Anthrax

1. Anthrax is a zoonotic disease primarily affecting ruminant herbivores such as cattle, sheep, goats, antelope, and deer that become infected by ingesting contaminated vegetation, water, or soil; humans are generally incidental hosts.
2. Other mammals can contract it (including humans). The disease is caused by a Grampositive, rod-shaped spore-forming bacteria known as anthrax (‘Bacillus anthracis’). It occurs naturally in the soil and could survive in the environment for decades.
3. The Bacillus anthracis has been found on most of the 5 continents. However, it is only in limited areas that anthrax is endemic, especially in the tropical forests of sub-Saharan Africa where it is widespread. Outbreaks of anthrax are common in West Africa where soils are alkaline and rich in calcium and other minerals.
4. Worldwide, the most commonly reported form of anthrax in humans is cutaneous anthrax (95%–99%).
5. In humans, the incubation period varies from 7 to 20 days and clinical manifestation depends on how the anthrax enters the body.
6. Four forms of anthrax are observed in humans:
   • The cutaneous form of anthrax accounts for more than 95% of natural infections and is rarely fatal when treated with appropriate antibiotics.
   • The injection form is similar to cutaneous anthrax, but it can spread more rapidly throughout the body.
   • The gastrointestinal form is less common, but more severe with frequent oropharyngeal manifestations.
   • The so-called inhalation form is the most severe form of anthrax, and the mortality rate is high unless the disease is treated promptly.

1. Suspect case: Any person who suddenly develops symptoms of one of the clinical forms of the disease:
   • Cutaneous form: any person with a skin lesion evolving over a period of 1 to 6 days, from a papule to a vesicle and then transforming into a blackish eschar, systematically accompanied by more or less extensive oedema.
   • Gastrointestinal form: Any person suffering from abdominal disorders characterised by nausea, vomiting, anorexia, followed by fever.
   • Respiratory (inhalation) form: any person with a brief prodrome suggestive of acute viral respiratory illness, followed by a fever. Viral respiratory disease, followed by rapid onset of hypoxia, dyspnoea and high fever, with enlargement of the mediastinum visible on enlargement of the mediastinum visible on x-ray.
   • Meningeal form: any person with sudden onset of high fever, which may be accompanied by convulsions, loss of consciousness, meningeal signs and symptoms; a form frequently seen in systemic infections, but may also have no other clinical symptoms of anthrax. Clinical symptoms of anthrax.

AND with an epidemiological link to suspected or confirmed cases in animals or to contaminated animal products.

1. Confirmed case: A case clinically compatible with cutaneous, respiratory, gastrointestinal forms, confirmed in the laboratory by:
   • Isolation of B. anthracis from the affected tissue or site; or
   • Demonstration of the presence of B. anthracis by at least two diagnostic tests.

Note: It may not always be possible to demonstrate the presence of B. anthracis in clinical specimens where the patient has been treated for the disease. Clinical specimens when the patient has been treated with antimicrobial agents.

Most human infections with B. anthracis result from handling B. anthracis–infected animals, their carcasses, or their meat, hides, or wool. Products derived from infected animals, such as drumheads and wool clothing, are additional, documented sources of human infection.

Anthrax has 4 main clinical presentations—cutaneous, ingestion, injection, and inhalation. Anthrax meningitis can complicate any of the 4 main clinical presentations. It can also occur with no obvious portal of entry; in which case it is called primary anthrax meningitis.

Spores introduced through the skin can result in cutaneous anthrax; abrasion of the skin increases susceptibility. Eating meat from infected animals can result in ingestion (also called gastrointestinal) anthrax. Reports since 2000 document B. anthracis soft-tissue infections in intravenous heroin users in northern Europe. Aerosolized spores from contaminated hides or wool can cause inhalation anthrax. Anthrax in humans generally is not considered contagious; person-to-person transmission of cutaneous anthrax has been reported only rarely.

 Cutaneous Anthrax

Cutaneous anthrax usually develops 1–7 days after exposure, but incubation periods as long as 17 days have been reported. Before antimicrobial therapy, almost a quarter of patients with cutaneous anthrax died. The case-fatality ratio is <2% with antimicrobial therapy.

Localized itching, followed by the development of a painless papule, heralds cutaneous anthrax. The papule then turns into a vesicle that enlarges and ulcerates, ultimately becoming a depressed black eschar, 7–10 days after the appearance of the initial lesion. Edema around lesions is characteristic, sometimes with secondary vesicles, hyperemia, and regional lymphadenopathy. Head, neck, forearms, and hands are the most commonly affected sites. Patients may have malaise and headache; about one-third are febrile.

Ingestion Anthrax

Ingestion anthrax usually develops 1–7 days after eating contaminated meat; however, incubations as long as 16 days have been reported. Left untreated, more than half of cases will die; with treatment, the case-fatality ratio decreases slightly, to <40%. There are 2 main types of ingestion anthrax: oropharyngeal and intestinal. Fever and chills are usual with either. The oropharyngeal type is characterized by severe sore throat, difficulty swallowing, swelling of the neck, and regional lymphadenopathy; airway compromise and death can occur. Nausea, vomiting, and diarrhea (which may be bloody) are more typical of intestinal anthrax; marked ascites may also develop. Later symptoms can include shortness of breath and altered mental status with shock and death occurring 2–5 days after disease onset.

