A Human Scourge
A Human Scourge
Animals are the usual victims of anthrax, but the disease has also plagued humans since ancient times. Human anthrax is not common, but medical experts estimate that between twenty and one hundred thousand cases occur globally each year. People of any age may be infected, usually by handling contaminated hides or eating infected meat. Most human victims are those people who work with animals or animal products, such as farmers, ranchers, veterinarians, wildlife workers, butchers, and wool-workers. However, skin, wool, furs, ivory tusks, and other animal parts can harbor anthrax spores for years, spreading the disease to the general public. Unlike contagious diseases, anthrax is not spread from person to person.
Human anthrax is most common in regions where animal anthrax is widespread, such as parts of Africa, Asia, southern and eastern Europe, South America, Central America, the Caribbean, Australia, and the Middle East. In these areas, afflicted animals sometimes transmit the disease to humans. In Tajikistan in Central Asia, for example, 338 cases of human anthrax were reported in 2000. Kenya, Zambia, India, Pakistan, and Indonesia also reported significant outbreaks of human anthrax in 2000 and 2001.
Human anthrax is rare in industrialized countries like the United States. During the early 1900s about two hundred people per year contracted anthrax in the United States. By the mid-1900s, however, industrial upgrades, improved animal rearing practices, strict controls on imported animal products, and sterilization of animal skins, hides, and hair greatly reduced the incidence of human anthrax. Thus, few cases were reported in the United States by the last quarter of the twentieth century. An additional reason for the reduced incidence of human anthrax in the nation may be that most farmers and ranchers have learned to recognize anthrax in animals and avoid handling diseased creatures. "It's usually fairly obvious when you know what to look for," observes Martin Hugh-Jones, a veterinarian at Louisiana State University who monitors anthrax. "[Animal victims of anthrax] bloat up fairly quickly.… You get blood coming out of the nose and anus in some cases and they don't have rigor mortis."9
In the early stages human anthrax can resemble the bite of a brown recluse spider, a severe reaction to a smallpox vaccination, or other diseases like influenza, tularemia (a bacterial infection), or herpes simplex (a viral infection). A definite diagnosis of anthrax is made by isolating Bacillus anthracis organisms from a victim or by finding large quantities of "anthrax antibodies" (substances that fight anthrax germs) in a person's blood. If a victim contracts a deadly form of anthrax, an early diagnosis is important for rapid treatment and recovery.
The Disease in Humans
Three forms of anthrax are seen in human beings—cutaneous anthrax, inhalation anthrax, and intestinal anthrax. Each is contracted in a different way. Cutaneous anthrax is caught when anthrax spores enter through cuts or abrasions in a person's skin. Inhalation anthrax is contracted by breathing in anthrax spores. And intestinal anthrax results when humans ingest anthrax spores.
Cutaneous anthrax is the most common, and least deadly, form of the disease in people. Even without treatment, the majority of victims recover. At one time, medical experts believed that more than 95 percent of human anthrax cases were cutaneous. However, recent studies have shown that other types of human anthrax are more common than was previously believed.
The incubation period for cutaneous anthrax—from the time spores enter the skin until symptoms appear—ranges from twelve hours to twelve days, but is usually two to five days. During this time, the anthrax spores germinate into bacterial cells, which multiply and produce toxins. The toxins cause small red lesions, which may be either macules (flat spots) or papules (elevated spots), to erupt at the sites of infection. The red spots, which may be mistaken for pimples or insect bites, generally appear on exposed areas of the body, such as the head, neck, face, arms, and hands.
Over the next seven to ten days the red lesions grow into ulcers, called eschars, that vary from about one-half inch to two inches in diameter. The centers of the eschars become hard, black crusts, which give the disease its name. Historically, the eschars were called malignant pustules, carbuncles, or charbons. The eschars themselves usually do not hurt. However, the areas around the eschars swell as they become engorged with bacteria-filled fluids, and this may be painful. In addition, lymph nodes near the eschars, which enlarge as they help fight the infection, may also cause great discomfort.
