§3.307 Presumptive service connection for chronic, tropical or
prisoner-of-war related disease, or disease associated with exposure to
certain herbicide agents; wartime and service on or after January 1,
1947.

\(a\) *General.* A chronic, tropical, prisoner of war related disease,
or a disease associated with exposure to certain herbicide agents listed
in §3.309 will be considered to have been incurred in or aggravated by
service under the circumstances outlined in this section even though
there is no evidence of such disease during the period of service. No
condition other than one listed in §3.309(a) will be considered chronic.

\(1\) *Service.* The veteran must have served 90 days or more during a
war period or after December 31, 1946. The requirement of 90 days'
service means active, continuous service within or extending into or
beyond a war period or which began before and extended beyond December
31, 1946, or began after that date. Any period of service is sufficient
for the purpose of establishing the presumptive service connection of a
specified disease under the conditions listed in §3.309(c) and (e).

\(2\) *Separation from service.* For the purpose of paragraph (a)(3) and
(4) of this section the date of separation from wartime service will be
the date of discharge or release during a war period, or if service
continued after the war, the end of the war period. In claims based on
service on or after January 1, 1947, the date of separation will be the
date of discharge or release from the period of service on which the
claim is based.

\(3\) *Chronic disease.* The disease must have become manifest to a
degree of 10 percent or more within 1 year (for Hansen's disease
(leprosy) and tuberculosis, within 3 years; multiple sclerosis, within 7
years) from the date of separation from service as specified in
paragraph (a)(2) of this section.

\(4\) *Tropical disease.* The disease must have become manifest to a
degree of 10 percent or more within 1 year from date of separation from
service as specified in paragraph (a)(2) of this section, or at a time
when standard accepted treatises indicate that the incubation period
commenced during such service. The resultant disorders or diseases
originating because of therapy administered in connection with a
tropical disease or as a preventative may also be service connected.
(Authority: 38 U.S.C. 1112)

\(5\) *Diseases specific as to former prisoners of war.* The diseases
listed in §3.309(c) shall have become manifest to a degree of 10 percent
or more at any time after discharge or release from active service.
(Authority: 38 U.S.C. 1112)

\(6\) *Diseases associated with exposure to certain herbicide agents*.

\(i\) For the purposes of this section, the term *herbicide* *agent*
means a chemical in an herbicide used in support of the United States
and allied military operations in the Republic of Vietnam during the
period beginning on January 9, 1962, and ending on May 7, 1975,
specifically: 2,4-D; 2,4,5-T and its contaminant TCDD; cacodylic acid;
and picloram. (Authority: 38 U.S.C. 1116(a)(4))

\(ii\) The diseases listed at §3.309(e) shall have become manifest to a
degree of 10 percent or more at any time after service, except that
chloracne or other acneform disease consistent with chloracne, porphyria
cutanea tarda, and acute and subacute peripheral neuropathy shall have
become manifest to a degree of 10 percent or more within a year after
the last date on which the veteran was exposed to an herbicide agent
during active military, naval, or air service.

\(iii\) A veteran who, during active military, naval, or air service,
served in the Republic of Vietnam during the period beginning on January
9, 1962, and ending on May 7, 1975, shall be presumed to have been
exposed during such service to an herbicide agent, unless there is
affirmative evidence to establish that the veteran was not exposed to
any such agent during that service. The last date on which such a
veteran shall be presumed to have been exposed to an herbicide agent
shall be the last date on which he or she served in the Republic of
Vietnam during the period beginning on January 9, 1962, and ending on
May 7, 1975. *Service in the Republic of Vietnam* includes service in
the waters offshore and service in other locations if the conditions of
service involved duty or visitation in the Republic of Vietnam.
(Authority: 38 U.S.C. 501(a) and 1116(a)(3))

\(b\) *Evidentiary basis.* The factual basis may be established by
medical evidence, competent lay evidence or both. Medical evidence
should set forth the physical findings and symptomatology elicited by
examination within the applicable period. Lay evidence should describe
the material and relevant facts as to the veteran's disability observed
within such period, not merely conclusions based upon opinion. The
chronicity and continuity factors outlined in §3.303(b) will be
considered. The diseases listed in §3.309(a) will be accepted as
chronic, even though diagnosed as acute because of insidious inception
and chronic development, except:

\(1\) Where they result from intercurrent causes, for example, cerebral
hemorrhage due to injury, or active nephritis or acute endocarditis due
to intercurrent infection (with or without identification of the
pathogenic micro-organism); or

\(2\) Where a disease is the result of drug ingestion or a complication
of some other condition not related to service. Thus, leukemia will be
accepted as a chronic disease whether diagnosed as acute or chronic.
Unless the clinical picture is clear otherwise, consideration will be
given as to whether an acute condition is an exacerbation of a chronic
disease. (Authority: 38 U.S.C. 1112)

\(c\) *Prohibition of certain presumptions.* No presumptions may be
invoked on the basis of advancement of the disease when first definitely
diagnosed for the purpose of showing its existence to a degree of 10
percent within the applicable period. This will not be interpreted as
requiring that the disease be diagnosed in the presumptive period, but
only that there be then shown by acceptable medical or lay evidence
characteristic manifestations of the disease to the required degree,
followed without unreasonable time lapse by definite diagnosis.
Symptomatology shown in the prescribed period may have no particular
significance when first observed, but in the light of subsequent
developments it may gain considerable significance. Cases in which a
chronic condition is shown to exist within a short time following the
applicable presumptive period, but without evidence of manifestations
within the period, should be developed to determine whether there was
symptomatology which in retrospect may be identified and evaluated as
manifestation of the chronic disease to the required 10-percent degree.

\(d\) *Rebuttal of service incurrence or aggravation*.

\(1\) Evidence which may be considered in rebuttal of service incurrence
of a disease listed in §3.309 will be any evidence of a nature usually
accepted as competent to indicate the time of existence or inception of
disease, and medical judgment will be exercised in making determinations
relative to the effect of intercurrent injury or disease. The expression
"affirmative evidence to the contrary" will not be taken to require a
conclusive showing, but such showing as would, in sound medical
reasoning and in the consideration of all evidence of record, support a
conclusion that the disease was not incurred in service. As to tropical
diseases the fact that the veteran had no service in a locality having a
high incidence of the disease may be considered as evidence to rebut the
presumption, as may residence during the period in question in a region
where the particular disease is endemic. The known incubation periods of
tropical diseases should be used as a factor in rebuttal of presumptive
service connection as showing inception before or after service.

\(2\) The presumption of aggravation provided in this section may be
rebutted by affirmative evidence that the preexisting condition was not
aggravated by service, which may include affirmative evidence that any
increase in disability was due to an intercurrent disease or injury
suffered after separation from service or evidence sufficient, under
§3.306 of this part, to show that the increase in disability was due to
the natural progress of the preexisting condition. (Authority: 38 U.S.C
1113 and 1153)

\[26 FR 1581, Feb. 24, 1961, as amended at 35 FR 18281, Dec. 1 1970; 39
FR 34530, Sept. 26, 1974; 43 FR 45347, Oct. 2, 1978; 47 FR 11655, Mar.
18, 1982; 58 FR 29109, May 19, 1993; 59 FR 5106, Feb. 3, 1994; 59 FR
29724, June 9, 1994; 61 FR 57588, Nov. 7, 1996; 62 FR 35422, July 1,
1997; 67 FR 67793, Nov. 7, 2002; 68 FR 34541, June 10, 2003\]

**Supplement *Highlights* references**: 7(8), 10(1), 12(1), 24(3),
30(1), 56(2), 57(1).

Reserved