264 DISEASE INJURING TURKEY 



away from the flock ; third, loss of appetite and more or 

 less prolonged emaciation. 



The first course which the disease may follow is seen 

 in young birds, in what is commonly known as "white 

 diarrhoea," frequently causing great mortality among 

 poults from five days to three weeks old, although deaths 

 may continue much beyond this period. In these cases, 

 death is sometimes preceded by a period of a day or two 

 of stupor, in which the bird remains by itself and refuses 

 food. This acute form is more likely to attack the 

 younger birds, and frequently causes the death of 90 per 

 cent, and occasionally the entire flock will be wiped out. 



If the disease does not show until after the birds are 

 three weeks old, it is likely to remain latent in them or 

 change into a slowly progressive form which may not 

 cause death for several months. In the typical chronic 

 form, the birds often hold their own against the disease 

 for a year or more, during which time emaciation gradu- 

 ally increases. In these birds, the disease is ultimately 

 fatal in the majority of cases. 



One of the most important features of this disease is 

 that turkeys having a chronic form of the disease are 

 especially susceptible to the effects of unfavorable con- 

 ditions. Quick fattening of a flock of turkeys for the 

 market, especially if the young birds are fed much corn, 

 often brings about a marked increase in the mortality. 



The organism which causes blackhead is a minute para- 

 site belonging to the lowest group of animal life, and is 

 called a cocidium, and is akin to the parasites of hydro- 

 phobia and malaria. The infection of the bird begins in 

 taking up, along with food and water, some of the para- 

 sites described. These may undergo a partial development 

 before being taken into the body of the bird, and after 

 entering the alimentary tract, where they liberate the orig- 

 inal infecting elements. These are able to impart infection 



