Imágenes de páginas
PDF
EPUB

Dr. MOHLER. The table referred to is as follows:

Bureau of Animal Industry-Progress in tick eradication July 1, 1906, to December 1, 1933

[merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small]

NOTE. No other areas released or requarantined during the calendar year 1933.

Mr. SANDLIN. There is not any doubt in your mind that there will be a complete eradication of cattle tick?

Dr. MOHLER. No, sir; none at all. I believe it is very easy now, if sufficient funds continue to be forthcoming. We have gone through the worst of our grief, because the people in the remaining infested territory are appreciating the benefits which are obtained as a result of tick eradication.

INVESTIGATION OF DISEASES OF ANIMALS

Mr. SANDLIN. The next item is diseases of animals, which is as follows:

Diseases of animals: For all necessary expenses for scientific investigations of diseases of animals, including the construction of necessary buildings at Beltsville, Maryland, the maintenance of the bureau experiment station at Bethesda, Maryland, and the necessary expenses for investigations of tuberculin, serums, antitoxins, and analogous products, $334,324: Provided, That of said sum $65,980 may be used for researches concerning the cause, modes of spread, and methods of treatment and preventlon of the disease of contagious abortion of animals.

Dr. MOHLER. The following statement is presented for inclusion in are printed hearings:

[blocks in formation]

Decrease, budget 1935, compared with estimated obligations,

1934.

$460,000

422,950

375,000

335, 046

334, 324

722

The reduction of $40,676 in the 1935 estimate of $334,324 below the appropriation of $375,000 for 1934 consists of:

Impoundment of 6%% of 15% pay cut..
Curtailment in 1934 working funds_-
Further reduction in working funds for 1935 ($3,000 for pathological
investigations of diseases of livestock, $1,000 for pathological in-
vestigations of diseases of poultry, $1,000 for pathological investi-
gations of stock poisoning by plants, $1,000 for investigation of
swine parasites, $3,000 for investigation of ruminant parasites,
$1,000 for investigation of miscellaneous parasites, $625 for inves-
tigation of treatment of livestock for internal and external para-
sites, and $5,000 for investigation and control of contagious abor-
tion of animals) __

5% salary restoration__

Total___

-$20, 704 -19, 250

1

-15, 625 +14, 903

-40, 676

CHANGE IN LANGUAGE

The change of language proposed in this item, whereby the words “and improvements" in line 4, and the words “and the necessary alteration of buildings thereon", are omitted, is submitted because it is anticipated that the bureau experiment station at Bethesda, Md., will be moved to Beltsville, Md., during the next 12 months. Improvements and alterations of existing buildings at the station will therefore be unnecessary.

WORK DONE UNDER THIS APPROPRIATION

The basic research and experimental work in animal diseases and parasites is conducted under this appropriation. It is essential to know the cause of disease and mode of dissemination, the life histories of parasites and their resistance to atmospheric conditions and chemicals before any effectual control or eradication methods may be devised and applied to either disease or parasites. This essential knowledge is gained only through research and experimentation.

ALLOTMENT OF P.W.A. FUNDS

Allotments under the National Industrial Recovery Act aggregating $347,980 have been made by the Public Works Administration for physical improvements, as follows:

(1), Maryland, Beltsville Farm, animal parasite studies: $82,980 for roads, repairs to buildings, fences, water system, clearing, new poultry parasite laboratory, animal shelters, an isolation laboratory, and a main laboratory building. (2) Maryland, Beltsville Farm: $265,000 for moving the animal disease research station from Bethesda, Md., and relocating this work at Beltsville, Md.

The reduction of $15,625 in working funds for 1935 includes:

(a) A decrease of $3,000 in pathological investigations of diseases of livestock.-This will be reflected in the inquiries on swine ehysipelas which have progressed to such a point that only a limited amount of study is now necessary to make certain refinements on the aggiutination test which has been developed in the last 2 years as a diagnostic agent.

(b) A decrease of $1,000 in pathological investigations of diseases of poultry.-Work in the past few years has developed a practical method of controlling and diagnosing pullorum disease. Limited investigations on the spread of the disease in adult birds are still in progress along with other minor phases of the inquiry.

