Bubonic plague

A tiny bug can make people sick.

This bug lives in small animals like rats. Fleas carry the bug to people. A flea bite can pass it on.

It can make your body feel bad. You might get a fever. It can make your head ache. Parts of your body might swell up. These swellings can be very painful.

Some parts of the skin can turn dark. This happens when the bug is inside. Doctors can find the bug in your blood. They use tests to see if you are sick.

Medicine can help you get well. Doctors give special medicine to fight the bug. This helps people stay safe. It is important to get help fast.

Many people lived through this long ago. It is still found in some lands today. We can stay safe by being careful around dead animals.

Bubonic plague is a sickness caused by a tiny germ. We call this germ Yersinia pestis.

Fleas often spread the germ to humans. These fleas live on small animals like rats. When a flea bites, the germ enters the skin. It then travels to the lymph nodes. These are small parts of the body's defense system. The nodes can swell and become very painful. We call these swollen parts buboes.

People may also feel very sick with a fever. Their skin might turn dark in some spots. This is called acral necrosis.

Doctors can find the germ in blood or fluids. They use antibiotics to treat the sickness. Antibiotics are special medicines that fight germs. Using them fast helps people stay safe. Without medicine, many people may die.

This disease has a long history. It caused the Black Death in the 14th century. That event killed many people in Europe and Asia. Today, cases still happen in places like Madagascar and Peru.

Bubonic plague is a serious sickness caused by a tiny germ. Scientists call this bacterium Yersinia pestis.

It is one of three types of plague. The other types are septicemic plague and pneumonic plague. This disease is important to study because it has changed human history. It can be very dangerous if it is not treated quickly.

The disease usually spreads through the bite of an infected flea. The Oriental rat flea is a very common carrier.

When the flea bites, the bacteria enter the skin. The bacteria then travel through vessels to a lymph node. This causes the node to swell and become very painful. These swollen parts are called buboes. They often appear in the neck, armpits, or groin. Sometimes, the skin can also turn dark, which is called acral necrosis.

History shows us how much this germ can impact the world. The Black Death swept through Asia, Europe, and Africa in the 14th century. This event killed an estimated 50 million people. It even killed about 25% to 60% of the people in Europe. Another major event was the Plague of Justinian in the 6th century. The third epidemic began in 1855 in the Yunnan Province.

These events changed how many people worked and how much they were paid.

Even today, doctors still find cases of the plague. Between 2010 and 2015, there were 3,248 documented cases globally. This resulted in 584 deaths during those years. The Democratic Republic of the Congo, Madagascar, and Peru have the most cases. In the United States, cases usually happen in rural areas. These include parts of Arizona, Colorado, and California.

In 2015, 16 people in the western United States developed the plague.

We can fight the plague using modern medicine and safety rules. Doctors use antibiotics like streptomycin or doxycycline to treat it. If a person gets medicine within 24 hours, they have a much better chance. Without treatment, the risk of death is 30% to 90%. With treatment, the risk of death is only around 10%.

We also stay safe by using pest control to manage rat populations.

Bubonic plague is a serious infectious disease caused by the bacterium *Yersinia pestis*.

It is one of three distinct types of plague. The other forms are septicemic plague and pneumonic plague. The specific type depends on how the bacteria enter the body. Bubonic plague is a major subject of study because it has shaped human history through massive pandemics. It remains a significant public health concern in specific parts of the world today.

The mechanism of infection often begins with a tiny parasite called a flea.

The Oriental rat flea, *Xenopsylla cheopis*, is a very effective carrier of the bacteria. Inside the flea, the *Y. pestis* bacteria form aggregates in the gut. This creates a biofilm that blocks the flea's foregut. When the flea tries to feed on a host, it regurgitates the infected blood into the bite wound. This process transmits the bacteria directly into the host's skin.

Once the bacteria enter the body, they travel through lymphatic vessels. They eventually reach a lymph node, which is a part of the immune system. The bacteria colonize and reproduce within the node, causing it to become inflamed and swollen. These swollen, painful lymph nodes are called buboes. They are most commonly found in the groin, armpits, or neck. In some cases, the infection can progress to septicemic plague, where bacteria enter the blood, or pneumonic plague, where they infect the lungs.

The symptoms of bubonic plague can be quite severe. Between one and seven days after exposure, a person may develop fever, headaches, and vomiting. The characteristic buboes can grow very large and painful, sometimes even breaking open. Another symptom is acral necrosis, which is the dark discoloration of skin on the fingers, toes, lips, or nose.

If the disease spreads to the lungs, patients may experience heavy breathing and coughing up blood. Without medical intervention, the mortality rate is between 30% and 90%.

History shows that *Y. pestis* has caused massive shifts in human civilization. The Black Death in the 14th century swept through Asia, Europe, and Africa. It killed an estimated 50 million people and took 25% to 60% of Europe's population. This loss of life caused wages to rise because there were fewer workers available.

Other major events include the Plague of Justinian in the 6th century CE. There was also a third epidemic that began in the Yunnan Province in 1855.

Modern medicine has changed how we manage this disease. Doctors use antibiotics like streptomycin, gentamicin, or doxycycline to treat infections. If treatment begins within 24 hours of the first symptoms, the risk of death drops to about 10%.

Public health officials also use pest control and sanitation to manage rat populations. In the past, cities used methods like quarantine or even machines to deliver sulphur dioxide to kill pests.

Plague is still documented in the modern world. Between 2010 and 2015, there were 3,248 documented cases globally, resulting in 584 deaths. The Democratic Republic of the Congo, Madagascar, and Peru report the highest numbers of cases.

In the United States, cases are rare but do occur in rural areas of states like Arizona and New Mexico. Understanding the relationship between humans, fleas, and rodents helps scientists continue to prevent new outbreaks.