(_c_) Attempt to control spread of parasitic infestation by using a parasiticide like copper sulphate in the drinking water. This is used in a 1-2000 solution. _d._ TUBERCULOSIS. This is an infectious and highly contagious disease caused by a highly-resistant germ which can live in soil for 2 years. (1) _Symptoms._ The young die suddenly and old birds waste away. Grayish white nodules appear in liver and spleen, basket ulcers in intestines, and yellow nodules in all parts of the body. (2) _Treatment._ There is no treatment for tuberculosis. Destroy all affected birds and thoroughly clean and disinfect loft. (3) _Prevention._ Keep all stray pigeons out of loft and maintain sanitary conditions at all times. _e._ ONE-EYE COLD (CONJUNCTIVITUS). (1) _Symptoms._ There is a watery discharge from the eye, and the surrounding membranes are frequently swollen. (2) _Treatment._ Place bird in a warm room and treat eye daily with one drop of metaphin, or one drop of 15 percent argyrol. (3) _Prevention._ Provide proper ventilation in the loft. Avoid dampness and drafts. _f._ GOING LIGHT. This is not a disease in itself but a symptom or result of a disease. Any pigeon showing loss of flesh should be isolated and observed until the affecting disease is determined. _g._ DIARRHEA. This is not usually a distinct disease, but the result of some other disease. (1) _Symptoms._ Droppings are green and watery. (2) _Treatment._ Sick birds should be isolated and observed to determine if they have some other disease. Feeding of rice will usually check the condition if it is caused by feed or drinking water. (3) _Prevention._ Sanitary loft conditions, proper diet, and fresh drinking water will help prevent it. _h._ SOUR CROP. Sour crop is caused by damp or mouldy grain, impure water or lack of grit. (1) _Symptoms._ The pigeon will sit with feathers ruffled. A greenish diarrhea usually accompanies sour crop. On examination the crop is found to be hard and distended. (2) _Treatment._ Hold the bird with head down and gently press on the crop until all feed has been removed. Flush out the crop with a solution of 4 teaspoons of bicarbonate of soda to a quart of warm water. Feed a light mixture, consisting mostly of rice, millet, kaffir corn, and other small seeds. Repeat the cleaning and flushing of the crop daily, if necessary, until this condition clears. (3) _Prevention._ Sanitary loft conditions, proper diet, and fresh drinking water will help prevent it. 53. External Parasites Many insects and related species live off other animals. Some of these parasites, like lice, live on the host but feed only upon bits of its feathers and tiny scales and excretions of the skin. Others are more vicious and suck blood from the animal. Diseases are often spread from bird to bird through the life habits of these parasites. _a._ LICE. Lice are undoubtedly the most common of these external parasites.