Playboy boss Hugh Hefner's wife Crystal Harris has been diagnosed with Lyme disease, a bacterial infection spread by ticks.

Harris has appealed for fans to get tested for the condition, which can affect the skin, joints, heart, and nervous system - after learning she had contracted it.

"If you have ever gone hiking, please get tested for Lyme disease... I was diagnosed a few days ago and have a long road ahead of me.

"Supposedly you get it from ticks but I have absolutely no recollection of being bit or having a rash or anything," Harris wrote on her instagram account.

She added: "Most importantly there are so many of you carrying Lyme that don't even know you have it. Probably because the ticks can be the size of specs. I always thought of ticks to be big and noticeable.

"The symptoms are vast and when it has been left untreated for a long time can turn into MS, Alzheimer's, Parkinson's, Dementia and ALS. Symptoms can range from sore muscles, sore back, sore neck, anxiety, fatigue, heart palpitations, muscle twitches, bladder pain, vision or hearing problems, swollen lymph nodes, flu like symptoms, brain fog, memory problems. Having just one of these could mean you have Lyme. Please please get tested. (sic)"

She is relieved to have a diagnosis after years of being told it was "all in her head" and feeling like a "hypochondriac".

She added: "It is a disease so many people are living with and is becoming an epidemic. I always thought I was a hypochondriac. Doctors told me it was just "stress" or "all in my head" but I finally figured it out and you can too.

"Lyme is also related to syphilis and can be sexually transmitted and also passed from mother to child during pregnancy. Lyme Disease lyme warrior."