Citation Nr: 1611220 Decision Date: 03/21/16 Archive Date: 03/29/16 DOCKET NO. 12-08 372 ) DATE ) ) On appeal from the Department of Veterans Affairs Regional Office in San Diego, California THE ISSUE Entitlement to service connection for hepatitis C. REPRESENTATION Veteran represented by: The American Legion WITNESSES AT HEARING ON APPEAL Veteran and spouse ATTORNEY FOR THE BOARD Debbie A. Breitbeil, Counsel INTRODUCTION The appellant is a Veteran who served from March 1969 to April 1970, to include a tour of duty in Vietnam, and was awarded a combat action ribbon. This matter is before the Board of Veterans' Appeals (Board) on appeal of a March 2010 rating decision of by the San Diego, California Department of Veterans Affairs (VA) Regional Office (RO). In July 2015, a videoconference hearing was held before the undersigned; a transcript of the hearing is associated with the claims file. In November 2015, the Board requested a medical expert opinion through the Veterans Health Administration (VHA) pursuant to 38 C.F.R. § 20.901(a), which was received in December 2015. He was provided a copy of the opinion and opportunity to respond, submit additional evidence or argument. In February 2016, the Veteran and his representative submitted written argument and evidence. FINDING OF FACT Hepatitis C was not manifested during active duty; the Veteran's hepatitis C was first diagnosed many years after, and is not shown to be related to, his service. CONCLUSION OF LAW Service connection for hepatitis C is not warranted. 38 U.S.C.A. §§ 1110, 5107(b) (West 2014); 38 C.F.R. § 3.303 (2015). REASONS AND BASES FOR FINDING AND CONCLUSION The Veterans Claims Assistance Act of 2000 (VCAA) The VCAA, codified in part at 38 U.S.C.A. §§ 5103, 5103A, and implemented in part at 38 C.F.R § 3.159, amended VA's duties to notify and to assist a claimant in developing information and evidence necessary to substantiate the claim. Under 38 U.S.C.A. § 5103(a), VA must notify the claimant of the information and evidence not of record that is necessary to substantiate a claim, which information and evidence VA will obtain, and which information and evidence the claimant is expected to provide. VCAA notice requirements apply to all five elements of a service connection claim: 1) veteran status; 2) existence of a disability; (3) a connection between the veteran's service and the disability; 4) degree of disability; and 5) effective date of the disability. Dingess v. Nicholson, 19 Vet. App. 473 (2006). VCAA notice, as required by 38 U.S.C.A. § 5103(a), must be provided to a claimant before the initial unfavorable adjudication by the RO. Pelegrini v. Principi, 18 Vet. App. 112 (2004). The RO provided pre-adjudication VCAA notice by letter dated in October 2009. The Veteran was notified of the evidence needed to substantiate the claim; that VA would obtain service records, VA records and records of other Federal agencies; and that he could submit records not in the custody of a Federal agency, such as private medical records or with his authorization VA would obtain any non-Federal records on his behalf, and how effective dates of awards and disability ratings are assigned. The letter also included a questionnaire on risk factors for hepatitis, which the Veteran returned in November 2009. VA has also made reasonable efforts to identify and obtain relevant records in support of the claim. 38 U.S.C.A. § 5103A (a), (b), and (c). The RO has obtained the Veteran's service treatment records and VA medical records. He has submitted a private physician's statement from Dr. Chabala; there is no indication that any additional available evidence remains outstanding. Moreover, a Board hearing was held before the undersigned in July 2015. In Bryant v. Shinseki, 23 Vet. App. 488 (2010), the Court held that 38 C.F.R. § 3.103(c)(2) requires that the Veterans Law Judge who conducts a hearing fulfill two duties to comply with the regulation: (1) to fully explain the issues and (2) to suggest the submission of evidence that may have been overlooked. During the July 2015 Board hearing the undersigned indicated that the hearing would focus on the issue of service connection for hepatitis C, and discussed the elements of the claim that were lacking to substantiate the claim, particularly evidence that the Veteran's hepatitis C infection occurred during his period of service. The Veteran was assisted at the hearing by an accredited representative from The American Legion. The representative and the undersigned asked the Veteran questions focused on the elements necessary to substantiate the claim, i.e., pertaining to the etiology of his hepatitis C. The Veteran and his