For many Americans, Norman, Oklahoma, is famous as the home of a college football powerhouse, the Oklahoma Sooners. But to public health officials around the world, Norman may be better known for the work of a family-run company founded in a barn on the fringes of the city.

Immuno Mycologics, aka Immy, started out in the late ’70s with a modest goal: make simpler tools to diagnose fungal infections. It’s now one of the fastest-growing private companies in the nation, built entirely on unique diagnostics. One of its most important developments in recent years is a rapid test, the Cryptococcal Antigen Lateral Flow Assay, or CrAg LFA, which global health experts believe could be key to stopping one of the planet’s biggest killers: cryptococcal meningitis.

Crypto, a fungal infection of the brain and spinal cord, is a threat primarily to people living with HIV/AIDS. A so-called opportunistic infection, it preys on those who lack access to the antiretroviral therapy that can keep HIV in check. Infection occurs when a person inhales the airborne spores of Cryptococcus , a fungus in soil around the world. A healthy person’s immune system can easily fight off the infection, but in someone whose immune system has been weakened, such as by HIV, the fungus often spreads from the lungs to other parts of the body—usually the meninges, the protective envelope surrounding the brain. There, it can impair the brain’s ability to reabsorb cerebrospinal fluid, producing a buildup within the skull. The result: a headache so excruciating “you cannot eat, you cannot talk, you do not know where you are,” says Rose Sabina, a survivor from Uganda. “The head wants to burst. The pain is too much.” The only means of relief is a lumbar puncture, or spinal tap, a procedure often performed without anesthesia in poor countries where staff and supplies are stretched thin. And even where such care is available, most patients die.