(c) A decrease of $1,000 in the pathological investigations of stock poisoning by plants. This will be taken up by a reduction in the personnel engaged on the project.

(d) A decrease of $1,000 in the investigation of swine parasites.-This will be met by suspension of the research work on trichinosis on the ground that the study has been carried to such a point that immediate further investigation is not urgent.

(e) A decrease of $3,000 in the investigation of ruminant parasites.-This will be taken care of by a reduction in the expenses of travel and the purchase of equipment. (f) A decrease of $1,000 in the investigation of miscellaneous parasites.-This will be done by a lapse of salary consequent on an expected vacancy in the subproject on tapeworms.

A decrease of $625 in the investigation of treatment of livestock for internal and external parasites. Fewer experimental animals will be needed during the year on this project.

(h) A decrease of $5,000 in the investigation and control of contagious abortion of animals. It has been the practice to carry on this investigation in cooperation with the experiment stations of seven States, alloting a small sum to each. Certain phases of the inquiry have reached a point where these allotments may be reduced.

INFECTIOUS ABORTION OF CATTLE AND SWINE

The most important work we are doing under this appropriation is the investigation of Bang's disease or infectious abortion.

The Bureau has given attention to the investigation of this most troublesome and costly animal plague for a number of years. Greatly increased interest has been taken in the disease of late years. not only because a realization of the enormous losses which it causes, estimated to exceed $50,000,000 per annum, is becoming more general, but because of the discovery, made several years ago, that the malady in both cattle and swine has a significance for human health. Though the importance of this menace to public health has not yet been fully determined, the knowledge that such a danger exists has caused much uneasiness among dairymen, health officers, and the consumers of milk. The researches of past years, as well as those in progress, lead to the belief that much of the loss now caused by infectious abortion in both cattle and swine can be prevented and a large measure of protection afforded against whatever danger there may be to human health from the malady when additional facts have been discovered and promising methods of combating it, that are now under investigation, have been perfected.

Investigations already made have led to the discovery of many facts concerning the nature of the disease, its modes of transmission, times when animals are particularly susceptible to infection, locations of the causal agent of the malady (Brucella abortus) within the body, duration of its persistence there, and the channels and times of its elimination, all of which have had a direct and very important. bearing on formulating methods of combating the disease, and, in addition, furnished the ground work for further promising researches. Important facts pertaining to artificial immunization have also been discovered which promise to be of real value in controlling and eradicating the malady.

Significant facts concerning abortion of swine and its relation to that of cattle have also been brought to light, which are believed will aid in dealing with infectious abortion in the two species of animals. The Bureau's present studies of the disease concern a number of its phases and includes artificial immunization during calfhood and at maturity, both before and after conception; the degree of virulence Br. abortus, intended for immunization purposes, should possess for best results from the standpoints of efficacy and safety; the significance and value of serological tests in detecting infected animals and in controlling the malady; the length of time infected pastures remain infectious for susceptible cattle; the importance of the eye and skin as channels through which cattle may become infected; further studies as to the nature and effects of infectious abortion of swine and its relation to that of cattle. Methods of control by blood testing and the elimination or segregation of reacting animals and also by vaccination are being tried in the field, and abortions due to other causes than Br. abortus, a problem of no little concern, are receiving attention.

The Bureau is also engaged in conducting, cooperatively with eight State universities or experiment stations, studies of the following projects: Nutritional deficiencies and abortion; the immunity and carrier problem in bovine infectious abortion; the relative pro

ductivity of dairy cows affected with abortion disease as compared with those that are not; the elimination of abortion disease by blood testing and segregation of reactors and other sanitary measures; a herd survey of reacting animals to determine the relation of the titer of reactions to udder infection; studies in the use of avirulent strains of Br. abortus as immunizing agents; collection and study of Br. abortus cultures; studies of serological tests; the final development in those cattle reacting to agglutination test in low titers; the role of reinfection with Br. abortus of abortion reacting cows; the use of chemotherapy in combating infectious abortion and breeding of animals resistant to the malady. Important results have already come from these cooperative projects.

The investigations of the past have yielded rich returns for the funds expended. The Bureau's independent researches, as well as those in cooperation with several State universities and experiment stations for the present fiscal year, have had to be curtailed and important experiments suspended.

