How many other people are there that has been diagnosed with neuromyelitis optica other than me?

Nmo prevalence: Your question is deceptively simple, and not really known. It also depends on whether you include caucasians, asians, africans, etc in the mix or not. Here are two approaches to answer the question....But in short, rare. One study estimated: http://www.Ncbi.Nlm.Nih.Gov/pubmed/19479168 another discussion says: http://www.Myelitis.Org/baltimore2001/wingerchuk_handout.Pdf.

Very few: This is very rare disease. The female to male ratio is greater than 4:1.It does not affect too many peoples. A serum auto-antibody marker, nmo-igg, is highly specific for the disorder.It should be treated with appropriate medication.There is no cure for nmo, but there are therapies to treat an attack while it is happening, to reduce symptoms, and to prevent relapses.