Citation Nr: 1442139 Decision Date: 09/22/14 Archive Date: 09/30/14 DOCKET NO. 10-36 170 ) DATE ) ) On appeal from the Department of Veterans Affairs Regional Office in Columbia, South Carolina THE ISSUE Entitlement to service connection for the cause of the Veteran's death. REPRESENTATION Appellant represented by: The American Legion WITNESSES AT HEARING ON APPEAL Appellant and her daughter ATTORNEY FOR THE BOARD S. Syverson, Associate Counsel INTRODUCTION The Veteran served on active duty from June 1964 to May 1968. He died in May 2009. The appellant claims as the Veteran's surviving spouse. This matter comes to the Board of Veterans' Appeals (Board) on appeal from a rating decision of the Department of Veterans Affairs (VA) Regional Office (RO) in Columbia, South Carolina. In June 2011, the appellant and her daughter testified at a videoconference hearing before the undersigned; a transcript of the hearing is of record. At the hearing, the appellant submitted additional evidence accompanied by a waiver of agency of original jurisdiction review. 38 C.F.R. § 20.1304(c) (2013). In April 2014, the Board referred this matter to the Veteran's Health Administration (VHA) for an advisory opinion, which was received in May 2014. The appellant and her representative were given the opportunity to provide argument or evidence with respect to the VHA opinion. In August 2014, the appellant's representative submitted a written brief, which is associated with the Virtual VA paperless claims file and has been considered in the disposition of the issue on appeal. FINDINGS OF FACT 1. The Veteran served in the Republic of Vietnam in 1967 and is presumed to have been exposed to herbicide agents. 2. At the time of his death, the Veteran did not have any disabilities for which service connection had been established. 3. The Veteran's death certificate lists the immediate cause of his death in May 2009 as rapidly progressive severe dementia, suspected Creutzfeldt-Jakob disease (CJD); CJD was confirmed by analysis of autopsy tissue in August 2009. 4. Creutzfeldt-Jakob disease is not a VA-recognized disease for which service connection may be presumed on the basis of herbicide exposure. 5. Creutzfeldt-Jakob disease was not demonstrated in service and the competent evidence of record preponderates against a finding that CJD was related to service, to include service in Vietnam and presumed exposure to herbicide agents. CONCLUSION OF LAW The criteria for entitlement to service connection for the cause of the Veteran's death have not been met. 38 U.S.C.A. §§ 1101, 1110, 1131, 1310 (West 2002 & Supp. 2013); 38 C.F.R. §§ 3.303, 3.307, 3.309, 3.312 (2013). REASONS AND BASES FOR FINDINGS AND CONCLUSION Duties to Notify and Assist The Veterans Clams Assistance Act of 2000 as amended (VCAA) and implementing regulations impose obligations on VA to provide claimants with notice and assistance. See, e.g., 38 U.S.C.A. §§ 5103, 5103A (West 2002 & Supp. 2013); 38 C.F.R. § 3.159 (2013). The notice requirements were met in this case by a letter dated in August 2009. The letter notified the appellant of the information and evidence needed to substantiate and complete a claim for service connection for cause of death, to include notice of what part of that evidence she should provide, what part VA would attempt to obtain, and how effective dates are determined. While the RO has not furnished a letter informing the appellant of how VA determines disability ratings, disability ratings are not relevant to a claim for service connection for the cause of a veteran's death, and there is no possibility of prejudice to the appellant. Furthermore, the requisite notice was provided prior to initial adjudication of the claim in the January 2010 rating decision. In addition, in the context of a claim for Dependency and Indemnity Compensation (DIC) benefits, which includes a claim of service connection for the cause of the Veteran's death, VCAA notice must include (1) a statement of the conditions, if any, for which a veteran was service connected at the time of his or her death; (2) an explanation of the evidence and information required to substantiate a DIC claim based on a previously service-connected condition; and (3) an explanation of the evidence and information required to substantiate a DIC claim based on a condition not yet service connected. Hupp v. Nicholson, 21 Vet. App. 342, 352-353 (2007), rev'd on other grounds, Hupp v. Shinseki, 329 Fed. App. 277 (Fed. Cir. May 19, 2009) (unpublished). In this case, the appellant asserts that the Veteran's Creutzfeldt-Jakob Disease (CJD), which caused his death, was related to his military service, to include service in Vietnam and exposure to Agent Orange. Regarding the Hupp requirements, although the August 2009 notice letter notified the appellant that the Veteran was not service-connected for CJD during his lifetime, she was not provided notice as to whether the Veteran was in receipt of service connection for any other disabilities. As the Veteran was not service connected for any other disabilities during his lifetime, any lack of notice pertaining to the first Hupp requirement is not prejudicial to the appellant's claim. The August 2009 letter satisfied the remaining Hupp requirements. Accordingly, the duty to notify has been satisfied. The VCAA also requires VA to make reasonable efforts to help a claimant obtain evidence necessary to substantiate his or her claim. 