Plague (black death)

-Definition:

It is a zoonotic disease circulating mainly among small animals and their fleas caused by Yersinia pestis bacteria (G-ve cocco-bacillus belongs to enterobacterecea) which rarely infects humans.

-Modes of Transmission:

It is transmitted between animals and humans by:

· Infected flea bite à bubonic plague

· Direct contact à septicaemic plague

· Inhalation à pneumonic plague

· Ingestion of infective materials (rare) à septicaemic plague

-Incubation Period:

1-3 days (pneumonic) or 2-6 days (bubonic)

-Clinical Picture:

1- Always begin by "flu like symptoms":

• General malaise

· High fever (hyperpyrexia) and Chills

· Headache and Body aches

· Nausea and Vomiting

2- Develop one of the "3 forms" according to the route of infection:

Bubonic plague: (the most common) Septicaemic plague Pneumonic plague: (the most virulent and least common)

-Complications: mainly to bubonic and septicaemic forms:

· DIC

· Meningitis and Convulsions

· Endotoxic Shock (a cause of death)

· Septic Shock from sever pneumonic form (a cause of death)

-Treatment:

Rapid treatment is critical for survival as: (within 24 hrs)

*Without Treatment, fatality rates: up to 90% for bubonic plague, 100% for septicaemic or pneumonic plague.

*With Treatment, fatality rate= 5-20%.

Drugs used: Streptomycin is the drug of choice; then Gentamycin, Doxycycline and Ciprofloxacin; but ß-lactams are not useful + Supportive treatment as O₂, IV fluids, Respiratory support …etc.

*For Full Text --> download from: Plague.pdf