Can your employer fire you for having hepatitas C?

It is probably the case that the employer can do this. As a general matter, in the absence of an employment contract, you may be fired for any reason, at any time (you are what's called an "employee at will"). The only reasons that you could not be fired would be those few reasons which are specifically made illegal--like, for example, racial discrimination.

The only category of protection which *might* protect someone with hep C is that it is illegal to discriminate against the disabled in employment. However, not all medical conditions are considered a disability for this purpose--in fact, most are not. To be a disability, there must be a pervasive impact on the ability to do normal life or work functions. It could be the case that a specific person's hep C condition rises to the level of disability, but most would not.

Moreover, even if, in a given case, having hep C were considered a disability, the law only requires "reasonable accomodations," which are accomodations which are not too expensive or disruptive, or which do not expose customers, coworkers, or the employer to potential liability or injury. There are many occupations--anyone in food service or in many hospitality conditions; nursury school teachers; home heath aids; etc.--where it would be potentially risky to have someone with hep C, so in those cases, even if the person in question were considered to have a legally cognizable disability, the employer could terminate him or her.

So, while for a definitive answer, it would be important to consult in detail with an employment law attorney, since the facts of the specific case are critical, as a general matter, an employer would seem to be able to terminate someone for having hapatitas C.