representative did not identify any pertinent evidence that may have been overlooked and that might substantiate the claim. Through his testimony the Veteran demonstrated that he has actual knowledge of the elements necessary to substantiate his claim. A deficiency in the conduct of the hearing is not alleged. The Board finds that, consistent with Bryant, the duties mandated by 38 C.F.R. § 3.103(c)(2) were satisfied. In January 2012, the Veteran was afforded a VA examination to assist him to determine the etiology of his hepatitis C (an addendum examination report was received in May 2012). As the examination reports were deemed inadequate to decide the claim, the Board arranged for a VHA medical expert advisory opinion, which was received in December 2015. The Veteran was provided a copy of the opinion, and afforded opportunity to respond. His representative submitted written argument and additional evidence consisting of copies of medical abstracts pertaining to hepatitis C. As there is no indication of the existence of additional pertinent evidence that remains outstanding, the Board concludes that no further assistance to the Veteran in developing the facts pertinent to the claim is required to comply with the duty to assist. Legal Criteria Service connection may be granted for disability resulting from injury or disease incurred in or aggravated by active military service. 38 U.S.C.A. § 1110; 38 C.F.R. § 3.303. Service connection means that the facts, shown by evidence, establish that a particular injury or disease resulting in disability was incurred coincident with service, or if preexisting such service, was aggravated by service. This may be accomplished by affirmatively showing inception or aggravation during service. 38 C.F.R. § 3.303(a). If a chronic disease is shown in service, subsequent manifestations of the same chronic disease at any later date, however remote, may be service connected, unless clearly attributable to intercurrent causes. 38 C.F.R. § 3.303(b). For the showing of chronic disease in service there is required a combination of manifestations sufficient to identify the disease entity and sufficient observation to establish chronicity at the time, as distinguished from merely isolated findings or a diagnosis including the word "chronic." 38 C.F.R. § 3.303(b). Where a condition noted during service is not shown to be chronic or where the diagnosis of chronicity may be legitimately questioned, a showing of continuity of symptomatology after service is required for service connection if the disability is one that is listed in 38 C.F.R. § 3.309(a). The theory of continuity of symptomatology under 38 C.F.R. § 3.303(b) does not apply to any condition that has not been recognized as chronic under 38 C.F.R. § 3.309(a). Walker v. Shinseki, 708 F.3d 1331 (Fed. Cir. 2013). Service connection may be granted for a disease diagnosed after discharge, when all the evidence, including that pertinent to service, establishes that the disease was incurred in service. 38 C.F.R. § 3.303(d). In the case of any veteran who engaged in combat with the enemy in active service with a military, naval, or air organization of the United States during a period of war, campaign, or expedition, the Secretary shall accept as sufficient proof of service connection of any disease or injury alleged to have been incurred in or aggravated by such service satisfactory lay or other evidence of service incurrence or aggravation of such injury or disease, if consistent with the circumstances, conditions, or hardships of such service, notwithstanding the fact that there is no official record of such incurrence or aggravation in such service, and, to that end, shall resolve every reasonable doubt in favor of the veteran. Service connection of such injury or disease may be rebutted by clear and convincing evidence to the contrary. 38 U.S.C.A. § 1154(b); 38 C.F.R. § 3.304(d). Competency is a legal concept in determining whether medical or lay evidence may be considered, in other words, whether the evidence is admissible as distinguished from weight and credibility, a factual determination going to the probative value of the evidence, that is, does the evidence tend to prove a fact, once the evidence has been admitted. Rucker v. Brown, 10 Vet. App. 67, 74 (1997). Competent lay evidence means any evidence not requiring that the proponent have specialized education, training, or experience. Lay evidence is competent if it is provided by a person who has knowledge of facts or circumstances and conveys matters that can be observed and described by a lay person. 