- !1. 1907. U. S. DEPARTMENT OF AGRICULTURE, i ~ = BUREAU OF ANIMAL INDUSTRY. BULLET! Q ^^^^Z = A. D. MELVIN, CHIEF OP BUMAU. 1 = 9 = 6 = THE DANGER FROM TUBERCLE BACILLI IN THE ENVIRONMENT OF TUBER- CULOUS CATTLE. BY E. C. SCHROEDER, M. D. V., Superintendent of Experiment Station, AND W. E. COTTON, Expert Assistant at Experiment Station WASHINGTON: GOVI-.KNMI \ 1 I'KINTING Issued May 11, 1907. U. S. DEPARTMENT OF AGRICULTURE, BUREAU OF ANIMAL INDUSTRY. BULLETIN No. 99. A. D. MELV1N, CHIEF OP BUKEAU. THE DANGER FROM TUBERCLE BACILLI IN THE ENVIRONMENT OF TUBER- CULOUS CATTLE. BY E. C. SCHROKDER, M. D. V., Superintendent of Experiment Station, AND W. E. COTTON, Expert Assistant at Experiment Station WASHINGTON: GOVERNMENT PRINTING OFFICE. 1907. BURIAU OF ANIMAL INDUSTRY. Chief: A. D. Mu\i.\. Aatixtiint Chirf: \. M. KARKIMJTHN. fit ii-f f/./A: K. r.. .IMM R, niin-hi-iiii<- IHrixiwi: M. I><>IOM. .hiff: JAMKS A. I:\IKKV. :i^i-ttiii iH'risitin : KICK I'. STKDIMIM. chief; MUKKIS WIMHH-N. -hief. rnthitlnijirnl Itirixinn: JoN K. Moinn;. chief; IlENBY J. WAMIHUEN, nit rllH'f. ViKinintini Itirix'mn: UICHAKD W. HICKMAN, chief. Itirininn nf '/,<>ol< rinti n ihut: ]'.. r. SCIIKOKDEB. \xxixtnnl: \\. K. Cm i. >v 2 LETTER OF TRANSMITTAL. U. S. DEPARTMENT OF AGRICULTURE, BUREAU OF ANIMAL INDUSTRY, Washington, D. C., April 4, 1907. SIR: I have the hon6r to transmit herewith, and to recommend for publication as Bulletin No. 99 of this Bureau, an article entitled " The Danger from Tubercle Bacilli in the Environment of Tuber- culous Cattle," by Dr. E. C. Schroeder and W. E. Cotton, of the Bureau Experiment Station. The investigations with which the article deals show that tuber- culous cattle, before they lose their general appearance of health, often pass feces heavily infected with tubercle bacilli, and that the same is true of healthy cattle that are permitted to swallow tubercle bacilli in their feed or in their drinking water. When test animals arc inoculated with such feces, or with milk soiled with such feces, they commonly become affected with tuberculosis. The work as a whole shows that the general condition or appear- ance of a tuberculous animal gives no indication as to the time when it w T ill begin to distribute tubercle bacilli #nd become dangerous; that the milk from all tuberculous cattle, irrespective of the condi- tion of their udders, should be regarded as dangerous, and that even the milk of healthy cows if it is drawn in the environment of tuber- -culous cattle may contain tubercle bacilli. Since the tuberculin test is the only practical means of detecting tuberculosis in the live animal before an advanced stage is reached, the importance of testing dairy cows with tuberculin and removing every reacting animal is again emphasized. Respectfully, A. D. MELVIN, Chief of Bureau. Hon. JAMES WILSON, Secretary of Agriculture. CONTENTS. rase. Introduction 7 Description of cattle used in experiments 8 Examination of feces for tubercle bacilli 8 Microscopic examinations 8 Inoculation tests with guinea pigs 9 Summary of feces examinations 11 Tests of saliva, nasal discharge, urine, and milk 11 Feces in milk the real danger from tuberculous cattle 13 Persons probably contract tuberculosis chiefly by ingestion IT Infectiousness of soiled milk shown by inoculation of guinea pigs 18 Additional feeding and inoculation tests 21 Conclusions 22 THE DANGER FROM TUBERCLE BACILLI IN THE ENVIRONMENT OF TUBERCULOUS CATTLE. INTRODUCTION. The manner in which tubercle bacilli are thrown out by and reach the environment of persons affected w r ith tuberculosis has been care- fully studied ; consequently, we know with practical certainty that all cases of human tuberculosis may be divided into two classes " open," or dangerous, and " closed," or less dangerous. A " closed " may at any time become an " open " tuberculosis, but it is from the latter only, which includes all persons whose lungs, air passages and im- mediately related structures are affected, that tubercule bacjlli are disseminated in a way dangerous to health. This is the view sanc- tioned by Dr. Robert Koch in his " Nobel lecture," delivered at Stockholm on December 10, 1905. Concerning tuberculous animals our knowledge is not so definite, but it is of the highest importance that we should know how tubercle bacilli are scattered by them, too, not that we may establish an " open " and a " closed " class, but to enable us to know how we can best prevent the transmission of tuberculosis from animal to animal and from animal to man. Many prominent investigators are convinced that tuberculosis of animals constitutes a serious danger for man ; others are not ; but all agree that it is an occasional danger, more frequently for children, whose diet consists largely of milk, than for adults. While this mat- ter awaits a solution and there is not perfect harmony among au- thorities, we may reasonably assume that it is better to guard against exposure to infectious material scattered by persons and animals than only against that scattered l>y persons. Protective measures that take into account the clearly defined menace and neglect the highly probable danger are insufficient, especially when the probable danger is, as in this case, believed to be actual by many men who are compe- tent to judge. But even if persons are eventually shown to be comparatively safe against infection from tuberculous animals, the manner of dissemina- tion is nevertheless an important economic problem, because animals have been repeatedly shown to l>e more susceptible to tuberculous in- o Translation in the Lancet of MM\ *\. 