38 U.S.C.A. § 5103A; 38 C.F.R. § 3.159(c), (d). In this case, VA obtained the Veteran's service treatment records and associated private medical records and other evidence provided by the appellant with the claims file. VA medical opinions were obtained in November and December 2009. Subsequently, given that CJD is a rare condition, the Board requested a VHA opinion from a neurologist. As discussed in further detail below, the Board finds that the May 2014 VHA opinion is adequate to make a decision on this claim as it is based on a review of the Veteran's history, describes his disease in detail, and supports its conclusion with an analysis the Board can consider and weigh against contrary opinions. See Stefl v. Nicholson, 21 Vet. App. 120, 123-24 (2007). The appellant was also provided an opportunity to set forth her contentions at a Board hearing conducted in June 2011. The record reflects that at the hearing the undersigned set forth the issue to be discussed, focused on the elements necessary to substantiate the claim, and sought to identify any further development that was required to help substantiate the claim. These actions satisfied the duties a Veterans Law Judge has to fully explain the issue and to suggest the submission of evidence that may have been overlooked. See Bryant v. Shinseki, 23 Vet. App. 488, 492 (2010) (holding that the requirements of 38 C.F.R. § 3.103(c)(2) apply to a hearing before the Board). Notably, neither the appellant nor her representative has asserted that VA failed to comply with 38 C.F.R. § 3.103(c)(2), nor have they identified any prejudice in the conduct of the hearing. Therefore, the Board finds that VA has complied with the VCAA's notification and assistance requirements. The claim is thus ready to be considered on the merits. Legal Criteria DIC is paid to a surviving spouse of a qualifying veteran who died from a service-connected disability. 38 U.S.C.A. § 1310; Darby v. Brown, 10 Vet. App. 243, 245 (1997). The death of a veteran will be considered as having been due to a service-connected disability when the evidence establishes that such disability was either the principal or a contributory cause of death. The service-connected disability is considered the principle cause of death when such disability, either singly or jointly with another condition, was the immediate or underlying cause of death or was etiologically related to the cause of death. To be a contributory cause of death, it must be shown that the service-connected disability contributed substantially or materially to death, that it combined to cause death, or that it aided or lent assistance to the production of death. It is not sufficient to show that it casually shared in producing death, but rather it must be shown that there was a causal connection. 38 C.F.R. § 3.312. In determining whether the disability that resulted in the death of a veteran was the result of active service, the laws and regulations pertaining to basic service connection apply. 38 U.S.C.A. § 1310. In this case, the Veteran's death certificate reflects that the immediate cause of his death was rapidly progressive severe dementia; CJD or similar suspected with pathology pending. An August 2009 report from The National Prion Disease Pathology Surveillance Center confirms the diagnosis of prion disease with the characteristics of sporadic CJD. The appellant asserts that the Veteran's CJD is related to his military service, to include service in Vietnam and Agent Orange exposure. Evidence of record shows that at the time of his death, the Veteran did not have any disabilities for which service connection had been established. Service connection will be granted if the evidence demonstrates that a current disability resulted from an injury or disease incurred in or aggravated by active military service. 38 U.S.C.A. §§ 1110, 1131; 38 C.F.R. § 3.303(a). Establishing service connection generally requires (1) evidence of a current disability; (2) evidence of in-service incurrence or aggravation of a disease or injury; and (3) evidence of a nexus between the claimed in-service disease or injury and the present disability. Shedden v. Principi, 381 F.3d 1163, 1167 (Fed. Cir. 2004); 38 C.F.R. § 3.303. Service connection may also be granted for a disease first diagnosed after discharge when all of the evidence, including that pertinent to service, establishes that the disease was incurred in service. 38 C.F.R. § 3.303(d) . Absent affirmative evidence to the contrary, there is a presumption of exposure to herbicides (to include Agent Orange) for all veterans who served in Vietnam during the Vietnam Era (the period beginning on January 9, 1962, and ending on May 7, 1975). 38 U.S.C.A. § 1116(f) (West 2002); 38 C.F.R. § 3.307(a)(6)(iii). If a veteran was exposed to an herbicide agent (to include Agent Orange) during active military, naval, or air service, certain enumerated diseases shall be service-connected if the requirements of 38 C.F.R. § 3.307(a)(6) are met, even if there is no record of such disease during service, provided further that the rebuttable presumption provisions of 38 C.F.R. § 3.307(d) are also satisfied. 