(on reassignment).
[¶ 1.] Jill Titus appeals from a circuit court decision overruling the Department of Labor’s holding that she was entitled to worker’s compensation benefits. The employer, Sioux Valley Hospital (Sioux Valley), self insures its worker’s compensation risk. We reverse.
FACTS
[¶ 2.] Titus began working at Sioux Valley in 1989 as a surgical technician. On August 20, 1992, while setting up for surgery, she was lifting a 44 pound piece of surgical equipment when she injured her back. Titus finished her shift but then stayed home from work for a few days to rest the injury. She reported the injury to Sioux Valley on the morning following her injury and was referred to Dr. David Hov-ersten, who diagnosed her with acute back strain, a diagnosis he later admitted was incorrect.
[¶ 3.] A CAT scan revealed a mild bulging of the disc at the L4-L5 and L5-S1 level. The disc was not herniated. Dr. Hoversten treated Titus conservatively. She was put on a 30-pound weight lifting restriction and was advised not to bend or twist. She was placed on drugs and began physical therapy. While these initial measures. brought her some pain relief, Titus continued to experience pain.
[¶ 4.] In February 1995, Titus returned to Dr. Hoversten complaining of increased back pain. Dr. Hoversten ordered an MRI which showed a slight central disc bulge with “marked desiccation of the disc.” Dr. Hoversten believed that Titus would require back surgery within six to ten years.
[¶ 5.] In 1995, Titus voluntarily left her job at Sioux Valley and began working as a surgical technician in Idaho. She held the job in Idaho from October 1995 until April 1997. Her duties were essentially the same except her work hours were shorter and the cases were usually less complicated.
[¶ 6.] In January 1997, Titus once again sought medical treatment for continuous back pain. She complained that the pain radiated to her leg and that she was unable to sit or stand without pain. She reported to the doctor that her pain was *390exacerbated by bending, twisting and lifting and that her back pain had worsened within the past two years. She indicated this worsening was particularly noticeable since December, 1996, a time which had been busier than normal for her. This time she saw Dr. Schneider.
[¶ 7.] After obtaining Titus’ medical records, including the 1995 MRI report, Dr. Schneider ordered another MRI in March 1997. This MRI showed a central disc protrusion with moderate central spinal stenosis. The report characterized this finding as a clear progression of the disc disease. The disc was now herniated with the bulge at twice the size it had been in 1995.
[¶ 8.] Since April 1997, Titus has undergone four back surgeries. She has not worked since then. Titus now appeals the circuit court decision denying her worker’s compensation benefits on the basis that she suffered an aggravation of her original back injury precluding recovery. She raises one issue on appeal:
Whether Titus’ current injury is a recurrence of her original work injury or an independent aggravation.
We reverse.
STANDARD OF REVIEW
[¶ 9.] We use a de novo standard of review for department findings which are based on deposition testimony and documentary evidence. Grauel v. South Dakota School of Mines and Technology, 2000 SD 145, ¶ 7, 619 N.W.2d 260, 262 (quoting Wagaman v. Sioux Falls Constr., 1998 SD 27, ¶ 12, 576 N.W.2d 237, 240).
[¶10.] WHETHER TITUS’ CURRENT INJURY IS A RECURRENCE OF HER ORIGINAL WORK INJURY OR AN INDEPENDENT AGGRAVATION.
[¶ 11.] In a worker’s compensation dispute, the claimant must prove all of the facts essential to compensation by a preponderance of the evidence. Davidson v. Horton Industries, Inc., 2002 SD 27, ¶ 28, 641 N.W.2d 138, 144. In order to meet this burden of proof, it is necessary that the claimant provide medical evidence. Enger v. FMC, 1997 SD 70, 565 N.W.2d 79. Titus argues that we have impliedly overruled this precedent and shifted the burden of proof to the employer/insurer in successive injury cases. This argument is based on her reading of Truck Ins. Exchange v. CNA, 2001 SD 46, 624 N.W.2d 705. However, that case involved a dispute between successive insurance carriers and is not applicable here.
