In Bass v. City of Richmond Police Dept., 258 Va. 103, 115, 515 S.E.2d 557, 563 (1999), the Supreme Court of Virginia re-affirmed the principle that an employer may rebut the presumption of Code 65.2-402(B) by proving by a preponderance of the evidence that: the claimant's disease was not caused by his or her employment; there was a non-work-related cause of the disease. When the commission determines that an employer has failed to overcome the statutory presumption, the claimant is entitled to an award of benefits. Id. at 552, 518 S.E.2d at 345