What is Anthrax?

Anthrax also called woolsorter’s disease, splenic fever, charbon or milzbrand, is a rare but serious infectious disease caused by Bacillus anthracis, an encapsulated, spore-forming, gram-positive, rod-shaped bacteria that live in soil that commonly infects domestic and wild animals around the world ¹. The origin of the name comes from the Greek word “anthrakis,” meaning black, in reference to the necrotic lesion seen in cutaneous anthrax ². Anthrax primarily affects cattle, sheep, and goats that ingest Bacillus anthracis spores lying dormant in the pasture. Although it is rare in the United States, people can get sick with anthrax if they come in contact with infected animals or contaminated animal products such as wool, meat, or hides ³. Human infection can arise from spores entering the skin by inoculation through a minor injury (cutaneous anthrax), through the lungs by inhalation (wool sorter’s disease or pulmonary anthrax) or by ingestion (gastrointestinal anthrax). Most anthrax infection (95%) is via the skin (cutaneous anthrax). However, anthrax is NOT contagious, which means you can’t catch it like the cold or flu ⁴. In rare cases, person-to-person transmission has been reported with cutaneous anthrax, where discharges from skin lesions might be infectious ⁵.

Anthrax is characterized by both toxins in blood which is caused by secretion of immunomodulating toxins (lethal toxin and edema toxin) and septicemia (blood poisoning by bacteria) which is associated with bacterial encapsulation ⁶. Anthrax toxins are composed of 3 entities: a protective antigen, a lethal factor, and an edema factor. The protective antigen is an 83-kd protein that binds to cell receptors within a target tissue. Once it is bound, a fragment is cleaved free to expose an additional binding site. The binding of edema factor at this site results in the formation of edema toxin; the binding of lethal factor results in the formation of lethal toxin.

Edema toxin acts by converting adenosine triphosphate (ATP) to cyclic adenosine monophosphate (cAMP). Cellular cAMP levels are increased, leading to cellular edema within the target tissue. Lethal factor is not well understood; it may inhibit neutrophil phagocytosis, lyse macrophages, and cause release of tumor necrosis factor and interleukin-1. Death from anthrax occurs as a result of the effects of lethal toxin. Near death or just after death, animals bleed from all body orifices.

People get anthrax by:

• Breathing in spores (wool sorter’s disease or pulmonary anthrax),
• Eating food or drinking water that is contaminated with spores (gastrointestinal anthrax),
• Getting spores in a cut or scrape in the skin (cutaneous anthrax). Most anthrax infection (95%) is via the skin (cutaneous anthrax).
• Injection anthrax, another type of anthrax infection in heroin-injecting drug users in northern Europe ⁷

Contact with anthrax can cause severe illness in both humans and animals. Anthrax becomes dangerous if it spreads widely through the bloodstream. The risk of anthrax spreading through the body is higher if the infection is acquired by inhalation or ingestion. The World Health Organization (WHO) estimates the annual global Anthrax incidence of between 2000 and 20,000 cases. It is rare in the United States, although in the year 2000, an outbreak of anthrax occurred in the ranches of North Dakota ⁸.

Anthrax can cause three forms of disease in people. They are:

1. Cutaneous anthrax, which affects the skin. Cutaneous anthrax can occur when workers who handle contaminated animal products get Bacillus anthracis spores in a cut or scrape on their skin. Most anthrax infection (95%) is via the skin (cutaneous anthrax). Cutaneous anthrax is considered to be the least dangerous. Infection usually develops from 1 to 7 days after exposure ⁹. Cutaneous anthrax is most common on the head, neck, forearms, and hands. It affects the skin and tissue around the site of infection. Without treatment, up to 20% of people with cutaneous anthrax die. However, with proper treatment, almost all patients with cutaneous anthrax survive.
2. Inhalation anthrax or pulmonary anthrax, which affects the lungs (< 5% anthrax cases). You can get this if you breathe in spores of the Bacillus anthracis bacteria. Inhalation anthrax can occur when a person inhales spores that are in the air (aerosolized) during the industrial processing of contaminated materials, such as wool, hides, or hair, in wool mills, slaughterhouses, and tanneries. Infection usually develops within a week after exposure, but it can take up to 2 months ¹⁰. Inhalation anthrax starts primarily in the lymph nodes in the chest before spreading throughout the rest of the body, ultimately causing severe breathing problems and shock. Without treatment, inhalation anthrax is almost always fatal. However, with aggressive treatment, about 55% of patients survive.
3. Gastrointestinal anthrax, which affects the digestive system (< 1% anthrax cases). You can get gastrointestinal anthrax by eating raw or undercooked meat from an animal infected with anthrax. Once ingested, anthrax spores can affect the upper gastrointestinal tract (throat and esophagus), stomach, and intestines, causing a wide variety of symptoms. Without treatment, more than half of patients with gastrointestinal anthrax die. However, with proper treatment, 60% of patients survive ¹¹.
4. Injection anthrax. Recently, another type of anthrax infection has been identified in heroin-injecting drug users in northern Europe ⁷. So far, no cases of injection anthrax have been reported in the United States. Injection anthrax symptoms may be similar to those of cutaneous anthrax, but there may be infection deep under the skin or in the muscle where the drug was injected. Injection anthrax can spread throughout the body faster and be harder to recognize and treat. Lots of other more common bacteria can cause skin and injection site infections, so a skin or injection site infection in a drug user does not necessarily mean the person has anthrax.

The type of illness a person develops depends on how anthrax enters the body. Typically, anthrax gets into the body through the skin, lungs, or gastrointestinal system. All types of anthrax can eventually spread throughout the body and cause death if they are not treated with antibiotics. Anthrax is categorized as a category A priority pathogen by the U.S. Centers for Disease Control and Prevention (CDC) because it is potentially capable of being disseminated as a bioweapon. Many Americans knew about anthrax from the 2001 bioterror attacks. In that attacks, someone purposely spread anthrax through the U.S. mail. This killed five people and made 22 sick ¹².

Anthrax is a reportable infection and the local authorities and the CDC must be notified immediately. The CDC has concise treatment recommendations based upon anthrax disease manifestations, including multiple alternative agents that may be considered in select patients ¹³.

Untreated, up to one-fifth of infected individuals die of anthrax disease. Prompt treatment with antibiotics is curative and most recover fully if it is diagnosed early. But many people don’t know they have anthrax until it is too late to treat. Anthrax vaccine to prevent anthrax is available for people in the military and others at high risk.