[¶ 12.] Given that the parties agree that her 1992 back injury was work related, the question is whether Sioux Valley is on the risk for her successive injury. Thus, we apply the last injurious exposure rule. Novak v. C.J. Grossenburg & Son, 89 S.D. 308, 232 N.W.2d 463 (1975). Under this rule,
[w]hen a disability develops gradually, or when it comes as a result of a succession of accidents, the insurance carrier covering the risk at the time of the most recent injury or exposure bearing a causal relation to the disability is usually liable for the entire compensation.
St. Luke’s Midland Regional Medical Center v. Kennedy, 2002 SD 137, ¶ 19, 653 N.W.2d 880, 885 (citations and quotations omitted).
[¶ 13.] This rule requires us to inquire “whether the successive injury is a mere recurrence or an independent aggravation of the first injury.” St. Luke’s, 2002 SD 137 at ¶ 20, 653 N.W.2d at 886. The original employer or insurer will be liable if the second injury is a recurrence of the first. However, if the second injury is an aggravation that independently contributes *391to the final disability, the subsequent insurer or employer is liable. Id. (citation omitted).
[¶ 14.] To find that the second injury was an aggravation of the first, the evidence must show:
1. A second injury; and
2. That this second injury contributed independently to the final disability.
Paulson v. Black Hills Packing Co., 1996 SD 118, ¶ 12, 554 N.W.2d 194, 196.
[¶ 15.] To find that the second injury was a recurrence of the first injury, the evidence must show:
1. There have been persistent symptoms of the injury; and
2. No specific incident that can independently explain the second onset of symptoms.
Id. In Enger, we stated, “[w]e look to whether a significant occurrence, amounting to an independent contribution to the final disability, causes an onset of increased or new symptoms.” Enger, 1997 SD 70 at ¶ 17, 565 N.W.2d at 84 (citations omitted). Just as in Enger, this Claimant’s disability already existed when she left Sioux Valley Hospital. Her deposition, which the ALJ and her doctors found credible, indicates that she experienced chronic pain from the time of her initial injury until she consulted her first physician in Idaho. Although there is some argument that she had new symptoms, a fair reading of the record is that her pain complaints were consistent and symptoms changed only as the problem naturally progressed. Dr. Hoversten, the only doctor to definitively state that continued employment independently contributed to the injury, had not seen Titus for at least three years and did not know what her job duties in Idaho entañed. Furthermore, Dr. Hoversten anticipated at the time he first saw her that her condition would require surgery within six to ten years.
[¶ 16.] Although none of the doctors could affirmatively state that the Claimant’s continued employment did not contribute to her disabüity that is not the test. The question is not whether later employment contributed to her disabüity, but whether it contributed to the causation of her disability. Enger, 1997 SD 70 at ¶ 17, 565 N.W.2d at 84 (stating, “the contribution of the second injury, however slight, must be to the causation of the disability” (emphasis in the original)). The answer is “no.” Here, there have been persistent symptoms of the injury and there is no specific incident that can independently explain the second onset of symptoms. Therefore, she has sustained her burden of proof under Paulson and Enger.
[¶ 17.] Moreover, at least three of the physicians indicated that her symptoms appeared to be a natural progression of her initial injury. For example, Dr. Schneider, the orthopedic surgeon, stated, “[w]ell it appears to me that she has [had] just a progression of problems since 1992. And I don’t think the work out here contributed any more to it than her going to the grocery store and getting something. This is just an ongoing thing that kind of worsened with time, that’s how it appears to me.” In essence, all of the doctors at some point indicated that her problems in Idaho and eventual need for surgery could have occurred simply because of her normal activities of daüy living. This is sufficient to meet her burden of showing causation by the first injury by a preponderance of evidence under Enger.
[¶ 18.] Accordingly, this was a continuation, a worsening, a recurrence, not an independent aggravation relieving Sioux VaUey Hospital of responsibñity. Reversed.
*392[¶ 19.] GILBERTSON, Chief Justice, and KONENKAMP, Justice, concur. [¶ 20.] AMUNDSON, Retired Justice, and ECKRICH, Circuit Judge, dissent. [¶ 21.] MEIERHENRY, Justice, not having been a member of the Court at the time this action was submitted to the Court, did not participate. [¶ 22.] ECKRICH, Circuit Judge, sitting for ZINTER, Justice, disqualified.