1900. 8 DANCKIt Ht.'M I I I - < \ I I f I . I'.-ction from animal- than from man. ami t iiU-milo-i- amon;: animal- is, from tin- stock owner'- point of view, one of the MT\ nrioOl c..n ditions with which tin- animal indu-trv ha- to .leal. In (hi- article are recorded son l-er\ ;i( i..n- on the tuU-rde liacilli expelled h\ cattle, and an attempt i^ made to -how hou the-e bacilli may U- scattered and In-come a great danger to animal-, and. as We lH'lie\e. al-n to man. DESCRIPTION OF CATTLE USED IN EXPERIMENTS. The cattle from which the material wa- olitained for the ol.-er\a- tion- require the following short d.-cri|)t ion : Cow No. 1 ha- Keen allected with tuln-rcido-i- for -everal year-. A-ide from a tuberculin te-t. which showed her to be tuleivuloii-. tliere i- nothing in her condition that would condemn her for use as a dairy cow. Cow No. 11. *l i- allected with advanced t iil>ercido-i-. She i- -till alive, quite thin, and has a severe and frequent cough. Cow-. No-, si. :')7I. and '.\*\ are three healthv animal- that \\.-re ^ fed a -mall amount of culture of tubercle l)acilli daily in tlu-ir drink- ing water during the time the ol>-ervatierculo-i- : they ai'e living, and the knowledge that they are t uU-rculoii- i- la-e.| entirely on a tuberculin te-i. Cow No. :U'J was found on autopsy to have a tul>cividoii- all'ection limited to one post-pharyngcal lymph gland. Cow No. 3~'.\ was found on autopsy to IK' affected with tulerculo-i- of the lung and liver and the mediastinal. portal, and me-enteric Ivinpli glands. The le-ioii- wei'e widely -cattered. luit not exten-ive. Cow No. 47<) is living, is in good condition, and \\a- u-ed until recently, and would be in use now. a- a private family cow. if a tuU'i-culin test had not .-hown that she i- a fleeted with tuln-milo-i-. EXAMINATION OF FECES FOR TUBERCLE BACILLI. Ml. It. . \-. Small portions of fe.-e-. taken at random from the interior of ma e- fre-ldy |>a e.| \<\ \\\<- cattle, unv -mrarcd "ii linn BqiUtW "f glass, which an- generally known in connection with microscopic work as cover-glasses. Similar preparation- were made with material gently scraped from the nmcoii- -urface. ju-t in-ide the anal orifice, of the rectum. The cover -gla e- \\ere dried, stained, and examined micro-copically. Tho-e made with material from tin- following cattle were found to contain bacteria identical in appear- ance with tuln-ivle bacilli: No-. 1. M. 11:'.. ,. :',7l. and IT*',. INOCULATION TESTS WITH GUINEA PIGS. 9 The number of bacilli per cover-glass varied with different cattle, and on different days with the same animal, from to 25, and were usually a little more numerous in the rectal scrapings than in the feces. . In some cover-glasses made with shreds of mucus picked from the feces the bacilli were much more numerous and in some instances innumerable. Cover-glass preparations similarly made with feces and rectal scrapings from nontuberculous cattle were found to be free from any- thing resembling tubercle bacilli. \Vith a simple microscopic examination it is difficult to distinguish between tubercle bacilli and some harmless micro-organisms known as acid-fast bacteria. At first it was believed that the bacilli in the preparations belonged in whole or in part to the latter group, but this view was not tenable after it was discovered that similar bacilli could not be found in material from nontuberculous cattle. INOCULATION TESTS WITH GUINEA PIGS. To establish absolutely that the bacilli were virulent tubercle germs, a series of inoculation tests with small animals was undertaken. Two lots of guinea pigs were inoculated from each of the following cattle: Nos. 1, 84, 113, 325, 373, 374, and 384, one lot with feces and the other with scrapings from the rectal mucosa. Cattle Nos. 329 and 372 were omitted from the inoculation experiments, as they had given negative results with microscopic examinations, and cow No. 47<> was received too late to be included. The guinea pigs were inoculated under the skin on the inside of the right thigh; each received an amount of material equivalent in weight to about one-eighth of a grain, and more than 25 per cent of them became affected with septicemia and died before a tuberculous affection had time to develop. The results obtained with the animals that lived long enough to contract tuberculosis are as follows: Cow No. A Guinea pigs inoculated April 28, 1906, with feces did not become tuberculous ; those inoculated on the same day with scrap- ings from the rectal mucosa were found on post-mortem examination to be affected with tuberculosis. Guinea pigs inoculated June 19, 190C), with feces, as well as those inoculated with scrapings from the rectal mucosa, were found on post-mortem examination to be affected with tuberculosis. Guinea pigs inoculated June 27, 1900, with feces, . M' ntOM i i in i: ri.nrs dell. M!,- I. I 1't.r the pre-elice (if tubercle bacilli, ami (hi- i- In iiearh tin- -MUM- -\trnt true of material -craped from the i-eeial iiiii<-<,-:i. \\ hieli i- colllpo-ed largely of feee-. Cattle feee- are a complex -llb-taiicc relati\e to the number ami different kind- of bacteria contained. Each inoculation i- followed by a local inflammation and -uppuration. ainl hence the tuU'ivIe liacilli that are |ire-ent. if their numler i- fe\\. have every chance to U> overcome by more rapidly growing organism-. The pathological condition- produced ly the latter may in thetn-elve- lie -llllicielit to prevent the tllliercle liacilli from e-tali li-hing them-elve.