~1000 BC, 542 AD, 1347 AD, ~1850 AD

Black Death is the name given to the terrible epidemic which swept around the world since pre-Biblical times. The epidemics were caused by particularly virulent forms of infections from the Yersinia pestis bacteria.

The earliest record of the disease appears in the Book of Samuel of the Old Testament and is called the Plague of Ashdod. In this account the malady hit in the city of Ashdod around 1000 BC.

In 542 AD another epidemic hit Constantinople (Istanbul Turkey) and is believed to have wiped out half of the population. Outbreaks continued throughout the Mediterranean region for the remainder of the sixth century and it is now considered a pandemic, or worldwide occurrence.

The next recorded pandemic entered Europe around 1347 AD at the sea ports of the Dorset Coast. By the summer and winter of 1348 it had infected London and most of England's cities and towns. In London about 100,000 people died and many villages and towns lost more than half of their populations. It is estimated that by 1352 deaths were one-third to half of England's total population. The epidemic had started in the Gobi Desert in the 1320's and gradually spread through trade caravans. In one two year period of this outbreak, over 20 million people died.

The latest pandemic was during the 1800's and began in China around the middle of the century. Over the next 75 years about 20 million died.

The disease is most commonly spread by the bite of infected fleas living on rodents such as rats. The infection causes inflammation and possible suppuration of the lymph nodes, especially in the groin. It can spread via the bloodstream to other parts of the body. In the lungs it causes pneumonia and then is spread by coughing and droplets of sputum.

The plague appears in three forms: bubonic, septicemic and pneumonic. The symptoms include swelling of the lymph glands in the neck, armpits and groin. The blackish coloring of these swellings give the disease its name of Black Death.

• The symptoms of bubonic plague include fever, chills, muscle aches, headache, swollen lymph glands and seizures.

• The main characteristic of the septicemic plague is an infection of the blood.

• The main characteristic of the pneumonic plague is an infection of the lungs. Some symptoms include cough, bloody sputum and difficulty breathing.

Today, plague occurs occasionally throughout the world. It is especially common in developing regions of Asia, Africa, and South America. Isolated cases occur each year in the United States from contact with disease-bearing wild rodents. International agreements require health authorities to report cases of plague so preventive measures may be taken.

The Plague is not the worst disease to strike human populations if measured by number of deaths versus a span of time. That distinction belongs to the pandemic of 1918, immediately following WW I, and it started in the United States.