Lewis was one of three 1964 San Francisco 49ers teammates who died of amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease, a rare ailment with an incidence estimated at 1 per 50,000 individuals in the general population.
[1] Others 49ers stricken by the disease included contemporaries Bob Waters and Matt Hazeltine and — a generation later — wide receiver Dwight Clark.
[1] Studies have been done examining the use of DMSO, painkillers, and the fertilizer used on the 49ers practice field in Redwood City, California in an effort to isolate a potential chemical connection.
[1] A possible connection between the disease and mild traumatic brain injury (concussion) is a matter of ongoing study.
This biographical article relating to an American football running back born in the 1940s is a stub.