700 MICROBIOLOGY OF THE DISEASES OF MAN AND ANIMALS. 



way in the disinfection of all the rooms. Leave the seals unbroken on the window and 

 doors for six hours, after which the rooms should be opened up and thoroughly aired. 

 The temperature of the room at the time of disinfection should not be below 70 F. 



No paper, cotton, cloth, wood, or other combustible material should be in or near 

 the disinfecting outfit for fear of fire, and no flame should be permitted in the room near 

 the disinfecting outfit. 



CARRIAGE OF INFECTION BY BIOLOGICAL AGENTS. 



The transmission of yellow fever and malaria by mosquitoes, in the 

 course of which the parasite causing the disease must undergo a whole 

 series of biological changes before the mosquito can become infective, 

 is now well understood as an example amongst ultra-microscopic para- 

 sites of a host cycle already well understood amongst certain higher and 

 much larger parasites. But the mechanical carriage of infectious 

 material by flies from privy vaults or bed pans or even mucous mem- 

 branes or open wounds to food and drink or to other mucous membranes 

 or wounds has not been very long established. 



That typhoid fever and dysentery have many times occurred in 

 epidemic form chiefly by the carriage of the infective agents by flies the 

 writer firmly believes as the result of personal investigation, as well as 

 from the reports of others. Similar mechanical carriage of infection on 

 the outside of the body has been attributed to rats, dogs, cats, even to 

 cows and horses. This must not be confused with the dissemination of 

 certain diseases by horses actually sick with the disease (glanders) or 

 carrying the germs in their intestines (tetanus), by cows actually sick of 

 tuberculosis, or by other similar instances of disease derived directly 

 from preceding cases in the lower animals. 



Another class of cases where lower animals convey disease by biting, 

 and yet act merely mechanically is instanced by the septicaemia some- 

 times arising from bites of well animals (rats, snakes, mosquitoes, etc.), 

 the teeth acting merely to admit to the tissues pathogenic forms acci- 

 dentally present in the animal's mouth or on the skin of the bitten 

 person. These must be distinguished from cases where the animal 

 transmits thus a disease from which it is itself suffering (as when a rabid 

 dog spreads rabies by biting other animals or man) and from true poison- 

 ing by injection of animal products at the time of biting (as done by 

 poisonous snakes, mosquitoes, etc.) 