38 C.F.R. § 3.159. Competent medical evidence means evidence by a person who is qualified through education, training, or experience to offer a medical diagnosis, statement, or opinion. 38 C.F.R. § 3.159. Lay evidence can be competent and sufficient to establish a diagnosis of a condition when (1) a lay person is competent to identify the medical condition, (2) the lay person is reporting a contemporaneous medical diagnosis, or (3) lay testimony describing symptoms at the time supports a later diagnosis by a medical professional. See Jandreau v. Nicholson, 492 F. 3d 1372 (Fed. Cir. 2007). In such cases, the Board is within its province to weigh that testimony and to make a credibility determination as to whether the evidence supports a finding of service incurrence and continuity of symptomatology sufficient to establish service connection. See Barr v. Nicholson, 21. Vet. App. 303 (2007). The Board, as fact finder, must determine the probative value or weight of the admissible evidence. Washington v. Nicholson, 19 Vet. App. 362, 369 (2005) (citing Elkins v. Gober, 229 F.3d 1369, 1377 (Fed.Cir.2000) ("Fact-finding in veterans cases is to be done by the Board")). When there is an approximate balance of positive and negative evidence regarding any issue material to the determination of a matter, the Secretary shall give the benefit of the doubt to the veteran. 38 U.S.C.A. § 5107(b); 38 C.F.R. § 3.102. Factual Background and Analysis The Board notes that it has reviewed all of the evidence in the Veteran's claims file, with an emphasis on the evidence relevant to these appeals. Although the Board has an obligation to provide reasons and bases supporting its decision, there is no need to discuss, in detail, every piece of evidence. Gonzales v. West, 218 F.3d 1378, 1380-81 (Fed. Cir. 2000) (VA must review the entire record, but does not have to discuss each piece of evidence.). Hence, the Board will summarize the relevant evidence, as appropriate, and the Board's analysis will focus specifically on what the evidence shows, or does not show, as to the claim. The Veteran claims that he was infected with the hepatitis C virus (HCV) during his period of service. In a November 2009 statement, he asserted that he no hepatitis C risk factors except for mass inoculations during service and his Vietnam service. In a March 2013 response to a February 2013 supplemental statement of the case (SSOC), he alleged that hepatitis C may be the result of receiving immunizations in service by means of a multi-use jet gun injection. He also stated that information from the CDC (Centers for Disease Control and Prevention) shows that the hepatitis C virus can remain dormant for up to 30 years prior to manifesting any symptoms of the disease, so that the fact there was no mention of symptoms related to hepatitis during his service is not problematic for his claim. He also cited to a medical report presented to Congress in 2000, in which it was found that HCV infection rates were higher in Vietnam veterans than in the general population. He objected to a VA examiner's finding, cited by the RO in the SSOC, that he had engaged in high risk sexual activity. At a July 2015 Board hearing, he testified that he believed his hepatitis C infection may have occurred as a result of his duties in Vietnam, repairing river boats in the Mekong Delta (by which he was possibly exposed to contaminated water and other products through cuts and scrapes). He also asserted that inoculations by jet guns in service may have led to his infection. It was discussed that there was no specific testing for hepatitis C back when he initially had hepatitis diagnosed by VA in 1976. Regarding risk factors, it was noted that he had used marijuana but not intravenous drugs. The Veteran's service department records show that he served on active duty from March 1969 to April 1970 to include combat duty in Vietnam, reflected by his award of a combat action ribbon. His military occupational specialty was machinery repairman. His service treatment records, including an April 1970 separation physical examination, are silent for any complaints, findings, or diagnosis of hepatitis or any symptom manifestations thereof during service. On the basis of the service treatment records alone, hepatitis C was not affirmatively shown to have had onset during service to establish service connection under 38 U.S.C.A. § 1110 and 38 C.F.R. § 3.303(a) (showing inception in service). Alternatively, a showing of continuity of symptomatology after service can also support the claim. 