Figure 1. Cutaneous anthrax

Footnote: Cutaneous anthrax on the neck with early ulcer and blisters (vesicles), evolving into an eschar (black scab)

[Source ¹⁴ ]

Figure 2. Cutaneous anthrax

Footnotes: Multiple dark papules with central umbilicus on patient’s right hand and on the 4th and the 5th fingers including diffuse edema. Similar lesions as in Figure 1 on extensor surface of the left arm.

[Source ¹⁵ ]

Figure 3. Bacillus anthracis

Footnote: Polychrome methylene blue stain of Bacillus anthracis.

Where is anthrax found?

Anthrax is most common in agricultural regions of ⁴:

• Central and South America,
• Sub-Saharan Africa,
• Central and southwestern Asia,
• Southern and eastern Europe, and
• The Caribbean.

Anthrax is rare in the United States ¹. However, sporadic outbreaks do occur in wild and domestic grazing animals such as cattle or deer. Anthrax is more common in countries that do not have programs that routinely vaccinate animals against anthrax. In the United States, veterinarians recommend yearly vaccination of livestock in areas where animals have had anthrax in the past.

How do animals get infected with anthrax?

Domestic and wild animals can become infected when they breathe in or ingest spores in contaminated soil, plants, or water ¹. These animals can include cattle, sheep, goats, antelope, and deer. In areas where domestic animals have had anthrax in the past, routine vaccination can help prevent outbreaks.

How is anthrax transmitted to humans?

Anthrax is extremely rare in the developed world but sporadically occurs among farmers in Africa, the Middle East and the Caribbean ¹⁶. Anthrax can also infect workers in the wool, hair or bristle industries, butchers and gardeners. However, anthrax is not contagious, which means you can’t catch it like the cold or flu.

Anthrax primarily affects sheep and cattle that ingest spores lying dormant in the pasture. Human infection can arise from spores entering the skin by inoculation through a minor injury, through the lungs by inhalation (wool sorter’s disease) or by ingestion (gastrointestinal anthrax). When this happens, the spores can be activated and become anthrax bacteria. Then the bacteria can multiply, spread out in the body, produce toxins (poisons), and cause severe illness.

People get anthrax by:

• Breathing in spores (wool sorter’s disease or pulmonary anthrax),
• Eating food or drinking water that is contaminated with spores (gastrointestinal anthrax),
• Getting spores in a cut or scrape in the skin (cutaneous anthrax). Most anthrax infection (95%) is via the skin (cutaneous anthrax).
• Injection anthrax, another type of anthrax infection in heroin-injecting drug users in northern Europe ⁷. So far, no cases of injection anthrax have been reported in the United States.

Certain activities can increase the chances of getting anthrax:

• Working with infected animals or animal products. Most people who get sick from anthrax are exposed while working with infected animals or animal products such as wool, hides, or hair.
  • Inhalation anthrax can occur when a person inhales spores that are in the air (aerosolized) during the industrial processing of contaminated materials, such as wool, hides, or hair.
  • Cutaneous anthrax can occur when workers who handle contaminated animal products get spores in a cut or scrape on their skin.
• Eating raw or undercooked meat from infected animals.
  • People who eat raw or undercooked meat from infected animals may get sick with gastrointestinal anthrax. This usually occurs in countries where livestock are not routinely vaccinated against anthrax and food animals are not inspected prior to slaughter. In the United States, gastrointestinal anthrax has rarely been reported. This is because yearly vaccination of livestock is recommended in areas of the United States where animals have had anthrax in the past, and because of the examination of all food animals, which ensures that they are healthy at the time of slaughter.
• Injection anthrax.
  • This is a newly discovered type of anthrax. This type of anthrax has been seen in northern Europe in people injecting heroin. So far, no cases of injection anthrax have been reported in the United States.

Is anthrax contagious?

No. You cannot catch anthrax from another person the way you might catch a cold or the flu. In rare cases, person-to-person transmission has been reported with cutaneous anthrax, where discharges from skin lesions might be infectious.

Who is at risk of anthrax?

Most people will never be exposed to anthrax. However, there are activities that can put some people at greater risk of exposure than others.

• Laboratory professionals. Laboratory workers who handle anthrax may be at risk for being exposed if proper safety precautions aren’t followed.
• People who handle animal products. Although rare, people can get anthrax after having contact with infected animals or their products, such as wool, hides, or hair. For this reason, people in certain occupations, like veterinarians, farmers, livestock producers, and others who handle animals and animal products may have an increased risk of exposure.
  
• Travelers. Anthrax can be found naturally in soil and commonly affects domestic and wild animals around the world, but it is most common in agricultural regions of Central and South America, Sub-Saharan Africa, Central and southwestern Asia, Southern and eastern Europe, and the Caribbean. Travelers should be mindful of what they eat and handle, as well as the souvenirs they bring home. Avoid eating raw or undercooked meat, and avoid contact with livestock, animal products and animal carcasses. Vaccination against anthrax is not recommended for travelers and is not available for civilian travelers.
• Mail handlers, military personnel, and response workers. Certain workers could be exposed to anthrax in the event of a bioterrorist attack, either during the attack or when responding to the emergency. Workers who could be at risk include mail handlers (if spores are sent through the mail), law enforcement personnel, healthcare workers, decontamination workers, and critical infrastructure workers who could be exposed to airborne (aerosolized) spores, depending on how the spores were spread.

Anthrax pathophysiology

Anthrax is primarily a zoonotic disease of herbivores (eg, cattle, sheep, goats, horses). Pigs are not immune, but they are more resistant, as are dogs and cats. Birds are usually naturally resistant to anthrax. Buzzards and vultures are naturally resistant to anthrax but may transmit the spores on their talons and beaks.

Anthrax (Bacillus anthracis) is a large, spore-forming, gram-positive rod. Persistence of spores is aided by nitrogen and organic soil content, environmental pH greater than 6, and ambient temperature greater than 15°C. Spores can exist indefinitely in the environment. Optimal growth conditions result in a vegetative phase and bacterial multiplication. Drought or rainfall can trigger anthrax spore germination, while flies and vultures spread the spores.

Virulence depends on the bacterial capsule and the toxin complex. The capsule is a poly-D-glutamic acid that protects against leukocytic phagocytosis and lysis. Experiments by Sterne demonstrated that the capsule is vital for pathogenicity.

The pathogenesis of anthrax follows the route of infection with three primary forms in humans: cutaneous, gastrointestinal and inhalational.

Humans are relatively resistant to cutaneous anthrax but any break in the skin can allow the organism to enter the skin. Once inside the circulation, the organism spreads rapidly and affects the lungs, kidney, and spleen. The organism can also enter the brain and cause meningitis which is universally fatal.

