The findings could also lead to a better understanding of diseases affecting humans, such as malaria, chagas disease and sleeping sickness. All these diseases are transmitted through a vector, an organism that spreads disease from one animal to another.
The researchers found evidence for leech-borne transmission of a little-known fungus-like organism of the genus Ichthyophonus, which infects the muscles of red-spotted newts and other amphibians in North America. It does not appear to kill amphibians but might affect their ability to reproduce. "This is the first evidence that newts are getting infected through the bites of leeches," said Thomas R. Raffel, a postdoctoral researcher at Penn State's Center for Infectious Disease Dynamics, and the study's lead author.
Early infections in the newts appear as clusters of small dark dots under the skin, which can later develop into a large area of swollen muscle. The swollen muscle contains many spores (also called spherules), each of which contains hundreds of infectious cells called endospores. Raffel and his colleagues think that the infection is transmitted when one of these spores bursts open and releases its endospores onto the mouthparts of a feeding leech. Their findings are outlined in the January issue of Journal of Parasitology.
In 2004, Raffel and his Penn State colleagues Peter J. Hudson, professor of biology, and James R. Dillard, then an undergraduate student and now with the Pennsylvania Department of Environmental Protection, conducted a survey of 16 red-spotted newt populations in lakes and ponds near Centre County, Pa. They found the disease in 12 of the 16 newt populations.
A strong correlation between infection prevalence and numbers of bloodsucking leeches, plus the