740 IOWA DEPARTMENT OF AGRICULTURE 



WHITE COMB (FAVUS). 



White comb, baldness, or favus of fowls is a contagious disease that 

 begins by the formation of white or grayish spots on the comb, ear 

 lobes or wattles. These spots are caused by the growth of a fungus 

 called LophojJhyton galUnae, and they continue to , enlarge, run to- 

 gether, and become more inflamed until all the skin of the head and neck 

 is much thickened, roughened, covered with crusts, and more or less 

 bare of feathers. In extreme cases this inflammation may extend over 

 the skin of other parts of the body, affecting the general health and 

 causing weakness, with, finally, exhaustion and death. 



Cmisation. — This disease is transmitted from fowl to fowl by simple 

 contact and is easily transmitted by inoculation from fowl to fowl. It 

 is most frequently seen affecting common fowls and turkeys, and may 

 be communicated by inoculation to mice and rabbits, but attempts to 

 infect lambs, dogs, rats, guinea pigs, and pigeons have failed. It is also 

 easily inoculated on man, producing large red, scaly patches on the 

 skin, and such patches sometimes develop spontaneously, being no doubt 

 due to contagion from affected fowls. 



The filaments of this fungus do not penetrate deeply into the skin, 

 but remain very near to the surface, and consequently the general health 

 does not suffer in the early stages of the disease. It is only when a large 

 area of skin is affected that there are symptoms, such as diminution of 

 appetite, loss of weight, and great weakness, which indicate the ab- 

 sorption of poisonous products. Young birds are believed to be more 

 susceptible than older ones, and some breeds appear to inherit a predis- 

 position to the disease, but no age or breed is entirely exempt from it. 



Symptoms. — ^Favus generally begins on the bare parts of the head as 

 small white or grayish spots, round or irregular in form, which increase 

 in number and size and join together until the whole surface is covered. 

 The affected spots are covered with dry, scaly, dirty-white crusts with 

 an irregular surface, and have an appearance of being formed of con- 

 centric deposits. Removing the deposit the skin beneath is seen to be 

 slightly inflamed and abraded. Often the circular spots enlarge regu- 

 larly and are covered by layers of scales thicker at the periphery than 

 at the center, which gives them a peculiar cup-shaped appearance. As 

 the disease advances the skin becomes thicker, until in the course of a 

 month it may reach one-third of an inch and considerably change the 

 appearance of the head. The neck and body are gradually invaded, the 

 feathers become brittle and break off, leaving a deep depression in the 

 center of a cup-shaped disk. Occasionally the disease is inoculated into 

 the feathered parts of the skin and begins there instead of on the bare 

 parts of the head, but this is exceptional. 



The disease when limited to the comb and wattles may disappear 

 without treatment, but after it has invaded the feathered parts it al- 

 most invariably continue to advance, and the birds grow weaker until 

 they die from this or some other disease to which their debilitated con- 

 dition has made them abnormally suscei)tible. 



Treatment. — When only the bare jiarts of the head are affected the 

 disease may be cured by applying tincture of iodine to the diseased 