38 C.F.R. § 3.303(b). However, it does not appear that service connection can be established for a chronic disease under 38 C.F.R. § 3.303(b) and 38 C.F.R. § 3.309(a). The Federal Circuit Court held that the theory of continuity of symptomatology under 38 C.F.R. § 3.303(b) does not apply to any condition that has not been recognized as "chronic" under 38 C.F.R. § 3.309(a). Walker v. Shinseki, 708 F.3d 1331 (Fed. Cir. 2013). Hepatitis C is not listed among the "chronic" diseases under 38 C.F.R. § 3.309(a). Thus, further discussion concerning continuity of symptomatology or chronicity is not necessary. In any event, the Veteran has not alleged any continuous (since service) symptoms of hepatitis C. For the foregoing reasons, continuity of symptomatology has not been established, and the preponderance of the evidence is against the claim of service connection for hepatitis C based on continuity of symptomatology under 38 C.F.R. § 3.303(b). The Board next turns to the question of whether service connection for hepatitis C may be granted on the basis that the disability is related to service, even if first diagnosed after service, when considering all the evidence, including that pertinent to service under 38 C.F.R. § 3.303(d). VA medical records show that after service the Veteran was hospitalized for hepatitis in February 1976. The various diagnoses at that time included infectious hepatitis, type A, and rule out chronic persistent hepatitis; and viral hepatitis, type B. The Veteran's habits at that time included alcohol and tobacco. In March 1976, the assessment was resolved hepatitis. Evidently, the Veteran experienced a recurrence of symptoms and was hospitalized again in September 1976, which resolved by October 1976. He was seen for another workup in December 1976, when laboratory studies showed his hepatitis was resolving. At that time, the Veteran denied alcohol and drug use prior to his illness. In February 1977, his assessment was stable status post hepatitis. Private records from Dr. Chabala, dated from 2002 to 2004, show that the Veteran was assessed with mild liver disease, questionably hepatitis B and C (he noted that the etiology of the Veteran's testing for hepatitis went back before the time hepatitis C was even recognized or before there was an ability to check for the disease). When the Veteran was seen for an annual physical examination in February 2002, he related he was at risk for hepatitis B and C due to his military occupational specialty while in Vietnam. In March 2002, it was noted he had a history of a liver biopsy in 1976, when hepatitis of questionable type was diagnosed. VA records beginning in 2008 show that the Veteran had definitively diagnosed hepatitis C. A liver biopsy in December 2008 was positive for hepatitis C and moderate fibrosis (the Veteran declined treatment at that time). He was seen for subsequent checkups in 2011 and 2012 (when he had another liver biopsy). Based on the medical records, hepatitis was first diagnosed in 1976. Although the initial assessments in 1976 do not indicate that the type of hepatitis was hepatitis C, later laboratory findings were not consistent with the Veteran ever having hepatitis type A or B. Further, as will be discussed private and VA physicians currently regard the 1976 treatment for hepatitis as the initial manifestation of hepatitis C. Regardless, the initial documentation of any type of hepatitis comes many years after the Veteran's discharge from service in 1970. It is acknowledged that hepatitis is a viral disease that may be asymptomatic at the time of infection; thus, service connection may still be granted even though the disability was first diagnosed after service, after considering all the evidence, including that pertinent to service under 38 C.F.R. § 3.303(d). Moreover, the Board has considered that the Veteran is a combat Veteran, and despite the fact that hepatitis was not documented during service, satisfactory lay or other evidence, if consistent with the circumstances, conditions, or hardships of such service, is acceptable proof of service incurrence of the disease (although clear and convincing evidence to the contrary may rebut service connection of such disease). 