Anthrax or splenic fever, as it was formerly called, is an infectious disease caused by Bacillus anthracis, a Gram-positive, rod-shaped bacterium. It mainly affects herbivores and infected animals may serve as a source of infection for humans, rendering anthrax a zoonotic disease. In recent years, the disease has attracted considerable attention as a potential bioterrorist threat. Clinically, there are three types of anthrax: cutaneous, gastrointestinal and inhalational. Initial symptoms differ between those variants of the disease, but all may lead to sepsis and death if not treated accordingly.
The classical variants of anthrax manifest as follows :
Anthrax meningitis may complicate any of the aforementioned variants of the disease. Patients developing anthrax meningitis suffer from high-grade fever, changes of their mental state, neck pain, and vomiting. All forms of anthrax may eventually give rise to toxemia, bacteremia, septicemia, septic shock, coma and death. Mortality is significantly higher, though, in pulmonary and gastrointestinal splenic fever than in cutaneous anthrax.
Anamnestic data are of major importance in the workup of anthrax cases: Specific symptoms are rare and the confirmation of exposure to livestock or animal products may be one of very view hints on an infection with Bacillus anthracis. A reliable diagnosis of anthrax requires the identification of the etiologic pathogen or its toxins, either by means of conventional techniques (microscopic examination, Gram stain, culture) or molecular biological approach . Samples may consist in fluid specimens of pulmonary or pleural effusion or serum, or may be obtained by means of bronchial biopsy, using oropharyngeal or wound swabs. It should be noted that treatment with antibiotics negatively affects the sensitivity of any method applied to isolate the causative bacterium .
In case of inhalational anthrax, chest radiographs may provide vital information before the onset of the acute phase of the disease. Radiographs obtained in this stage typically show pulmonary infiltrates, pleural effusion and mediastinal widening and lymphadenopathy . However, computer tomography is considered more sensitive with regards to the detection of mediastinal lymph node involvement than radiography, and this finding is much more specific for anthrax than mediastinal widening.
In the United States, the Centers for Disease Control and Prevention published the following guidelines on the clinical management of anthrax :
Some patients have been applied corticosteroids in an attempt to reduce anthrax-associated edema. However, conclusive results as to the efficacy of such an approach have not yet been presented.
If left untreated, all forms of anthrax are potentially life-threatening. However, self-limiting courses are regularly observed in cases of cutaneous anthrax. All possible measures should be taken to assure an early diagnosis and timely initiation of treatment, since progression from local disease to sepsis rapidly ensues death.
Anthrax is caused by Bacillus anthracis, a Gram-positive, rod-shaped, obligate pathogen. Bacillus anthracis may be encountered in its vegetative form or in form of spores. The disease is most commonly contracted by the inhalation, oral uptake or cutaneous inoculation of spores . Of note, those spores are extremely resistant to heat, pressure, ultraviolet and ionizing radiation, chemical agents and disinfectants and may survive for decades in soil, i.e., long periods of time may pass between outbreaks . Within the host - either the animal or a human being - the spores germinate, which gives rises to vegetative state Bacillus anthracis that releases three proteins that form two toxins, as described below.
Anthrax endemic regions comprise the Middle East, West Africa, Central Asia, parts of India, and South America, but outbreaks may occur anywhere even though some countries claim freedom of splenic fever . Indeed, outbreaks have recently been reported in different parts of Europe  . Because the disease primarily affects herbivores, people with occupational exposure to susceptible animals like cattle and sheep, but also goats and horses, have a greater risk of contracting anthrax. Similarly, those working with contaminated animal products are more likely to become infected. The overall risk of human-to-human-transmission is considered to be close to cero .
In humans, individuals of any age and both genders are affected equally.
The vast majority of infections with Bacillus anthracis is contracted by inhalation, oral ingestion or cutaneous inoculation of the pathogen :
Bacillus anthracis has two major virulence factors: anthrax toxins and an antiphagocytic polyglutamic capsule . In early stages of the infection, anthrax toxins presumably target immune cells like dendritic cells, macrophages and neutrophils, interfere with chemotaxis, release of chemokines, cytokines and reactive oxygen species, among others, and even induce cell death. The pathogen's antiphagocytic capsule also contributes to the evasion of the innate immune response. In sum, both anthrax toxins and capsule largely facilitate pathogen survival at the port of entry and allow for the subsequent dissemination of Bacillus anthracis. In late stages of the disease, anthrax toxins mediate possibly highly life-threatening effects on the cardiovascular system and most likely a variety of other organ systems .
In 1970, the Anthrax Vaccine Adsorbed has been licensed in the United States. It was initially used to protect those at greater risk due to possible occupational exposure, but may also be applied to immunize military personnel and anyone else considered to be at risk in a specific situation. The vaccine has been proven to be safe and effective . Ongoing research aims at producing better defined vaccines in more convenient formulations and presentations .
On the other hand, both antibiotic treatment and vaccination are effective measures in controlling anthrax outbreaks in animals. Infected animals usually respond favorably to antimicrobial therapy and even if its survival cannot be achieved, pathogen loads are significantly reduced.
Anthrax is an infectious disease usually affecting cattle and sheep or other livestock . People who work with infected animals or contaminated animal products are at risk of inhaling spores of the causative pathogen, Bacillus anthracis. This bacterium may also enter into the human body via skin lesions or upon the ingestion of contaminated, undercooked food. Depending on the port of entry, patients may develop inhalative, cutaneous, or gastrointestinal anthrax. While cutaneous anthrax may run a self-limiting course, all variants of the disease are potentially life-threatening and may lead to sepsis, shock and death. If an early diagnosis is achieved and antibiotic treatment is initiated in a timely manner, the infection can be controlled in most cases. However, progression to sepsis is still associated with particularly high mortality. In industrialized countries, vaccines are available to protect individuals at risk. However, this does generally not apply to developing countries in Africa and Asia, where most cases occur. Still, according to current knowledge, splenic fever may occur in any country. Contrasting opinions exist regarding the real risks of a potential bioterrorist attack involving Bacillus anthracis.
Anthrax or splenic fever, as it was formerly called, is a zoonotic disease: It mainly affects animals, namely cattle, sheep, goats, and horses, and people working with infected animals or processing contaminated animal products are at risk of contracting the disease. The causative agent of the disease is called Bacillus anthracis and it is able to form highly resistant spores that may be inhaled or ingested by human beings, but that may also penetrate the skin in case of wounds:
Combined antimicrobial treatment is recommended in case of infection with Bacillus anthracis. An early diagnosis is essential for a favorable prognosis. Complete recovery is to be expected if treatment is initiated in a timely manner.