Plague is a disease caused by a kind of bacteria. In nature, the disease is spread from rodents to humans by the bite of a flea. During the fourteenth century, this illness spread across the world in three large waves, killing one-third to one-half of the population in places where outbreaks occurred.
Thanks to improved sanitation and living conditions, outbreaks of plague are now rare. However, up to 2, cases are reported each year worldwide, including about 15 cases in the southwestern U. Symptoms of pneumonic plague include high fever, chest pain, cough, shortness of breath and coughing up bloody fluid or mucus. Unless antibiotic treatment is started within 24 hours, the patient can quickly go into shock and die.
For patients who do not receive immediate treatment, the death rate is nearly percent. Symptoms of pneumonic plague typically appear within one or two days after exposure to the bacteria. People get bubonic plague from infected animals. The bacteria are spread by bites from infected fleas, bites or scratches from infected animals, or direct contact with infected animal carcasses.
People get pneumonic plague by inhaling droplets that contain plague bacteria. The droplets are released into the air when infected people — or animals — cough.
However, if plague were to be used as a weapon, the bacteria could be released into the air on purpose. The possible use of plague as a weapon has been studied for at least 60 years. Both the U. The first sign of a pneumonic plague attack would be a wave of people seeking medical treatment for severe respiratory problems, about one to two days after the attack.
The infection can be transmitted from person to person via airborne droplets -- coughing or sneezing. Outbreaks still occur today, with an outbreak in Madagascar last year infecting more than 1, people.
The deer mouse is a potential source of diseases including the plague, salmonellosis and hantavirus. Hide Caption. Often, humans become infected after being bitten by fleas that have bitten infected animals like deer mice and voles.
Another easy way humans become infected is after their pet, mainly a house cat, hunts an infected rodent and then bites the owner or is host to infected fleas. The first known outbreak of plague in the United States came after infected rodents from China that were on ships mingled with urban rats in port cities.
Los Angeles had an outbreak of plague in The California ground squirrel is highly susceptible to becoming infected with the plague and transmitting it widely to other squirrels. Signs and symptoms include:. Pneumonic plague affects the lungs. It's the least common variety of plague but the most dangerous, because it can be spread from person to person via cough droplets. Signs and symptoms can begin within a few hours after infection, and may include:.
Pneumonic plague progresses rapidly and may cause respiratory failure and shock within two days of infection. Pneumonic plague needs to be treated with antibiotics within a day after signs and symptoms first appear, or the infection is likely to be fatal.
If you begin to feel ill and have been in an area where plague has been known to occur, seek immediate medical attention. You'll need treatment with medication to prevent serious complications or death. In the United States, plague has been transmitted to humans in several western and southwestern states — primarily New Mexico, Arizona, California and Colorado. Worldwide, plague is most common in rural and semirural parts of Africa especially the African island of Madagascar , South America and Asia.
The plague bacteria, Yersinia pestis, is transmitted to humans through the bites of fleas that have previously fed on infected animals, such as:. The bacteria can also enter your body if a break in your skin comes into contact with an infected animal's blood.
Domestic cats and dogs can become infected with plague from flea bites or from eating infected rodents. Pneumonic plague, which affects the lungs, is spread by inhaling infectious droplets coughed into the air by a sick animal or person. The risk of developing plague is very low.
Worldwide, only a few thousand people develop plague each year. However, your plague risk can be increased depending on the area where you live and travel, your job, and your hobbies. Plague outbreaks are most common in rural and semirural areas that are overcrowded, have poor sanitation and have a high rodent population. The greatest number of human plague infections occur in Africa, especially the African island of Madagascar.
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