-. That the acid-fast bacteria oh-erved in the feees of co\v No. 1 are certainly infectious tubercle bacilli i- demon- -t rated absolutely by tin- occurrence of tnl>crciilo-U amon^ the guinea l>i^. That the feces and the scrapings from the rectal mnco-a inoculated into guinea pi;:- that remained free from tnlx-p culosis did not contain infectious tubercle bacilli can not IM- averted positively. Itis(|iiite likely that the liacilli were pre-ent but did not have a chance to ^\ actually into the ti ue-. and thi- view i- -up- ported by the fact that acid-fast bacteria were shown to IK- pre-ent in the feces of the cow on each of the three days on which the inocu- lations were made. Coir No. 84- Guinea pi^T* inoculated May '2, !!'<)'.. with feee- did not U'come tuberculous: those inoculated with -craping from the rectal mucosa were found on post-mortem examination to be a fleeted with tuberculosis. Guinea pi<:s inoculated on other day> from this cow died affected with septicemia Ix'fore taberctlloafl had time to develop. ^^ Caw No. 11-L Guinea piirs inoculated with either feces or >crap ings from the rectal mucosa on April -_'7. I'.KM'I; June !'., HHMl, and June "27. r.KX'i, were all found on post-mortem examination to be affected with tulx-rculo-i-. Cows Nos. 325, 373, 374, and 384- Guinea pigs inoculated with feces and >craping> from the rectal muco-a either died from ->-\> ticemia before tulx-rculo-i- had time to develop or were found to IK' free from le-ions of tul>erculo-i> on po-t -mortem examination. It wa- -howii in anothei- experiment ' : that the acid-fa-t bacteria micro-copically demon-t rated in the feee- of cow- No-. :',7l and :'.M were virulent tuU'rcle bacilli. The feces in the experiment referred to were fed to four hogs with the re-ult that three of them became affected with tulx-milo-i-. The rea-on- why the incr of guinea pig- for long p riod- of lin.r. ami other guinea pig- \vere injected with it. intra-abdominally. from time to tinir. without causing di-ea-e >f any kind. Tin- urine of the rows was drawn from their Madder- through a catheter with anti-eptic precaution- and placed for thirty minutes in the tubes of a small electrical centrifugal machine that n 2,000 revolutions per minute. As the spcci'ic gravity of tubercle bacilli i> comparatively lii^ r h, had any IM-CII present in the urine thi- trrati'inent would have thrown them to the Imttnm of the tulns ( )nly the lower third <>f the urine in each tube v. for i i:dcause the location of the na-al chambers seems well adapted for their frequent infection with ma- terial expelled from the lung. Cow No. \\:\ sutlers with frequent severe paroxysms of coughing, during which her mouth is open and the air is largely, if not wholly, impelled through it. This ma\ count for the presence of tulxrcle bacilli in her saliva and their absence from her nasal discharge. Subsequent niicrowoplr oxaniinntioiiH of the suliva of cow No. ll.'J. In cover-Klafwra made from the WMliinent in tubes in \vhieu It was mlx^l with normal ttalt rotation aud then centrifugalized. showed the presence of tul>-r. ! bacilli. THE REAL DANGER FROM TUBERCULOUS CATTLE. 13 Cow No. 1 is much less severely affected than No. 113, and the ab- sence of positive results from inoculations with her saliva and nasal discharge is attributed to the infrequency and mildness with which she coughs. Her cough is rarely more than a gentle effort to clear her throat, and any substance expelled from her lung would barely pass her fauces and would be swallowed without reaching the for- ward portions of her mouth. The regurgitation and remastication of food that is practiced naturally by ruminants would tend to clear her throat as much as to infect it with swallowed infectious material. The infectious material expelled from the lung and swallowed does not necessarily lodge in the rumen, from which regurgitation takes place, and certainly does not become as thoroughly and evenly mixed with the contents of the rumen as it is with the feces. The absence of positive results from the inoculations and feeding tests with milk is in perfect harmony with the writers' past experi- ences with milk from tuberculous cows with healthy udders when the milking is done with proper care against the introduction of infec- tious material that is not associated with the interior of the udder or the milk-secreting structures. The danger that milk may become infected from the environment of tuberculous cows is so great that we are justified in asserting that the few positive results we have had during many years with intra-abdominal injections of guinea pigs with milk