HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Plastridge, W. N. Articles by White, G. C. Search for Related Content PubMed Articles by Plastridge, W. N. Articles by White, G. C.

Some observations on the eradication and control of Bang's disease

Departments of Animal Diseases and Dairy Industry, Storrs Agricultural Experiment Station, Storrs, Connecticut

ABSTRACT

During the period 1925–1939, the number of cows' blood samples tested annually increased from 2,373 to 42,700; the number of herds from 27 to 624; and the number of herds passing one or more negative tests from 4 to 473.

The average incidence of infection observed in infected herds at the time of the initial tests was found to be about 25 per cent.

The average number of suspicious reactors that became positive was 16.6 per cent in herds which were negative in the preceding test; 26 per cent in herds in which spread of infection was slow; and 63.6 per cent in herds in which spread of infection was rapid.

Of 149 infected herds, 64.5 per cent required from one to two tests for eradication; 22.7 per cent required from three to four, and 12.7 per cent, more than four tests.

The principal source of reinfection was found to be association with infected animals, either as the result of adding cows or bulls from untested or infected herds, or of animals breaking into or out of pasture. Association with infected horses or swine accounted for several "breaks," and in some instances available evidence indicated that infection resulted when people went directly from infected to negative herds.

Bacteriological examinations of fetuses and placental material obtained from 36 aborting cows in 24 herds which were free from Bang's disease, as shown by the standard tube agglutination test, were all negative for Brucella abortus.

In general, available information indicated that "breaks" are preventable. In about half of the reinfected herds, regular six-month retests detected new infection before it had a chance to spread to more than one or two animals.

At the present time many negative herds exist on farms which adjoin farms on which there are untested or known infected herds. As the eradication program progresses and sources of new infection are eliminated the number of "breaks" from these sources may be expected to decrease materially.