38 C.F.R. § 3.309(e). When a claimed disorder is not included as a presumptive disorder, direct service connection may nevertheless be established by evidence demonstrating actual causation. See Combee v. Brown, 34 F.3d 1039, 1043-44 (Fed. Cir. 1994). Factual Background Evidence submitted by the appellant includes various internet resources, including a post from a VVA message board indicating that the author's brother was a Vietnam veteran who died of CJD and that the author knew of 12 other Vietnam veterans who died of CJD. The appellant also submitted an article titled Molecular analysis of prion protein gene (PRNP) in Korean patients with Creutzfeldt-Jakob disease, which notes that several cases of CJD have been reported in Korea and concluded that the two CJD patients tested had a sporadic type of CJD, but not a familial type. Another source showing that Korea has had cases of CJD was submitted. A pamphlet on CJD describes the disease, its three major categories (sporadic, hereditary, and acquired), how it is diagnosed, how it is treated, and its causes; the source notes that in some cases the incubation period may be as long as 40 years. A fact sheet from the Center for Disease Control and Prevention notes that classic CJD is not related to "mad cow" disease and is distinct from "variant CJD," another prion disease that is related to BSE (bovine spongiform encephalopathy). A 2005 internet article states that "until proven otherwise CJD must be considered potentially orally-transmissible via blood." An article printed from UpToDate in June 2010 states that prion diseases, including CJD, are neurodegenerative diseases that have long incubation periods and progress inexorably once clinical symptoms appear. The article notes that approximately one case of sporadic CJD occurs per 1,000,000 population per year with a worldwide distribution and that the incidence of CJD is increased 30- to 100-fold in certain geographic regions including areas of North Africa, Israel, Italy, and Slovakia, due primarily to clusters of familial CJD. The article notes that small clusters of sporadic CJD cases have been reported, including in the United Kingdom, suggesting that some sporadic CJD cases may result from exposure to a common external factor, but that the significance of these possible clusters remains unclear. The appellant submitted a highlighted CJD fact sheet from the National Institutes of Health. The highlighted portions note that: CJD usually appears later in life and runs a rapid course, with onset of symptoms typically occurring at about age 60; in sporadic CJD, the disease appears even though the person has no known risk factors for the disease; CJD belongs to a family of human and animal diseases known as the transmissible spongiform encephalopathies (TSEs) and other human TSEs include kuru, which was identified in people of an isolated tribe in Papua New Guinea and has now almost disappeared; a variant, called the panencephalopathic form occurs primarily in Japan; there is no single diagnostic test for CJD, and the only way to confirm a diagnosis of CJD is by brain biopsy or autopsy; some researchers believe an unusual "slow virus" or another organism causes CJD, but the agent that causes CJD has several characteristics that are unusual for known organisms such as viruses and bacteria, including a long incubation period before symptoms occur, in some cases as long as 50 years; and that exposure to brain tissue and spinal cord fluid from infected individuals should be avoided to prevent transmission of the disease through these materials. A discussion of CJD and blood donation from the Red Cross website concludes that if you have a biologic relative who has been diagnosed with CJD you should not donate blood until more is known about CJD and the risk to the blood supply. The appellant also submitted several letters from the Veteran's physician, Dr. G.T.B. A September 2009 letter notes that after the Veteran's death he underwent a biopsy that confirmed that he died of a spongiform encephalopathy, which is most likely CJD. Dr. G.B.D. states, "At this point in time, there is no known source for [the Veteran's] infection. However, the fact that he was stationed in Vietnam for quite some period of time makes it likely that that is where he encountered this Prion disease." A report from the National Prion Disease Pathology Surveillance Center confirmed the diagnosis of prion disease with the characteristics of sporadic CJD MV2, with features of MM2. The report notes that the prion disease is not familial according to the current criteria for familial prion diseases. A November 2009 VA opinion by Dr. W.L.B. notes that CJD is a disease of rapid progression leading to death from onset in just a few months. Dr. W.L.B. states, "It is highly unlikely that a prion would remain present in the brain for 40 years or more before expressing itself. There is no evidence to my knowledge in any medical literature to support such a contention . . . ." Dr. W.L.B. states that