from tuberculous cows with unaffected udders were not due to tubercle bacilli that were drawn with the milk, but to tubercle bacilli that dropped into it or into the milk pail from the exterior of the cow, despite all precautions to the contrary. Since it does not seem reasonable for tubercle bacilli to leave the body with the urine unless the genito-urinary apparatus is affected, similarly it does not seem reasonable for them to pass out with the milk through a healthy udder. FECES IN MILK THE HEAL DANGER FROM TUBERCULOUS CATTLE. The results of the tests point to the conclusion that the real danger from tuberculous cattle lies in the manner in which tubercle bacilli are disseminated with their feces. The average number of acid-fast bacilli found in the feces of tuberculous cattle leaving the greater number in the rectal scrap- ings and selected shreds of mucus out of consideration is 6 per cover-glass. That these bacteria are tubercle bacilli has been suffi- ciently demonstrated by the positive results obtained with the inocu- lation tests and by their absence from the cover-glasses prepared with the feces of nontuberculous cattle. Now, let us calculate what this signifies as to the amount of infection that may be scattered by a single tuberculous cow in one day. 11 DANGER FKnM II i:l K< I'I. )f8 CATTI.I The cover ula-- e- u.i, ,;n, fiillv \\eighed on a delicate balance U'fore ainl after -preading a layer of feces on them. The am it of moi-t free- per cover-glass was found to have a maximum weight of one thirtieth of a grain: il \\a- usually I*-, ami frequently not more than one-half as much. When OIK- of the prepared CO\.T irla e- i- c\aiiiiii*o! with the microsco|M i the lir-t condition noticed i- that only a portion of it. rarely one half, i- -ullicieiit ly Iran-parent for the detection of tulxTclr liacilli. It is reasonable to assume that the thicker, opa<|iie portion- of the lilm of feee- are heavier and con- tain a luger number of bacilli than the lighter, transparent portion-: hence, the tulierele bacilli that come into view after prolonged -earch are less than half the number actually pre-ent. To one who is familiar with microscopic work it would not ap|>ear unreasonable if we made the flat a ertion that it is impos-ible to find more than 1<> IXT cent of the tul>ercle ;erms that are present in cover-jrlasx- of the kind we made for our examinations. But it is not necessary to present the fact in this extreme. If we take only the actual av-r- age number of tubercle bacilli -ecu, and the maximum weight of feces per cover-glass, we have 6 bacilli in one-thirtieth of a grain of feces, and we can not avoid feeling amazed at the amount of infec- tion which this represents as leaving the body of a tuberculous cow daily. A cow of average size passes about 30 pounds of moist feces each day, and if the whole of this mass could IK- -pread on cover-glasses similar to our preparation, it would be sufficient to make 6,300,000 preparations, which would contain 37,800,000 microscopically de- monstrable tubercle bacilli. It is a significant fact that our microscopic examination- indicate that the bacilli in the feces. excepting tho>e in the >hred- and masses of mucus that do not enter into the pre-ent calculation, are evenly distributed, so that we do not have -ome portions of the feces that are very infectious and others tht are innocuou-. Practically it i- all infectious, and every part of it is dangerous, and the mucus -bred- alone show extreme infect iousness. The even distribution of the bacilli likewise indicate- that they entered the inte-tine at the upper end of the digestive tract, as a considerable amount of churning. such as the food receives in the stomach and intestines, is required to effect this distribution. Tuberculous persons from whom tuU'rde bacilli are U'ing dissem- inated can lie taught to use various precaution- that will reduce to a minimum the danger to health in their environment. Sputa can be expectorated into receptacles containing germicidal fluids, and a cloth can IK* held liefore the mouth during paroxy-m- of coughing and at once treated so as to destroy the infectious material that i- HOW MILK IS INFECTED WITH TUBERCLE BACILLI. 15 impelled against or into it. Such persons can have individual sleep- ing apartments, and they should be prevented from coming into con- tact with articles of diet that are used by healthy persons. Their own individual generosity, when they are informed of their condi- tion and its danger to health, will with rare exceptions induce them to take many precautions for the safety of their families and associates. Healthy persons, when they are informed of the danger involved in close contact with those affected with tuberculosis, and know that a chronic cough must be regarded as a very suspicious circumstance, can do much for their own protection by avoiding association on terms of close intimacy with persons who are actually or probably tuberculous. With cattle we have a different state of affairs. Effective germi- cidal substances are too expensive and their proper application to large masses of feces daily is too difficult and troublesome for prac- tical purposes. Feces are dropped everywhere in the environment of cattle