Report on the Agricultural Experiment Stations, 1953 Page: 24
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24 REPORT ON EXPERIMENT STATIONS, 1953
Since spread of the disease-this is also true of several others of a
serious nature-is primarily tied in with the practice of feeding raw
garbage to hogs, recommendations for curbing or controlling this
practice have been made and are receiving favorable attention in most
States. Meanwhile, the California station, in cooperation with the
Department and with veterinarians of the California State Department
of Agriculture, is conducting studies on the problem. A new
complement fixation test developed in the past year by the California
station is providing ready identification of all available types of
vesicular exanthema virus. This makes it possible to identify the disease
without resorting to animal inoculations, a time-consuming and
costly process, since swine are the only known readily susceptible
animals. The test is performed with vesicular material collected from
hogs in the field, and the results can be obtained within 24 hours.
Meanwhile, the station is not overlooking the possibility of finding
a small animal that might prove to be a suitable host for the virus.
They have found that dogs exposed by tongue (intradermal lingual)
injections of the virus were irregularly susceptible to A, B, and F types.
Four immunologically distinct types of the virus have been reported
previously in California, but only three types A, B, and F, have been
isolated recently. Samples originating in the Midwest without exception
were found to be due to type B virus. This station has shown
that hogs which have been infected with one type of vesicular exanthema
virus can later be infected with another type. Promise of a
successful adaptation of the test for specific identification of vesicular
exanthema will provide a less time-consuming and less expensive
method of differentiating between it and foot-and-mouth disease.
This is an important contribution when one considers the ever-present
threat of possible outbreaks of the latter disease and the fact that it
must always be considered as a possibility when vesicular exanthema
Diseases of Sheep
Listeriosis of sheep
During the 20 years that have elapsed since Listeria monocytogenes
was shown to be the cause of circling disease or listeriosis in sheep,
this disease has become of increasing economic importance. Losses
from the nervous form of the disease or from abortions may at times
be very high. Listeriosis appears to be spread from flock to flock
through the transfer of carrier sheep that apparently show no symptoms
of the disease. Limited experiments conducted at the North
Dakota station show that bacterins prepared from killed listeria
organisms will protect sheep against the disease under farm conditions.
The Nebraska station reports that three types of infection with
listeria can be distinguished in experimental and natural listeriosis
of sheep. In one type the infection is confined to the brain, in the
second both brain and visceral organs are involved, and in the third
type the infection exists in visceral organs only. The station also
reports that considerable evidence has accumulated to associate the
feeding of silage with outbreaks of natural listeriosis. Although this
relationship has not been conclusively demonstrated, many lamb
feeders exclude silage from their rations because of the risk involved
in feeding it.
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United States. Office of Experiment Stations. Report on the Agricultural Experiment Stations, 1953, book, 1953; Washington D.C.. (digital.library.unt.edu/ark:/67531/metadc5989/m1/26/: accessed October 24, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.