Even without medication, 80 percent of cutaneous anthrax victims recover as their immune systems fight off the disease. In survivors, the eschars remain limited to the sites of infection and dry up and heal after one to two weeks. Permanent scars, however, may remain at the locations of the original lesions. Proper early treatment of cutaneous anthrax does not stop the formation of eschars but usually prevents death.
About 20 percent of untreated cases of cutaneous anthrax become systemic (spread throughout the body). In these cases the victims exhibit high fever, weakness, and widespread edema. Systemic cutaneous anthrax usually results in death from septicemia, caused by large quantities of Bacillus anthracis organisms and their toxins circulating in the blood. With appropriate early antibiotic treatment, septicemia is rare.
A possible complication of all forms of human anthrax is anthrax meningitis. This occurs when anthrax bacteria infect the membranes around the brain and spinal cord, which can result in high fever, stiff neck, severe headache, fatigue, nausea, vomiting, agitation, seizures, delirium, and coma. Anthrax meningitis almost always results in death.
Cutaneous Anthrax Outbreaks
Early in the twentieth century, several outbreaks of human cutaneous anthrax were attributed to contaminated shaving brushes. During World War I (1914–1918) large numbers of British and U.S. soldiers—as well as many British civilians—contracted cutaneous anthrax from horsehair shaving brushes purchased from Japan. The horsehair in the brushes was traced to China and Siberia. During the epidemic 149 U.S. troops stationed in Great Britain contracted anthrax, and 22 died from the disease. In the 1920s and 1930s infected shaving brushes from Japan were also responsible for cutaneous anthrax outbreaks in New York City and other parts of the United States.
Later in the century human cutaneous anthrax declined in the United States, with fewer than 230 cases reported from the 1940s through the 1990s. A number of these illnesses occurred in the 1950s, when large numbers of wool products were manufactured in the nation. During that time cutaneous anthrax outbreaks affected workers in wool and hair industries in several states, including Colorado, Pennsylvania, North Carolina, Louisiana, and New Hampshire. In 1955, for example, five workers at a mill in Monroe, North Carolina, contracted cutaneous anthrax from imported goat hair. The origin of the disease was eventually traced to a shipment of wool from Iran and Iraq. Later, in the 1970s, other cases of cutaneous anthrax occurred when infected goatskin drumheads were imported as souvenirs. In a more unusual case, a girl in Louisiana developed cutaneous anthrax after carving figures from contaminated horse bones.
Though human cutaneous anthrax in the United States is now rare, the disease is still occasionally seen in people that work with animals. In 2000, for example, a man in North Dakota developed cutaneous anthrax after disposing of five infected cow carcasses. And, in summer 2001, a ranch hand in west Texas contracted cutaneous anthrax after skinning a buffalo that had died of the disease.
Naturally occurring human anthrax is now uncommon in industrialized nations, but the disease remains a problem in developing regions. In October 2000, for instance, thirty-three people in Kazakhstan contracted cutaneous anthrax after slaughtering infected animals. Similarly, in October and November 2001, forty people in Zimbabwe developed cutaneous anthrax—also after handling meat from infected cattle. In addition, a group of San bushmen in South Africa became infected with cutaneous anthrax after butchering and cooking a dead cow found in a field.
Medical experts note that many of these human victims were among the world's poorest people, who either do not know about the hazards of anthrax or are too hungry to care. In fact, some impoverished people knowingly consume anthrax-contaminated animals rather than starve. This happened in a village of "untouchables" (the lowest caste of people) in India. Huseyin Caksen, a physician at Turkey's Yuzuncuyil University, observes: "Human anthrax will be difficult to overcome. As long as there is poverty, we will have this disease."10
Turkey periodically experiences human anthrax epidemics. This is especially true in rural parts of the country, where people keep livestock. In 2000, for example, 396 people in Turkey developed cutaneous or other forms of anthrax. In one instance, two children contracted cutaneous anthrax after their foreheads were smeared with infected cow's blood as part of a traditional ritual. According to researchers, blood-smearing ceremonies such as this may be a significant factor in infecting children with cutaneous anthrax in some countries.