in stables, fields, and barnyards, and on roadways. They are splashed on the bodies of cattle, and frequently cattle lie down and get their bodies coated with them, and this is especially true of the parts of the body close to the udder. Feces are thrown against partitions of stalls and walls of stables and are promiscuously switched about by the soiled tails of animals, and no precaution or measure of cleanliness can entirely prevent them from getting into the milk pail occasionally and on the hands and clothing of the stable attendants and milkers frequently. We have seen large quantities of milk strained in many dairies, but have not found the dairy in which the milk was removed from the cows with a degree of cleanliness so per- fect that the cloth or screen through which it was strained did not show the presence of some cattle hairs and fragments of a substance suspiciously like feces. In some dairies the quantity of feces that enters the milk pail, both fresh and dry, to judge from that which collects in the strainer through which it is poured, is comparatively large. The precautionary measures that can be used by the dairy- man are limited by the price of milk. He can not afford to use meas- ures the cost of which is so great that their application would convert his business into a philanthropic enterprise. Regarding the dairy industry, we know the two following impor- tant facts: (1) That the commonest disease with which cows are affected is tuberculosis, and (2) that milk in some form reaches prac- tically all persons. The person who does not use milk, cream, butter, or cheese is a rare exception to a general rule, and the family that uses no fresh dairy product can hardly be said to exist. When we know how completely cattle feces may be charged with tubercle bacilli and how easily milk may be infected from this 1 ' I'AM.I.K I IK'.V | 1 r.| RCrUU' -oiirce, and contemplate thi- fad. keepm;.' in mind tin- wide di-tribii lion that dairy product* hav>. nnl add to our knowledge -ome of tin- re-ult- recent 1\ obtained and puUi-hed by competent in\ . i i-;ii,.r-. we mii-t conclude that the eradication '' t ubeivulo-i- aiming cattle can not U too vi^oroii-lv urired or pursued. <)iiro\\n investigation- ha\e-hown that pulmonary t iiberculo-i- i~ the mo-t common form of the di-ca-e in animal-, irre-pedive of the point at which the tuberculous infection enters the body, and that tubercle Imcilli may pa through the inte-tinal wall and reach the lnnr without caii-ini: \i-iUe di-ease of (lie inte-tinal nm< Nicholas and Dex-os and IJavenel |>rovcil ly feeding healthy dojrs on tnU'rciiloii- fluids and examining the chyle in the thoracic duct a feu hours later that tuln-rclc bacilli may readily pa-s through the intestinal wall and infect the animal without causing lesion- in the intestine* For the U'liefit of readers who are not informed on the -ul)je<-t of anatomy it may IM- well to say that the thoracic duct i- the common trunk of all the lymphatic ves-els that drain the abdominal cavity and the orirans contained in it. and an additional larr' portion of the iMxly. and that it discharges it- contents into the anterior vena ca\a. one of the lar^e veins in which the blood i- returned to the heart. The material discharged by the duct into the vein is carried with the blood directly to the heart and pumped by the heart to tin- lunr. where it i- filtered through the exceedingly fine capillary network in which the blood is arterialixed. It can readily IM- >een that tuU-rcle bacilli that have pas-ed through the intestinal wall and through the lyni|)hatics into the thoracic duct have a clear way to reach and in IV, -i the lnnr. Vallce calls attention to the fact that the lunr is the favorable loca- tion of the tuU-rcle bacilln- in all -pecie- of animal-, and he made ex|)ei-iments tlint indicate that infection through the dii g CAT! LB. I M I i I |i.t -M -- "I -'.II I l> MII.K Mlo\\ N l\\ INI Id I.ATION 'l (.1 IM \ The-c fuel- make it de-irahle to know -omethin;: definite about the liriiilicance of tin- frequently DllAToidftblfl int rod net i ...... f frees into milk. and we have tried to jain Iirht on the >ubject by inoculating guinea pi<:> \\itli milk into which small fragment- of fro-- from tnl>erculoii- cow- were placed in a manner a- nearly AS possible like that which occur- in a dairy stable. Normal, fiv-h milk from healthy cow- \\a- -oiled with -mall masses of fece> from cow > No-. I. s|. \\l\, :\~2'. and :'>!'>. The amount intn> hiced into each -ample of milk wa- very small. ulnMit as much n- woiild enter in jiroport ion to the volume of milk in a dairy -talile in which average cleanline-s i- practiced. Some of the -oiled milk \\a- injected without further treatment and >ome wa- -trained through linen cloth and then injected. The injection- were intra- alidomiiiiil. and each irninca |>iir received a dose of ." cubic centi- meter-. To make -ure that the milk u>ed in this experiment wa- free from infections material U'foiv it was -oiled with the feres, a nimilxT of jruinea pii:- were injected with it from time to time in its pure un- -oiled -tate. Such ruinea pijrs remained well until they were killed. and on po-t-mortem examination were found to Ix* free from le-ion- of di-ea-c. The following tables irive the results obtained with the injection- of -oiled milk. No table is riven for cow No. '.V2~>. as no tulM-rculo-i- wa- cau-4'd by the milk soiled with her feces. In all other re-pert - the inoculations were identical with tho-e of cow No. :'T:'. Id xitltx of iii jn tin;/ in limn ;//x iritli nnnniil milk (from ///// i . MII.K NOT STKAINKP. No. of . . r - " MOD. Date of l.