The Plague is caused by Yersinia pestis bacteria.
Yersinia Pestis a kind of bacillus. Bacillus (a rod-shaped bacterium) travels from person to person through the air, as well as through the bite of infected fleas and rodents.
Yersinia pestis bacteria is transmitted between rodents.
The French biologist Alexandre Yersin discovered Yesinia Pestis at the end of the 19th century
Yersinia pestis is a gram-negative, non-motile, rod-shaped, bacterium, without spores.
Several species of rodents serve as the main reservoir for Y. pestis in the environment.
The transmission of Y. pestis also occurs by fleas.
The bacterial has the ability to suppress and avoid normal immune system responses.
It affects the host cell’s ability to communicate with the immune system, hindering the body bringing phagocytic cells to the area of infection.
It is a facultative anaerobic organism that can infect humans via the Oriental rat flea (Xenopsylla cheopis).
It causes the disease plague, which takes three main forms: pneumonic (infects people by pneumonia), septicemic (poisons the blood), and bubonic (swollen inflamed lymph nodes in the armpit or groin).
Plague has caused several major epidemics in Europe and Asia over the last 2,000 years.

Words

feudal system (n) – the social and land-owning system of western Europe in the Middle Ages. Feudalism was a social system in which ownership of land was granted by a lord to an individual in exchange for his military service. The unit of land given in the agreement was called a fief.

For example:
The medieval European system of fiefs, homage, and service to the king.

The Byzantine system of pronoia, where land grants were given in exchange for military and administrative duties.

The Russian system of boyars, who held lands from the tsar and owed him loyalty and service.

The Japanese system of shogunate, where daimyo controlled lands and samurai served them as warriors.

Sentence: If I lived in a feudal system, I would be homeless.

rhyming couplet (n) – A rhyming couplet is a pair of successive lines that rhyme. It’s usually the last words at the end of each line that rhyme.

Sentence:

I’m Andy, and I taste like candy.
That’s how I got Sandy and Mandy.

I give them some rhyming couplets.
And out pop some tuplets.

Which one belongs to which?
I don’t care cuz all I need is a big dandy sandwich.

vow (noun) – a solemn promise

Sentence: I vow to conquer the world!

visor (n) – A visor is a movable part of a helmet that can be pulled down to cover the face.

sentence: I got on my bike and lowered my visor.

bishop (n) – a senior member of the Christian clergy, usually in charge of a diocese and empowered to confer holy orders.

Sentence: The bishop life may be too boring for me.

chivalry (n) – courteous behavior. Combination of qualities that encompasses courage, honor, courtesy, justice, and a readiness to help the weak.

We should all strive cultivate Chinese chivalry.

Honor (n) – Something with a lot of respect. A privilege.

Sentence: I wear it with honor.

Honor (v) – To regard with high respect.

Sentence: Honor your parents!

Medieval Ages (n) – Middle Ages, the period in European history from the end of Roman civilization in the 5th century to the period of the Renaissance.

Sentence: I feel sorry for those who lived in the Medieval Ages.

Knights (n) – During the middle age, a man who served his sovereign or lord as a mounted soldier in armor.

Sentence: The death rate of knights is close to ninety percent.

personality (n) – a combination of qualities that forms an individual’s character.

Sentence: I may not be rich, but I have a great personality!