in his opinion the Veteran's CJD is not caused by or the result of his military service. A December 2009 VA opinion by Dr. W.A.C. reports that it is less likely than not that CJD is related to military service, including in Vietnam. Dr. W.A.C. notes, "It is impossible for me to say that his developing this disease is likely to his having been in the Service when we [the medical community] do not completely understand the disease." Dr. W.A.C. notes that the Veteran was discharged from service approximately 40 years before he developed the disease and that there has been no link to Vietnam and prion disease. Dr. W.A.C. also notes that there is "no sufficient data or evidence whatsoever" to support the opinion that the Veteran's CJD is related to his being in Vietnam. The Veteran's physician, Dr. G.T.B., wrote a June 2010 letter in response to the two VA opinions. Dr. G.T.B. reiterated his opinion that the Veteran as likely as not acquired the prion that resulted in his biopsy-proven CJD while he was in the service. Addressing the November 2009 VA opinion by Dr. W.L.B., Dr. G.T.B. states that Dr. W.L.B.'s assessment of CJD was not correct. Dr. G.T.B. explains that CJD has a potentially long incubation period before symptoms manifest and notes that there are reported cases showing an incubation period of 30 years. Dr. G.T.B. opines that given the rarity of the disease, "it is thoroughly plausible and even likely that longer incubation periods are possible." Dr. G.T.B. cites several sources discussing the potentially long incubation period of CJD. Addressing the December 2009 VA opinion by Dr. W.A.C., Dr. G.T.B. first points out that the Veteran's postmortem biopsy confirmed that he had an acquired, not a familial, form of CJD. Next, Dr. G.T.B. notes that although Dr. W.A.C. mentioned bovine spongiform encephalopathy, the biopsy confirmed that this was not the variant of CJD that the Veteran had, making it unlikely that he acquired the disease from eating beef products. Dr. G.T.B. concludes: Finally, Dr. [W.A.C.] comes to the conclusion that because no hard evidence exists to link [the Veteran's] time in Vietnam to his contracting CJD that it is less than likely that he did so. This is not a logical conclusion. We do not know where [the Veteran] acquired CJD but since there is no evidence that it was inherited and there is no evidence that it came from beef then it is quite clear that he is just as likely to have acquired it in Vietnam as in the US. Given the different dietary habits and varying levels of sanitary conditions in Vietnam at the time it is as likely as not he acquired CJD there. Dr. G.T.B. concludes his discussion by acknowledging that he cannot say that the Veteran acquired CJD in Vietnam and explaining that based on the evidence available and the flawed VA examinations, it remains his opinion that the Veteran as likely as not acquired CJD, which resulted in his death, while in U.S. military service. In May 2014, Dr. Moss, a neurologist, provided a VHA opinion. Dr. Moss set forth an accurate factual background and noted his thorough review of the claims file, which revealed no significant information from the active duty records that might have bearing on the CJD. Dr. Moss noted that the cause of sporadic CJD is unknown. He explained that while there are geographical "hot spots" where the incidence of CJD is higher than expected, this is only for the "familial" forms of CJD, which was not the case for the Veteran as shown by pathology testing. Dr. Moss explains that there is no increase incidence of CJD in the Republic of Vietnam and after review of the literature there does not appear to be any association of CJD and the Republic of Vietnam. Dr. Moss observes that statements made to imply otherwise in the claims file are not, in his opinion, founded in scientific fact. Dr. Moss further notes that "[t]here is absolutely no association of CJD and agent orange exposure." Dr. Moss concludes that there is no information that in any way can link the Veteran's service in Vietnam to his later diagnosis of CJD. Additional evidence includes statements by the appellant. A March 2010 typewritten statement that appears to have been written by the Veteran's daughter and was signed by the Veteran's wife asserts that the long incubation period of up to 40 years, the absence of risk factors such as corneal transplants or neurosurgical procedures, the fact that the Veteran was not exposed to individuals who suffered fatal ballistic injuries and did not travel outside of the U.S. after service, and the disease being so rare, all support an in-service origin or exposure to the virus or prion that causes CJD. The statement asserts that the Veteran travelled to Guam while in service and notes that another fatal disease similar to CJD in humans is Kuru, which is geographically unique to Papua New Guinea. The statement asserts that the symptoms of CJD mirror Parkinson's Disease and are very similar to other neurodegenerative disorders, such as progressive supranuclear palsy, which are known health outcomes of exposure to herbicides. Finally, the statement relays the Veteran's recollections regarding Agent Orange exposure and notes that "[o]ver the