The human body is a complex and wonderful thing. As we observe with cars and refrigerators, however, the more complicated something is, the more that can go wrong. You have likely not heard of any of these very rare diseases, nor will you likely ever see them. We are going to explore them just for fun, and let’s keep it that way:

Congenital Insensitivity to Pain with Anhidrosis (CIPA). This is an extremely rare inherited nervous system disorder, which prevents the feeling of pain, heat, cold, or even the need to urinate. It’s present from birth, and victims might bite off the tip of their tongue, break bones, or damage their cornea if they neglect to brush a foreign object from their eye.

While it might seem like a wonderful thing to not feel discomfort, pain is a life-saving physical response to danger.

Fish Odor Syndrome. This is a rare genetic metabolic disorder. As the name implies, there is an offensive fishy body odor, usually present from birth. It is due to an excessive excretion of the chemical trimethylaminuria (TMA) in the urine, sweat, and breath.

More common in women than men, the odor appears to be the only symptom. Treatment includes certain dietary restrictions, using acidic lotions and soaps to remove the chemical from the skin, and antibiotics.

Alien Hand Syndrome. Some refer to this as the Dr. Strangelove syndrome. A hand seems to go rogue and the sufferer feels that it has a will of its own. Also known as anarchic hand, it was documented in 1908 by a German neuropsychiatrist.

This condition occurs in those who have had the two hemispheres of their brains surgically separated, or have suffered a stroke, or possibly have had Creutzfeldt-Jacob disease (the human form of mad cow disease).

Cotard Delusion. This condition is also known as Walking Corpse Syndrome, and was first described in 1880. The person wakes up one day and thinks that they have died, that they no longer exist, or that their flesh is rotting off.

Yes, of course, it’s all in their head, but an actual physical cause has been found: the brain regions responsible for facial recognition and emotion have become disconnected. Their appearance has lost its association with their sense of self, resulting in extreme cognitive dissonance. The only known effective treatment is electroconvulsive therapy (electroshock).

Morgellon’s Disease. I have seen this condition more than once: sufferers feel as though they have parasites or foreign material moving in, or coming out of, the skin. They feel things crawling, biting, and stinging from beneath the surface of the skin. This causes a constant urge to scratch, resulting in insomnia as well as terrible skin lesions.

They have no actual physical disease, or organisms under their skin, and whether there is a neurological cause is not yet known. Most health care professionals believe that Morgellon’s disease is a form of psychosis and that the symptoms are imagined. While there is no specific cure for Morgellon’s disease, individuals who suffer from this condition have been found to benefit from medications that treat psychosis or tic disorders.

This isn’t technically a disease, but it is rare and perhaps the single most disgusting thing I have seen in my own practice: Maggot Infestation. A fly lays eggs, which turn into larvae, or maggots.

Flies will lay their eggs anywhere that appears to be safe and will provide a food supply. This is why humans or rotting food may be a host. Removing the food source, or treatment with boiling water, bleach, or hydrogen peroxide, will eliminate the problem. My patient was an older man with dementia who loved to sit in his garden for hours. His wife brought him in with toe pain – and I will admit that I elected to skip lunch that day.

Let’s hope that this is the last you’ll ever hear of these diseases!