13 



animals that have recovered from the disease are still able to trans- 

 mit it for a variable length of time. Professor Hess found that 

 animals that had apparently recovered gave olf the germ of the 

 disease five months later. Here, then, we have a carrier exactly 

 similar to the typhoid carriers, or the diphtheria spreaders, of 

 which you are all familiar. In addition to the diseased animals 

 and those that had apparently recovered the germs of the disease 

 are transmitted frequently on the clothing of men who are caring 

 for them, and by pigs, cats, and birds. As the germ is able to 

 live for considerable length of time it can be carried on hay, grain, 

 feed bags, or any other articles that may come in contact with the 

 diseased animal. Milk from infected herd and milk cans that have 

 come in contact with such animals also spread the virus. It is 

 necessary, therefore, that every article that may become contami- 

 nated by the diseased animals should be kept from sound cattle. 



Although the cause of Foot and Mouth Disease is not defi- 

 nitely known, it has been shown that it will be destroyed in the 

 saliva of the diseased animals when it is kept at a temperature of 

 37 degrees centigrade for a short time, but it has been known to 

 retain its power to produce disease for a period of several months 

 1vhen kept at zero temperature centigrade. 



The economic importance of Foot and Mouth Disease is not 

 generally understood. Because it has a low mortality, people some- 

 times think it is of not much importance. Professor Bang has 

 pointed out that where dairy cows recover, the cost from the loss 

 of milk, etc., in Germany, has been 50 marks (twelve and one-half 

 dollars) . In the Netherlands it has been shown that it cost $20 for 

 every sick animal that recovered. Professor Bang has pointed out 

 that "there are many instances of the disease developing a very 

 malignant character, with a mortality of from 5 to 50 per cent, 

 among adult animals, and from 50 to 80 per cent, among young 

 animals. Malignant Foot and Mouth Disease of this kind is most 

 apt to attack dirty and overcrowded farms, but they may occur in 

 a very malignant form with numerous sudden deaths reminiscent 

 of anthrax. Such epidemics have been observed in many different 

 countries, both in former and recent times. In 1839 2,000 head of 

 cattle died in the cantons of Berne and Fribourg in Switzerland; 

 in 18T2 in the French Department of Nievre, more than 20 per 

 cent, of the calves and over 22 per cent of the pigs were destroyed 

 by the disease in the course of two months. In the summer of 

 1892 there died in Bavaria, over 3,000 head of cattle, and in 1896 