years, [the Veteran] has exhibited known side effects of Agent Orange such as Hypertension, he and his wife suffered a stillborn birth in 1974, and his children have experienced problems with infertility and miscarriages." A September 2010 statement submitted in conjunction with the appellant's substantive appeal asserts that the panencephalopathic form of CJD is, like the Veteran's form, sporadic, and occurs primarily in Japan. The appellant asserts that the Veteran went to Japan during service. The appellant also asserts that the Veteran went to Guam during service and that Kuru, which like CJD is a TSE, has been found on the pacific islands of Guam. The appellant contends that muscle soreness and stiffness is a symptom of CJD and that the Veteran's service treatment records show he was treated for muscle stiffness throughout service. She asserts that "this could be when he encountered or had already encountered CJD." She also asserts that oral surgery has been another theory of contracting CJD and the Veteran had oral surgery while in service. The appellant further asserts that CJD goes misdiagnosed and others could have died thinking they had Alzheimer's disease when in fact it was CJD and that Alzheimer's disease "use to not be considered an in-service connected disease and has since been proven to be." The appellant also asserts that the Veteran received medical attention during service for a history of sore throat and cough with inflammation. She contends that his immune system had to have been weakened to have a history of this condition and that his immune system may have been too weakened to fight off exposure to a prion disease or he could have already been exposed. The appellant also notes that exposure to brain tissue and spinal fluid from infected individuals should be avoided to prevent transmission of the disease and asserts that the Veteran was in combat and was certainly in contact/close range with blood and other body parts. She reports that the Veteran told her that he had a friend's brain pieces "splatted on him." She also asserts that there is a threat of spreading CJD through blood because anyone with CJD or who has a blood relative with CJD cannot give blood to the Red Cross or donate organs. Finally, she asserts that the Veteran was exposed to Agent Orange, which could have been the agent that "began the mutation." Analysis The dispositive question in this case is whether the Veteran's CJD was at least as likely as not related to his military service, to include service in Vietnam, exposure to herbicide agents, and claimed service in Guam and Japan. In evaluating a claim, the Board must determine the value of all evidence submitted, including lay and medical evidence. Buchanan v. Nicholson, 451 F.3d 1331, 1335 (Fed. Cir. 2006). The evaluation of evidence generally involves a three-step inquiry. First, the Board must determine whether the evidence comes from a "competent" source. The Board must then determine if the competent evidence is credible, or worthy of belief. Barr v. Nicholson, 21 Vet. App. 303, 308 (2007) (observing that once evidence is determined to be competent, the Board must determine whether such evidence is also credible). The third step of this inquiry requires the Board to weigh the probative value of the proffered evidence in light of the entirety of the record. Competent medical evidence is evidence provided by a person who is qualified through education, training, or experience to offer medical diagnoses, statements, or opinions. Competent medical evidence may also include statements conveying sound medical principles found in medical treatises. It also includes statements contained in authoritative writings, such as medical and scientific articles and research reports or analyses. 38 C.F.R. § 3.159(a)(1). 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(a)(2). Lay evidence may be competent and sufficient to establish a diagnosis of a condition when: (1) a layperson is competent to identify the specific medical condition; (2) the layperson is reporting a contemporaneous medical diagnosis; or (3) lay testimony describing symptoms at the time supports a later diagnosis by a medical professional. Jandreau v. Nicholson, 492 F.3d 1372, 1377 (Fed. Cir. 2007). Similarly, laypersons are competent to opine as to some matters of causation, and the Board must determine on a case-by-case basis whether a veteran's particular disability is the type for which lay evidence is competent. See Davidson v. Shinseki, 581 F.3d 1313, 1316 (Fed. Cir. 2009); Kahana v. Shinseki, 24 Vet. App. 428, 433 n.4 (2011). In weighing the evidence, where there is conflicting medical evidence, the Board may not ignore or disregard any medical professional's opinion, but may favor one medical opinion over another by providing an adequate statement of reasons or bases. See Willis v. Derwinski, 1 Vet. App. 66, 70 (1991). A medical opinion is most probative if it is factually accurate, fully articulated, and based on sound reasoning. See Nieves-Rodriguez v. Peake, 22 Vet. App. 295, 304 (2008). Applying these principles, the Board will analyze the evidence to determine whether it establishes that it is at least as likely as not that