BUEEAU OF ANIMAL. INDUSTEY. 261 



fection. As this method requires about one month in which to estab- 

 lish protection, efforts have been made to shorten this period by the 

 use of certain laboratory products which consist of a vaccine requir- 

 ing only one application and an antibacterial serum. In a general 

 way fa^•orable results were obtained in experimental rabbits by the 

 use of certain substances precipitated from nondialyzed cultures, but 

 these all failed when applied to the larger animals. Likewise, an 

 autogenic vaccine had no effect when tested against virulent bacilli. 



Numerous experiments have shown, however, that an immediate 

 passive immunitv can be conferred by the use of blood from a highly 

 immunized animal, one which will resist five thousand times the mini- 

 mal lethal dose of the most virulent strains of anthrax bacilli ; also 

 that simultaneous injections of the most virulent strains of bacilli, or 

 of attenuated bacilli, and such a serum, confer an active immunity. 

 Hence by the use of this method an existing outbreak can be checked, 

 or the disease can be prevented, as by the ordinary vaccines. As the 

 serum confers immediate passive immunity, it is not deemed wise to 

 employ virulent bacilli for producing the active immunity, but it is 

 safer to inject simultaneously with the serum the usual Pasteur vac- 

 cines, or a single vaccine which corresponds in strength to the No. 2 

 Pasteur vaccine. 



BLACKLEG VACCINE. 



During the fiscal year ended June 30, 1910, the Pathological Division 

 - prepared and distributed among stock raisers about 1,000.000 doses of 

 blackleg vaccine. The high standard of efficiency of the vaccine pre- 

 pared by this Bureau has been maintained, as is shown by reports 

 made by the stock raisers who have used the vaccine. Reports on 

 vaccine distributed during the fiscal year ended June 30, 1909, show 

 that out of 578,990 cattle reported as vaccinated only 2.242 (0.38 per 

 cent) died. Comparison with previous reports shows a material de- 

 crease in the losses from this disease before vaccination, and also a 

 slight decrease in the percentage of losses after vaccination. 



RABIES. 



Rabid animals have continued to arrive at the laboratory for exam- 

 ination during the year in but slightly decreased numbers from those 

 received during the year before. The number of positive cases 

 received each month shows that the infection has been constantly 

 present in animals of the infected localities. 



During the year IIG cases have been examined, consisting of 100 

 dogs, 7 cattle, G cats, 2 mules, and 1 sheep, which had bitten at least 

 59 persons and 40 animals. Other animals may have been bitten of 

 which no record was made, as a rabid dog in his wanderings across 

 the country is liable to snap at every animal (hat he miiy chance to 

 meet, and in many instances these attacks escape observation, yet these 

 are the cases Avliich perpetuate the disease among the dogs of the 

 infected rcf^ions. Of the llG suspected cases examined, 75 were found 

 to be positive. The following table gives data regarding these posi- 

 tive cases. It will be seen that 58 of these cases came from the District 

 of Columbia. 



