) respiratory collapse. Historical mortality was 92%, but when treated early   Illness progressing to the fulminant phase has a 97% mortality regardless of treatment.

A lethal infection is reported to result from inhalation of about 10,000–20,000 spores, though this dose varies amongst host species.Like all diseases there is probably a wide variation to susceptibility with evidence that some people may die from much lower exposures; there is little documented evidence to verify the exact or average number of spores needed for infection. Inhalational anthrax is also known as woolsorters’ or ragpickers’ disease as 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 laid on ground that had spores on it is unknown. This mode of infection is used as a bioweapon.

Gastrointestinal infection in humans is most often caused by eating anthrax-infected meat and is characterized by serious gastrointestinal difficulty,  vomiting of blood, severe diarrhea, acute inflammation of the intestinal tract, and loss of appetite. Some lesions have been found in the intestines and in the mouth and throat. After the bacteria invades the bowel system, it spreads through the bloodstream throughout the body, making even more toxins on the way. Gastrointestinal infections can be treated but usually result in fatality rates of 25% to 60%, depending upon how soon treatment commences.

Cutaneous (skin) anthrax

Anthrax skin lesion

Cutaneous (on the skin) anthrax infection in humans shows up 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. Cutaneous infections generally form within the site of spore penetration between 2 and 5 days after exposure. Unlike bruises or most other lesions, cutaneous anthrax infections normally do not cause pain.

Cutaneous anthrax is rarely fatal if treated, but without treatment about 20% of cutaneous skin infection cases progress to  toxemia and death

عن admin

2 تعليقان

  1. found your site on del.icio.us today and really liked it.. i bookmarked it and will be back to check it out some more later

  2. Your blog constantly makes me think, I have just bookmarked it!

اضف رد

لن يتم نشر البريد الإلكتروني . الحقول المطلوبة مشار لها بـ *

*

إلى الأعلى