DOI Artikel:
Smith, Theobald: The Department of Animal Pathology of the Rockefeller Institute, Princeton, N. J.
DOI Seite / Zitierlink: https://doi.org/10.11588/diglit.57254#0521
time, provided an example of these conditions. It was early found that besides the
dominant factor — B. abortus (Bang) — other subsidiary infectious microorganisms
were to be encountered. Among these were a vibrio, a mould, B. pyogenes, etc. Since
these were described they have been found under like conditions in countries other
than the United States. Their occurrence helps to interpret otherwise obscure diag-
nostic indications and to apply preventive measures.
Infectious abortion has recently taken on a new significance because of its re-
lation to undulant (Malta) fever in man. It was found that most of the human strains
of B. abortus resemble those found in swine. The discussions of the subject are
very active at the present time, and it seems not improbable (Smith) that swine
and even goat strains of B. abortus may, through the commingling of animals, have
become adapted to the udders of the cow. Probably the genuine B. abortus of cattle
does not produce true undulant fever. Another result of the investigation of
B. abortus has been the devising of the blood test, by the aid of which cows carrying
the microorganism may be gradually eliminated from the herd.
Hog Cholera and other Swine Diseases. Hog cholera has been studied inter-
mittently, and a fairly satisfactory method of protective immunization against the
filterpassing virus has been secured. When very severe epizootics arise, the highly
virulent virus is capable of breaking through the artificial protective mechanism.
Hence this investigation is being continued in Order to secure more resistant immuni-
zation. In the course of events, other infections have appeared in the immunized
swine, among which are destructive diseases induced by the hog cholera bacillus,
a paratyphoid strain of organism. The entire field of infectious swine diseases, owing
to their interrelations, calls for restudy. It is int eres ting to note that in 1918 a widely
prevalent disease appeared in the Western part of the United States (Iowa) which
bore certain clinical resemblances to human influenza and inflicted severe economic
losses. Each autumn since then the disease has reappeared and has spread rapidly.
Its economic importance arises less from its mortality (under 5 per Cent) than from
its retarding effects on the growth and maturing of the swine. Since this disease is
absent from the location in which the Department of Animal Pathology is situated,
it can be investigated more satisfactorily there than in the region of its endemic
occurrence and is now a subject of study (Lewis, Shope, TenBroeck).
Blackhead and other Poultry Diseases. Blackhead, a disease of turkeys some-
times affecting chickens, has also been investigated. The disease may be prevented
by rearing incubator hatched birds on soil not previously traversed by older birds.
Once connection with the older generation is severed, the disease does not appear.
Its parasitic incitant is a protozoan which multiplies in and destroys the mucous
membrane of the ceca, and invades and injures the liver. It was found that a round
worin (Heterakis) which inhabits the ceca of normal birds prepares the way, by
producing injury of the mucosa, for the inroad of the protozoan. Thus two distinct
parasites operate in succession in producing blackhead (Smith, Graybill).
In the course of modern food production, poultry are now reared in large flocks
to supply eggs and the animals themselves for human consumption, and thousands
of birds are confmed together. This has led to outbreaks of epidemic and endemic
diseases, which have become urgent objects of study. The field is a very large one,
since there is hardly an organ of the common fowl which is not the seat of some in-
503
dominant factor — B. abortus (Bang) — other subsidiary infectious microorganisms
were to be encountered. Among these were a vibrio, a mould, B. pyogenes, etc. Since
these were described they have been found under like conditions in countries other
than the United States. Their occurrence helps to interpret otherwise obscure diag-
nostic indications and to apply preventive measures.
Infectious abortion has recently taken on a new significance because of its re-
lation to undulant (Malta) fever in man. It was found that most of the human strains
of B. abortus resemble those found in swine. The discussions of the subject are
very active at the present time, and it seems not improbable (Smith) that swine
and even goat strains of B. abortus may, through the commingling of animals, have
become adapted to the udders of the cow. Probably the genuine B. abortus of cattle
does not produce true undulant fever. Another result of the investigation of
B. abortus has been the devising of the blood test, by the aid of which cows carrying
the microorganism may be gradually eliminated from the herd.
Hog Cholera and other Swine Diseases. Hog cholera has been studied inter-
mittently, and a fairly satisfactory method of protective immunization against the
filterpassing virus has been secured. When very severe epizootics arise, the highly
virulent virus is capable of breaking through the artificial protective mechanism.
Hence this investigation is being continued in Order to secure more resistant immuni-
zation. In the course of events, other infections have appeared in the immunized
swine, among which are destructive diseases induced by the hog cholera bacillus,
a paratyphoid strain of organism. The entire field of infectious swine diseases, owing
to their interrelations, calls for restudy. It is int eres ting to note that in 1918 a widely
prevalent disease appeared in the Western part of the United States (Iowa) which
bore certain clinical resemblances to human influenza and inflicted severe economic
losses. Each autumn since then the disease has reappeared and has spread rapidly.
Its economic importance arises less from its mortality (under 5 per Cent) than from
its retarding effects on the growth and maturing of the swine. Since this disease is
absent from the location in which the Department of Animal Pathology is situated,
it can be investigated more satisfactorily there than in the region of its endemic
occurrence and is now a subject of study (Lewis, Shope, TenBroeck).
Blackhead and other Poultry Diseases. Blackhead, a disease of turkeys some-
times affecting chickens, has also been investigated. The disease may be prevented
by rearing incubator hatched birds on soil not previously traversed by older birds.
Once connection with the older generation is severed, the disease does not appear.
Its parasitic incitant is a protozoan which multiplies in and destroys the mucous
membrane of the ceca, and invades and injures the liver. It was found that a round
worin (Heterakis) which inhabits the ceca of normal birds prepares the way, by
producing injury of the mucosa, for the inroad of the protozoan. Thus two distinct
parasites operate in succession in producing blackhead (Smith, Graybill).
In the course of modern food production, poultry are now reared in large flocks
to supply eggs and the animals themselves for human consumption, and thousands
of birds are confmed together. This has led to outbreaks of epidemic and endemic
diseases, which have become urgent objects of study. The field is a very large one,
since there is hardly an organ of the common fowl which is not the seat of some in-
503