What was the process of infection for black plague?
The infection of black plague, also known as bubonic plague, primarily occurs through the bites of infected fleas that have fed on rodents carrying the Yersinia pestis bacterium. The process of infection can be explained as follows:
1. Transmission from Rodents:
- The primary reservoir of Yersinia pestis is rodents, particularly rats. When these rodents become infected with the plague bacteria, they develop septicemia, and the bacteria multiply rapidly within their bloodstream.
- Infected rodents display symptoms such as lethargy, fever, and enlarged lymph nodes (known as buboes). As the infection progresses, the rodents may succumb to the disease and die.
2. Infestation of Fleas:
- Fleas that feed on infected rodents ingest the Yersinia pestis bacteria along with their blood meal. Inside the fleas' digestive system, the bacteria multiply and can block the flea's proventriculus (a valve-like structure that regulates blood flow within the flea).
- As a result of this blockage, the fleas become unable to feed properly and exhibit a behavior known as "blocked flea syndrome." They remain attached to the host and continue to attempt feeding, increasing the chances of transmitting the infection.
3. Transmission to Humans (Bubonic Plague):
- When an infected flea bites a human, it regurgitates the bacteria-laden blood back into the bite wound. The bacteria can enter the human's lymphatic system and cause inflammation and swelling of the lymph nodes closest to the bite, forming buboes (swollen lymph nodes).
- Typically, the buboes develop within 2 to 6 days after the bite. These swollen lymph nodes can be painful and may reach the size of a chicken egg or larger. Other symptoms of bubonic plague may include fever, chills, weakness, headaches, and nausea.
4. Potential Progression (Septicemic Plague):
- In some cases, the infection may progress from bubonic plague to septicemic plague, where the bacteria enter the bloodstream and multiply rapidly. This can cause high fever, chills, weakness, confusion, and organ failure. Septicemic plague is a severe form of the disease and can be fatal if not treated promptly.
5. Transmission via Respiratory Droplets (Pneumonic Plague):
- Rarely, the infection can spread to the lungs, causing pneumonic plague. This form is highly contagious and can be transmitted through respiratory droplets when an infected person coughs or sneezes. Pneumonic plague can be fatal if not diagnosed and treated early.
It's important to note that not all flea bites from infected rodents will result in transmission of the plague bacteria. However, individuals living in areas where plague is known to be present or those handling potentially infected animals should take precautions to prevent exposure and seek medical attention if they experience symptoms of the plague.