360 ANNUAL REPORTS OP DEPARTMENT OF AGRICULTURE. 



and unexpected improvement was gained. Observations from this 

 case suggested an experiment in treatment which is now under way, 

 but which has not progressed far enough to furnish any definite 

 conclusions. Experiments for the purpose of discovering some 

 reliable means of diagnosis, especiall,y modifications of the comple- 

 ment-fixation test, have been continued throughout the year, but with- 

 out satisfactory results. 



llie fact that the virus from swamp fever will pass through filter 

 tubes which are capable of excluding all visible contaminating or- 

 ganisms suggested that this process might be a means of isolating 

 and possibly of cultivating the virus. It seemed reasonable to assume 

 that the virus might be cultivated in infected serum which had been 

 filtered, inasnuich as it would thus remain in the same medium in 

 wdiich it had developed during its life in the body of the animal from 

 which the blood w\as drawn. Repeated incubations of such material 

 for various periods under both aerobic and anaerobic conditions have 

 failed to produce any evidences of growth which could be detected by 

 the usual methods of microscopic examination. The failure of these 

 cultures to grow proves that the virus can not be cultivated by the 

 usual bacteriological methods. However, the certainty of the presence 

 of the virus in the filtered serum and the fact that it can survive for 

 some time in serum from which all contaminating elements have 

 been removed afford encouragement to further efforts at cultivation. 



DOURINE. 



The reappearance of dourine of horses in the United States was 

 brought to the attention of the bureau by State Veterinarian Gibson, 

 of Iowa, in 1911, Avhen inembers of the bureau confirmed its existence 

 in that State by clinical and microscopic examinations. All the 

 affected and exposed animals were either killed or quarantined, but 

 not before several exposed animals had been shipped to Texas, Arkan- 

 sas, and North Dakota, to which States they were readily traced and 

 disposed of according to the conditions found. Two exposed stallions 

 were taken to Canada before the disease was recognized, and these 

 animals also were killed. Extensive examinations of all cases which 

 had been bred to infected animals were carefully made, and the 

 results indicated a comparatively limited dissemination of the 

 infection. 



The chronic character of the disease and the fact that affected 

 animals may show no indications of the infection for a long period 

 make its diagnosis very difficult ; consequentl}^ suspected animals must 

 be placed under a prolonged quarantine. 



Following the success in diagnosing various infectious diseases by 

 the complement-fixation test, the possibility of the application of 

 this method for the diagnosis of dourine has been carefully consid- 

 ered by the bureau. The numerous attempts which were first under- 

 taken were not successful, due to the difficulty of obtaining a satis- 

 factory antigen for the test. The blood, organ extracts, bone marrow, 

 etc., of affected animals were utilized for the preparation of antigen, 

 but without uniform satisfaction. While still working with these 

 various antigens the results of the investigations of Winkler became 

 known. His studies showed the possibility of utilizing an antigen 

 from another trypanosomiasis than dourine, nagana in this instance, 



