By Rachael Rettner
MyHealthNewsDaily

Here's a reason to get your flu shot that you probably haven't considered: infection with swine flu may trigger baldness.

A new report from Japan suggests a link between alopecia areata, a condition in which patches of hair fall out, and swine flu. The researchers report that seven patients experienced hair loss one to four months after developing the illness.

The exact cause of alopecia areata is unknown, but it is thought to occur when the immune system attacks a person's hair follicles, causing the hair on their head to fall out. Rarely, patients may lose all the hair on their head, or on other parts of their body. While the condition may have a hereditary component, a "trigger" from the environment, such as a traumatic event or illness, may also be needed to set off the disease.

Previous studies have linked viral illnesses, including infections with the Epstein-Barr virus, and onset of alopecia areata. The new findings suggest flu infection may be another trigger of this form of baldness, said study researcher Dr. Taisuke Ito, an assistant professor of dermatology at Hamamatsu University School of Medicine in Japan.

Between 2009 and 2010, the researchers examined seven patients with hair loss following swine flu infection s that caused high fever. Four of the cases were recurrences of the condition, and three were first-time occurrences. On average, hair loss occurred 1.5 months after swine flu infection in those who experienced recurrences, and 2.7 months after swine flu infection in those who experienced first-time hair loss.

All of the patients were under 30 years old, and four were under 10. Three of the cases involved females.

In one case, a 4-year-old girl first experienced alopecia areata in 2006, but recovered completely. Then in 2010, she contracted swine flu and had hair loss two months later.

"I consider it very plausible," that a flu infection could trigger hair loss, said Nanette Silverberg, director of pediatric and adolescent dermatology at St. Luke's-Roosevelt Hospital Center in New York City, who was not involved in the study. "I definitely have seen individuals develop autoimmune conditions," after infection with common viruses, Silverberg said. (An autoimmune condition is one in which the immune system attacks the body's own tissues, rather than foreign germs.)

The fact that more than half of the cases were recurrences of alopecia areata further suggests that certain people are genetically predisposed to develop the condition, Ito said.

Individuals who have had alopecia areata in the past should consider getting their flu vaccination, Silverberg said.

The study was published online Dec. 5 in the Journal of Dermatology.

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