Since the early hours of Wednesday last week, a strange outbreak has been making its way around one area in the Pacific Northwest US. Five people have experienced an unidentified illness that appears to cause vivid hallucinations and is claimed to be spread through touch.

The first to experience the symptoms was a 78-year-old woman in North Bend, Oregon who called 911 complaining that seven or eight people were “trying to take the roof off her vehicle,” Oregon Live reports.

Within a few days, her 54-year old caregiver, two policemen, and a hospital worker all experienced similarly confused delusions and visual hallucinations, KVAL local news reports. All these people came into contact with each other at some point in the North Bend or Bay Area Hospital in Oregon.

The Coos County Sheriff’s Office posted a statement saying that they have started an ongoing Hazmat investigation of all the reported cases. At the first house, they reportedly found no evidence of contaminants and all their blood tests appeared normal.

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At first, it was suspected that the woman’s Fentanyl (a painkilling opiate) drug patch could be to blame. However, that could not account for the following cases.

The police statement added that the two policemen have been cleared from hospital, while the medical officer (who is still in hospital) was found to have recently been exposed to the flu. The woman and her caregiver remain in care, while the investigation continues.

Popular Science spoke to Professor James Giordano from Georgetown University Medical Center's Department of Neurology and Biochemistry, who explained that a contaminant is most likely the cause. Nevertheless, he said other factors such as a shared psychotic delusion, known as Folie à deux, is not out of the realms of possibility.