A fungus-like parasite
has been found in several kinds of North American amphibians, including bullfrogs and the red-spotted newt. But scientists couldn't explain how they were getting infected.
Now, some Pennsylvania State University biologists think they have the answer, at least for the newts - and it is not for the squeamish:
Blood-sucking leeches.
The researchers can't prove it directly, but the leeches appear to be carrying the parasite from newt to newt with their bites.
They cited several lines of evidence in a recent issue of the Journal of Parasitology, after studying newt populations in 16 lakes and ponds in central Pennsylvania.
First, the more leeches that the team found in a particular pond, the more likely the newts in that pond were to show signs of infection - swelling and clusters of small black dots on the skin.
Also, signs of infection were concentrated on the body parts most likely to be bitten by leeches, such as the head and throat. And infections were observed growing out of the telltale spots of blood under the skin, left behind by leech bites.
The infection doesn't seem to kill the newts, but it does appear to stop them from breeding, according to Penn State's Thomas Raffel, the study's lead author. Similar infections have been linked to deaths in other amphibians, a class of animals that is in worldwide decline.
Raffel concedes that the subject of his research is likely to disgust some, but notes that the newt-loving leech is not the same kind that feeds on people.
"I don't worry about them at all," Raffel says. "The first couple times I handled the leeches, I was kind of like 'eecchh!' But you kind of get used to it."
- Tom Avril