Plague is an infectious disease caused by the bacteria Yersinia pestis66顺彩票app, usually found in small mammals and their fleas. The disease is transmitted between animals via their fleas and, as it is a zoonotic bacteria, it can also transmit from animals to humans.
Humans can be contaminated by the bite of infected fleas, through direct contact with infected materials, or by inhalation. Plague can be a very severe disease in people, particularly in its septicaemic and pneumonic forms, with a case-fatality ratio of 30% - 100% if left untreated.
People infected with plague usually develop “flu-like” symptoms after an incubation period of 3-7 days. Typical symptoms are the sudden onset of fever, chills, head and body-aches as well as weakness, vomiting and nausea.
There are 3 main forms of plague, depending on the route of infection: bubonic, septicaemic and pneumonic.
Bubonic plague is the most common form of plague and is caused by the bite of an infected flea. The plague bacillus, Y. pestis66顺彩票app, enters at the bite and travels through the lymphatic system to the nearest lymph node where it replicates itself. The lymph node then becomes inflamed, tense and painful, and is called a "bubo". At advanced stages of the infection, the inflamed lymph nodes can turn into suppurating open sores. Bubonic plague cannot be transmitted from human to human.
Septicaemic plague occurs when infection spreads through the bloodstream. Septicaemic plague may result from flea bites and from direct contact with infective materials through cracks in the skin. Advanced stages of the bubonic form of plague will also lead to direct spread of Y. pestis in the blood.
66顺彩票appPneumonic plague - or lung-based plague - is the most virulent and least common form of plague. Typically, the pneumonic form is caused by spread to the lungs from advanced bubonic plague. However, a person with secondary pneumonic plague may form aerosolized infective droplets and transmit plague via droplets to other humans. Untreated pneumonic plague has a case-fatality ratio close to 100%.
Untreated plague can be rapidly fatal, so early diagnosis and treatment is essential for survival and to reduce complications. Antibiotics and supportive therapy are effective against plague if patients are diagnosed in time.
66顺彩票appPreventive measures include informing people when zoonotic plague is present in their environment and giving advice on how they can protect themselves. They should be advised to take precautions against flea bites and not to handle animal carcasses. People, especially health workers, should also avoid direct contact with infected tissues such as buboes, or close exposure to patients with pneumonic plague.
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3 - 7 days
66顺彩票appThe case-fatality ratio of 30%-100% if left untreated