plague

What are the three forms of plague?

Bubonic plague

septicemic plague

pneumonic plague

What is the most common form of plague?

Bubonic plague.

How is bubonic plague usually acquired?

Through the bite of an infected flea.

What are the signs and symptoms of bubonic plague?

High fever and enlarged, painful lymph nodes called buboes.

What are buboes?

Swollen, tender lymph nodes characteristic of bubonic plague.

What are the signs and symptoms of septicemic plague?

High fever, shock, DIC, bleeding into the skin, and gangrene of fingers and toes.

What are the signs and symptoms of pneumonic plague?

Fever, headache, cough, pneumonia, chest pain, shortness of breath, and bloody sputum.

Which form of plague can spread person to person?

Pneumonic plague.

What organism causes plague?

Yersinia pestis.

What type of bacterium is Yersinia pestis?

A Gram-negative, facultatively anaerobic, nonmotile rod.

What microscopic appearance is characteristic of Yersinia pestis?

A safety-pin appearance.

What virulence factor of Yersinia pestis contributes to septicemic plague?

Endotoxin.

How does Yersinia pestis enter the body?

Usually through a flea bite.

What happens in the flea before transmission?

Yersinia pestis forms a biofilm that blocks the flea's digestive tract.

How does a blocked flea transmit plague?

The flea regurgitates bacteria into the bite wound while feeding.

What enzyme helps Yersinia pestis spread through tissues?

Pla protease.

What does Pla protease do?

It inactivates complement proteins and promotes bacterial spread through lymphatics and capillaries.

What happens when Yersinia pestis reaches the lymph nodes?

It survives inside macrophages and multiplies.

What causes the buboes seen in bubonic plague?

An acute inflammatory response in infected lymph nodes.

How does Yersinia pestis avoid phagocytosis?

It produces a capsule.

What are YOPs?

Yersinia outer proteins that help the bacterium evade host defenses.

What causes septicemic plague?

Large numbers of bacteria entering the bloodstream and releasing endotoxin.

How does pneumonic plague develop?

The bacteria spread from the bloodstream to the lungs or are inhaled directly.

Plague Pathogenesis Summary

Flea bite → bacteria enter skin → survive in macrophages → multiply in lymph nodes → buboes form → bacteria enter bloodstream → endotoxin causes septicemic plague → lungs may become infected causing pneumonic plague.

What type of disease is plague?

A zoonotic disease.

What is the primary reservoir for plague?

Wild rodents and their fleas.

Why is plague considered a bioterrorism concern?

It is classified as a Category A bioterrorism agent.

How is plague treated?

With antimicrobial medications, especially when given early.

What supportive treatments may be needed for plague?

Rehydration and ventilation.

How can plague be prevented?

Rodent control, flea control, insect repellent, and avoiding contact with infected animals. DEET

What antibiotic can be used after exposure to plague?

Doxycycline

Is there currently a widely used plague vaccine?

No