Page:Popular Science Monthly Volume 84.djvu/292

288 milk by flies is a common occurrence. Hundreds of bacteria have been counted on the feet of flies caught in the cow stables.

Some sanitarians believe that many infant lives would be saved if the fly could be kept away from the baby's milk. A recent investigation in New York City carried out by Dr. Donald B. Armstrong (published in the Journal of the American Medical Association, January 17, 1914,) seems to show that there is some connection between flies and infant mortality. The author's results seem to indicate that the fly is a much neglected factor in the etiology and transmission of summer diarrhea. He thinks that greater attention should be given to the elimination of the insect by all those interested in prevention of infant mortality. Two areas were covered by his investigations, both practically alike in population and other conditions. The first area was subjected to every possible precaution against flies. The means were educational campaign, exhibition of picture films of flies in a nearby theater, screening of the 1,700 doors and windows, and placing of large fly traps in the courtways, yards and stables. The second area was permitted to pursue its usual insanitary course. In the protected area the total days of sickness of diarrheal diseases among infants was 273, in the unprotected area 984.

According to Farmer's Bulletin 540, U. S. Department of Agriculture, the stable fly, also known as the wild fly, the straw fly and the biting house fly, commonly breeds in horse manure, especially if straw is present, as is usually the case. It has been believed, although lacking confirmation, that infantile paralysis and pellagra are communicated by this species. It has been more definitely demonstrated that this fly is instrumental in spreading some diseases of domestic animals. Aside from these facts it is a tormentor of live stock. Horses and cattle suffer more than other animals, but sheep, goats, hogs, dogs and cats are known to be infected by these flies. Even man is not immune. A tropical disease of camels, horses and cattle, known as "surra," is communicated by this fly. Anthrax, glanders and possibly other diseases of cattle, also communicable to man, may be transmitted by the stable fly. Although the chief breeding places are straw stacks, the manure piles commonly found near stables where horses are kept furnish suitable breeding places. Adult flies may follow for considerable distances traversing roads and, when engorged with blood, settle on nearby objects. Other teams passing along the same highways are subsequently attacked. It is evident that with the reduction of horses and horse stables this pest will be greatly reduced.

Flies do not generally act as intermediate hosts in the transmission of disease. Usually they carry the germs on their feet or in the intestinal tract and infect food by walking over it or dropping on it. The danger from flies is greater than from mosquitoes. The latter act as intermediate hosts and carry the virus of malaria, yellow fever and other diseases.