Medical Interests: The Return of the Black Death

Last month within Kyrgyzstani, a fifteen-year-old boy died of bubonic plague after being bitten by an infected flea. This is of huge interest because naively I thought the bubonic plague had died out, but today 1000-3000 cases occur globally each year. Although 90% of infections occur in Africa, by contrast in the US annually on average seven people catch the plague. In July this year, camping sites around Los Angeles were closed because a squirrel tested positive for plague.

The bubonic plague is caused by a bacterium, Yersinia pestis and transmission of the infection occurs by rats, squirrels and other rodents. The biggest problem for epidemics is when rodents begin to die, as the infected fleas need a new host. Buboes within the lymph glands (in the groin) begin to swell and cause immense pain; this is where the name ‘Bubonic’ plague comes from.

An example of an epidemic of the Bubonic plague was during the 1300’s when it was known as the ‘Black Death.’ At the time it wasn’t known what caused the blisters and swellings, but recent work from archaeologists identified the bacterium Yersinia pestis within skeleton DNA. It was known as the Black Death due to high death rates down to the lack of medical advancement and antibiotics. It became fatal because it caused haemorrhaging of blood vessels in the fingers and nose leading to gangrene. This became infected and spread to the lungs causing pneumonic plague. This increased the risk because pneumonic plague could be spread by droplet infection such as coughs or sneezes.

Bubonic is only one type of plague the infected bacterium can also cause pneumonic plague as I previously mentioned and then the third one is septicemic plague. The transmission is the same, however its symptoms such as weakness, abdominal pain and bleeding beneath skin or other organs is caused by the multiplication of the bacterium within the bloodstream. Skin and other tissues may turn black and die, especially on fingers, toes, and the nose. Septicemic plague can occur as the first symptom of plague, or may develop from untreated bubonic plague.