|Location Where Organisms Naturally Occur, Disease Produced, and Mode of Transmission|
These organisms can be encountered outside of a bioterrorism event and produce human disease. It's important to be familiar with the geographic areas where these organisms naturally occur and the how disease is transmitted.Bacillus anthracis: Bacillus species inhabit the soil, water, and airborne dust. Anthrax is the disease produced, which is transmitted to humans via direct contact with infected herbivorous animals. This is where the disease is primarily encountered. Anthrax is controlled in animals in the United States, so the disease is rare. In humans, most cases are cutaneous infections found in people that handle animals and animal products, including veterinarians and agricultural workers. Anthrax is consistently present in the animal population of some geographical regions, such as Iran and Pakistan, but only small numbers of animals experience the disease at any given time. Yersinia pestis: Y. pestis is found primarily in rodents, but can also be found in several animal species, such as cats, rabbits, camels, squirrels. Animal to human transmission most commonly occurs via a flea bite, causing the most common form of the disease known as the bubonic plague. Human-to-human transmission occurs by either flea bite or respiratory droplets. This causes an overwhelming disease known as pneumonic plague, which is the most likely form that would be implicated in the event of a bioterrorist attack. Human cases of the plague continue to occur in many countries, including Africa, the southwestern United States, parts of Asia, and the former Soviet Union. Francisella tularensis: Many animals, including rodents, rabbits, deer, and raccoons act as host for this organism. Humans and domesticated animals, such as horses, cattle, cats, and dogs can become infected. The infection is transmitted to domesticated animals by ticks and biting flies. Humans are most commonly infected from the bite of an infected tick or fly. Other means of infection include direct contact with the blood of infected animals when skinning game, eating contaminated meat, drinking contaminated water, or inhaling the organisms produced by aerosols. F. tularensis carries a high risk of laboratory acquired infection and documented cases of infection have occurred. Most cases of tularemia are reported in the southern and south-central United States.
|Location Where Organisms Naturally Occur, Disease Produced, and Mode of Transmission, continued:|
Brucella species: Brucella is distributed in nature worldwide and found in domesticated and wild animals, such as cattle, sheep, and pigs. Infection with Brucella species, known as brucellosis, is caused in humans by exposure to infected animal fluids or food products. This includes ingesting non-pasteurized dairy products, such as milk or cheese, inhaling aerosols, and skin contact with the fluids of infected animals. Brucellosis poses an increased risk of occupational exposure to laboratory, veterinary, and slaughterhouse workers. Brucella is the most commonly reported laboratory-associated bacterial infection.Burkholderia mallei and B. pseudomallei: Most Burkholderia are found in soil, but B. mallei is only found in mammals. B.mallei is the causative agent for Glanders which primarily affects animals such as donkeys, mules, and horses. Horses, the organism's natural host, are highly susceptible to infection. Human infection is rare and usually occurs in people working with infected animals or laboratory workers handling the organism. The organism is endemic in Africa, Asia, the Middle East, and Central and South America, and usually enters via the eyes, nose, mouth, abrasions or cuts in the skin, or through inhalation. B. pseudomallei is found in soil and water and can accidentally infect animals, plants, and rarely humans. It is the causative agent of melioidosis, which is endemic in areas of southeast Asia, Taiwan, and northern Australia. The organism generally enters through cuts in the skin, ingestion of contaminated water, or by inhalation of an aerosol.