Inhalational anthrax leads to accumulation of Bacillus anthracis spores within the lung alveoli. The spores are engulfed by immune cells (macrophages, neutrophils, dendritic cells) and transported to regional lymph nodes where the bacteria germinate, multiply, and begin toxin production. This results in systemic clinical illness, and pathologically to toxin-induced cell damage and cell death. As the disease progresses, bloodstream infection occurs leading to septic shock. Patients can present suddenly and may deteriorate rapidly.

Cutaneous anthrax results from inoculation of Bacillus anthracis spores through the abraded skin into subcutaneous tissues. The bacteria subsequently germinate and multiply locally and begin toxin production. This leads to the characteristic edema and cutaneous ulceration.

Gastrointestinal anthrax occurs due to ingestion of contaminated meat, with spores introduced into the gastrointestinal tract, causing bacterial replication, mucosal ulcerations, and bleeding.

• Primary intestinal anthrax predominantly affects the cecum and produces a local lesion similar to the lesion produced in the cutaneous form. In this illness, spores invade the gastrointestinal mucosa. In some cases, necrosis and ulceration at the site of infection produce gastrointestinal hemorrhage.
• As spores are transported to mesenteric lymph nodes, replication and bacteremia begin. Ascites and ileus follow as the lymphatic system becomes occluded with the large number of bacilli. Peritoneal fluid is turbid with the presence of leukocytes and red blood cells from hemorrhagic adenitis. Vascular stasis occurs, and the stomach and intestine become edematous.
• Oropharyngeal anthrax is a variant of intestinal anthrax and occurs in the oropharynx after ingestion of meat products contaminated by anthrax. Oropharyngeal anthrax is characterized by throat pain and difficulty in swallowing. The lesion at the site of entry into the oropharynx resembles the cutaneous ulcer.

Recently, injection anthrax has been described in northern European injection drug users, resulting in symptoms similar to cutaneous anthrax but with a deeper infection which may include myositis ¹⁷.

Anthrax meningitis may complicate any form of anthrax, with bacteremia and hematogenous spread to the central nervous system (brain and spinal cord). It also has occurred without a primary focus. The meninges are characteristically hemorrhagic and edematous. The mortality rate is near 100%.

Anthrax symptoms

People get infected with anthrax when Bacillus anthracis spores get into their body. The symptoms of anthrax depend on the type of infection and can take anywhere from 1 day to more than 2 months to appear. All types of anthrax have the potential, if untreated, to spread throughout the body and cause severe illness and even death.

Cutaneous anthrax symptoms

Cutaneous anthrax develops usually between 1 to 7 days after skin exposure. Cutaneous anthrax symptoms can include ¹⁸:

• A group of small blisters or bumps that may itch
• Swelling can occur around the sore
• A painless skin sore (ulcer) with a black center that appears after the small blisters or bumps
• Most often the sore will be on the face, neck, arms, or hand.

Most often cutaneous anthrax starts as a localized infection on exposed skin (usually face, hands or arms). It looks like an insect bite and is known as a “malignant pustule”. Usually painless, an itchy bump appears with surrounding redness. After a day or so, it blisters then ulcerates. At this stage, it is about 1–3 cm in diameter and circular in shape, surrounded by small blisters (satellite vesicles) and marked swelling of the surrounding skin. Characteristically, the ulcer develops a black scab, which is called a necrotic eschar. Within a couple of weeks, the infection heals leaving a scar. Without appropriate treatment, the mortality rate for cutaneous anthrax can approach 20%.

The infection occasionally results in a red streak tracking to nearby lymph glands (lymphangitis). These lymph nodes then often swell and become sore.

Pulmonary anthrax symptoms

Inhalation anthrax symptoms can include ¹⁸:

• Fever and chills
• Chest Discomfort
• Shortness of breath
• Confusion or dizziness
• Cough
• Nausea, vomiting, or stomach pains
• Headache
• Sweats (often drenching)
• Extreme tiredness
• Body aches

Inhalation anthrax presents following an incubation period of approximately 1 to 6 days post-exposure, with a non-specific prodromal phase including fever, sweats, nausea, vomiting, malaise, chest pain and nonproductive cough ³. The second stage of illness occurs as bacterial replication in mediastinal lymph nodes results in hemorrhagic lymphadenitis and mediastinitis, and progression to bacteremia. Fever, dyspnea (shortness of breath) and stridor from increasing lymphadenopathy impacting the airways, and ultimately respiratory failure and hemodynamic collapse occur. Meningitis also occurs in up to 50% of inhalation anthrax cases, with a headache, confusion, and progression to coma. Chest x-rays classically demonstrate a widened mediastinum (the result of significant lymphadenopathy [swollen lymph nodes]) without pulmonary infiltrates, though pleural effusions and/or pulmonary infiltrates both of which may be hemorrhagic can also be seen. The time from onset of symptoms to death ranges from 1 to 10 days.

Gastrointestinal anthrax symptoms

Gastrointestinal anthrax symptoms can include ¹⁸:

• Fever and chills
• Swelling of neck or neck glands
• Sore throat
• Painful swallowing
• Hoarseness
• Nausea and vomiting, especially bloody vomiting
• Diarrhea or bloody diarrhea
• Headache
• Flushing (red face) and red eyes
• Stomach pain
• Fainting
• Swelling of abdomen (stomach)

Gastrointestinal anthrax results from ingestion of contaminated, undercooked meat or ingestion of spores inhaled into the nasopharynx and can include oropharyngeal and/or intestinal symptoms ¹⁹:

• Fever and chills
• A group of small blisters or bumps that may itch, appearing where the drug was injected
• A painless skin sore with a black center that appears after the blisters or bumps
• Swelling around the sore
• Abscesses deep under the skin or in the muscle where the drug was injected

Injection anthrax symptoms are similar to those of cutaneous anthrax, but injection anthrax can spread throughout the body faster and be harder to recognize and treat than cutaneous anthrax. Skin and injection site infections associated with injection drug use are common and do not necessarily mean the person has anthrax.

Injection anthrax presents as a grouping of small vesicles or papules at the injection site, with progression to painless ulcerative lesion similar to cutaneous anthrax. Injection anthrax may make it more difficult to recognize and may progress more rapidly to systemic illness than cutaneous anthrax.

Anthrax causes

Anthrax is caused by Bacillus anthracis, a gram-positive bacillus. Bacillus anthracis has a diameter of 1-1.5 µm and a length of 3-10 µm. It is usually straight but may be slightly curved. The ends of the bacilli are truncated, not rounded. Anthrax bacilli tend to form into long chains and may appear similar to streptobacilli on cultures.

