Koro: The genital-shrinking disease with a Malaysian origin

Have you ever looked at your genitals in shock, believing it had shrunk? Have you ever become so anxious about the condition, worrying that it’ll keep on shrinking until it completely disappears from view?

Have you not been convinced it wont, even after rushing to your doctor and being told there’s no evidence of shrinkage nor any underlying conditions that could lead to it.

A delusional disorder

This is a mental condition known as Koro. What’s fascinating about the name is that it is derived from the Malay word, “kura-kura” (tortoise), specifically referring to the head of the reptile that ducks into its shell and totally disappears from view.

When someone suffers from Koro, their genitals don’t actually shrink. Instead, they become delusional, believing that it does.

This causes anxiety and acute panic, despite no evidence of shrinking based on long-term medical follow-ups and regular measurements.

This condition isn’t unique to males as females too suffer from Koro, imagining their vulva or nipples are shrinking.

Those suffering from Koro believe their genitals will completely shrink into their abdomen in time, causing their untimely death in the end.

Koro from a cultural perspective

Koro is a culture-specific disorder that has existed for centuries in Asia particularly South East Asia.

The condition gained notoriety and the attention of western medicine in the fall of the 19th century and early 20th century when an outbreak of such cases was identified in Sulawesi, Indonesia.

According to Chinese history and civilisation, this mental disorder is known as Sou Yang. It’s origins can be traced to an ancient Chinese medical textbook, Huangdi Neiching (Yellow Emperor’s Classic of Internal medicine) believed to be written around 200–300 B C, which states: “As yang (the male genitals) retracts into the abdomen, death is inevitable.”

Koro outbreaks have occurred at a scale of an epidemic in Singapore, Thailand, Indonesia and southern China.

However, outbreaks have also been known to occur in non-Asian countries like Sudan, US, Canada, France and Britain.

The Mirror Neuron theory

One of the theories on how Koro became so widespread is the Mirror Neuron theory, the same used to explain the phenomena of mass hysteria across human history.

Mirror Neuron refers to the circuit of neurons localised to certain parts of the brains of humans and primates.

These neurons are activated when one acts and when one observes the same action performed by another, creating resonance in the activity and condition.

The resonance increases the amplitude of an act which eventually leads to mass hysteria.

The Mirror Neuron theory is thought to be an important mechanism on how humans are able to imitate and learn things from others with great accuracy. It also plays an important role in one’s assimilation into a new social circle.

This article first appeared in hellodoktor.com and was reviewed by Panel Perubatan Hello Doktor. The Hello Health Group does not provide medical advice, diagnosis or treatment.