THE PATHOLOGICAL DIVISION. Investigations in this Division have been continued under the direction of Dr. John R. Mohler, chief, and while its regular work in relation to rabies, blackleg, tuberculosis, glanders, and the examination of the carcasses of wild animals that have died at the National Zoological Park has been carried on as in former years, there has been much time devoted to matters which are not of a routine or customary nature. SWAMP FEVER IN HORSES. In cooperation with the Minnesota Experiment Station the investigations into this disease have been continued. Work has also been done at and near San Antonio, Tex., as the infection has proven as disastrous in those southern latitudes as it has in the colder climates of Minnesota and the Dakotas. The facts relative to the transmission of the infection, which were mentioned in the report of 1907, have been fully substantiated by the investigations of the past season. Furthermore, it has been proved that guinea pigs, rabbits, dogs, and cattle are immune to the disease. Experiments are now under way to determine the infectiousness of the urine and feces, the vitality of the virus, its transmission by feeding as well as by intermediate hosts, and the changes to be found in the blood and urine of infected horses. Enlarged quarters have been recently acquired, which will permit the study of a greater number of affected animals, and the work can therefore be pushed to better advantage than under the less favorable conditions of the past. GLANDERS. The appearance of cases of glanders with considerable regularity among the horses and mules of the District of Columbia and vicinity serves to prove that the disease is well established in this region and that constant care will be necessary to hold it in subjection. The agglutination method of diagnosis has been used repeatedly during the year and with an increasing degree of satisfaction. Familiarity with its use will no doubt make it a valuable agent in the detection and eradication of glanders. EPIZOOTIC LYMPHANGITIS. This is a chronic contagious disease, caused by a specific organism, the Saccharomyces farciminosus, and is characterized by a suppurative inflammation of the subcutaneous lymph vessels and the neighboring lymph glands. The disease was first described by Italian and French veterinarians, and the specific organism was discovered by Rivolta in 1873. The presence of the disease in the United States was first observed by Pearson in 1907, although it is probable that it has existed in various parts of the country for many years. Its presence has also been established in Ohio, Iowa, North Dakota, and California, as well as in our island possessions (the Philippines, Porto Rico, and Hawaii). CHRONIC BACTERIAL DYSENTERY OF CATTLE. In March and April there were received at the pathological laboratory the large intestines of several cows which had died of a peculiar disease. These specimens showed thickening and corrugation of mucous membrane, with a few scattered hemorrhagic areas. Stained smears made from all these cases showed the presence of acid-fast bacteria, thicker and shorter than the avian tubercle bacillus, which fact, together with the history and symptoms of the affection, caused the diagnosis of chronic bacterial dysentery to be made. The disease is characterized by a chronic and progressive diarrhea, loss of appetite in the later stages of the disease, and marked emaciation, with anemia. This disease has only recently been recognized in this country, although there is no doubt that it prevails extensively. The course of the malady covers a period varying from two months to two years, according to the severity of each specific case. In 1904 Markus reported this disease in Holland, and subsequently it was observed in Belgium, Switzerland, Denmark, and Great Britain. TUBERCULOSIS. The immunizing experiments which this Division had previously inaugurated for the study of protective agencies against tuberculosis in cattle have been continued throughout the year, and a number of animals that had been inoculated with living human tubercle bacilli as a means of protection have since been slaughtered and examined. While many of these cattle have shown great and increased resistance to tuberculosis, no method has yet been found which is reliable enough to justify its general application to the tuberculous herds of the country. The testing of infected butter has been continued, and in the later experiments of this nature the conclusions reached through former work have been confirmed. Tubercle bacilli will retain their vitality. and virulence while in butter under common market conditions for at least five months. EXHIBIT AT THE INTERNATIONAL TUBERCULOSIS CONGRESS. During the year a call was sent out to the various cities at which Federal meat inspection is maintained, asking the inspectors to lay aside the most striking specimens of tuberculosis that they might chance to meet, especially those showing infection of mammary organs either in cattle or swine, later shipping them to the Pathological Division for preservation. The response to this request was very hearty, and many rare specimens were received. These were properly hardened and then preserved in Kaiserling's fluids, and the choicest were placed in glass containers or mounted in gelatin for exhibition at the International Congress on Tuberculosis or at some later exhibition at which pathological specimens are shown. TYPHOID BACILLI. The viability of the typhoid bacillus has been investigated, both in butter and in milk. On the one hundred and fifty-first day after the manufacture of butter from milk infected with typhoid bacilli, living colonies of these bacilli developed on plates that were made from the butter. This proves that typhoid bacilli will retain their vitality under these conditions for one hundred and fifty-one days, and that during this period of time these micro-organisms are ready to multiply whenever placed in suitable environment. The length of time that typhoid bacilli will remain active in milk under common market conditions far exceeds the length of time that it is ordinarily kept before being put to some domestic use. Examinations at repeated intervals showed that the organisms retained active motility for at least twenty days, whence we must conclude that milk offers an unsurpassed culture medium for the growth of typhoid bacilli, and that when once contaminated such milk continues to offer a menace to the people consuming it. RABIES. The Pathological Division has continued to examine all animals brought to the laboratory suspected of having rabies, and all dogs that have bitten anyone and been killed as a consequence. It was found that there had been a decided increase in the prevalence of rabies in the District of Columbia, so much so, in fact, that a muzzling order was issued by the District Commissioners in accordance with law, after the situation had been vigorously presented by the Secretary of Agriculture. A great number of stray dogs found wandering the streets were impounded and destroyed, and this, together with the muzzling order, has probably greatly impeded the spread of the disease. However, the disease is still present and will continue so long as unmuzzled, improperly muzzled, or unrestrained dogs are allowed to run the streets. A comparison of the number 10765-10--3 of cases shown in the appended table with the number given in the preceding year's report clearly shows that the disease was not only on the increase, but greatly on the increase, and justifies the enforcement of muzzling in spite of the protests made by some sympathetic owners of dogs who consider only the inconvenience to the dogs while manifesting an utter disregard for the safety of human life in the community. It still seems necessary to impress upon some people that rabies is not a fantasy, but a fact, and this has been brought home to more than one individual during the past year in the most convincing way through being bitten by his own or some vagrant rabid dog. During the fiscal year ending June 30, 1908, there were examined the brains of 111 dogs, 2 cattle, 1 pig, and 3 cats. Of these, 77 dogs, 1 cow, 1 pig, and 3 cats were found to have been affected with rabies, and 61 of the rabid dogs were furnished by the District of Columbia, being over five times as many as last year. It was found that the most satisfactory method of diagnosis was by demonstrating the presence of Negri bodies in sections of the hippocampus major. The touch method of making preparations for examination for Negri bodies has not been uniformly successful in our hands, and in practically every case sections have been made of the brain tissues before staining. In only a few cases was it necessary to make inoculations of rabbits to arrive at a diagnosis. Cases of rabies investigated by the Bureau of Animal Industry during the fiscal year 1908. a History incomplete, not indicating whether persons or animals had been bitten, .do.. Cases of rabies investigated by the Bureau of Animal Industry during the fiscal year 1908-Continued. 1907. Oct. 30 1288 Dog..... Silver Springs, None made.. Positive.... Positive..... 2 dogs. a Carcass too badly decomposed for experimental purposes. History incomplete, not indicating whether persons or animals had been bitten. |