Methods used in screening for anthrax

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Anthrax screening is the practice of testing people who may have been exposed to anthrax for the disease, even though they exhibit no symptoms.

There is no screening test for anthrax; there is no test that a doctor can do for any susceptible person that affirms that he has been exposed to or carry it.

The only way an exposure can be determined is through a public health investigation.

Using Nasal Swabs for Anthrax Screening

Nasal swabs and environmental tests are not tests to determine whether an individual should begin anthrax treatment. These kinds of tests are used only to determine the extent of exposure in a given building or workplace.

A nasal swab test involves placing a swab inside the nostrils and taking a culture. The Center for Disease Control and Prevention (CDC) and the US Department of Health and Human Services do not recommend the use of nasal swab testing to determine whether a person has been exposed to anthrax bacteria (Bacillus anthracis) or as a means of diagnosing anthrax.

At best, a positive result may be interpreted only to indicate exposure; a negative result does not exclude the possibility of exposure. Also, the presence of spores in the nose does not mean that the person has inhalation anthrax. The nose naturally filters out many things that a person breathes, which can include bacterial spores. To have inhalation anthrax, a person must have the bacteria deep in the lungs, and also have symptoms of the disease.

Another reason that nasal swabs are not recommended is that most hospital laboratories cannot fully identify anthrax spores from nasal swabs. They are only able to tell that bacteria which resemble anthrax bacteria are present.

Hand-held assays (sometimes referred to as "Smart Tickets") are sold commercially for the rapid detection of Bacillus anthracis. These assays are intended only for the screening of environmental samples. Considered as instant screening devices , any positive samples should be forwarded to authorities for more sensitive and specialized confirmatory testing.

Initial Screening Tests (such as Gram stain) may be positive within 2 hours if the sample is large and contains a lot of Bacillus anthracis and the concentration of bacteria is high. However, a positive reading on this first test must be confirmed with a second, more accurate test. This confirmation test, conducted by a more sophisticated laboratory, takes much longer. The length of time needed depends in part on how fast the bacteria grow, but results are usually available 1 to 3 days after the sample is received in the laboratory.

These tests are used to narrow the definition of the sample. The confirmation tests take much longer, depending in part on how fast the bacteria grow, but are usually available 24-48 hours after the sample is received by the laboratory.

Facing Anthrax

PREVENTION

Effective decontamination of people can be accomplished by a thorough wash down with antimicrobial effective soap and water.

Waste water should be treated with bleach or other anti-microbial agent.

Effective decontamination of articles can be accomplished by boiling contaminated articles in water for 30 minutes or longer.

Chlorine bleach is ineffective in destroying spores and vegetative cells on surfaces, though formaldehyde is effective.

Burning clothing is very effective in destroying spores.

After decontamination, there is no need to immunize, treat or isolate contacts of persons ill with anthrax unless they were also exposed to the same source of infection.

Vaccination

Livestock vaccine:

Before the mechanisms of humoral and cellular immunity were understood, researchers demonstrated that inoculation of animals with attenuated strains of B. anthracis led to protection (1,2).

Subsequently, The first anthrax vaccines in 1881, only a few years after Robert Koch had proven Bacillus anthracis the cause of the disease (1877). This is the Louis Pasteur and Greenfield vaccines that were based on live-attenuated cultures of Bacillus anthracis and effectively protected livestock from the disease. (3,4).

Since then, this vaccine has served as the principal veterinary vaccine in the Western Hemisphere.

The use of livestock vaccines was associated with occasional animal casualties, and live vaccines were considered unsuitable for humans.

Edema injection

In 1904, the possibility of using acellular vaccines against B. anthracis was first suggested by investigators who discovered that injections of sterilized edema fluid from anthrax lesions provided protection in laboratory animals (5,6).

This led to exploration of the use of filtrates of artificially cultivated B. anthracis as vaccines (7--11) and thereby to the human anthrax vaccines currently licensed and used in the United States and Europe today.

Anthrax vaccine Adsorbed

Antibiotics are the first line of defense against anthrax infection. However, early

identification and treatment are critical for successful outcome. Even with aggressive

antibiotic therapy, five of the eleven victims of the 2001 anthrax postal attacks died,

underscoring the need for improved vaccines and anti-toxins for civilian protection.

The current FDA licensed anthrax vaccine (BioThrax® Anthrax Vaccine Adsorbed) is approved

for the prevention of anthrax infection. AVA is a first generation anthrax vaccine made

from cell free filtrates of whole bacterial cultures of Bacillus anthracis. This vaccine was

FDA licensed in 1970.

Disadvantages :

Requires five doses over a period of eighteen months to achieve protective immunity.

Serious allergic reactions, including anaphylactic shock, have been observed during post-marketing surveillance in individuals receiving BioThrax&trade.[12]This is because of its synthesis from a culture filtrate derived from anthrax bacteria so it contains a number of different proteins, some of which are believed to contribute to the adverse events

Recombinant Protective Anthrax

SparVaxâ„¢ is a novel second generation recombinant protective (rPA) anthrax vaccine being

developed to protect against inhalation anthrax, the most lethal form of anthrax infection in

humans.

It contains a single, highly purified protein, Protective Antigen, which is produced

using a standard production strain of E.coli.

SparVaxâ„¢ has been shown to stimulate protection against anthrax by eliciting a specific immune response to one of the primary proteins excreted by the Bacillus anthracis organism.

Advantages :

Highly consistent

Improved purity and well-characterized vaccines that can be made using industrial biotechnology manufacturing capabilities on a large scale to meet flexible needs, such as surge capacity, at a reasonable cost.

Treatment

Early and continuous intravenous therapy with antibiotics may be lifesaving.

Treatment for anthrax infection and other bacterial infections includes large doses of intravenous and oral antibiotics prophylaxis treatment.

The cutaneous (skin) form of anthrax can be treated with penicillin, tetracycline, erythromycin, and ciprofloxacin (Cipro) for about 60 days.

The pulmonary form of anthrax is a medical emergency because this is the most lethal type. It may be treated by Ciprofloxacin or doxycycline and one or two additional antibiotics: rifampin, vancomycin, penicillin, ampicillin, chloramphenicol, imipenem, clindamycin, and clarithromycin. Initial treatment is by vein (intravenous, or IV), followed by medicine by mouth.

In May 2009, Human Genome Sciences submitted a Biologic License Application (BLA, permission to market) for its new drug, raxibacumab (brand name ABthrax) intended for emergency treatment of inhaled anthrax.[13] If death occurs from anthrax the body should be isolated to prevent possible spread of anthrax germs. Burial does not kill anthrax spores.A blood sample taken in a sealed container and analyzed in an approved laboratory should be used to ascertain if anthrax is the cause of death.

Early detection of sources of anthrax infection can allow preventive measures to be taken. In a bioterrorism attack, individuals exposed to anthrax will be given antibiotics before they become sick. Most experts think that the vaccine will also be given to exposed individuals who are victims of a bioterrorist attack.

The response to the treatment depends on the type of anthra , age of patient & overall health.(14)

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