portions are encountered. This service will 

 include diagnosticians and epidemiologists for 

 vector-transmitted diseases, industrial and 

 phytotoxicological diseases, radiation diseases, 

 mycotic, protozoal, and viral diseases. Other 

 teams will be trained in the investigation of 

 such exotic diseases as rinderpest, foot-and- 

 mouth disease, and virulent strains of New- 

 castle disease of poultry. 



Records of past anthrax outbreaks suggest 

 that alternate wet weather and drouth, where 

 the organism is established in the soil, may 

 cause increased incidence of the disease. The 

 prediction of a 1959 increase in the Southern 

 Great Plains was followed by the identification 

 of at least four foci of infection. The impor- 

 tation of infected cattle from Mexico caused a 

 fifth outbreak. 



Studies of hog cholera and immunization 

 procedures in the Corn Belt indicated that 

 weather may also favor complications follow- 

 ing vaccination with modified viruses. Seque- 

 lae were reported more common during hot, 

 humid weather. The need to continue use of 

 virulent virus was not established. 



COOPERATIVE PROJECTS WITH 

 OTHER LABORATORIES 



Salmonellosis 



Because of the importance of serological typ- 

 ing in a program to control salmonellosis in 

 domestic farm animals and poultry, a coopera- 

 tive program was established with U.S. Public 

 Health Service. 



A bacteriologist has been assigned by the 

 Division to the Communicable Disease Center 

 in Georgia to conduct typing and identification 

 of enteric organisms of animal origin. This has 

 enabled State animal disease diagnostic labora- 

 tories to submit more cultures for study and 

 typing. This laboratory activity will be trans- 

 ferred to the National Animal Di.sea.se Labora- 

 tory in 1961. 



Lept-ospirosis 



The relationship between leptospirosis in 

 wildlife and livestock is under study by an epi- 

 demiological team in cooperation with the New 



Bolton Center of the University of Pennsyl- 

 vania. 



It is important to establish the role of wild- 

 life leptospirosis in the study area because of 

 many favorable opportunities for the transmi.s- 

 sion of infection to domestic animals and to 

 humans. This team is using the agglutination- 

 lysis test and several nutrient media to isolate 

 and identify leptospira from livestock, the 

 water supply, and from wildlife in the vicinity 

 of the diseased herds. 



The motility of leptospira and their lack of 

 resistance to drying makes water a principal 

 means of spread. Investigators have found 

 leptospira are adversely affected by acidic wa- 

 ter; they lose motility at a pH below 6.0. They 

 prefer alkaline water. Stream pH in the area 

 of study varies from 6.9 to 8.5. Many streams 

 and pools persist throughout the year, and dur- 

 ing their low stages in summer, animals stand- 

 ing in them may become infected. 



Although the project has been active for less 

 than 6 months, much information regarding 

 the role of wildlife has accumulated. The dem- 

 onstration of Leptospira poniona infection in a 

 woodchuck indicates the importance this com- 

 mon inhabitant of pastures might assume in 

 control of bovine leptospirosis. One outbreak 

 was investigated in which blood cultural isola- 

 tions were made from 8 of the 22 cattle in the 

 herd. The source of infection was found to be 

 carrier animals which were introduced into the 

 herd less than a month before the blood isola- 

 tions were made. 



A national survey of serological techniques 

 used in the diagnosis of leptospirosis was com- 

 pleted this year. Check samples were submitted 

 to all laboratories conducting leptospii'osis 

 tests. 



The results indicated considerable variation 

 in procedures. Adoption of a standard test with 

 strict adherence to details of procedure would 

 improve the uniformity of results. Efforts are 

 being made to encourage the adoption of a 

 standard serological technique. The various 

 tests, such as the agglutination-lysis te.st, are 

 being studied to determine the sources of their 

 inherent variation. A serological method for 

 detecting dairy herds infected with leptospii'O- 

 sis by means of the composite herd milk sam- 

 ple has been developed. Serum samples of ani- 



42 



