What is hystomiosis?

It seems there might be a typo in your question, as "hystomiOSis" does not correspond to any recognized medical term. If you meant "histoplasmosis," it is a fungal infection caused by the Histoplasma capsulatum fungus, often found in soil contaminated with bird or bat droppings. It primarily affects the lungs but can disseminate to other parts of the body, especially in immunocompromised individuals. Symptoms can range from mild respiratory issues to severe illness, depending on the person's health and the extent of the infection.