Bubonic plague: A less severe form of the plague caused by the same bacterium. It is characterized by swollen lymph nodes (buboes) and can be transmitted through fleas or direct contact with infected animals.
Yersinia pestis: The bacterium responsible for causing both bubonic and pneumonic plagues. It is primarily found in rodents and transmitted to humans through fleas or direct contact.
Contagious disease: A disease that can be easily spread from one person to another through various means such as respiratory droplets, physical contact, or contaminated surfaces.