-Mth. Kemark*. .Inti- 19,1908 .Inly -.M.1906 TiiU-n-n en. iin.l abilominal lymph Klnn TiiU-n-n i~i i.f in. m-iiter Ir R|HIII|>. 7..1 1 do d<> Tut.. r.-nl"-i of liver, -pl.-i-n. mnl Hixlomlnal lymph Klandm 761 -;. - .tun.- 1'J. 1'jnr, MII.K STI:.\IM:I. July 2I.190H I HIM- A 1906 J1.1906 ifT.-.-t.-.| with |H-ritotiitl. .\li.-r.- Hi.- w..nl " .li.-l " Is n^.-.l In tin- rvmnrkn. HIP until tli>y w.-r- killed for \>*l iii-.rtem pxamlnatioii. plir" remained KESULTS OP GUINEA-PIG INOCULATIONS. 19 Results of injecting guinea pigs with normal milk (from healthy cows) soiled with feccs from cow No. 113 (tuberculous).* MILK NOT STRAINKD. No. of guinea pig- Date of in- jection. Date of death. b Remarks. 7503 7504 May 29,1906 do July 23,1906 do Generalized tuberculosis. Tuberculosis of liver and spleen. 7505 . do .do Do. 7506 ...do... do Generalized tuberculosis. 7607 do do Tuberculosis of liver spleen and abdominal lymph glands 7508 do do. Do. 7573 June 9, 1906 do Generalized tuberculosis. 7574 do do Do. 7575 .. do .. do Do. 7576 do do. Do. 7592 7593 June 18,1906 do July 24,1906 . . . do Do. No lesions of disease. 7594 7595 do do do do Tuberculosis of liver. Tuberculosis of spleen. MILK STRAINED THROUGH CLOTH. 7596 June 18, 1906 7597 ' do July 23,1906 do . Tuberculosis of liver and spleen. Generalized tuberculosis. 7598 ' do do Tuberculosis of liver, spleen, and abdominal lymph glands. 7599 do do Do. In connection with this cow it should he observed that 17 of a total of 18 guinea pigs inoculated with milk that was soiled with her feces became affected with tubercu- losis, and that the amount of feces added to the milk was so small that not one guinea pig of the 18 that received intraperitoneal injections became affected with peritonitis. "Except where the word "died" is used in the remarks, the guinea pigs remained alive until they were killed for post-mortem examination. Results of injecting guinea pigs with normal milk (from healthy coics) soiled with feces from cow ]Vo. 84 (tuberculous). MILK NOT STRAINED. No. of guinea pig. Date of injec- tion. Date of death. a Remarks. 7638 7639 7640 June 21, 1906 do do. July 25,1906 July 5,1906 July 25,1906 Tuberculosis of lung, liver, and spleen. Died, affected with peritonitis. Tuberculosis of liver and spleen. 7641 do June 26 1906 Died affected with peritonitis. 7642 do July 25,1906 Tuberculosis of liver and spleen. MILK STRAINED THROUGH CLOTH. 7643 7644 June 21,1906 . do Julv 25,1906 June 22 1906 Tuberculosis oi liver and spleen. Died affected with peritonitis. 7645 do .. .do .... Do. 7646 do do Do 7647 .. .do do Do. 7673 76/4 June 22, 1906 ... do July 24,1906 do No lesions oi disease. Do 767i> 7676 do do do ... .do Do. Do. 7677 ... do do Do 7678 ; do do Do. "Except where the word " died " is used In the remarks, the guinea pigs remained alive until they were killed for post-mortem examination. HANOI l: PROM I I l:i R . \ I I 1. 1.. '/ in in linn ./in//../ //.>* ,i-iili not null mill, (from lnltliti nurs) n<,ih >l ir it I MII.K WOt MI: \IM:I- s of In. Hon. IMI. ..f.lratl.." Ki-nmrk- !- .' : Jim.- 'JO, 1806 July .M.1806 . ..do. Do. .... .1" 1).. MM Jim.- 7,1806 Jin..- >1M6 Jllllr II.. I'."*, l'i. .1. .iiI.-.-i.-.| with |..Tiionitiv 7M1 J'lh a, 1908 ii.-ii.Tnli/-I lutH-rvulosls. IK. 76M do Do. MII.K sn:.\i\i:i. niKoi i;n ' : H : Jni..- 20,1908 Jill) Jl.l'.M. No lesions of disease. Do Do Do. Kxo'|.t wli.-iv tin- word " died " Is used In the remarks, tin- milm-n pls r.-iuiiim-. ,-ili\.- until tli.-y were killed for post-mortem examination. A- the tables -how. both tin' strained and unstrained milk -<>i|.-d with ft'c's from r<>\\- No-. 1. ^1. and 11:5. and the im>traincd milk soih-d with frrr- iVoiii cow No. :'.7:'.. ucrc infTtion> for guinea pigs. Add to this cow No. :>_'."> with negative rc-iilt-. and we have one cow that was fed tulx'rcle bacilli in her drinking water and four all'ected with naturally acquired tulM-rculo>is. The fnrnn-r and three of the latter were j)a->inr tnhercle bacilli in their feres in sufficient num- ber- and of sufficient virulence to make the infection of milk exposed in their environment easily po>-ible. No U'tter evidence can !< |>re- sented to support the conclusion that the pr->ence of a ed. -hoiild not he tolerated. She is a direct danger to the healthy c-iltle that are '-.xpoM'd to her. and may IM- re>|)on>il!e for the introduction of infec- tion- material into their milk, and thu- make it dani:'rou- for use by JMTXHIS or animal-. It must not IK* supposed that the cow- u-ed in the-e tests were old. invalid animal-, -o badly alfected with tulM-rculo-i- that no . -cientioii- dairyman would retain them in his herd. With the -in;_ r le |tion of cow No. 11:',. their condition, a- far a- could IK- deti-r mined by a -imple. unaided, phy-ical examination, was In-tter than that of the majority of dairy cows in actual u-e. They looked letter nouri-hed. and their hair wa- -moot her. glossier, and cleaner. The slight. infre|iient coiiirh with which they were affected would not have attracted the attention of the ca-ual ob-erver. and mijrht ha\-- hone-tlv attributed hv mo-t dairvmen t dust in the air of the I KKDING AND INOCULATION TESTS. 