the Veteran's CJD is related to his service under any of the asserted theories of causation. The Board will first discuss the appellant's arguments related to service in the Republic of Vietnam, not including exposure to Agent Orange. Next, the Board discusses the theory that CJD is due to Agent Orange exposure. Finally, the Board will address the appellant's remaining theories, including those related to claimed service in Guam and Japan. The appellant asserts that the Veteran acquired CJD in Vietnam. She has advanced several arguments in support of this theory, including pointing to the absence of other risk factors, discussing service treatment records that showed complaints of muscle stiffness and sore throat and cough, and contending that the Veteran could have contracted CJD through exposure to blood and brain tissue during service. She has submitted supporting materials discussing possible transmission through exposure to brain materials and blood from infected individuals. As noted above, the Board must determine on a case-by-case basis whether a lay person is competent to opine as to the causation of a particular disorder. Kahana, 24 Vet. App. at 433 n.4. In this case, the appellant's opinion regarding the etiology of CJD amounts to testimony concerning a medical disease process that took place over potentially many years, which extends beyond the type of immediately observable cause-and-effect relationship about which a layperson is competent to testify. See Jandreau, 492 F.3d at 1377 n.4 ("Sometimes the layperson will be competent to identify the condition where the condition is simple, for example a broken leg, and sometimes not, for example, a form of cancer."). Although the appellant is capable of reporting the circumstances of the Veteran's service, as he described them to her, she is not qualified to provide a competent opinion as to whether it is at least as likely as not that the Veteran incurred CJD while in Vietnam. As the appellant's opinion is not competent, it has no probative value. See Layno v. Brown, 6 Vet. App. 465, 469 (1994) ("As a general matter, in order for any testimony to be probative of any fact, the witness must be competent to testify as to the facts under consideration."). To the extent that the appellant may be competent to opine as to the cause of the Veteran's CJD, her opinions are outweighed by the May 2014 VHA opinion, to which, as discussed below, the Board assigns significant probative value. Assuming that the appellant's descriptions of the Veteran's service, including exposure to brain tissue and blood, are credible, and taking into account the articles submitted that advocate avoiding brain tissue and blood from infected individuals, only a speculative link between service and CJD is raised, particularly given the rarity of the disease, which makes it unlikely that the Veteran was exposed to tissue or blood from an infected individual. See, e.g., National Institutes of Health, CJD fact sheet (CJD affects about one person in every one million people per year worldwide). This evidence is insufficient on its own to show that CJD was at least as likely as not incurred in Vietnam, but will be weighed against the probative medical evidence of record. Regarding internet and medical sources submitted by the appellant, the Board finds that the VVA message board post regarding Vietnam veterans with CJD is relevant evidence, to the extent that the existence of other Vietnam veterans with CJD may suggest a possible association between CJD and Vietnam service, and will be weighed against the medical evidence of record. See Horn v. Shinseki, 25 Vet. App. 231, 245 (2012) (Lance, J., dissenting) ("Relevant evidence is anything that 'has a tendency to make a fact more or less probable than it would be without the evidence.'" (quoting Fed. R. Evid. 401(a)). The articles regarding incidents of CJD in Korea are not relevant. Absent some indication that the Veteran served in Korea, which the appellant has not asserted, or some link between incidents of CJD in Korea and Vietnam, the fact that cases of CJD have been reported in Korea does not have any tendency to make a relationship between the Veteran's service and CJD more or less probable than it would be without the evidence. See id. To the extent that the articles are submitted to support the appellant's theory that clusters of sporadic CJD exist and that the Veteran may have been exposed to such, they are relevant. However, the Board finds the VHA opinion more probative than the lay assertions by the appellant, as discussed below. Further, the Board notes that a source submitted by the appellant states that "the significance of these possible clusters remains unclear." February 2010 UpToDate article. Although the other sources provided by the appellant provide helpful background information regarding CJD, they are of little probative value as to the dispositive issue of the cause of the Veteran's CJD as they do not address the facts of his case. No question as to the competency or credibility of the opinions of the various medical professionals has been raised. Assessing their probative value, the Board recognizes, as pointed out by Dr. G.T.B., that the