Plague is an infectious disease of over one hundred animals, including rats and humans. Infection occurs from flea bites and can go from people to rats, people to people, or rats to rats. Just one bacillus is enough to infect a person; people usually get plague from being bitten by rodent flea that is carrying the plague from bacterium or by handling an infected animal. Millions of people in Europe died from plague in the middle ages, when human homes and places of work were inhabited by flea infested rats. Many died in Surat in India, a few years ago, due to plague. Today, modern antibiotics are effective against plague, but if an infected person is not treated promptly, the disease is likely to cause illness or death.
Globally, the World Health Organization reports 1000 to 3000 cases of plague every year.
There are three forms of plague
• Primary pneumonic plague
• Bubonic plague – most common
• Primary septic plague
Primary pneumonic plague: This is the most serious and highly infectious form; it may occur in localized and sometimes devastating epidemics.
• Bacteria invade victim’s lungs
• Lungs fill with frothy bloody liquid
• Spread is common; from person – person
Bubonic plague: It is a contagious often fatal epidemic disease caused by the bacterium, Yersinia pestis, transmitted from person to person or by the bite of fleas from an infected host, especially rats, and characterized by chills, fever, vomiting, diarrhea and formation of buboes.
• Bacteria invade lymph nodes, which swell and are called buboes.
• Blood vessels break, causing internal bleeding.
• Dried blood under the skin turns black, hence the name. “Black death”.
• Spread is slow from person to person.
• Mortality is very high in untreated cases.
• Early treatment with antibiotic is very effective.
Primary septicemic plague: This type of plague is rare and is diagnosed by blood smear or blood culture. This may be a form of bubonic plague in which the buboe is obscure and may include pharyngeal tonsillar infection.