Nail Fungus on the Rise in the U.S.
Nov. 17, 2000 -- Think nail fungus is something you'd never have to worry about? New research suggests you should think again. A fungal infection of the fingernails or toenails -- called onychomycosis -- is more prevalent than previously thought and may be on the rise, according to a study in the October issue of the Journal of the American Academy of Dermatology.
A little more than 1,800 people participated in the study that was conducted at 12 locations in Canada and the U.S.
About 14% of the people were found to have nail fungus -- marked by thick, discoloured nails and confirmed through a nail-clipping test.
Previous studies from other countries report rates of nail fungus ranging from about 3% to about 7%. Even though it's hard to tell what the incidence was previously, the high frequency of nail fungus in this study may indicate an increasing incidence in the U.S., according to the researchers.
The study found several factors to be associated with increased risk of nail fungus: older age, male sex, and diseases affecting the circulatory system, including diabetes and high blood pressure.
On the other hand, race, a family history of nail problems or athlete's foot, and participation in various sports or gardening were not associated with an increased risk.
"It's a very common disease, and [14%] may still be an underestimate," says co-author Richard Summerbell, PhD, a senior researcher with a group in the Netherlands that focuses on fungus. At the time of the study, he was with the Ontario Ministry of Health Mycology Laboratory in Canada.
He says it's difficult to look at nail infection in isolation since it's usually linked to foot or skin infection by the same fungus. Plus, there's a genetic component involved. A Florida skin specialist found that about 75% of kids whose parents were susceptible to a certain fungus also were likely to develop the same susceptibility.
These children often become infected in the family home before the age of 7, Summerbell says, and the risk of developing nail fungus increases with each year. "By age 60 or so, the infection tends to work its way up under the ball of the toe and start infecting the nail bed."
Increased immigration also could be a factor contributing to the increase, says Charles Lynde, MD, a senior dermatologist at the Lynde Centre for Dermatology and associate professor with the department of dermatology at the Toronto Hospital in Canada. Nail fungus is more prevalent in certain parts of the world, like China, he says.
"Certainly, the rates have increased over the last 30 to 40 years," Lynde, who was not involved with the study, tells WebMD. "But whether it's increased rapidly over the past four to five years, I'm not so sure."