Lyme disease or a complication of delusional parasitosis?

To the Editor

Recent debate regarding the existence of Lyme disease in Australia has been broadcast on local media (Lord, 2013; Martin, 2013). Advocates for the existence of Lyme disease in Australia report that patients with suspected Lyme disease present to multiple doctors and that they receive no clear diagnosis for their non-specific symptoms until they are diagnosed with Lyme disease and successfully treated with antibiotics. Lyme disease is a tick-borne bacterial infection which has been more commonly reported in certain states of America (Schmid, 1985). However, cases have also been reported in Australia (Maud and Berk, 2012).

A 32-year-old female living in suburban Sydney presented with images that she had downloaded from the Internet in an attempt to convince me that she had Lyme disease and not a mental illness. She had seen an infectious diseases physician who had told her that Lyme disease did not exist in Australia. However, she firmly believed that she had been bitten by a tick and that insects had continued to bite her over a 6-month period. As a result of her distress, she had shaved off her hair and fumigated her house several times. It was suspected that the rash she presented with was a result of scratching and disinfecting her skin. On her second appointment, she presented a matchbox containing small, dead insects which she believed were ticks that she had collected from her home. Although she also had non-specific physical symptoms that may have been consistent with Lyme disease, her continued strong belief that she was being bitten by ticks and the presence of a ‘matchbox’ sign (Lee, 1983) supported a diagnosis of delusional parasitosis. She was successfully treated over several months with 150 mg of venlafaxine and cognitive-behavioural therapy.

Despite the current controversy regarding the presence of Lyme disease in Australia, delusional parasitosis and somatoform disorders should continue to be considered when assessing patients who present with concerns that they have Lyme disease.