38 U.S.C.A. § 1154(b). The central question presented here is whether any event in service bears a causal relationship to the diagnosis of hepatitis C after service. It is well-known in medical literature that hepatitis C is spread primarily by contact with infected blood or blood products. For example, unsterilized needles that might be used in applying a tattoo and intravenous drug use are recognized risk factors for hepatitis. Also, there is a lack of any scientific evidence to document transmission of hepatitis C by air gun injector, although it is "biologically plausible." See Veterans Benefits Administration (VBA), Fast Letter 04-13 (June 29, 2004) (stating that there have been no case reports of hepatitis C transmitted by an air gun transmission, and one case report of hepatitis B transmitted by an air gun injection.). As earlier noted, in his statements the Veteran has denied all typical risk factors for hepatitis C and has asserted his belief that his hepatitis C infection was the result of exposure to contaminated blood through the use of immunization jet injectors and/or to contaminated water/other products through cuts and scrapes while repairing river boats in Vietnam. The Veteran may have had these in-service risk factors, as alleged, but whether such modes of transmission were responsible for his contraction of the hepatitis C virus is a medical question that he is not competent to answer. Regarding a determination of the etiology of the Veteran's hepatitis C, VA outpatient records show that in November 2008 the Veteran reported that he did not know how he contracted hepatitis C as he had no risk factors (i.e., no history of tattoos/body piercings, intravenous drug use, known hepatitis C contact, or blood transfusion). A December 2008 record indicates that the Veteran's hepatitis C problems dated to "1975" when he was treated for acute viral hepatitis. The Veteran's treating physician, Dr. Perry, opined in a March 2012 statement that it was at least as likely as not that the Veteran's hepatitis C infection dates back to 1976. Thus, there is competent evidence that the hepatitis C may be traced back to within five or six years of the Veteran's April 1970 separation from service. The record contains private and VA medical opinions specifically addressing the question of whether the Veteran's hepatitis C may be related back even further, specifically to his period of service. The probative value of a medical opinion is generally based on the scope of the examination or review, as well as the relative merits of the analytical findings, and the probative weight of a medical opinion may be reduced if the physician fails to explain the basis for an opinion. Sklar v. Brown, 5 Vet. App. 140 (1993). Among the factors for assessing the probative value of a medical opinion are the thoroughness and detail of the opinion. Prejean v. West, 13 Vet. App. 444, 448-49 (2000). The probative value or evidentiary weight to be attached to a medical opinion is within the Board's province as finder of fact. The guiding factors in evaluating the probative value of a medical opinion include whether the opinion is based upon sufficient facts, whether the opinion is the product of reliable principles, and whether the opinion applied valid medical analysis to the significant facts of the case in order to reach the conclusion submitted in the opinion. Nieves-Rodriguez v. Peake, 22 Vet. App. 295, 302 (2008). A mere conclusionary opinion is insufficient to allow the Board to make an informed decision as to the weight to assign to the opinion against contrary opinions. Stefl v. Nicholson, 21 Vet. App. 120, 125 (2007). At the time of a VA examination in January 2012, the examiner reviewed the Veteran's history of the two hospital admissions for acute hepatitis in 1976 as well as records indicating he was hepatitis A negative in December 2008 and hepatitis B negative in September 2008. The examiner also noted that the Veteran denied that he was a substance abuser, but observed that he was positive for THC in February 2011. The examiner opined that it was less likely than not that the Veteran's hepatitis C was incurred in or caused by service. He reasoned that the Veteran's hospital admissions and subsequent outpatient visits in 1976 were most likely his acute infection with hepatitis C, and that it was not likely the Veteran had hepatitis C during service as he had no symptoms suggestive of hepatitis and no documented medical visits for hepatitis or any other acute viral syndrome during service. In support of his claim, the Veteran furnished a medical opinion from Dr. Chabala, who in statements in March 2012 noted that the Veteran was under his medical care. He related the following about the Veteran: his hepatitis been diagnosed since 1976; his past history was negative for intravenous drug use; he had no classical high risk activities for hepatitis C (including blood transfusions, sexually transmitted diseases, or high risk sexual exposure); and his "only realistic risk factors of significance" were his Vietnam tour and exposure to group inoculation with air guns. Dr. Chabala declared the Veteran's hepatitis C infection was through "contaminated injection equipment and/or blood contaminated cuts and abrasions received during recovery and repair operations performed