The policy does not define the term "microorganism," so we turn to the dictionary. "Scabies" is defined as "an infestation of the scabies mite (Sarcoptes scabiei)." "Microorganism" is defined as "any organism too small to be viewed by the unaided eye, as bacteria, protozoa, and some fungi and algae." "Organism" is defined as "a form of life considered as an entity; an animal, plant, fungus, protistan, or moneran."

This description of scabies from MedicineNet.com leaves no doubt that scabies are a form of life too small to be viewed by the human eye:

Scabies is an itchy, highly contagious skin disease caused by an infestation by the itch mite Sarcoptes scabiei. Mites are small eight-legged parasites (in contrast to insects, which have six legs). They are tiny, just 1/3 millimeter long, and burrow into the skin to produce intense itching, which tends to be worse at night. The mites that infest humans are female and are 0.3 mm-0.4 mm long; the males are about half this size. Scabies mites can be seen with a magnifying glass or microscope. The scabies mites crawl but are unable to fly or jump. They are immobile at temperatures below 20 C, although they may survive for prolonged periods at these temperatures.

Ambiguities in the policy must be read in favor of the insured, and exclusions must be narrowly read. However, the common meaning of the terms "microorganism" and "organism" leave no room for ambiguity. Scabies mites are alive and microscopic. Thus, scabies can be considered microorganisms. It is our interpretation of the facts that scabies are excluded here by the microorganism exclusion.