Because the virus had infected his brain, Ryker's only chance at life was to undergo an experimental treatment called the Milwaukee Protocol.
The treatment involves putting the patient into a coma while administering anti-viral drugs.
The majority of rabies cases reported to the CDC are contracted from wild animals such as raccoons, skunks, bats and foxes.
Early symptoms include fever, headache and weakness.
As the disease progresses to the brain, patients experience hallucinations, increased saliva, confusion, paralysis and usually die within days.
Rabies kills about 60,000 people every year worldwide, mostly children in Africa and Asia, according to the CDC.