恙虫
つつがむし

Translation: illness bug
Habitat: deep in the mountains
Diet: human blood

Appearance: Tsutsugamushi are large, insect-like yōkai which live deep in the mountains along the Sea of Japan. Tsutsugamushi larvae are orange. Adults are red, with massive mandibles, long antennae, and a pincer-like tail. They feed on the blood and the life force of humans living in rural areas.

Behavior: Tsutsugamushi spend most of their lives hidden away from human eyes, but they emerge at night and creep into homes to drain the blood from villagers. They cause all kinds of illnesses in the people they feed upon, from fever, headache, muscle pain, coughing, and gastrointestinal symptoms, to hemorrhaging and blood clotting. They often kill their hosts.

Interactions: Doctors investigating the bodies of people suffering from or killed by these yōkai found that they all had one common symptom: dark lesions all over their bodies. Because no culprit was ever found, they concluded that a species of invisible yōkai was sucking people’s blood while they slept.

The sickness caused by these yōkai was named tsutsugamushi disease. Because it was caused by a supernatural creature, it had to be treated by supernatural forces, such as the magic of an onmyōji.

Origin: The sickness attributed to these yōkai is now known to be scrub typhus. It is caused by parasites transmitted to humans by harvest mites. It occurs all over of East Asia and the Pacific islands. It was a problem for troops on both sides of the Pacific War. If recognized early enough the disease can be treated. Without treatment it is often fatal.

There are about one hundred different species of mites which transmit scrub typhus in Japan. In Japanese it is still called tsutsugamushi disease, and these mites are collectively called tsutsugamushi. The parasite which causes the illness is known as Orientia tsutsugamushi–named after the yōkai.