21 stable. These cows illustrate anew the fact that the danger from tuberculosis does not rest on an intensely infectious character of the disease, but on its insidiousness and concealed and secret nature, which enables it to come and develop and spread infection without warning. Strictly speaking, the best as well as the worst cow in appearance relative to health must be suspected until she has been proven sound by a tuberculin test. ADDITIONAL FEEDING AND INOCULATION TESTS. Two additional tests were made for the presence of tubercle bacilli in the environment of tuberculous cattle. (1) The mixed feces of cows Nos. 1 and 113 w r ere fed, together with cornmeal and bran, to four healthy hogs, and (2) earth from the outside of the stable in which the tuberculous cattle were housed, near the door through which the manure was removed, was microscopically examined and used for guinea-pig inoculations. Before the feeding experiments began tlje hogs used in them were tested w r ith tuberculin without showing a reaction, and hence must be regarded as originally free from tuberculosis. The feeding was continued about six weeks, and shortly after it was stopped the hogs were again tested with tuberculin. With the second tuberculin test all four gave the reaction indicative of the presence of tuberculosis. When the hogs were killed and examined post-mortem it was found that one was affected with tuberculosis of the lung and liver and the submaxillary, prescapular, and mesenteric lymph glands, and the other three with tuberculosis of the submaxillary lymph glands. The submaxillary glands, not alone from the results obtained with this experiment, but also from other observations on a larger number of animals, must be regarded as the first structures in the bodies of hogs to become affected when they contract tuberculosis through the ingestion of infectious material. The fact that the four hogs contracted tuberculosis shows that the feces contained active, virulent tubercle bacilli, and likewise, as was pointed out in a former publication,* that much of the tuberculosis that occurs among hogs may be due to a method of feeding exten- sively practiced in the West turning hogs behind cattle when in- sufficient care is taken against the presence of tuberculosis among the cattle. Hogs that are exposed to cattle feces or have access to manure heaps from stables in which cattle are kept may at any time become tuberculous if the cattle are affected. This practice and the feeding of skim milk, especially when tubercle bacilli have been concentrated in it by the separation of the cream from the milk with a centrifugal <* Bulletin 88, Bureau of Animal Industry. 22 I.\.\..M: i I;M\I in. \ i i 1.1 . machine, are prol.ahly tin- most frequent cail-es of t lllcivu|o-i~ among hog-. That tuU-rcle Imrilli may IN- dropped, -pla-hed. -pra\ed. "'' -\\itched into milk when it i- obtained I'rum tiiliereiilou- co\\ - <.r ha- heen exposed to tin- environment of tulerculou- cattle ha- already been pointed out. but can not !* too often repeated. The microscopic examination of the earth from the out-ide of the -table in \\hieh the tuberculous cattle Used ill the-e experiment- \\eiv kept revealed the presence of nuineroii- acid fa-t bacilli. Most of the inM-ulatehowed either no le-ion- of a>e (in a fe\\ in-taneev> or very extensive le-ion- that coidd ea>ily U- mistaken for tul>erculo>i>. hut were -how n liy micro-copic examination to IM- IKMltabercalocu and due to the action of other hacteria than tuln-rele hacilli. Ih-nce we can not assert definitely that the acid-fa-t l>a teria found in the -ample- of earth on miero-copic examination \\en- tulNTele hacilli. as acid-fa-t hacteria are \ery common in the -oil in :uid around -talle- and liarn-. CONCLUSIONS. 1. TnU-rcle hacilli are diss4>ininate is shown to !M> the case l>y micro-<-o|)ic examination. ly iiMM-nlation tests with guinea pijr> aiul l>\ iiiL r -tion experiment- wit h hogs. 2. Feces are the most dangerous factor in the dissemination of tuU-rcle hacilli l>y cattle affected with t uherciilo-i-. In this resjiect feces must IK- regarded as having a place with cattle -imilar to that commonly accorded to sputa with tuU'rculou- per-on-. 3. It is not alone the feces of visibly affected cattle which di--emi- nate tubercle hacilli in a way that is dangerou- to man and animal-. but also the feces of cattle -o -lightly affected that the diagno-i- \' tulx'rculosis with them tlepends entirely on the aj)plication of the tulxrculin te-t. 4. Tulxrc'le hacilli that are -wallowed l>\ cattle are to a great extent passed entirely through the dige-ti\e tract and out with the feces without loss of infect iollslie . As cattle do not expectorate. the infectious matter that is coughed up from their lung- i- -wal- lowed, passed through their Inxlie-. and -cattered with their feces. 