116 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



experimental work. Cooperative work was carried on with the Vir- 

 ginia and Delaware Agricultural Colleges and the New York State 

 Veterinary College. Experimental treatment of infected herds with 

 biological products was undertaken, but sufficient time has not 

 elapsed to allow the drawing of definite conclusions. Immune serum, 

 for experimental use, is being produced at the Bethesda station, and 

 results of scientific interest have been obtained. 



Results obtained in the use of various methods of control indicate 

 that sanitary measures and control of breeding are still the most 

 reliable means of combating the disease, and literature giving details 

 of this system of treatment has been widely disseminated. 



The correspondence seems to indicate that equine abortion is also 

 on the increase, but not to the same degree as bovine abortion. A 

 few reports of abortion in hogs were received. Inasmuch as the 

 disease in these species manifests itself similarly to bovine abortion 

 and is transmitted by the same agencies, the same methods of sanita- 

 tion and breeding control are advocated. 



SWAMP FEVER INVESTIGATIONS. 



An experiment in insect transmission of swamp fever or infectious 

 anemia of horses with Tabanida flies was entirely negative. A 

 healthy horse was exposed to the bites of flies which had access to a 

 horse having a case of natural infection and which had been under 

 observation at the station since 1909, yet the disease was not trans- 

 mitted. The continued infectiousness of the blood of the infected 

 animal was nevertheless afterwards proved by inoculation of the 

 other horse. During the six years that the infected horse has been 

 kept, both Tdbanus and Stomoxys flies have been seen in the stalls 

 during the summer season, yet no spontaneous cases of the disease 

 have developed in exposed healthy horses. 



Experiments in serodiagnosis have not yielded a satisfactory 

 diagnostic procedure. 



The increasing economic importance of the disease is evidenced by 

 the fact that it has gained a foothold in New York, where it was not 

 recognized prior to 1914. 



AMEBIC DYSENTERY. 



An opportunity was presented to study a spontaneous outbreak of 

 disease in monkeys in which the lesions observed corresponded quite 

 closely with those found in amebic or tropical dysentery of man. 

 Protozoan organisms were found having the general structure and 

 characteristics of the amebas generally considered the causative 

 agents of human tropical dysentery. The disease prevailed among 

 a group of spider monkeys kept in a large exhibition cage at the 

 National Zoological Park, and during the course of three months 

 nine monkeys became affected, eight of which died of dysentery. 

 Marked lesions were present in the large intestine and in two in- 

 stances liver abscesses were observed. The amebas were numerous in 

 both intestinal and liver lesions. 



This outbreak is of special interest, since there appears to be no 

 similar case recorded, and because our knowledge of the occurrence 

 of this disease in animals is very meager. It sems probable that the 

 affection was introduced with imported monkeys. The possibility of 