on river boats in the rivers of the Mekong Delta" in Vietnam. (He recalled another patient of his had been infected from contaminated sewage.) He asserted that the chances of the Veteran's exposure in Vietnam were "very high" whereas his chances of exposure in civilian life were "incredibly low"; thus, there was a greater than 50 percent chance that the Veteran's hepatitis C was related to military exposure. In May 2012, the VA examiner furnished an addendum opinion after reviewing the record, including Dr. Chabala's opinion. The examiner confirmed his previous conclusion, with the same rationale, which is unfavorable to the Veteran's claim. He added that although the Veteran claimed he did not abuse substances, at least one urine drug screen had been positive in the past as documented in the prior examination history. He therefore opined that the Veteran's "post service drug abuse and/or sexual activity related to drug intoxication" was the source of his hepatitis C; and that the onset of hepatitis C was after service and not during service, with its initial onset in 1976, resulting in his hospital admission. To reconcile the conflicting medical opinions, the Board in November 2015 sought a medical expert opinion through the VHA. The question that was posed to a specialist in infectious diseases was the following: is it at least as likely as not (i.e., a 50 percent or greater probability) that the Veteran's diagnosed hepatitis C is related to a risk factor during his period of active duty service from March 1969 to April 1970. The consulting specialist was requested to identify all of the Veteran's risk factors for acquiring hepatitis C, as indicated in the record; note when each risk factor occurred (i.e., during service or post-service?); and discuss the degree of likelihood that any risk factor in service may have led to the development of hepatitis C infection in the Veteran. The specialist was also asked to comment on the statements offered by the VA treating physician, the VA examiner, Dr. Chabala. In December 2015, a VHA expert (a physician section chief in infectious disease) responded that based on a review of the claims file, there was a less than 50 percent chance that the Veteran acquired hepatitis C during his period of active duty service. The consulting specialist acknowledged the common and less common risk factors for hepatitis C, and the fact that the Veteran denied all of them. She explained her conclusion - with a detailed discussion of symptoms and clinical and laboratory incubation periods - that when the Veteran presented for care in February 1976, he had acute, and not chronic, hepatitis C at that time. (She described how the Veteran's symptoms and laboratory pattern in February 1976 supported a diagnosis of acute hepatitis C rather than chronic hepatitis C.) Further, she asserted that given the Veteran's presentation with acute hepatitis C in February 1976, it would have been "highly unlikely" that his exposure to hepatitis C occurred during active duty because the clinical latency period of acute hepatitis C was up to three months prior to the onset of symptoms. Thus, she opined that his exposure to hepatitis C must have been in the last three months of 1975. She commented upon the other medical opinions of record, to include that of Dr. Chabala, who she stated had failed to make a distinction between acute and chronic hepatitis C, thus allowing him to "ignore clinical incubation periods that are critical to the conclusion" and leading him to invoke hepatitis C risk factors "that can hardly be proven to exist, such as mass injection with an air gun and swimming in the Mekong Delta many years before." She provided a list of medical references relating to the study of hepatitis C. The VHA opinion was sent to the Veteran in December 2015, and in February 2016 the Veteran's representative responded with written argument and the submission of medical extracts pertaining to hepatitis C and its etiology. The representative contended that VA was negligent in 1976 for diagnosing hepatitis A, which the Veteran never had. He argued that VA "focused on the time and ignored the mode" regarding transmission of hepatitis C, discussing how the "viable possible modes of infection" were either during service or related to posttraumatic stress disorder (PTSD). Regarding the latter, the representative stated that "[a]ccording to VA medicine PTSD facilitates bad decisions, especially those with risks of ... hepatitis C transmission." [The Veteran has established service-connection for PTSD; effective from October 2009.] He also stated that it was "definitely against the odds to have an acute onset phase