A gram-negative bacterium called Yersinia pestis causes plague. Plague is a deadly fatal “disease” and it killed millions of people during its three pandemic outbreaks. Due to the discovery of the causative agent of the plague by Alexandre Yersin, it was named as Yersinia pestis. Two types of plagues, bubonic plague, and pneumonic plague are caused by the bacteria. The bacteria use some rodents and fleas as a transmission vector. Fleas need a specific temperature and humidity for its developmental stages. The victim of the plague is not infectious for normal people. Symptoms of bubonic plague include severe headache, bleeding in mouth, restlessness, limb pain, and irritation. Sometimes, Yersinia makes its way to the liver, lungs, spleen, and other organs of the body. The patient feels burning fever and wishes to take a bath with cold water. A rapid diagnostic test is applied to assess the level of disease. An early diagnosis can lead to more chances to cure the disease. Vaccine for the bubonic plague was designed at the start of the last century but it is not efficient rather it is reactogenic. Antibiotics for bubonic plague are more efficient but fail for pneumonic plague.