Diagnosis
The woman’s appearance and mental status are consistent with schizophrenia; however, a diagnosis of scabies is not possible if she is really seeing the “bugs” on her body, as opposed to just imagining them. The scabies mite can only be seen with the aid of a microscope.
We looked for the bugs to confirm her story. While this could have been a case of delusions of parasitosis, on close inspection small “bugs” were indeed visible on her abdomen and along the seams of her pants. Multiple nits appeared attached to the hairs of her head, and a “bug” is noted to be feeding on the nape of her neck. This homeless woman has a massive infestation of body and head lice (Figure 2).
In the past she may have had a scabies infestation, but there was no documentation in the chart of any skin scrapings looked at under the microscope for diagnosis. It is more likely that she has been chronically infested with lice. Due to her mental illness, this patient may have been misdiagnosed with scabies based on the assumption that her claim to see the bugs was a hallucination. A close exam may not have been performed due to her mental illness and poor hygiene, along with the health care providers’ fears of catching scabies. Repeated documentation of scabies may have discouraged further investigation into another cause.
Pediculosis
Lice are bloodsucking obligate parasites. There are hundreds of millions of cases of pediculosis worldwide affecting men, women, and children from all socioeconomic classes.
Three types of lice infest humans: the head louse (Pediculus humanus capitis), the body louse (Pediculus humanus corporis), and the pubic louse (Phthirus pubis). Lice cling to hairs with their clawlike legs and pierce the skin, inject saliva, and then defecate while obtaining their blood meal. When exposed to lice, people clinically experience little irritation from the first bite, but after a short period they become sensitized. A hypersensitivity reaction—producing reddening of the skin, itching, and overall inflammation— subsequently develops.