Bacillus anthracis produces a capsule that is easily visualized using a methylene blue or India ink stain. Ground-glass–appearing colonies are adherent and appear gray or white on blood agar. Colonies measure 4-5 mm in diameter and have characteristic comma-shaped protrusions.

Anthrax commonly affects hoofed animals such as sheep, cattle, and goats. Humans who come into contact with infected animals can get sick with anthrax as well.

There are three main routes of anthrax infection: skin (cutaneous), lung (inhalation), and mouth (gastrointestinal).

Cutaneous anthrax occurs when anthrax spores enter the body through a cut or scrape on the skin.

• It is the most common type of anthrax infection.
• The main risk is contact with animal hides or hair, bone products, and wool, or with infected animals. People most at risk for cutaneous anthrax include farm workers, veterinarians, tanners, and wool workers.

Inhalation anthrax develops when anthrax spores enter the lungs through the airways. It is most commonly contracted when workers breathe in airborne anthrax spores during processes such as tanning hides and processing wool.

• Breathing in spores means a person has been exposed to anthrax. But it does not mean the person will have symptoms.
• The bacterial spores must germinate or sprout (the same way a seed sprouts before a plant grows) before the actual disease occurs. This process usually takes 1 to 6 days.
  Once the spores germinate, they release several toxic substances. These substances cause internal bleeding, swelling, and tissue death.

Gastrointestinal anthrax occurs when someone eats anthrax-tainted meat.

Injection anthrax can occur in someone who injects heroin.

Anthrax may also be used as a biological weapon or for bioterrorism.

Anthrax prevention

Anthrax is rare, and most people will never be exposed to it. There is a vaccine licensed to prevent anthrax, but it is only recommended for routine use in certain groups of at-risk adults (for example, some members of the military and laboratory workers).

For people who have been exposed to anthrax but do not yet have symptoms, certain antibiotics can be used to prevent illness from developing.

Antibiotics to prevent Anthrax after exposure

Antibiotics can prevent anthrax from developing in people who have been exposed but have not developed symptoms. Antibiotics work in two main ways, by killing the anthrax or by stopping the anthrax from growing. When the anthrax can’t grow anymore, it dies. Two of the antibiotics that could be used to prevent anthrax are ²⁰:

• Ciprofloxacin
• Doxycycline

Each of these antibiotics offers the same protection against anthrax. Anthrax spores typically take 1 to 7 days to be activated, but some spores can remain inside the body and take up to 60 days or more before they are activated. Activated spores release toxins—or poisons—that attack the body, causing the person to become sick. That’s why people who have been exposed to anthrax must take antibiotics for 60 days. This will protect them from any anthrax spores in their body when the spores are activated.

Preventing anthrax from animal hides

Imported animal hides have been associated with a number of anthrax cases in the United States. Cases have occurred in drum makers using these hides. Cases have also occurred in people who have handled or been near the drums or in the environment where they were made. Some imported hides may contain anthrax spores, and although this is rare, there is no way to test for the presence of spores on hides.

To protect against anthrax spores, be sure to use hides that came from:

• Animals from the United States
• Animals that were imported with an international veterinary certificate showing that they have undergone the appropriate government inspection

Preventing anthrax during travel

Visitors to areas where anthrax is common or where an outbreak is occurring in animals can get sick with anthrax if they have contact with infected animal carcasses or eat meat from animals that were sick when slaughtered. They can also get sick if they handle animal parts, such as hides, or products made from those animal parts, such as animal hide drums. If you are visiting these areas, do not eat raw or undercooked meat and avoid contact with livestock, animal products, and animal carcasses.

Anthrax vaccine

Anthrax vaccine is not typically available for the general public. Anthrax vaccine is only recommended for people who are at an increased risk of coming into contact with or have already been exposed to Bacillus anthracis, such as certain U.S. military personnel, laboratory workers, and some people who handle animals or animal products (such as veterinarians who handle infected animals). Talk with your healthcare professional if you have questions about the anthrax vaccine. You can also contact your state health department to learn more about where to get the vaccine in your community if it is recommended for you.

The anthrax vaccine helps protect most people from anthrax, including inhalation anthrax (the most deadly form that can happen when someone breathes the bacterial spores into their lungs), but cannot prevent all cases. Anthrax vaccine can also help prevent anthrax from developing in people who have been exposed to the bacteria but have not developed symptoms. A study showed that the anthrax vaccine protects about 9 people out of every 10 vaccinated prior to exposure to Bacillus anthracis bacteria. The effectiveness of the anthrax vaccine is around 93% for people completing the primary series and maintaining the booster vaccinations.

To build up protection against anthrax, people need 5 doses over a period of 18 months. However, it is unknown how long that protection lasts so people who are recommended to get this vaccine are advised to get a booster dose each year to stay protected.

Anthrax vaccine type

There is one anthrax vaccine licensed for use in the United States by the Food and Drug Administration (FDA) ²¹:

• Anthrax Vaccine Adsorbed (BioThrax): It is given to people 18 through 65 years old at increased risk of exposure in 5 doses, with a booster dose each year thereafter for those that continue to be at increased risk of exposure ²². It is given, in combination with antibiotics, as a three-dose primary series after exposure.

Composition of the Anthrax vaccine

Each 0.5 milliliter (mL) dose of anthrax vaccine adsorbed or BioThrax (Emergent BioSolutions) is made from cell-free filtrates of microaerophilic cultures of an avirulent, nonencapsulated strain of Bacillus anthracis. Each dose includes the 83kDa protective antigen protein and 1.2 milligrams per milliliter (mg/mL) aluminum. Each dose also includes the following preservatives: 25 micrograms per milliliter (µg/mL) benzethonium chloride and 100 µg/mL formaldehyde. Anthrax vaccine contains no dead or live bacteria.

Anthrax vaccine dosage and administration

Anthrax vaccine is given via intramuscular or subcutaneous injection only. Each dose is 0.5 mL.

Pre-Exposure Prophylaxis

Anthrax vaccine is approved for use in three groups of adults 18 to 65 years of age who may be at risk of coming in contact with anthrax because of their job.

These at-risk adults will receive Anthrax vaccine before exposure:

• Certain laboratory workers who work with anthrax or Bacillus anthracis
• Some people who handle animals or animal products, such as some veterinarians
• Some members of the United States military
• Some emergency and other responders whose response activities might lead to exposure

To build up protection against anthrax, these groups should get 5 shots of anthrax vaccine over 18 months (3 doses of anthrax vaccine, followed by 2 booster doses for ongoing protection). To stay protected, they should get annual boosters. The shots are injected into a muscle (intramuscular).

