Although it has been commonly thought that athlete's foot and toenail fungus spread from person to person, researchers say it's the first time they've been able to provide evidence for it.
Using high-tech molecular biology techniques, researchers were able to trace the spread of the same tiny organisms, called dermatophytes, responsible for the common foot infections within families.
"Doctors have never been able to caution patients with certainty that toenail fungus or athlete's foot can spread from one family member to another," says researcher Mahmoud Ghannoum, PhD, of University Hospitals Case Medical Center, in a news release.
"What we can see from the current findings is the value of treating toenail fungus and athlete's foot to try to prevent its spread from person to person."
Foot Infections Spread Within Families
Researchers say more than 35 million people are affected by toenail fungus, which causes the affected toenails to become discolored, brittle, thickened, and flaky.
The infection is known as tinea pedis, and is caused by a group of tiny organisms called dermatophytes -- the same fungus responsible for athlete's foot. That common foot infection causes a rash on the skin of the foot and affects 10% of the population.
Researchers studied 57 families in which at least one member had toenail fungus and/or athlete's foot. Of these families, 19 had at least two members who were infected.
Using a combination of microbiology and DNA matching techniques, researchers were able to confirm that identical infection-causing dermatophytes were present in 42% of affected family members.
Researchers say matching the DNA of the same dermatophytes among members of the same household clearly indicates each family member had the identical strain of dermatophyte, which confirms that the infection was transmitted from one family member to the other, either directly or indirectly.
Questionnaires completed by the participants showed the likelihood of the spread of the foot infection within a household was tied to the strain of fungus and whether anyone in the family had nail discoloration or scaling of the skin on the side of the foot and/or a past history of toenail fungus and athlete's foot.
"This study raises questions we will look at in the future," says Ghannoum. "For instance, why did the infection spread among some families but not others, and why did some members of a household become infected while others did not? When we can answer these questions, we will be closer to knowing how to eradicate these very common and highly persistent infections."
The results of the study were presented today at the 46th ICAAC annual meeting of the American Society for Microbiology in San Francisco. Novartis Pharmaceuticals funded the study. Novartis is a WebMD sponsor.
SOURCES: Ghannoum, M. "Evidence Showing That Dermatophytes Spread Among Family Members," presented at 46th ICAAC annual meeting of the American Society for Microbiology, San Francisco, Sept. 29, 2006.
By Jennifer Warner
Reviewed by Louise Chang