According to the Southeast Missourian story:
"Terry Brown of Ellsinore, Mo., was camped in the area of the Current River known as the Clubhouse on Saturday, his 50th birthday, when he was bitten on the thumb while trying to remove a young copperhead from a tent around 10 p.m., according to Carter County deputy coroner Eric McSpadden. The Clubhouse area is about two miles south of Big Spring."Within 15 minutes of the bite he was unconscious, recovered consciousness in the ambulance and died 9 hours later in the hospital. This raises several questions. The sudden loss of consciousness suggests some other factor such as preexisting heart disease. Another possible factor is allergic reaction to the venom. According to the CDC "Although rare, some workers with a severe allergy to snake venom may be at risk of death if bitten."
The snake was reported to be a "young copperhead," decreasing the likelihood that he would have received a large amount of venom. Copperhead venom is one the least toxic of the five venomous snakes of Missouri.* In general, bites on distal extremities tend to be the least serious, presumably due to a slower transmission of venom to the body.
None of this is to say that snake bites are not serious events to be respected. Hopefully this news won't lead to a rash of snake killings, many of which would involve nonvenomous species. While their removal from home and garden is justified, they are a legitimate part of nature in the wild.
The MDC's Fresh Afield blog has a good discussion of snake bites in general including their treatment. Jeff Brigger, the herpetologist from MDC commented on the story for CBS in this story.
* The order of toxicity, timber rattler, cottonmouth, pygmy rattler, massasauga and copperhead. MDC