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Brucellosis Eradication
Task Force Report The Brucellosis Eradication Task Force met on Tuesday, April 5, 2005 from
1:30 PM to 6:00 PM CST, during the NIAA 2005 Annual Meeting in St. Paul
Minnesota, with 34 people present. Dr.
Max Coats served as the Chair and the Vice-Chair Dr. Claude Barton was
unable to attend due to illness in the family The committee session focused on a variety
of topics related to the ongoing efforts to eradicate brucellosis in the
US. The
following speakers presented relevant information: Dr.
Debbie Donch, Brucellosis in Cattle: A View from USDA’s Veterinary: Her
presentation provided a summary of recently disclosed brucellosis infected
herds as well as projected dates when the two remaining Class A states
will be able to apply for class Free Status if no additional infected
herds are disclosed. Dr.
John Korslund, Swine
Brucellosis: Adapting the PRV Model: Dr. Korslund’s remarks included
a summary of the national status picture, Free status 49 states and stage
2 one state which is expected to apply for stage 1 (Free) status in the
next few months. During FY 2004 and FY 2005, three infected herd
situations were reported. On each in Georgia, Florida, and Hawaii. In
addition he described several weaknesses in the National surveillance
system. Some details of efforts underway to revise the UM&R were
presented. The proposed changes are expected to be completed this fall. Dr.
Ton Linefeld, Greater Yellowstone Area Brucellosis: Dr. Linfeld
presented an overview of the Greater Yellowstone Interagency Brucellosis
Committee which he chairs. Described were the composition, goals, mission
and objectives of the group. He reviewed the expired MOU and discussed the
status of efforts to establish a new document. The
replacement document is in the final phases of coordination and approval
and release of the completed document is expected in the very soon. The
past accomplishments of the Committee were presented along with a synopsis
of completed field studies, research projects. Planned activities were
described. The Montana, Wyoming and Idaho state plans were very briefly
presented. The next meeting of the GYIBC to be held in Jackson Hole, WY
May 24 and 35 was announced. Dr.
Jim Logan, A Brief Historical Perspective of Brucellosis in Wyoming and
Wyoming’s Brucellosis Surveillance and Response to the USDA Review:
Dr. Logan presented materials prepared by Dr. Barton who was unable to
attend due to a family illness. Background information including cattle
population and distribution was presented along with information on the
geological and environmental characteristics of the area. General
management practices and distribution on ranches was mentioned as well as
the distribution of significant wildlife populations. A brief synopsis of
the history of brucellosis in Wyoming was presented. The review process,
objectives and recommendations were outlined and the follow up review was
mentioned. Dr Logan’s presentation focused on Wyoming’s brucellosis
surveillance and response to the USDA review. He detailed the initial state response including the revision
of state regulations implementing change of ownership and first point of
concentration testing and mandatory Calfhood vaccination. Also testing of
all cattle that trailed through Grand Teton National Park was mandated.
Extensive public information and outreach efforts occurred. However in
1999 as a result of fading industry support, mandatory first point testing
was discontinued, change of ownership testing in the 5 highest risk
counties became voluntary. It was noted that the population of bison
increased from an estimated 320 in 1997 to approximately 1000 today. The
estimated seropositive rate is 70 %. The clear message is that the cattle
industry can only expected to manage the disease in the domestic
population and that elimination of the disease in the free ranging
population must occur if the disease is to be eliminated in cattle. Dr.
Dewayne Oldham, The State of Wyoming’s Response to the Reoccurrence of
Brucellosis in Cattle:
Dr Oldham’s presentation was in two parts the first was a review of
the Wyoming cattle brucellosis situation. After being free of cattle
brucellosis since 1975, four cases have been disclosed since November
2003. The first was detected by the slaughter surveillance system. The
initial herd testing December 2003 found 31 reactors and 20 suspects in a
herd of 395 cattle. The infection was confirmed by culture of B abortus
biovar 1 and the herd was depopulated in January 2004. Subsequent testing
of 11 contact herds containing 3972 cattle failed to disclose additional infection, however trace out
testing of 12 head that had been previously been sent to a feedlot
disclosed 6 reactors and as a result, Wyoming lost their ‘Free’
status. In June of 2004 a single animal in a group of 105 head being
tested prior to movement was test positive and subsequently found to be
infected with B abortus Biovar 4. Testing of the 3 contact herds found one
to also be infected with B abortus Biovar 4. Later in June 2004 a group of
50 head were tested at a market in SD and two were classified as suspects.