In persons who are at risk for hematoma formation following intramuscular injection, Anthrax Vaccine Adsorbed (BioThrax) may be administered by the subcutaneous route. The pre-exposure prophylaxis schedule for BioThrax administered subcutaneously is 0, 2, 4 weeks, and 6 months with booster doses 6 and 12 months after completion of the primary series, and at 12-month intervals thereafter ²².

Table 1. Pre-Exposure Anthrax Vaccine Prophylaxis

Schedule	Route of Administration	Dosing Schedule
Primary Series	Intramuscular	0,1, and 6 months
Booster Series	Intramuscular	6 and 12 months after completion of the primary series and at 12-month intervals thereafter

Post-Exposure Prophylaxis

In November 2015, the FDA also approved the Anthrax vaccine for use after exposure to anthrax for people 18 through 65 years of age. In certain situations, such as a bioterrorist attack involving anthrax, anthrax vaccine might be recommended to prevent the disease in people after they have been exposed to the anthrax germs. If this were to happen, people who were exposed would get 3 shots of anthrax vaccine over 4 weeks plus a 60-day course of antibiotics.

During an emergency, the only people who should not get the anthrax vaccine after possible exposure are those who have had a serious allergic reaction to a previous dose of anthrax vaccine. These people would receive the 60-day course of antibiotics only.

Table 2. Post-Exposure Anthrax Vaccine Prophylaxis

Schedule	Route of Administration	Dosing Schedule
Primary Series	Subcutaneous	0, 2, and 4 weeks post-exposure combined with antimicrobial therapy

Anthrax vaccine side effects

Most people who get an anthrax vaccine do not have any serious problems with it. With any medicine, including vaccines, there is a chance of side effects. These are usually mild and go away on their own within a few days, but serious reactions are also possible.

Mild problems following an anthrax vaccine can include:

• Reactions where the anthrax shot was given
• Redness
• Swelling
• Soreness or tenderness
• A lump or bruise
• Itching
• Muscle aches or temporary limitation of movement in the arm where the shot was given
• Headache
• Feeling tired

Problems that could happen after any injected vaccine

• People sometimes faint after a medical procedure, including vaccination. Sitting or lying down for about 15 minutes can help prevent fainting, and injuries caused by a fall. Tell your healthcare professional if you feel dizzy, have vision changes, or have ringing in the ears.
• Some people get severe arm pain and have difficulty moving the arm where a shot was given. This happens very rarely.
• Any medicine can cause a severe allergic reaction. Such reactions from a vaccine are very rare, estimated at about 1 in a million doses, and would happen within a few minutes to a few hours after the vaccination.
• As with any medicine, there is a very remote chance of a vaccine causing a serious injury or death.

Who should NOT get Anthrax vaccine?

Because of age or health conditions, some people should not get certain vaccines or should wait before getting them. Read the guidelines below and ask your healthcare professional for more information.

Tell the person who is giving you an anthrax vaccine if:

• You have had a life-threatening allergic reaction or have a severe allergy.
  • Anyone who has had a serious allergic reaction to a previous dose of the anthrax vaccine should not get another dose.
  • Anyone who has a severe allergy to any vaccine component should not get a dose. Tell your healthcare provider if you have any severe allergies, including latex. Your healthcare professional can tell you about the vaccine’s ingredients.
• You have been previously diagnosed with specific illnesses or conditions.
  • If your immune system is weakened due to medication or illness.
  • If you have had anthrax disease in past.
• You are not feeling well.
  • If you have a mild illness, such as a cold, you can probably get the vaccine. If you are moderately or severely ill, you should probably wait until you recover. Your healthcare professional can advise you.
• Pregnant women
  • Anthrax vaccination may be recommended for pregnant women who have been exposed to anthrax. However, when risk to anthrax exposure is low, pregnant women are not recommended to get the vaccine.

Anthrax vaccine contraindications

Do not administer Anthrax Vaccine Adsorbed (BioThrax) to individuals with a history of anaphylactic or anaphylactic-like reaction following a previous dose of Anthrax Vaccine Adsorbed (BioThrax) or any component of the vaccine, including aluminum, benzethonium chloride, and formaldehyde ²².

Anthrax diagnosis

Doctors in the United States rarely see a patient with anthrax. Your doctor will ask you what kind of work you do, along with other questions to determine the likelihood of your having been exposed to anthrax. Your doctor will first want to rule out other, more-common conditions that may be causing your signs and symptoms, such as flu (influenza) or pneumonia.

The CDC has developed detailed recommendations for patient evaluation by suspected anthrax exposure and clinical syndrome. Cutaneous, gastrointestinal, inhalation, injection and meningeal anthrax can be diagnosed using a combination of microbiology and pathology testing methods. Depending on the clinical features, relevant specimens include PCR, gram stain, and cultures, from blood, pleural fluid, site of ulceration, cerebrospinal fluid, and stool. Patients may also need routine diagnostic evaluations such as complete blood count (CBC) and chest x-ray. Testing for relevant pathogens on the differential diagnosis may need to be incorporated into the evaluation as well ²³.

If inhalation anthrax is suspected, chest X-rays or CT scans can confirm if the patient has mediastinal widening or pleural effusion, which are X-ray findings typically seen in patients with inhalation anthrax.

Anthrax test

You may have a rapid flu test to quickly diagnose a case of influenza. If other tests are negative, you may have further tests to look specifically for anthrax, such as:

• Skin testing. A sample of fluid from a suspicious lesion on your skin or a small tissue sample (biopsy) may be tested in a lab for signs of cutaneous anthrax.
• Blood tests. You may have a small amount of blood drawn that’s checked in a lab for anthrax bacteria.
• Chest X-ray or computerized tomography (CT) scan. Your doctor may request a chest X-ray or CT scan to help diagnose inhalation anthrax.
• Stool testing. To diagnose gastrointestinal anthrax, your doctor may check a sample of your stool for anthrax bacteria.
• Spinal tap (lumbar puncture). In this test, your doctor inserts a needle into your spinal canal and withdraws a small amount of fluid. A spinal tap is recommended any time doctors suspect systemic anthrax — anthrax other than cutaneous — due to the possibility of meningitis.

