Watery diarrhea is a primary symptom of microsporidiosis, along with abdominal pain, weight loss, loss of appetite, dehydration, and passing gas (flatulence).
Microsporidiosis can be difficult to diagnose. Microsporidia are very small organisms and, in most cases, can only be detected using an electron microscope. Even then, some labs may miss the infection. Polymerase chain reaction (PCR), similar to viral load technology for HIV infection, can be used to help diagnose microsporidiosis.