Injection Anthrax

Anthrax in injection drug users usually develops within 1–4 days of exposure; death occurs in more than a quarter of confirmed cases. Cases present with severe soft-tissue infection manifested by swelling, erythema, and excessive bruising at the injection site; pain may be less than anticipated for the degree of swelling. In approximately one-third of cases, patients become septic.

Inhalation Anthrax

Inhalation anthrax usually develops within a week after exposure, but the incubation period may be prolonged (up to 2 months). Before 2001, fatality ratios for inhalation anthrax were 90%; since then, they have fallen to 45%. During the first few days of illness, most patients exhibit fever, chills, and fatigue. These symptoms may be accompanied by cough, shortness of breath, chest pain, and nausea or vomiting, making inhalation anthrax difficult to distinguish from influenza and community-acquired pneumonia. This is often described as the prodromal period.

Over the next day or so, shortness of breath, cough, and chest pain become more common, and nonthoracic complaints such as nausea, vomiting, altered mental status, diaphoresis, and headache develop in one-third or more of patients. Upper respiratory tract symptoms occur in only a quarter of patients, and myalgias are rare. Altered mental status or shortness of breath generally brings patients to the attention of the medical establishment and heralds the fulminant phase of illness.

Anthrax Meningitis

Anthrax meningitis may develop from hematogenous spread of any of the clinical forms of anthrax, or it may occur alone; half of all reported cases are sequelae of cutaneous anthrax. The condition should be suspected in patients with anthrax who have severe headache, altered mental status (including confusion), meningeal signs, or neurologic deficits of any kind. Most, but not all, cases of anthrax meningitis are fatal.

Animals can become infected when they ingest spores of the bacteria from contaminated soil, plants, water or food products. Humans can become secondary hosts and develop anthrax after exposure to contaminated animals or animal products. Spores of the bacteria can enter the body through the skin, gastrointestinal tract, airborne or by injection. This is primarily an occupational hazard for veterinarians, farm workers and people who process hides, hair, wool and bone products. The disease is generally considered to be non-contagious. However, there are rare cases of person-to-person transmission.

Clinicians can use any of several methods to make a laboratory diagnosis of anthrax infection: bacterial culture and isolation of B. anthracis; detection of bacterial DNA, antigens, or toxins; or detection of a host immune response to B. anthracis. Anthrax lethal toxin can be detected in acute-phase serum, although serologic testing of host antibody responses requires acute- and convalescent-phase sera for diagnosis.

Diagnostic procedures for inhalation anthrax include thoracic imaging studies to detect a widened mediastinum or pleural effusion. Drainage of pleural effusions can be useful for diagnosis and can increase survival, as it removes a nidus for toxin. Unless contraindicated, lumbar puncture should be performed to rule out meningitis in all patients with systemic illness.

All types of anthrax can be treated with antibiotics (penicillin and other antimicrobials) either orally or intravenously. Symptomatic therapy and supportive treatment may also be required in some severe cases.

The main actions for the prevention and management of epidemics are:

• In animals in:
  • rapid identification and treatment of infected animals,
  • Enhanced case monitoring,
  • prophylaxis, vaccination and quarantine,
  • restricting access to sources suspected of being infected (food or pasture),
  • proper disposal of carcasses,
  • Disinfection of infected premises and equipment.
• In humans:
  • The rapid identification of the animal source of an epidemic, the people exposed to the source, the human cases,
  • Outpatient treatment of simple skin cases,
  • the administration of antibiotics and supportive care for patients who are routinely ill.

To prevent anthrax exposures while visiting anthrax-endemic countries, travelers should avoid direct and indirect contact with animal carcasses and should not eat meat from animals butchered after having been found dead or ill. No tests are available to determine if animal products are free from B. anthracis spore contamination.

There is a vaccine to prevent Anthrax, but it is not available for the general public. This vaccine requires six shots over an 18-month period with periodic boosters.

While there is an anthrax vaccine, it is only recommended in very specific populations with a high occupational risk for anthrax exposure. The anthrax vaccine is not recommended for the general public or health care providers currently, though certain emergencies could warrant vaccination.

Anthrax is one of the most likely agents to be used in a biological attack. It only takes a small amount of anthrax to infect a large number of people and it can be released quietly and without anyone knowing.

In 2001, bioterrorists used the postal system to infect 22 individuals with anthrax, resulting in five deaths. Several nations are believed to be capable of producing and weaponized anthrax. Experts believe that the manufacture of a lethal anthrax aerosol is beyond the capability of individuals or groups without access to advanced biotechnology. In the event of an anthrax attack, press releases, news reports, health department websites, and other methods would be used to communicate who is at risk. Schools, convention centers, and other familiar places would be used to distribute anthrax medication if a large number of people were exposed. To prepare for this and other emergencies, detailed medical histories should be maintained for each member of your household. Allergies, current medical conditions, current medications, and the weight of any children are essential components of a medical history.