Published Date: 2006-07-24 00:00:00
Subject: PRO/AH/EDR> Anthrax, bison, bovine - USA (SD)
Archive Number: 20060724.2044
ANTHRAX, BISON, BOVINE - USA (SOUTH DAKOTA)
A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
Date: Mon 24 Jul 2006
From: Sam Holland <Sam.Holland@state.sd.us>
Anthrax has again appeared in South Dakota livestock. Dr. Sam
Holland, State Veterinarian, reports the disease has struck a group
of unvaccinated cattle in Hyde County. The State Veterinarian was
called on Sun 23 Jul 2006, and the state veterinary diagnostic lab
confirmed the diagnosis on Mon 24 Jul 2006.
Dr. Holland reports the case involves a pasture containing a group of
approximately 100 unvaccinated cow-calf pairs with initial death loss
of 5 cows. "In spite of repeated recommendations, some producers fail
to preventively vaccinate their herds," says Dr. Holland. The
infected herd was scheduled to be immediately treated with
antibiotics, vaccinated and carcasses properly disposed of under the
supervision of the local veterinary practitioner and the Animal Industry Board.
Anthrax is a very serious quarantinable disease because it can cause
the rapid loss of a large number of animals in a very short time.
Animals are often found dead with no illness detected. Anthrax is
communicable to humans and other animals through carcasses, so strict
enforcement of quarantine and proper burning and burying of carcasses
suspected to have died from anthrax is important. Anthrax is not
usually spread from animal to animal, and quarantines are imposed to
prevent further soil contamination by movement of affected livestock.
Dr. Holland states producers and veterinarians have been urged to
make anthrax vaccination part of routine health programs. Not doing
so presents the risk of further environmental contamination, animal
and public health risks, fire risks, and associated costs.
Dr. Holland reports that anthrax spores survive in contaminated soil
indefinitely and that much of South Dakota has the potential of
experiencing an outbreak.
Significant climate changes such as drought, floods, and winds can
expose anthrax spores to grazing livestock. Alkaline soils, high
humidity and high temperatures present conditions for the anthrax
spores to vegetate and become infectious to grazing livestock.
Dr. Holland says he advised practicing veterinarians to be alert for
anthrax in his April and July 2006 newsletters. Rendering companies
have also been alerted so that carcasses are not rendered but
properly burned and buried on the farm.
Sam D. Holland, DVM
State Veterinarian, Exe. Secy.
South Dakota Animal Industry Board
411 South Fort St.
Pierre, SD 57501
[Sam added in his covering note: "What do you know!! Anthrax appeared
in an unvaccinated cattle herd -- 3 days later than our 1st case last
year  -- very hot and dry here. Flies are almost nonexistent. I
checked some of my cows in a pasture 20 miles east of here yesterday
when the temperature was 101 F, and I commented to the caretaker that
there were very few flies. He said it has been that way this year, no
need to gather and spray or pour the cows for flies!! The herd with
anthrax may have had access to a stubble field, and it may have been
slightly cultivated, so had minor earth moving, but basically very
hot as last year when anthrax started to show up."
Hot weather significantly reduces the innate resistance of grazing
livestock. This will theoretically reduce the effective ID50 needed
to infect an animal, and thereby more modest numbers of spores in the
soil can infect grazing animals, which otherwise would not be
affected. This, I have always presumed, is one of the key reasons why
anthrax occurs mainly in the hot summer months in livestock and
wildlife, quite apart from all the other factors. The 2 outbreaks in
drought-struck North Dakota have been singular without secondary
outbreaks. One can expect that the same will apply in South Dakota.
In my experience, any secondarily-affected animals in this Hyde
County herd are probably from licking any extravasated blood near the
primary case, because of the salt in that blood, plus bovine
curiosity to sample everything with their mouths. Many thanks to Sam
for sharing this information. - Mod.MHJ]