The only ways to confirm an anthrax diagnosis are:

• To measure antibodies or toxin in blood
• To test directly for Bacillus anthracis in a sample:
  • blood
  • skin lesion swab
  • spinal fluid
  • respiratory secretions

Samples must be taken before the patient begins taking antibiotics for treatment.

Prior to sending specimens to the CDC for anthrax diagnostic testing, first consult with and obtain authorization from your state health department and contact the CDC Emergency Operations Center for an anthrax testing consultation. Once approval has been obtained from your state health department and from CDC, submit your specimen following the recommendations below.

Cutaneous anthrax

• Lesion Swabs
  • Vesicular lesions: Two swabs of vesicular fluid from an unopened vesicle, one for culture and one for real-time polymerase chain reaction (PCR).
  • Eschars: Two saline-moistened swab samples, rotated underneath the eschar, one for culture and one for real-time PCR.
  • Ulcers: Sample the base of the lesion with two saline-moistened swabs, one for culture and one for real-time PCR.
• Biopsy
  • A full thickness biopsy of a papule or vesicle, including adjacent skin, for histopathology, special stains, and immunohistochemistry (IHC).
  • Note: For patients who are not on antibiotic therapy or who have been on therapy for < 24 hours, a second biopsy sample should be collected at the same time and submitted for culture and real-time PCR.
• Serum
  • An acute (≤7 days after symptom onset OR as soon as possible after a known exposure event) serum sample to test for anthrax lethal factor toxin.
  • Acute and convalescent (14–35 days after symptom onset) serum samples for serologic testing.
• Plasma
  • An acute plasma sample to test for anthrax lethal factor toxin.
  • Note: Plasma is the preferred specimen for anthrax lethal factor toxin testing.
• Blood
  • If there are signs of systemic anthrax infection (i.e., febrile or hypothermia, tachycardia, tachypnea, hypotensive), collect blood specimen before starting antimicrobial therapy for culture and real-time PCR.
• CSF
  • To be submitted for patients with severe headache, meningeal signs, altered mental status, seizures, or focal signs for culture and real-time PCR.
• Autopsy tissues
  • To be collected in fatal cases for histopathology, special stains, and immunohistochemistry.

Gastrointestinal anthrax

• Oropharyngeal lesion swab, if present
  • To be tested for culture and real-time PCR.
• Serum
  • An acute (≤7 days after symptom onset OR as soon as possible after a known exposure event) serum sample to test for anthrax lethal factor toxin.
  • Acute and convalescent (14–35 days after symptom onset) serum samples for serologic testing.
• Plasma
  • Acute plasma samples for testing of anthrax lethal factor toxin.
  • Note: Plasma is the preferred specimen for anthrax lethal factor toxin testing.
• Blood
  • To be drawn before starting antimicrobial therapy for culture and real-time PCR.
• Ascites fluid
  • To be tested for culture, real-time PCR, and anthrax lethal factor toxin testing.
• Rectal swab
  • To be tested for culture and real-time PCR.
• Autopsy tissues
  • To be collected in fatal cases for histopathology, special stains, and immunohistochemistry.

Inhalation anthrax

• Serum
  • An acute (≤7 days after symptom onset OR as soon as possible after a known exposure event) serum sample to test for anthrax lethal factor toxin.
  • Acute and convalescent (14–35 days after symptom onset) serum samples for serologic testing.
• Plasma
  • An acute plasma sample to test for anthrax lethal factor toxin.
  • Note: Plasma is the preferred specimen for anthrax lethal factor toxin testing.
• Blood
  • To be drawn before starting antimicrobial therapy for culture and real-time PCR.
• Pleural fluid
  • To be tested for culture and real-time PCR, as well as anthrax lethal factor toxin.
• CSF
  • To be submitted for patients with severe headache, meningeal signs, altered mental status, seizures, or focal signs for culture and real-time PCR.
• Biopsy
  • Pleural and/or bronchial biopsies for immunohistochemistry.
• Autopsy tissues
  • To be collected in fatal cases for histopathology, special stains, and immunohistochemistry.

Injection anthrax

• Serum
  • An acute (≤7 days after symptom onset OR as soon as possible after a known exposure event) serum sample to test for anthrax lethal factor toxin.
  • Acute and convalescent (14–35 days after symptom onset) serum samples for serologic testing.
• Plasma
  • An acute plasma sample to test for anthrax lethal factor toxin.
  • Note: Plasma is the preferred specimen for anthrax lethal factor toxin testing.
• Blood
  • To be drawn before starting antimicrobial therapy for culture and real-time PCR.
• Biopsy
  • Tissue biopsy from localized lesion tissue debridement.
• Autopsy tissues
  • To be collected in fatal cases for histopathology, special stains, and immunohistochemistry.

Meningeal anthrax

Meningitis can complicate cases of cutaneous, gastrointestinal, inhalation, and injection anthrax cases. Meningitis may also be the primary sign of anthrax in patients without a clear source of exposure. The following specimens should be submitted in patients with severe headaches, meningeal signs, altered mental status, seizures, or focal signs.

• Serum
  • An acute (≤7 days after symptom onset OR as soon as possible after a known exposure event) serum sample to test for anthrax lethal factor toxin.
  • Acute and convalescent (14–35 days after symptom onset) serum samples for serologic testing.
• Plasma
  • An acute plasma sample to test for anthrax lethal factor toxin.
  • Note: Plasma is the preferred specimen for anthrax lethal factor toxin testing.
• Blood
  • To be drawn before starting antimicrobial therapy for culture and real-time PCR.
• CSF
  • To be tested for culture and real-time PCR.
• Autopsy tissues
  • To be collected in fatal cases for histopathology, special stains, and immunohistochemistry.

Anthrax treatment

Doctors have several options for treating patients with anthrax, including antibiotics and antitoxin.

• The standard treatment for anthrax is an antibiotic such as ciprofloxacin (Cipro), doxycycline (Vibramycin) or levofloxacin. Which single antibiotic or combination of antibiotics, and the length of treatment, will be most effective for you depends on how you were infected with anthrax, your age, your overall health and other factors. Treatment is most effective when started as soon as possible.
• An antitoxin product may be recommended as a treatment adjunct (add-on) together with a multidrug antibiotic regimen, and there are multiple products that have been developed including both monoclonal and polyclonal antitoxins.
• Anthrax immune globulin (Anthrasil) should also be considered with CDC consultation as adjunctive therapy for systemic anthrax treatment ²⁴. Human anthrax immune globulin was approved by the FDA in March 2015. It provides passive immunity to adults and children exposed to inhalational anthrax. It is used in conjunction with appropriate antibiotic therapy ²⁴.

