Anthrax, an acute infectious disease, has three main types: cutaneous (through the skin), inhalation (through the lungs, the most deadly) and gastrointestinal (through digestion). Scholars believe that anthrax originated in Egypt and Mesopotamia. Some even blame it for the biblical fifth plague of ancient Egypt, a sickness affecting horses, cattle, sheep and camels. The contagion was also a familiar one in ancient Greece and Rome. Getty Images
In the late 19th century, German scientist Robert Koch discovered that Bacillus anthracis, the bacterium that causes anthrax, formed spores that were able to survive for very long periods of time in many different environments. After growing the bacteria and injecting it into animals, he described a novel concept: that a specific microbe could cause a specific disease. SSPL/Getty Images
The first anthrax vaccine is alternately credited to Koch's French contemporaries Louis Pasteur, seen here, and Jean Joseph Henri Toussaint. SSPL/Getty Images
The development of a live spore vaccine to protect animals from anthrax led to a dramatic decline in human cases: only 18 cases of inhalation anthrax in the 20th century, the Centers for Disease Control and Prevention says. The first human vaccine was created in the 1950s, and penicillin quickly became the preferred treatment for those who caught the illness.
Here, assistants in a bacteriology production unit prepare batches of anthrax for experimental research in May 1964. Central Press/Getty Images
Anthrax emerged as a biological weapon in Europe in World War I. Japan began producing the bacteria for use as a weapon in the 1930s. The United States experimented with biologic agents such as anthrax during World War II, and the United Kingdom held field trials of anthrax-laden munitions on a small Scottish island called Gruinard. The island was then sealed off to the public for almost 45 years. PAMPC/AP
U.S. soldiers in Kuwait in 1998 are vaccinated against anthrax, one of the germ warfare agents suspected to be in Iraq's arsenal of banned weapons of mass destruction. RAED QUTEINA/AFP/Getty Images
Anthrax was sent via anonymous letters to news agencies in Florida and New York and a congressional office building in Washington after the September 11, 2001, attacks. Five people were killed, including two postal workers, and 17 people sickened. No arrests were ever made. Justin Sullivan/Getty Images
Vado Diomande, a New York drum-maker, was diagnosed with inhalation anthrax in 2006 after processing goat skins he'd picked up in Africa. Here, a NYPD hazmat team prepares to enter his apartment.
A Connecticut woman developed gastrointestinal anthrax in 2009 after attending an event where contaminated drums were played. In 2010, an outbreak among heroin users in Northern Europe led doctors to diagnose a new type: injection anthrax. Jonathan Fickies/Getty Images
In June 2015, the Pentagon announced that the Defense Department may have accidentally shipped live anthrax samples to 86 labs in 20 states, the District of Columbia and seven foreign countries. There were no infections as a result of the shipments. Cmdr. Franca Jones, director of medical programs for chemical and biological defense, demonstrates the protocol for shipping anthrax samples. Alex Wong/Getty Images
In July, thirteen people were hospitalized amid an outbreak of anthrax in western Siberia. Experts with the Russian Ministry of Agriculture believe the cause of infection was the thawing of the frozen carcass of a reindeer that died 75 years ago. Yamalo-Nenets Autonomous District