of hepatitis C infection... the norm is by far to have no symptoms until time has passed." To support such statements, copies of medical records dated in 1976 [already of record] and various medical/other articles were submitted. The articles pertained to a test to detect hepatitis C (published 1989), non-A and non-B hepatitis and their chronic sequelae (published 1976 and 1979), a NIH fact sheet regarding hepatitis C and its risk factors, and a VA/DoD clinical practice guideline for managing PTSD (dated October 2010). The NIH fact sheet notes, i.a., that most people do not have any symptoms until the hepatitis C virus causes liver damage, which can take 10 or more years to occur, and also that when symptoms of hepatitis C do occur, they can begin one to three months after coming into contact with the virus. The VA/DoD guideline noted that persons with PTSD may have high rates of health risk behaviors and was a "predictor" of a risk factor for such blood-borne infections as hepatitis C. After carefully considering the positive, or favorable, medical evidence as well as the negative, or unfavorable, medical evidence, the Board finds that the preponderance of the evidence is against the Veteran's claim. The VA and private medical evidence appear to be in agreement that the Veteran's current hepatitis C was initially manifest in 1976. However, the medical opinions differed on the issue of the timing of the contraction of the HCV. Dr. Chabala was alone in opining that the Veteran's risks factors during service were responsible for his hepatitis C infection. The other opinions indicated that post-service factors were the source of the infection. The Board concludes that the unfavorable evidence, particularly the VHA opinion, outweighs the favorable evidence. There is no indication that Dr. Chabala had reviewed the Veteran's medical records of treatment for hepatitis in 1976, to ascertain his symptom presentation and laboratory studies at that time. If he had, perhaps he would have made a distinction between acute and chronic hepatitis C, as had the VHA expert, and arrived at a different conclusion regarding the etiology of the Veteran's hepatitis C. In contrast, the VHA expert (and to a lesser extent the VA examiner) explained in detail that the Veteran's presentation in February 1976 was an acute infection with hepatitis C, and the fact that it was acute hepatitis C meant that his exposure to the HCV occurred in the previous months rather than years so that in-service infection was highly unlikely. In other words, the VA examiner and VHA expert did not medically relate the Veteran's current hepatitis C to service. Furthermore, Dr. Chabala's opinion that the Veteran's probability of hepatitis C exposure during service was very high, in contrast to it being incredibly low in civilian life, focused on the Veteran's risk factors for viral transmission without due consideration of his medical history and clinical presentation with hepatitis in 1976. He also did not cite to any medical literature, as had the VHA expert, to support his conclusions. Greater weight may be placed on one medical opinion over another opinion depending on factors such as reasoning employed by the medical professional, and whether or not, and to what extent, they reviewed prior clinical records and other evidence. Gabrielson v. Brown, 7 Vet. App. 36 (1994). For the reasons previously discussed, the Board finds the VHA opinion is entitled to greater probative weight than the opinion of Dr. Chabala. The VHA expert took into account a complete review of the Veteran's claims file and medical history, provided a complete rationale as to her conclusions that were based on the significant facts in the record and statistical data from referenced medical articles, and cited to the deficiencies in the opinion of Dr. Chabala. While it is acknowledged that the VHA expert did not endorse any particular risk factor for leading to the infection of hepatitis C, as had Dr. Chabala and the VA examiner who pointed to in-service sources and post-service sources, respectively, she provided clear reasons based on medical science for rejecting in-service risk factors to include those described by the Veteran and Dr. Chabala. Further, it is entirely plausible that an exact source of the Veteran's hepatitis C infection is indeterminable, particularly given the passage of time (more than 30 years) since he was initially seen with symptoms of hepatitis and the question of whether he is able to recall specific events going back decades that may have led to infection. While his statements to the effect of contracting hepatitis C in service are speculative or based on