November 2009 VA opinion by Dr. W.L.B. is based on the incorrect assessment that there is no evidence in medical literature to support the contention that a prion could remain inactive in the brain for 40 years or more before expressing itself. Rather, medical evidence of record does support the contention, including a fact sheet from the National Institutes of Health that notes that the agent that causes CJD has several characteristics that are unusual for known organisms, including that in some cases, the incubation period may be as long as 50 years. Therefore, the Board assigns no probative value to the November 2009 VA opinion. The December 2009 VA opinion by Dr. W.A.C., as pointed out by Dr. G.T.B., appears to have failed to take cognizance of the fact that pathology confirmed that the Veteran's CJD was sporadic, rather than familial or a bovine variant. However, Dr. W.A.C. did not base his opinion on an incorrect conclusion that the Veteran's CJD was familial, rather he based his opinion on the lack of understanding of the disease in the medical community and the absence of evidence to support a relationship to Vietnam. Therefore, Dr. W.A.C.'s opinion is of some, if little, probative value. Turning to the opinions by Dr. G.T.B., in September 2009, he stated, "At this point in time there is no known source for [the Veteran's] infection. However, the fact that he was stationed in Vietnam for quite some period of time makes it likely that that is where he encountered this Prion disease." Dr. G.T.B. does not explain why it is likely that the Veteran encountered CJD in Vietnam. Dr. G.T.B. reviewed the November and December 2009 VA opinions and the Veteran's service treatment records in conjunction with his June 2010 statement in which he observed that it is not known where the Veteran acquired CJD, "but since there is no evidence that it was inherited and there is no evidence that it came from beef then it is quite clear that he is just as likely to have acquired it in Vietnam as in the US." Although Dr. G.T.B.'s factual premise is consistent with the evidence, the Board does not follow his logic. Although the exact dates of the Veteran's Vietnam service have not been established, his service treatment records suggest that he served in Vietnam for approximately one year. In a March 2010 statement, the appellant reported that the Veteran did not travel outside of the U.S. after service. Absent some additional, missing evidence, such as an increased incidence of CJD in Vietnam or evidence suggesting that the incubation period is uniform enough to be used as a measure for dating the time of exposure, the Board does not follow Dr. G.T.B.'s conclusion that the Veteran was as likely to have acquired the disease in a country in which he spent relatively little time as opposed to the country where he lived most of his life. Dr. G.T.B. continues to state that "[g]iven the different dietary habits and varying levels of sanitary conditions in Vietnam at the time it is as likely as not [the Veteran] acquired CJD there." Dr. G.T.B. does not explain the relevance of dietary habits (having already stated that it is unlikely that the Veteran acquired the disease from eating beef products) or sanitary conditions to CJD. In sum, the Board finds Dr. G.T.B.'s opinions to be lacking a rationale explaining his conclusions, one of which appears to be based on less than sound reasoning. Therefore, the opinions are entitled to little weight. See, e.g., Nieves-Rodriguez, 22 Vet. App. at 304 ("[M]ost of the probative value of a medical opinion comes from its reasoning."). The May 2014 VHA opinion by Dr. Moss, a neurologist, provides an accurate factual background, including that: the Veteran served in the Republic of Vietnam; agent orange exposure is assumed; the Veteran became symptomatic with a rapidly progressive dementia that resulted in his death; assessment of brain tissue made a definitive diagnosis of CJD; and the findings were not consistent with the familial form of CJD. Dr. Moss reviewed the claims file and relevant literature. He noted that the claims file revealed no significant information from the active duty records that might have bearing on the CJD. He observed further that the cause of sporadic CJD is unknown and that geographical "hot spots" are associated with familial forms of CJD, which was not the case for the Veteran per pathology testing. Dr. Moss found after review of literature that there does not appear to be any association between CJD and the Republic of Vietnam and that statements made to imply otherwise in the claims file are not founded in scientific fact. He concluded that there is no information that in any way can link the Veteran's service in the Republic of Vietnam to his later diagnosis of CJD. The Board finds that the May 2014 VHA opinion is entitled to substantial probative weight because it is factually accurate, fully articulated, and based on sound reasoning. Nieves-Rodriguez, 22 Vet. App. at 304. Dr. Moss clearly explains the basis for his conclusion that there is no evidence that can relate the Veteran's CJD to his service based on valid medical or scientific analysis. In sum, the sources submitted by the appellant are of slight probative value and suggest only a possibility or speculative link between the Veteran's service and CJD. The opinion's by Dr. G.T.B. are entitled to little weight as they are conclusory. The Board finds that this evidence is outweighed by the VHA opinion, to which the Board assigns significant probative value, as discussed above. Therefore, it is not at least as likely as not that the Veteran's CJD was incurred in or otherwise related to his service in Vietnam. The appellant also asserts that the Veteran's CJD, which is the confirmed cause of death, is due to exposure to Agent Orange. As an initial matter, the Veteran's service records indicate service in Vietnam in 1967, and it is therefore presumed that he was exposed to herbicide agents. 