Anthrax in the United States

From MicrobeWiki, the student-edited microbiology resource

Introduction

Description of Anthrax

Anthrax is a severe disease caused by the bacteria Bacillus anthracis. It can infect both humans and animals (mostly in herbivorous mammals), and although human contact does not spread the disease, humans can get infected from touching or inhaling spores from contaminated animal products. Even eating rare meat from an infected animal is enough to cause anthrax. Symptoms will generally appear within 7 days after infection. The infection can affect the skin, respiratory tract, and gastrointestinal tract.

Cutaneous Anthrax

The most common type of anthrax, cutaneous (skin) anthrax, happens when a person has a cut of some type on the skin, allowing the bacteria to enter. An itchy lesion usually forms at this site, but after 1-2 days, it turns into a vesicle, and later, an ulcer. The surrounding lymph nodes are may also be subject to swelling. The ulcer, generally 1-3cm in diameter, contains a black necrotic (dead) center and is typically painless. However, if left untreated, approximately 20% of cutaneous anthrax cases can lead to death.

Respiratory (Pulmonary) Anthrax

The most common type, cutaneous (skin) anthrax, happens when a person has a cut of some type on the skin, allowing the bacteria to enter. An itchy lesion usually forms at this site, but after 1-2 days, it turns into a vesicle, and later, an ulcer. The surrounding lymph nodes are may also be subject to swelling. The ulcer, generally 1-3cm in diameter, contains a black necrotic (dead) center and is typically painless. However, if left untreated, approximately 20% of cutaneous anthrax cases can lead to death.

Gastrointestinal Anthrax

Gastrointestinal anthrax usually results from eating infected meat. The infection severely inflames the intestines, causing severe diarrhea and vomiting of blood, initially preceded by nausea, decreased appetite, and fever. If it goes untreated for long enough, toxaemia and shock will occur, leading to death. Gastrointestinal anthrax can also occur in the oropharyngeal – the symptoms then become a sore throat, difficulty in swallowing, fever, swollen lymph nodes, and toxaemia. Even with treatment, about 50% of oropharyngeal anthrax infections are fatal.

Description of the microbe

Include a link if there is an existing microbewiki page. Ex. Salmonella typhi

Transmission of disease

How is it transmitted? Is there a vector (animal/insect)?

Outbreak of anthrax in the United States

Although human anthrax was historically known to be contracted from high exposures to animals and animal products that were infected with Bacillus Anthracis spores, the spread of human anthrax in the United States took on a different approach. The problem arises during early October to November in 2001, as the United States of America announced its first ten confirmed cases of human anthrax from bioterrorism. The outbreak of this disease was caused by inhalation of anthrax from exposure of the disease.

Spread of anthrax in the U.S.

Intentional contaminated letters and packages were mailed to various districts of the U.S., targeted victims remained helpless and vulnerable to the Bacillus anthracis spores upon opening and handling. As a result from this event, the U.S. postal office was affected drastically as all of the initial patients were either employees of the postal office, mail handlers and sorters.

Effects of anthrax on the U.S. citizens

The problem caused by this hazardous disease in America results in various health issues along with social disruption and an economic crisis. Symptoms include of chills, a fever, difficulty coughing, constant sweats, fatigue, and typical feelings of morning sickness; nausea and vomiting. As an outcome of the ten initially infected citizens, all displayed abnormal chest x-rays; infiltrates, mediastinal widening, and pleural effusion. With efforts to restore health to the ten patients, methods of multiple drug antibiotics were used along with guidance and supportive care, however only 60% of the patients survived.

Prevention

In the United States, the primary way to reduce the risk of exposure is through controlling the livestock. Proper disposal of anthrax infected carcasses and vaccination of at risk herds can help reduce exposure. The most effective and proper way of eliminating the exposure is through incineration of the contaminated soil. Patients that have died from anthrax should be isolated and contaminated materials should be properly disposed of through incineration. It is important that following the first detection of an anthrax infection in a herd, the surrounding animals should be removed and isolated from the field. The animals will then need to be monitored for a period of time and all the animals should be vaccinated if needed.

Vaccines

Vaccines can be used to prevent the disease in humans and animals. In the United States however, only high-risk groups such as military personnel are given the vaccine. Vaccine is not recommended for public use in the United States as anthrax cases are very rare and potential adverse side effects have been reported in some patients.

Anthrax Vaccine Adsorbed(AVA)

Anthrax Vaccine Adsorbed (AVA) is the only licensed human vaccine in the United States. The vaccine does not contain any dead or living bacteria cells but rather anthrax protective antigen protein so that vaccine cannot give an infection to the person. In a controlled study in which 379 employees received the vaccines, 414 received placebo, and 340 received neither vaccines or placebo, the study documented a vaccine efficacy of 92.5% for protection against anthrax (cutaneous and pulmonary). The duration of this protection is unknown in humans but in animals it has been known to have an effect from one to two years after two doses.

Treatment

Antibiotics

Antibiotics can be used before and after the patient has come in contact with the disease. This therapy is shown to result in a substantial recovery in individuals and animals infected with anthrax if taken immediately. Antibiotics can also be used for prevention and treatment in asymptomatic patients that may have been in exposed to the anthrax but have shown to have less of an effect on the spore form of the disease. It is important to note that antibiotics can kill the bacteria, but do not have an effect on anthrax toxins so late treatment of the infection can be detrimental.

What else could be done to address this problem

Are there solutions that could be successful but haven't been implemented due to political or economic reasons? Are there successful efforts in other countries? Are there reasons why these efforts may or may not be successful in the country you've focused on? etc. etc.

References

[Sample reference] Takai, K., Sugai, A., Itoh, T., and Horikoshi, K. "Palaeococcus ferrophilus gen. nov., sp. nov., a barophilic, hyperthermophilic archaeon from a deep-sea hydrothermal vent chimney". International Journal of Systematic and Evolutionary Microbiology. 2000. Volume 50. p. 489-500.

Edited by [insert your names here!], students of Rachel Larsen



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