HONOLULU — the media frenzy surrounding reports of bedbug infestations in new York may increase acute anxiety and mood disorders. Although the numbers of cases are few — just 10 in the study reported here — Evan Rieder, MD, of Langone Medical Center, and colleagues are urging colleagues to be aware of the risk associated with the current bedbug outbreak. “They’ve occurred in patients with a history of psychiatric illness and without,” Rieder told MedPage Today during an interview at his poster at the American Psychiatric Association meeting here. among the 10 patients diagnoses included anxiety, depression, and relapse of controlled bipolar disorder. Others were diagnosed with monosymptomatic delusional disorder — imagining that one is crawling with pests, even though no infestation exists. Action Points  

• Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.
• Explain that the media frenzy surrounding reports of bedbug infestations in new York may increase acute anxiety and mood disorders.

“If you’re always struggling with seeing the world as an unsafe place, its easy [for something like this] to bolster your delusions,” said Kenneth Silk, MD, of the University of Michigan, chair of APA’s scientific program committee, who was not involved with the study.

Silk relayed the example of working in an emergency department in Michigan the morning after September 11 and seeing a series of bipolar disorder patients — a greater number than usual, he said — with exacerbations of mania: “We felt the event definitely had something to do with the exacerbations of illness.”

As the prevalence of bedbug infestation has risen considerably in new York City and globally in recent years, so has worry about the insects, Rieder said.

Some savvy pest control companies have coined the term “bedbug psychosis” to describe the paranoid feelings that often accompanying a confirmed infestation.

Rieder and colleagues presented detailed review of six of the 10 cases, who ranged in age from 21 to 75. Two of the patients — 21- and 23-year-old women — who relapsed after their bedbug ordeal had controlled bipolar disorder, while a 75-year-old woman had a schizophrenia.

“Any doctor seeing patients [with bedbug infestation and preexisting psychoses] should be on alert,” Rieder told MedPage Today. “These people can decompensate even if they’ve been medically stable for a significant period of time.”

Two others who developed some form of psychiatric illness only had a history of depression or anxiety — including a 39-year-old male patient who developed delusional disorder — and one, a 22-year-old woman, had no prior medical or psychiatric history.

Most of the conditions resulted from increasing anxiety and depression, tied to various factors including greater social isolation and financial distress due to the expense of fumigation, the researchers said.

Rieder and colleagues also conducted a review of the literature and found that bedbug-related psychiatric issues have not been addressed. Thus, more research is needed into the mechanisms underpinning the association, they said.

Rieder speculated that bedbugs create a unique problem compared with other pests such as cockroaches and mice because their effects are felt a bit more personally, as the latter don’t have such a close, physical effect on humans.

Bedbugs are also much harder to detect and exterminate, which could reduce a patient’s ability to feel confident about being secure in their space, Rieder said.

Similarly, he said, the bed is associated with comfort and protection, and not knowing whether the pests are there can undermine that.

“There’s something about the sanctity of the bedroom and the fact that bedbugs are attracted to warmth and blood that violates something that’s really personal,” Rieder said. “Mice and rats aren’t taking a blood meal from human beings.”

Silk agreed, noting that does seem to be a personal intrusion compared with other pests — “especially if it involves a place that you retreat to for comfort.”

It’s also unclear why certain patients develop psychotic symptoms in response to real or threatened infestations, while others do not — an area that also needs further review, the researchers said.

They concluded that physicians who diagnose bedbug infestation or those who treat patients already dealing with an infestation should screen those patients for new psychiatric symptoms.

The researchers reported no conflicts of interest.