Samples frog the suspects were reported to be B abortus Biovar 1.
Extensive investigation followed and it appears that the cultures being
positive were due to a laboratory error. As a result of these events
Wyoming has increased their surveillance activities, increased the staff
of the Wyoming Livestock Board enhanced their communication and outreach
activities the Wyoming game and Fish Department has increased their
surveillance efforts. The Governor appointed a special group to study the
situation and make recommendations. Dr Frank Galey, Dean of the University
of Wyoming’s College of Agriculture was chosen to be Chair of the
Governors Brucellosis Coordination Team. Dr Oldham presented information
provided by Dr Galey who was unable to attend this meeting. The charge to
the team was to identify issues, best management practices and make
recommendations related to four topics. Those were: brucellosis in
cattle-regaining and maintaining brucellosis free status; provide a
roadmap for future cases: address human health; and reducing and
eventually eliminating brucellosis in wildlife paying special attention to
elk feed grounds. The ‘team’ was composed of 19 members and 10
technical advisors. The group sought broad based public input. They
developed 28 recommendations and rendered their report to the Governor on
11 January 2005. The implementation phase is underway and the team is
charged to reconvene annually. Dr.
Bret Marsh, Exploring New Solutions to Long-Standing Challenges: Brucellosis
in the GYA Dr.
Phil Elzer, Enhancing Brucellosis through Vaccine Research at LSU:
Dr Elzer provided an overview of the processes involved in developing
a brucellosis vaccine. Models currently in use include cattle, swine, and
goats. A brief description of methods of evaluating vaccine candidates was
provided followed by an explanation of the development processes. These
process included evaluation of he colonization activity of the candidate,
assessment of the pathogenesis and safety of the candidate and finally an
assessment of the efficacy of the vaccine candidate. Dr Elzer provided
some information on a broad range of candidate vaccines being considered.
They included assorted B abortus RB-51 derivatives, assorted B suis
VTRS-1derivtives, some B abortus mutant and ‘ghost’ candidates, and
candidates provided by other institutions from the US and overseas. Dr
Elzer stresses the need to be able to conduct large scale field trials as
part of a complete assessment of vaccines and that current regulations
are, on occasion making it necessary to conduct these activities overseas.
Dr.
Arnold Gertonson, Recent and ongoing Research Related to Brucellosis in
the Greater Yellowstone Area:
Dr. Gertonson presented information prepared by his colleague Dr Jack
Ryan. A study conducted to assess differing results observer with RB51 in
bison showed that the variable doses of vaccine did not produce the
observed variation in protection previously reported. Also described was a
study to begin this fall in elk using S19 , RB51, and ;superRB51. Work is
underway evaluating several immunocontraceptive vaccines in both elk and
Bison. Studies related to mechanisms of transmission have shown that
aborted fetal disappearance takes place in 1 to 3 weeks depending on the
time of year, while environmental persistence of Brucella abortus at the
site of a calving or abortion for 2 to 3 weeks dependant on weather and
ecological factors. A study to evaluate possible venereal transmission is
scheduled this fall and will employ S19 as a surrogate for field strain B
abortus. Inoculation by the ocular,
intrauterine and intravaginal routes will be employed in this study. A
quarantine feasibility study is set to begin this spring if the
appropriate animals are trapped. This project will involve 200 bison
calves that are tested negative at the time of capture. These animals will
be placed in a specially constructed facility, closely monitored, tested
multiple times and detained in the facility for 2 gestations. During the
project 100 animals will be necropsied and in all goes well 100 animals
will ‘graduate’. These animals will be placed in selected locations
but will continue to be followed for a period of 2 years. Dr.
Steven Olsen, Update on Brucellosis at
the National Animal Disease Center Dr.
Olsen briefly discussed the benefits achieved from the sequencing of the
Brucella genome. He indicated that several fragments are unique to B suis
and B melitensis. Information was presented on ‘fingerprint’ diversity
among isolates and how this information can be used in molecular
epidemiology assessments of a disease event. Old Business: New Business: All
previous resolutions and position statements related t this committee were
reviewed. Two were determined to be appropriate without change while
changes are recommended for three items. General discussion: Committee Session adjourned at 6:00 PM. |