38 C.F.R. § 3.306(a)(6)(iii). However, CJD is not disorder which may be presumed to be due to herbicide exposure during military service. 38 C.F.R. § 3.309(e). The Board has also considered whether service connection might be established based on proof of actual direct causation from herbicide exposure. Combee, 34 F.3d at 1044. The appellant contends that the Veteran's CJD is related to in-service herbicide exposure. In support of this contention she cites to similarities between CJD and Parkinson's Disease, which may be presumed to be due to herbicide exposure, progressive supranuclear palsy, which she contends is a known health outcome of exposure to herbicides, and Alzheimer's disease. She also makes statements related to the Veteran's exposure to Agent Orange; as noted above, herbicide exposure is presumed based on the Veteran's service. Given the rarity of CJD and the fact that there is not consensus, even in the medical community, as to its cause, the appellant, a lay person, is not competent to opine as to any possible relationship between CJD and herbicide exposure. To the extent that the appellant may be competent to provide such an opinion, given the complexity of the disease involved, her opinion is entitled to little weight. Therefore, the Board finds the opinion of the trained medical professional who provided the May 2014 VHA opinion to be of the most probative value. After review of the literature, the neurologist found "absolutely no association of CJD and agent orange exposure." Therefore, service connection for CJD is not warranted based on in-service herbicide exposure, on either a direct or presumptive basis. The appellant has also asserted that the Veteran went to Guam during service and that Kuru, which like CJD is a TSE, has been found on the pacific islands of Guam. However, the Veteran's death certificate and August 2009 report from the National Prion Disease Pathology Surveillance Center confirm that the cause of death was sporadic CJD of the MV2 and MM2 classifications; although MV2 is also known as a Kuru plaque variant, see February 2010 UpToDate article, Kuru itself was not diagnosed. Similarly, the appellant asserts that the Veteran went to Japan during service and that panencephalopathic form of CJD is a sporadic CJD that occurs primarily in Japan. The National Institutes of Health fact sheet submitted by the appellant identifies panencephalopathic CJD as a variant form of CJD, a "v-CJD." The August 2009 report from the National Prion Disease Pathology Surveillance Center identified sporadic CJD of the MV2 and MM2 classifications; panencephalopathic or variant CJD was not reported. As neither Kuru nor panencephalopathic or variant CJD was identified in the autopsy tissue analysis, the claimed presence of the Veteran in Guam and Japan does not make it at least as likely as not that sporadic CJD is related to service. Finally, the appellant also asserts that CJD could be related to the Veteran's oral surgery while in service and submitted a 2005 article stating that CJD is potentially orally transmissible via blood and that sterility from prions cannot be guaranteed even in "sterilized" medical and dental instruments. The neurologist who provided the May 2014 VHA opinion noted a thorough review of the Veteran's claims file - including service treatment records, which include a notation that the Veteran underwent oral surgery - and found "no significant information from the active duty records which might have bearing on the CJD." The Board finds the opinion of the trained medical professional who completed the VHA opinion based upon a review of the facts of the Veteran's case to be more probative than the appellant's lay statements and the 2005 article discussing the potential that CJD is orally-transmissible via blood, which raises only a speculative possibility of such a link in the Veteran's case. For the foregoing reasons, the preponderance of the evidence is against the claim for service connection for the cause of the Veteran's death. The benefit-of-the-doubt doctrine is therefore not for application, and the claim must be denied. See 38 U.S.C.A. § 5107(b); 38 C.F.R. § 3.102 ; see also Gilbert v. Derwinski, 1 Vet. App. 49, 54 (1990). ORDER Service connection for the cause of the Veteran's death is denied. ____________________________________________ SONJA A. MISHALANIE Acting Veterans Law Judge, Board of Veterans' Appeals Department of Veterans Affairs