What is anthrax?

Introduction
Cause and Symptoms
Bacillus anthracis
Epidemiology
Diagnosis and treatment
biological warfare agent
References
Further reading


Anthrax is a bacterial zoonosis caused by Bacillus anthracis, a spore-forming gram-positive bacterium commonly found in the soil of endemic areas. It is primarily a disease of herbivorous wildlife and livestock that occasionally infects other carnivores or omnivores, including humans.

Anthrax. Image Credit: Kateryna Kon/Shutterstock.com

Humans contract the disease through unintentional contact with infected animals or animal products. Infections in humans have a high fatality rate if not recognized and treated promptly.

B.anthracis is identified as a possible biological weapon in addition to naturally acquired forms of anthrax, and the risk of obtaining anthrax from laboratory products B.anthracis spores highlights the need for anthrax surveillance, prevention and control in countries where the disease is endemic.

Cause and Symptoms

The causative agent of anthrax is B.anthraciswhich is an aerobic, spore-forming, rod-shaped bacterium.

The disease has three forms: cutaneous, inhalation and gastrointestinal, which occur when endospores enter the body through cracks in the skin, through inhalation or ingestion, respectively. Human anthrax is cutaneous in 95% of cases and inhaled in 5%. Gastrointestinal anthrax is extremely rare, occurring in less than 1% of all cases. Anthrax meningitis is a rare consequence of one of three forms of the disease.

The lung infection has an incubation period of 1 to 6 days and is characterized initially by flu-like symptoms in humans, delaying identification in the early phase before rapidly deteriorating into a shock-like syndrome independent of the cytokines with meningitis, multiple organ failure, cardiac arrest. , And the dead.

Symptoms of gastrointestinal anthrax include nausea, loss of appetite, bloody diarrhea, and fever with stomach pain. Humans contract the disease through unintentional contact with sick animals or animal products, or through ingestion or handling of infected animal meat. Anthrax can be transmitted from animal to animal or from human to human.

Cutaneous anthrax occurs when spores enter the body through breaks in exposed skin. Spores germinate locally or in regional lymph nodes within macrophages, and vegetative forms are expelled. The incubation period varies from one to twelve days.

The first skin lesion is a painless or itchy papule with a disproportionate amount of edema progressing to a vesicular form (1-2 cm). Fever and regional lymphadenopathy are possible side effects. The gallbladder then ruptures, resulting in an ulcer and a black eschar that comes off in 2 to 3 weeks. Purulence is observed only in non-anthrax secondary infections. Airway involvement may result from edema associated with infection of the face or neck.

Bacillus anthracis

B.anthracis comes in two forms: vegetative cells (which live in the host) and spores, which live in the soil or environment. It is 1-1.2 µm wide, 3-5 µm long, and appears to have a chain-like structure under the microscope. Although it is an aerobic bacterium, B.anthracis can thrive in an anaerobic environment due to its ability to sporulate. It can live as spores for several years in soil, air and water.

The spores are unaffected by harsh environments and are resistant to high temperatures, pressure, pH, chemicals, UV, and nutrient deprivation. B.anthracis is commonly found in soil as endospores, where it can survive for decades. B.anthracis possesses two key virulence factors: a poly-D-glutamic acid capsule and a tripartite toxin. Pathogenic B.anthracis bacteria form a capsule that mimics the host’s immune system by hiding germs from macrophages.

Epidemiology

B.anthracis the spores can live in the soil for many years and are found all over the world, even if the infection is only found in specific regions. Anthrax is most prevalent in agricultural areas of Central and South America, sub-Saharan Africa, Central and Southwest Asia, and Southern and Eastern Europe. Although outbreaks of human anthrax continue to occur in livestock and wild herbivores in the United States, Canada, and Western Europe, human anthrax is now rare in these locations.

Anthrax

Anthrax. Image Credit: Kateryna Kon/Shuttestock.com

Diagnosis and treatment

According to the CDC, a confirmed case of anthrax is clinically compatible with the isolation of B.anthracis or has at least two supporting positive tests using serological or other methods. The most common diagnostic method is routine culture with confirmation by immunohistochemical staining or real-time PCR.

Given the possible severity of anthrax infection, the first suspicion of illness should prompt antibiotic treatment until the diagnosis is confirmed. Although antibiotics are crucial in the treatment of B. anthracis, their effectiveness may be related to factors other than bacterial clearance. Immunization of animals is an essential strategy to prevent and control anthrax in animals and, therefore, prevent human infection.

Immunotherapy has remained one of the most popular treatment options for people with fulminant-stage pulmonary or gastrointestinal anthrax. Passive immunization with therapeutic antibodies is becoming one of the most important mainstays of emergency prophylactic treatment in the event of exposure to antibiotic-resistant anthrax spores, as expected in deliberate bioterrorism attacks, or the onset delayed from standard post-exposure treatment when toxemia has set in.

B.anthracis is resistant to a wide range of antimicrobial drugs, including first-generation cephalosporins. Third-generation cephalosporins and trimethoprim-sulfamethoxazole are not effective against the bacteria. In all situations, antimicrobial susceptibility testing should be performed and therapy should be modified accordingly.

biological warfare agent

Anthrax has had the potential to be used as a biological warfare agent since World War II, when it was studied along with many other infectious agents for use as a biological weapon. Low visibility, high potency, relatively easy delivery, accessibility, and the ability to generate drying-resistant spores are all characteristics of anthrax that make it a good bioweapon. This has earned it the infamous reputation of a dangerous ‘category A’ infection.

Although anthrax infection is rare, the possibility of mass epidemics remains, whether due to bioterrorism or injection drug use. Further research is needed to define the mechanisms behind late-stage anthrax, as well as to design and test effective management measures that can be applied on a large scale. Bioterrorism prevention measures must be designed and implemented.

References

Further reading

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