Colorado teen death blamed on hidden form of plague

The 16-year-old died June 8, but the cause was only made public late Friday when health officials, at the urging of the boy's parents, put out a warning to make sure others who may have visited his family's rural home near Fort Collins hadn't been sickened by the fleas that could have infected him.

There are three main forms of the plague and all are caused by the same bacteria, Yersinia pestis, which is typically spread by fleas that have fed on infected rodents.

In the most common form, bubonic plague, the infection spreads through the body's tissue into the lymphatic system, producing tell-tale swelling of the lymph nodes.

In septicemic plague, the bacteria directly enters the blood stream and, without the swelling, its symptoms of fever, chills and abdominal pain, can look like the flu.