How soon after exposure do symptoms appear?

Symptoms usually begin within 2 to 6 days after exposure to the plague bacteria.

Ref: http://www.dhpe.org/infect/plague.html

What are the signs and symptoms of plague?

When a person is bitten by an infected flea or is infected by handling an infected animal, the plague bacteria move through the bloodstream to the lymph nodes. The lymph nodes swell, causing the painful lumps ("buboes") that are characteristic of bubonic plague. Other symptoms are fever, headache, chills, and extreme tiredness. Some people have gastrointestinal symptoms.

If bubonic plague goes untreated, the bacteria can multiply in the bloodstream and produce plague septicemia (septicemia plague), severe blood infection. Signs and symptoms are fever, chills, tiredness, abdominal pain, shock, and bleeding into the skin another organs. Untreated septicemia plague is usually fatal.

Pneumonic plague, or plague pneumonia, develops when the bacteria infect the lungs. People with plague pneumonia have high fever, chills, difficulty breathing, a cough, and bloody sputum. Plague pneumonia is considered a public health emergency because a cough can quickly spread the disease to others. Untreated pneumonic plague is usually fatal.

How do people get plague?

• By the bites of infected fleas
• By direct contact with the tissues or body fluids of a plague-infected animal
• By inhaling infectious airborne droplets from persons or animals, especially cats, with plague pneumonia
• By laboratory exposure to plague bacteria

Ref: http://www.dhpe.org/infect/plague.html