For people who have been exposed to anthrax but do not yet have symptoms, certain antibiotics can be used to prevent illness from developing (see Antibiotics to prevent Anthrax after exposure).

Some cases of injection anthrax have been successfully treated with surgical removal of infected tissue.

Although some cases of anthrax respond to antibiotics, advanced inhalation anthrax may not. By the later stages of the disease, the bacteria have often produced more toxins than drugs can eliminate.

Along with antibiotics, people with serious cases of anthrax need to be hospitalized. They may require aggressive treatment, such as continuous fluid drainage, fluids and medicines to tighten blood vessels and raise blood pressure (vasopressors) and help breathing through mechanical ventilation.

Antibiotics

All types of anthrax infection can be treated with antibiotics, including intravenous antibiotics (medicine given through the vein). If someone has symptoms of anthrax, it’s important to get medical care as quickly as possible to have the best chances of a full recovery. Doctors will select antibiotics that are best for treating anthrax and that are best for the patient based on their medical history.

For adults with systemic anthrax (inhalational, intestinal, meningitis, injection), the CDC expert panel recommends the following:

Table 3. Treatment of Systemic Anthrax Without Meningitis

Adults	Children
1. Bactericidal agent
Ciprofloxacin 400 mg every 8 hours	Ciprofloxacin 30 mg/kg/day divided every 8 hours (max dose, 400 mg/dose)
Alternative
Levofloxacin 750 mg every 24 hours -OR-	Meropenem 60 mg/kg/day divided every 8 hours (max dose, 2 g/dose) -OR-
Moxifloxacin 400 mg every 24 hours -OR-	Levofloxacin < 50 kg: 20 mg/kg/day divided every 12 hours (max dose, 250 mg/dose) >50 kg: 500 mg every 24 hours -OR-
Meropenem 2 g every 8 hours -OR-	Imipenem 100 mg/kg/day divided every 6 hours (max dose, 1 g/dose) -OR-
Imipenem 1 g every 6 hours -OR-	Vancomycin 60 mg/kg/day divided every 8 hours (max dose, 2 g/dose); trough target, 15-20 mcg/mL
Doripenem 500 mg every 8 hours -OR-
Vancomycin 60 mg/kg/day divided every 8 hours (max dose, 2 g/dose); trough target, 15-20 mcg/mL
PLUS
2. Protein synthesis inhibitor
Clindamycin 900 mg every 8 hours -OR-	Clindamycin 40 mg/kg/day divided every 8 hours (max dose, 900 mg/dose)
Linezolid 600 mg every 12 hours
Alternative
Doxycycline 200-mg loading dose followed by 100 mg every 12 hours -OR-	Linezolid < 12 years: 30 mg/kg/day divided every 8 hours >12 years: 30 mg/kg/day divided every 12 hours (max dose, 600 mg/dose) -OR-
Rifampin 600 mg every 12 hours	Doxycycline < 45 kg: 4.4 mg/kg loading dose (max 200 mg) followed by 4.4 mg/kg/day divided every 12 hours (max 100 mg/dose) >45 kg: 200 mg loading dose followed by 100 mg every 12 hours -OR-
	Rifampin 20 mg/kg/day divided every 12 hours (max dose, 300 mg/dose)

[Source ²⁵ ]

Table 4. Treatment of Anthrax Meningitis

Adults	Children
1. Bactericidal agent
Ciprofloxacin 400 mg every 8 hours	Ciprofloxacin 30 mg/kg/day divided every 8 hours (max 400 mg/dose)
Alternative
Levofloxacin 750 mg every 24 hours -OR-	Levofloxacin < 50 kg: 16 mg/kg/day divided every 12 hours (max 250 mg/dose) ≥50 kg: 500 mg every 24 hours -OR-
Moxifloxacin 400 mg every 24 hours	Moxifloxacin Age 3 months to < 2 years: 12 mg/kg/day divided every 12 hours Age 2-5 years: 10 mg/kg/day divided every 12 hours Age 6-11 years: 8 mg/kg/day divided every 12 hours Age 12-17 years, < 45 kg: 8 mg/kg/day divided every 12 hours (Max 200 mg/dose) Age 12-17 years, ≥45 kg: 400 mg every 24 hours
PLUS
2. Second bactericidal agent
Meropenem 2 g every 8 hours	Meropenem 120 mg/kg/dose divided every 8 hours (max 2 g/dose)
Alternative
Imipenem 1 g every 6 hours -OR-	Imipenem 100 mg/kg/day divided every 6 hours (max 1 g/dose) -OR-
Doripenem 500 mg every 8 hours -OR-	Doripenem 120 mg/kg/day divided every 8 hours (max 1 g/dose) -OR-
Ampicillin 3 g every 6 hours -OR-	Vancomycin 60 mg/kg/day divided every 8 hours (max 2 g/dose); target trough, 15-20 mcg/mL -OR-
	Ampicillin 400 mg/kg/day divided every 6 hours (max 3 g/dose)
PLUS
3. Protein synthesis inhibitor
Linezolid 600 mg every 12 hours	Linezolid < 12 years old: 30 mg/kg/day divided every 8 hours ≥12 years old: 30 mg/kg/day divided every 12 hours (Max 600 mg/dose)
Alternative
Clindamycin 900 mg every 8 hours -OR-	Clindamycin 40 mg/kg/day divided every 8 hours (max 900 mg/dose) -OR-
Rifampin 600 mg every 12 hours -OR-	Rifampin 20 mg/kg per day divided every 12 hours (max 300 mg/dose) -OR-
Chloramphenicol 1 g every 6-8 hours	Chloramphenicol 100 mg/kg per day divided every 6 hours (max 1 g/dose)

Footnotes: Anticipate a therapy duration of at least three weeks or until clinical improvement, whichever comes last, as clinical improvement may take several weeks. Thereafter, patients should complete a 60-day course of antibiotics with oral monotherapy to prevent relapse involving dormant endospores. Oral antibiotic should be dosed according to guidelines for postexposure prophylaxis.

[Source ²⁵ ]

Antitoxin

When anthrax spores get inside the body, they can be “activated.” When they become active, anthrax bacteria can multiply, spread out in the body, and produce toxins—or poisons. Anthrax toxins in the body cause severe illness.

After anthrax toxins have been released in the body, one possible treatment is antitoxin. Antitoxins target anthrax toxins in the body. Doctors must use antitoxin together with other treatment options.