In the past, human inhalation anthrax was sometimes called "wool-sorters' disease" because of its prevalence among woolworkers in industrial mills. This form of human anthrax is uncommon, but very deadly. Without treatment, almost all victims die. With immediate, intense medical treatment, however, some patients survive.
In the United States only eighteen cases of inhalation anthrax were reported between 1900 and 1978, mostly among people who worked with goat wool or goat skins. After 1978 there were no known cases of inhalation anthrax in the United States until the anthrax mail attacks of 2001.
Inhalation anthrax is contracted when anthrax spores enter a person's lungs. The victim's immune system attacks the spores, but some spores survive and make their way to lymph nodes near the respiratory system. The spores germinate in the lymph nodes, where anthrax bacteria multiply and produce toxins. Symptoms appear soon afterwards.
The incubation period for inhalation anthrax ranges from one to sixty days, but is usually between one and ten days. The first stage of the disease resembles influenza, with symptoms such as low-grade fever, chills, muscle aches, fatigue, sore throat, coughing, and headache. This phase, which can last from a few hours to a few days, is sometimes followed by a very brief period of improvement.
As the bacterial population increases and the level of toxins rises, inhalation anthrax enters the second, or fulminant (severe), stage. This phase is characterized by tissue destruction, bleeding, fluid buildup in the mediastinum (the region around the heart and between the lungs), and increased inflammation of the lymph nodes. The anthrax bacteria may also spread to the liver, spleen, kidneys, and other organs, which become dark in color and bleed.
During the fulminant stage the victim becomes extremely ill and often exhibits symptoms such as high fever, extreme shortness of breath, profuse sweating, bluish skin color, abnormally low blood pressure, vomiting, severe chest pain, abdominal pain, and shock. Up to 50 percent of people suffering from inhalation anthrax also develop anthrax meningitis. Without very early treatment, about 99 percent of inhalation anthrax victims die from septicemia two to four days after the first symptoms appear. Once the fulminant stage begins, even high doses of medicine cannot control the disease, and death follows within twenty-four hours.
A serious outbreak of inhalation anthrax occurred in 1957 at a mill in Manchester, New Hampshire. Nine laborers became ill, and four died of inhalation anthrax. Nearly a decade later, a worker at a machine shop across from the mill also died of inhalation anthrax.
Prior to 2001 the last fatal case of inhalation anthrax in the United States occurred in 1976, when a California weaver contracted the disease after working with goat hair imported from Pakistan.
Human intestinal anthrax—acquired by eating meat, fruits, or vegetables contaminated with anthrax spores—has generally been considered a rare form of the disease. A report published in 2002, however, notes that intestinal anthrax is greatly underreported, especially in rural parts of developing countries. There are two reasons for this: Most doctors are not familiar with intestinal anthrax, and poor regions have too few medical clinics to adequately diagnose and report the disease.
According to Thira Sirisanthana, a professor of medicine and director of the Research Institute for Health Sciences at Chiang Mai University in Thailand, and Arthur E. Brown, chief of the Department of Retrovirology at the Armed Forces Research Institute for Medical Sciences in Thailand, human intestinal anthrax may be more common than human cutaneous anthrax in some outbreaks. The physicians observe that "in some community-based studies, cases of gastrointestinal anthrax outnumbered those of cutaneous anthrax," and "the apparently overwhelming predominance of the cutaneous form of anthrax is rather a reflection of the difficulty of diagnosis of the [intestinal] form." The scientists also assert that "mild cases of [intestinal anthrax] attract little attention, and people with severe infections, leading to death within two to three days, may never reach a medical facility."11
In any case, intestinal anthrax is much more serious than cutaneous anthrax. If left untreated, intestinal anthrax results in death in 25 to 65 percent of victims. In recent years known deaths from intestinal anthrax have occurred in Gambia, Uganda, Turkey, Thailand, India, and Iran. No cases of intestinal anthrax have ever been confirmed in the United States.
Eating herbivorous animals is the leading cause of intestinal anthrax in humans. The animals eat forage contaminated with anthrax spores, get sick, and die. The disease is then passed on to humans who eat their flesh. This is especially likely to occur if the meat is undercooked.