conjecture, the VHA expert explained how from a medical standpoint the initial manifestation of his current hepatitis C in 1976 could not be related to risk factors prior to 1975. The Board finds that the VHA opinion has the most probative weight of the medical opinions in the record, and is also persuasive evidence against the Veteran's lay statements with regard to hepatitis C risk factors during service resulting in infection. Regarding the statements and evidence submitted by the Veteran's representative in February 2016, the Board finds that assertions of VA negligence for diagnosing hepatitis A in 1976 have no bearing on the VA and private opinions regarding the etiology of the Veteran's hepatitis C and current recognition of his initial treatment for hepatitis C in 1976. Moreover, identification of a mode of the Veteran's hepatitis C infection is not paramount to the question of determining whether the infection occurred during or after service; risk factors were indeed considered by all physicians who rendered an etiological opinion, but the VHA examiner ultimately found that the Veteran's medical history and medical science were integral in determining that infection was highly unlikely to have occurred during service as claimed by the Veteran. The assertion that the Veteran's PTSD may have led to the Veteran's hepatitis C is vague and purely speculative, as there is no basis presented for relating one to the other. The statement that the odds are against an acute onset phase of hepatitis C, when typically symptoms arise after much time has passed, is not necessarily supported in the source provided by the representative; the NIH fact sheet acknowledges that hepatitis C symptoms [such as of an acute stage] can begin one to three months after coming into contact with the virus. To the extent the Veteran asserts that there is an association between his hepatitis C and his period of service - whether it is related to an air gun injection or from particular exposure to contaminated blood or other products during the performance of his duties in Vietnam - his opinion as a layperson is limited to inferences that are rationally based on his perception and does not require specialized education, training, or experience. See 38 C.F.R. § 3.159(a) (defining competent lay and medical evidence). Although he is competent to describe symptoms of hepatitis C, see Layno v. Brown, 6 Vet. App. 465, 469-71 (1994) (lay testimony is competent as to symptoms of an injury or illness, which are within the realm of personal knowledge), hepatitis C is not a condition found under case law to be capable of lay observation, and the determination as to the presence of hepatitis C (which is confirmed through laboratory testing) therefore is medical in nature and not capable of lay observation. That is, the question of the etiology of hepatitis C constitutes a complex medical question beyond the realm of lay observation. See Jandreau v. Nicholson, 492 F.3d 1372, 1377 (Fed. Cir. 2007). It is not argued or shown that the Veteran is otherwise qualified through specialized education, training, or experience to offer an opinion on the critical question in this case. Therefore, to the extent the Veteran's statements are offered as proof of the causation, or infection, of hepatitis C, the statements are not competent evidence, and must be excluded, i.e., they may not be considered as competent evidence favorable to the claim. However, the medical opinion provided by the VHA expert in December 2015 is based on a review of the onset, clinical course, and status of the Veteran's hepatitis C. The VHA expert is qualified by education and experience to offer an opinion on the etiology of the currently diagnosed hepatitis C, and she concluded that it was not at least as likely as not that the Veteran acquired hepatitis C during service, as claimed by the Veteran. She provided rationale for the opinion, which was grounded in the medical science of analyzing symptom manifestations and clinical and laboratory incubation periods for the disease, and she explained how Dr. Chabala's favorable opinion lacked critical consideration of certain medical principles pertaining to hepatitis C. Thus, the competent medical evidence opposes rather than supports the Veteran's claim. As the preponderance of the evidence weighs against the claim for service connection for hepatitis C, the benefit-of-the-doubt standard of proof does not apply. 38 U.S.C.A. § 5107(b). ORDER The appeal seeking service connection for hepatitis C is denied. ____________________________________________ George R. Senyk Veterans Law Judge, Board of Veterans' Appeals Department of Veterans Affairs