The number of fungal meningitis cases thought to be caused by a tainted steroid drug keeps rising, and experts say it could be months before the full extent of the outbreak is known. So far, 268 cases of meningitis and three patients with fungal joint infections have been reported in 16 states. Twenty-one people have died. The drug linked to the cases was recalled at the end of September, and no doses have been given out since then. But cases will likely keep coming, researchers say, because the fungus in question has a long incubation period, meaning it can be months between steroid injection and symptom onset.