There are two types of human intestinal anthrax—oropharyngeal (mouth and throat) and abdominal—acquired when spores enter the lining of the digestive system. Oropharyngeal anthrax results when spores enter the upper digestive tract, and abdominal anthrax is contracted when spores enter the lower digestive tract. Once inside the digestive tract the spores germinate and multiply. The anthrax bacteria are then carried to nearby lymph nodes where they continue to proliferate and produce toxins. The incubation period for intestinal anthrax ranges from one to seven days, but is usually two to five days.
Early symptoms of oropharyngeal anthrax may include high fever; ulcers on the mouth, tongue, tonsils, and esophagus; and inflammation of nearby lymph nodes. Swelling of the mouth and esophagus may cause trouble swallowing and difficulty breathing. If breathing problems become severe, the victim may die of suffocation. Like other forms of anthrax, untreated oropharyngeal anthrax can become systemic, leading to death from massive septicemia.
Outbreaks of oropharyngeal anthrax have been reported in Africa and Asia. In 1982, for example, in Chiang Mai, northern Thailand, the handling and ingestion of infected water buffalo meat resulted in fifty-two cases of human cutaneous anthrax and twenty-four cases of human oropharyngeal anthrax. Three of the oropharyngeal anthrax victims died. A less severe outbreak of oropharyngeal anthrax occurred in Turkey in 1986. Six people contracted the disease and three died. Seven years later, in 1993, Turkey once again experienced an outbreak of this disease.
Abdominal anthrax is diagnosed more frequently than oropharyngeal anthrax. Early signs of abdominal anthrax include intestinal lesions, inflammation of abdominal lymph nodes, fever, loss of appetite, abdominal pain, vomiting, and fatigue. As the disease progresses victims experience more severe symptoms, such as fluid buildup in the abdomen, bloody diarrhea, and bloody vomit. In very severe cases the victim may die of intestinal perforation (holes in the intestine). If intestinal anthrax becomes systemic, it can resemble the final stages of inhalation anthrax and lead to death from septicemia. Death rates from intestinal anthrax are high because the disease is difficult to diagnose in the early stages. Therefore, victims may not receive timely treatment.
The worst recorded epidemic of human intestinal anthrax occurred in Saint Domingue (Haiti) in the eighteenth century and killed thousands of people. The outbreak began soon after an earthquake demolished part of the island on June 3, 1770, destroying bakeries, homes, buildings, and food storehouses. Historian Michel-Placide Justin describes the epidemic:
The unfortunate slaves in the north of Saint-Domingue therefore experienced the most frightful famine.… The Spaniards, whose [cattle ranches] were being thinned out daily by a terrible [disease] … sought to salt or smoke all their ill or dead animals.… These meats, known as tassau in the colonies … spread to the slaves the [germ] of the disease.… A type of epidemic disease, called charbon [anthrax], spread throughout all the neighboring dwellings of the Spaniards or the routes they frequently used. Within six weeks, more than fifteen-thousand white and black colonists perished of this terrible disease.12
Another epidemic of human intestinal anthrax occurred in Udon Thani Province in Thailand in 1982. After thirty-six water buffalo and seven cattle died of anthrax, 102 people who ate meat from the infected animals became ill. Twenty-eight of those people developed cutaneous anthrax, and the 74 other victims—3 of whom died—contracted intestinal anthrax.
Two years later, in 1984, an epidemic of intestinal anthrax occurred in Uganda when 155 people who feasted on an anthrax-infected zebu (an oxlike animal) became ill. The outbreak was reported two days after exposure, and the victims were quickly hospitalized and treated. Most of the patients recovered, but nine victims—all children—died from intestinal anthrax.
In 2000 in the United States, three people in a family of farmers in Minnesota developed symptoms of intestinal anthrax after eating hamburgers from a cow that had died of the disease. However, the family members were treated with medication and recovered before the disease could be confirmed.
People have sought ways to control the ravages of anthrax since ancient times. The losses caused by this dreadful disease finally began to come under control in the late nineteenth century, with the development of effective anthrax vaccines and improved treatments for both animals and people.