5. Hacilli may reach the environment of tul>erculou- cattle from their mouths, but this is evidently of ran- occurrence compared with the dissemination through feces, especially when the cattle are not visibly tuler-iilou-. '. The nasal discharge of tul>erculoii- cattle \va- found to l>e five from infectious material. Cow No. 11-". i- ><> severely a fleeted with CONCLUSIONS. 23 tuberculosis that this freedom in her case seems to indicate that nasal discharge rarely contains tubercle bacilli. It is possible that a larger number of tests may modify this conclusion. 7. Urine is probably free from tubercle bacilli when the genito- urinary organs are riot affected and no infectious material has been introduced into it after it has been passed. The practical signifi- cance of this conclusion lies in its bearing on the question whether tubercle bacilli are ever thrown out by tuberculous subjects through unaffected secretory organs with otherwise normal secretions. 8. Milk from tuberculous cows with unaffected udders we believe to be free from infection until it has become contaminated with feces or some other material that contains tubercle bacilli from the outside of the cows or from their environment; that is to say, it is not be- lieved that tubercle bacilli are eliminated with the milk from tuber- culous cows unless disease of the udder or structures connected with it is present. This conclusion is drawn from the present series of investigations and is supported by our earlier work relative to the milk of tuberculous cows. The present investigations include only a few cows and a comparatively small number of guinea pigs. The earlier investigations extend over a dozen years, during which milk from scores of tuberculous COW T S was injected into the abdominal cavities of hundreds of guinea pigs. When milk injections into guinea pigs are made by pathologists or bacteriologists as a test for the presence of infectious material, un- usual, though not always sufficient, precautions are taken at the time of milking to protect the milk from contamination with foreign matter of any and every kind that may reach it from the exterior of the cow or her environment. It follows that the scientific injections give nearly accurate results as to the frequency with which tuber- culous cows pass tubercle bacilli w T ith their milk; but they give no data at all as to the frequency with which milk from tuberculous cows, or healthy cows in a tuberculous environment, contains in- fectious material when it is drawn and handled with the ordinary precautions that a dairyman can economically practice. The observations made by the writers definitely show that the frequency with which milk contains tubercle bacilli is greatly under- estimated, especially when it is milked in the customary way from tuberculous cows with healthy udders, or from entirely healthy cows in a tuberculous environment. 9. It has been positively shown that the introduction of a small quantity of feces from tuberculous cattle into normal milk is equiva- lent to the introduction of a sufficient amount of infectious material to cause a generalized tuberculosis in guinea pigs that are given intra- abdominal injections of small amounts of such soiled milk. This "24 |. \Nii i: i i;..\i i i r.u:. (7LOU8 CAT1 IM. is lriU> Hot only \\ ill) llir fece- of ;i -r\c|-e|\ ;i llede. I cow. like Nil. I 1.",, "I- ;i row thai i- -\\allo\\in;: culture- of tulx-rcle bacilli, like No. -I. l>ut also \\ itli tin- feet- of co\\ - thai are not known to In- affected \\ ith tul>erculo-i- until a tuberculin te-t or po-t -mortem e\aminat ion lia- Ixvn made, a- co\\ - No-. I ami :\!:\. Tlie quantity of feces introduced into the milk wa- no ^n-ater than frr<|iirntl\ ruin- \\itli ordinary milking. |(>. We are iinae|iinintel \\ith any im-an* ly \\hieli it can le .|e termilieo! \\heli rattle or llieir fee.- Iti-eome . la nireron- t< the health of per-on- or animal-: In-nee e\ei-y eo\v known t< ! all.--ied with tuU-reuN^i.- mn-t le regarded a- positively danjjerou-. I'hy-ieal e..n dition .'i\e- no infor-mation from whieh it i- |>o--ille to determine how -erion-ly a eo\\ i- atl'eetetl uilh t nherenlo-i- or how freely -lie i- -eatterinir tnlH-rel* 1 Kaeilli. Cattle atleeted with advanced tulM-rcnlo- -i- from which infection is lH-inr di--eminated in a dan^erou- way may retain the ap|H>arance and in of pel- fed health. Frequently nothing abnormal ean iM-detei-ted alout them after the ino-t -earchinj; examination ly the owner or e\cn hy a trained veterinarian: and In-sides it i- not eii-tomary to make ean ful examinations or to employ profeional men to do -o until cattl" -how marked symptom* of li.-ea-e. 11. In order to jruard :irain.-t the -pread of tnlM-rculo-is amon^ ,- : ,t- tle and other animals, and more especially for the protection of JMT- -on-. every dairy cow should Ix- periodically tested with tiilx'iviiliii. and every cow that -ho\\ - a react ion indi<-alin^ that she i- alledcd with tuberculosis should at once, repirdle of her general appearance or condition oi - semblance of health, le removed from use a- a dairy cow and from all contact with dairy cattle or other healthy animal-. If segregation is practiced, it should he complete, so that no healthy animal will IK- exposed to feees that may swarm with living, virulent tubercle bacilli. O