220 



THE TELOSPORASIDA AND THE COCCIDIA PROPER 



to nitrophenide, 45% to sulfaquinoxaline 

 and 57% to nitrofurazone. Twenty-two 

 percent were resistant to all 3 drugs, 18% 

 to 2 and 18"f to 1. None were resistant 

 to nicarbazin, which had only recently 

 been placed on the market. They produced 

 resistance against sulfaquinoxaline in 1 

 strain of E. acerviilina and 2 strains of 

 E. lenella by exposure to suboptimal dos- 

 ages of the drug during 15 serial passages, 

 but 1 strain of E. tenella was not rendered 

 resistant to nitrophenide, nitrofurazone or 

 nicarbazin by the same method for 15 ser- 

 ial passages. 



Drug resistance is becoming increas- 

 ingly common. It seems to develop with 

 especial ease against glycarbylamide. As 

 a consequence, we are in a race between 

 the discovery of new coccidiostats and the 

 development by the parasites of resistance 

 against the older ones. In the long run, 

 prevention of coccidiosis without reliance 

 on drugs appears to hold more promise. 



Prevention and Control : Coccidian 

 oocysts are extremely resistant to envir- 

 onmental conditions. They may remain 

 alive in the soil for a year or more (War- 

 ner, 1933; Farr and Wehr, 1949; Koutz, 

 1950). They will not sporulate in the ab- 

 sence of oxygen, and they are killed in 

 time by subfreezing temperatures. Thus, 

 Edgar (1954) found that the oocysts of E. 

 tenella vieve dead after 7 days at -12° C. 



Ordinary antiseptics and disinfectants 

 are ineffective against them. Pe'rard 

 (1924), for instance, found that the oocysts 

 of rabbit coccidia would sporulate unharmed 

 in 5% formalin, 5% phenol, 5% copper sul- 

 fate, or 10% sulfuric acid. Horton-Smith, 

 Taylor and Turtle (1940) confirmed this 

 with E. tenella and added 5% potassium 

 hydroxide and 5% potassium iodide to the 

 list. Indeed, the standard storage solu- 

 tions for coccidian oocysts are 2. 5% 

 potassium bichromate or 1% chromic acid 

 solution. 



The oocysts may be destroyed by 

 ultra-violet light, heat, desiccation or 

 bacterial action in the absence of oxygen. 

 Long (1959) found that exposure to a tem- 

 perature of 52° C for 15 minutes killed 



the oocysts of E. tenella and E. maxima. 

 However, Horton-Smith and Taylor (1939) 

 found that even a blowtorch did not kill all 

 the oocysts on the floors of poultry houses 

 unless it was applied long enough to make 

 the wood start to char. The problem is 

 to reach and maintain a lethal temperature 

 at the spot where the oocysts are. 



While formaldehyde fumigation is in- 

 effective against coccidia, Horton-Smith, 

 Taylor and Turtle (1940) showed that am- 

 monia fumigation is of practical value. 

 E. tenella oocysts were killed by an 

 0.0088% solution of ammonia in 24 hours, 

 by an 0. 044% solution in 2 hours and by an 

 0.088% solution in 45 minutes. They fu- 

 migated poultry houses successfully with 

 3 oz. ammonia gas per 10 cu. ft. For 

 satisfactory results, the houses should be 

 sealed so that the gas does not leak out. 



Boney (1948) found that methyl bro- 

 mide is also an effective fumigant. It in- 

 activated sporulated oocysts of E. tenella 

 in the litter or soil when applied at the 

 rate of approximately 1 lb. per 1000 square 

 feet (0. 3 ml per sq. ft. ). It prevented in- 

 fection in brooder houses using artificially 

 contaminated cane pulp litter on wooden 

 floors when used as a space fumigant at 

 the rate of 2 lb. per 1000 cu. ft. 



Since it is practically impossible under 

 farm conditions to prevent chickens from 

 picking up at least a few oocysts, preven- 

 tion of coccidiosis depends upon preventing 

 a heavy enough infection to produce disease 

 while at the same time permitting a symp- 

 tomless infection (coccidiasis) to develop 

 and to produce immunity. This can be 

 accomplished by proper sanitation and 

 management. Strict sanitation is effective 

 alone, but it is usually supplemented by 

 the use of a coccidiostatic drug. 



Young chickens should be raised apart 

 from older birds, since the latter are a 

 source of infection. If birds are raised on 

 the floor, each new brood of chicks should 

 be placed in a clean house containing clean, 

 new litter. The litter should be kept dry, 

 stirred frequently and removed when wet. 

 The feeders and waterers should be washed 

 in boiling water before use, and should be 