The need for intensive studies on infectious abortion was never greater than at present, as new promising leads are found. There is every reason for believing that future studies will be as fruitful as those of the past and even more so, because each new fact discovered adds to our equipment for bringing more of them to light. Mr. CANNON. How long are pastures dangerous when infected with this disease?

Dr. MOHLER. They are not usually dangerous longer than 60 days, unless you have pastures such as the places that I have spoken of in California, where the rain falls only during a certain season of the year and there is much loose, dry sand. You can see these cattle in these barren pastures standing in 3 or 4 inches of sand. This does not allow the sun and the light to get to the germs. Mr. THURSTON. Do the rains wash it off like they do on rolling pasture?

Dr. MOHLER. No, sir.

Mr. CANNON. Does this disease affect human health? Is it communicable to human beings as in the case of tuberculosis?

Dr. MOHLER. Oh, yes.

Mr. CANNON. That is strange, doctor, because a nursing calf does not contract the disease. The young heifers are not infected, if they are removed from their mothers before they reach puberty. Dr. MOHLER. That is true.

Mr. CANNON. How could the disease be communicated to individuals?

Dr. MOHLER. You cannot reason by an analogy like that. We do not know why, but nurslings do not always get the disease of their mothers. They are immune for a certain period. These calves that you speak of are only immune up to the time of puberty. You take a calf and test the blood and it is negative. Then put it out in the pasture with the rest of the herd and in due course have it served by a bull. If it is an infected herd, it probably will abort that first calf, because the germs do not show their presence until pregnancy occurs. What you say is absolutely true about your calves.

Mr. CANNON. The way we are combating the disease in our State is that we are segregating the infected from the uninfected animals. We allow the calves to remain with their mothers but before they

attain puberty, we remove them to fresh pasture, away from their mothers. Then that calf is absolutely free. That is invariably the case. That is the way we are preserving our fine stock. Where a cow has, after time, recovered, but is still a carrier, we take her calf and remove it any time before puberty. That calf is clear of the disease, no infection at all. In that way we are again building up our heads which have been devastated by this malady.

Dr. MOHLER. That is the kind of work that we are doing. We are investigating along those lines.

Mr. CANNON. I think I understand the point that you have made. Dr. Mohler. I see the fallacy of my reasoning. I was wrong about

that.

Dr. MOHLER. What you have said is correct about calves, however. As a rule, the udder is the reservoir for this germ up to the time of pregnancy. Then, for some reason, it has a predilection for the womb, the uterus, and it migrates to that point and causes abortion. The cow that you are speakikng of had a normal calf. How do you know she has Bangs' disease? As I understand you take the calf away before it comes in contact with the other diseased cattle. do you not?

Mr. CANNON. They recover, Dr. Mohler. Our experience is that they recover after they have had the disease, but they are still carriers and if left with the herd they will infect the whole herd.

Dr. MOHLER. That is right. You are doing a good thing there. Calves seem to have immunity up to a certain period, practically until puberty. You do not get a positive blood test on such calves except very rarely. Of course, if you take these healthy calves away from any infection, they remain free.

Mr. HART. But there is no certainty that they are free?

Dr. MOHLER. No: there is no certainty of it. However, that has no bearing on whether you or I or our babies, drinking milk from aborting cows, will not get that disease which is known in human medicine as undulant fever.

Mr. HART. I have heard that women have undulant fever.

Dr. MOHLER. In Iowa the State and Public Health Service have done a great deal of work. They tested the butchers in the different packing houses at Waterloo and Mason City, and found that a rather large percentage of the men who were handling live animals, especially the pigs, reacted to the blood test for undulant fever. Of course, the milk is not as dangerous as they thought was the case two or three years ago. If it were, we would all have undulant fever. because of the great percentage of abortion in the dairy herds of the country.

Mr. CANNON. Tuberculous infested milk is dangerous?

Dr. MOHLER. Yes: especially to children.

Mr. HART. Pasteurization will do away with that?

Dr. MOHLER. That is true. It will remove such a hazard. That is what we are recommending.

Mr. CANNON. Of course, the difficulty is that very little milk is pasteurized, that is consumed on the farm?

Dr. MOHLER. That is true.

a home-pasteurizing outfit.

It is difficult to take proper care of

« AnteriorContinuar »