Roy Pascoe, age 15, of Panama City, Fla., for his question:

WHAT IS ELEPHANTIASIS?

Elephantiasis is a skin disease that is most common in tropical countries. A tiny worm usually causes the disease and mosquitos usually carry the worm.

The disease receives its name because the affected skin becomes rough like the hide of an elephant.

When a mosquito carrying the disease bites a person, it is possible for the worm to enter the body and it then becomes lodged in the lymph vessels. A less common form of elephantiasis is caused by the streptococcus bacterium.

Elephantiasis is characterized by fever, roughening of the skin and swelling of a part of the body, most often a leg. Often the swollen body part becomes permanently enlarged.