Since the 2001 attacks in the United States, researchers have developed antitoxin therapies — Raxibacumab (ABthrax) and Obiltoxaximab (Anthim) — for inhalation anthrax. Instead of going after the bacteria that causes the disease, these medications help eliminate the toxins caused by the infection. Anthrax immunoglobulin also may be used to neutralize the toxins. These medications are given in addition to antibiotics and are available to doctors through the U.S. Centers for Disease Control and Prevention.

• Raxibacumab is a human IgG1 gamma monoclonal antibody directed at the protective antigen of Bacillus anthracis. It is produced by recombinant DNA technology in a murine cell expression system. This agent was approved by the FDA in December 2012 for treatment of inhalational anthrax or for prevention when alternative therapies are not available or appropriate. It is used as part of a combination regimen with appropriate antibiotic drugs ²⁶. The efficacy of raxibacumab as a prophylactic agent and after disease onset was assessed in 4 randomized controlled animal model trials to provide surrogate endpoints applicable to human use ²⁷.
• Obiltoxaximab is another monoclonal antibody directed at the protective antigen of Bacillus anthracis that was approved by the FDA in March 2016. It is a chimeric IgG1 kappa monoclonal antibody ²⁸.

Cutaneous anthrax treatment

Cutaneous anthrax is treated with antibiotics. Oral ciprofloxacin or doxycycline are effective, except in cases with extensive edema or head and neck involvement, when a multidrug intravenous regimen is recommended. Treatment must be started straight away to reduce the chance of the anthrax spreading from the initial skin lesion.

• Traditionally, treatment has been with intravenous or intramuscular penicillin for 7–10 days. However, for uncomplicated cutaneous anthrax, an oral tetracycline, especially doxycycline, is given in an outpatient setting. It is also suitable for those allergic to penicillin.
• With recent concerns that Bacillus anthracis in the setting of bioterrorism may be resistant to penicillin and tetracycline, a quinolone such as ciprofloxacin is becoming the antibiotic of choice. It is particularly used for inhaled anthrax infection. Initially, it should be given intravenously, and then continued orally for up to 60 days.

In some cases, it is necessary to surgically scrape off the black eschar from the anthrax ulcer. It is essential that this is done with antibiotic cover as interfering with the wound could encourage the spread of the bacteria. If the eventual scar is unsightly, a plastic surgeon may be able to improve its appearance later.

Table 5. Treatment of Cutaneous Anthrax

Nonpregnant adults	Pregnant/lactating women	Children
Recommended therapy
Ciprofloxacin 500 mg every 12 hours	Ciprofloxacin 500 mg every 12 hours	Ciprofloxacin 30 mg/kg/day divided every 12 hours (max dose, 500 mg/dose)
Doxycycline 100 mg every 12 hours		Amoxicillin 75 mg/kg/day divided every 8 hours (max dose, 1 g/dose)
Levofloxacin 750 mg every 12 hours
Moxifloxacin 400 mg every 24 hours
Alternative therapy
Clindamycin 600 mg every 8 hours	Levofloxacin 750 mg every 12 hours	Doxycycline < 45 kg: 4.4 mg/kg/day divided every 12 hours (max dose, 100 mg/dose) >45 kg: 100 mg every 12 hours
Amoxicillin 1 g every 8 hours (susceptible strain only)	Amoxicillin 1 g every 8 hours (susceptible strain only)	Clindamycin 30 mg/kg/day divided every 8 hours (max dose, 600 mg/dose)
		Levofloxacin < 50 kg: 16 mg/kg/day divided every 12 hours (max dose, 250 mg/dose) >50 kg: 500 mg every 24 hours

Footnote: Treatment duration 7-10 days

[Source ²⁵ ]

Inhalation anthrax treatment

All cases of inhalation anthrax should be considered a bioterror event and appropriate decontamination steps should be in place. Healthcare workers should wear masks and gloves and splask protection devices. Contaminated individuals should immediately wash hands with detergent and water. Place clothing in a plastic bag for evaluation.

In brief, treatment for inhalational anthrax requires a multidrug regimen with one bactericidal agent + 1 protein-synthesis inhibitor. Intravenous ciprofloxacin + clindamycin or linezolid are the preferred agents ³. In patients with meningitis, a 3-drug regimen comprised of 2 bactericidal agents from different drug classes (fluoroquinolone + beta-lactam) + 1 protein-synthesis inhibitor are recommended.

A newer treatment for inhalational anthrax is the monoclonal antibody raxibacumab or oblitoxaximab. It is used as part of combination therapy with appropriate antibiotic agents.

Gastrointestinal anthrax treatment

Gastrointestinal anthrax develops after eating contaminated meat usually from raw or under cooked meat or liver of infected animals. The incubation period for the gastrointestinal anthrax is usually 2 to 5 days but may be as short as 15 hours. When spores germinate in the intestinal tract, they cause ulcerative lesions. These lesions can occur anywhere and may in severe cases, result in hemorrhage, obstruction or perforation ²⁹. Gastrointestinal anthrax mortality rate is not precisely known, although rates have been estimated at 4 to 50% ³⁰.

All patients with suspected gastrointestinal anthrax should be begun immediately on IV antibiotics with co-administration of an antitoxin (raxibacumab) or anthrax immune globulin (Anthrasil) and should receive aggressive supportive care and then exploratory laparotomy are keys to survival ³⁰. All patients with suspected systemic illness should be admitted to inpatient for treatment. Early diagnosis and clinical suspicion are critical to improving outcomes. Workup should include standard fever workup pending the clinical situation, often including blood cultures and urine samples.

Anthrax prognosis

Most cases of anthrax are the cutaneous type, are mild, and these usually with or without treatment. If treated early with appropriate antibiotics, the mortality rate of cutaneous anthrax is less than 1%-2% ³¹.

However, other forms of anthrax are potentially fatal, with inhalational anthrax carrying the worst prognosis. Inhalational anthrax and its subsequent systemic infection (e.g, septicemia, hemorrhagic leptomeningitis) have a mortality rate approaching 100%. Even with present-day critical care capabilities and modern medical technology, the mortality rates of gastrointestinal and inhalational anthrax remain 40% and 45%, respectively ³². If treatment is initiated during the incubation period of 1-6 days and before the manifestation of symptoms, mortality can decrease to 1%.

Oropharyngeal or intestinal anthrax carries a less favorable prognosis than cutaneous anthrax but a more favorable prognosis than inhalational anthrax. Patients with oropharyngeal anthrax may develop airway obstruction (as may those with inhalational anthrax or cutaneous anthrax involving the neck). Intestinal anthrax is more difficult to diagnose given its initial nonspecific syndrome and is associated with higher morbidity and mortality rates ³².

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