Todd Fassler was bitten by a rattlesnake in San Diego, Calif., and the hospital billed him $153,000. (KGTV – 10News.com)

Earlier this month a guy named Todd Fassler was bitten by a rattlesnake in San Diego, KGTV San Diego reports. In itself this isn't terribly unusual — the CDC estimates that roughly 7,000 to 8,000 people a year get bitten by a venomous snake in the United States. And somewhere between five and six people die from these bites each year.

What raised eyebrows, though, was Fassler's hospital bill — all $153,000 of it. KGTV reporter Dan Haggerty shared it on Twitter. Take a look.

It’s not clear whether Fassler has insurance — and whether these are dollar amounts that he will in fact have to pay out of pocket. But the confusion over health-care pricing is common for Americans who receive bills and can’t be sure where the numbers come from. I reached out to Fassler for comment, but he wasn't immediately available.

Here's what we do know based on that photo: The bulk of his hospital bill — $83,000 of it — is due to pharmacy charges. Specifically, charges for the antivenin used to treat the bite. KGTV reports that Fassler depleted the antivenin supplies at two local hospitals during his five-day visit. Nobody expects antivenin to be cheap. But $83,000?

There's currently only one commercially available antivenin for treating venomous snakebites in the United States -- CroFab, manufactured by U.K.-based BTG plc. And with a stable market of 7,000 to 8,000 snakebite victims per year and no competitors, business is pretty good. BTG's latest annual report shows CroFab sales topped out at close to 63 million British pounds, or $98 million dollars, last fiscal year. The antivenin costs hospitals roughly $2,300 per vial, according to Bloomberg, with a typical dose requiring four to six vials. In some cases multiple doses are needed, according to CroFab's promotional Web site.

BTG has fought aggressively to keep competitors off the market. A competing product, Anavip, just received FDA approval this year and likely won't be on the market until late 2018. This lack of competition is one reason that snakebite treatments rack up such huge hospital bills -- $55,000. $89,000. $143,000. In May of this year, a snakebit Missouri man died after refusing to seek medical care, saying he couldn't afford the bill.

But the other reason hospitals charge so much is the byzantine negotiating process that happens between hospitals and insurance companies to determine the final payout amount. In the case of the $143,000 snakebite in 2012, for instance, Scripps Hospital in San Diego explained that "it is important to understand that these charges are not reflective of what Scripps will be paid. At this time, the patient’s insurance company has not yet paid the bill, and Scripps is in negotiations with the company for the final amount."

In many cases, a hospital bill isn't actually a bill, but essentially an instrument in a complex negotiation between insurers and caregivers, with bewildered patients stuck in the middle. It's difficult to know which charges are real and which ones aren't, and which bills to pay and which ones to ignore. It's one reason medical debt is a huge factor in so many bankruptcies.

Hospital bills that amount to legal fictions certainly don't help consumers keep themselves out of debt trouble. Todd Fassler's bill is a perfect example -- he left the hospital on July 9, 2015. His bill said his $153,000 payment was due by July 27.