HISTOMONAS 



79 



Cooper and Skulski (1957) among others. 

 Nithiazide (l-ethyl-3-[ 5-nitro-2-thiazolyl] 

 urea) was introduced by Cuckler et al. 

 (1956, 1957) and Cuckler and Malanga 

 (1956). 



These drugs have both prophylactic, 

 suppressive and therapeutic value. En- 

 heptin is usually fed continuously in the 

 mash at the rate of 0.05% for prevention 

 and suppression. If feeding is begun 

 within 2 days after the infective dose of 

 Histomonas is given in an experimental 

 infection, it will almost completely pre- 

 vent the disease. If it is begun later than 

 this, it will suppress the disease as long 

 as it is continued, but after it is withdrawn, 

 histomonosis will reappear in the flock. 

 If enheptin is to be used in treating turkeys 

 which already show signs of disease, 0. 1 

 to 0. 2% of the drug is mixed in the feed. 

 Not all the birds will recover, but quite a 

 high percentage do. Acetylenheptin is 

 used in much the same way. The preven- 

 tive level of nithiazide in the feed recom- 

 mended by the manufacturer in 1958 was 

 0.03%. 



Potential hazards are often associ- 

 ated with feeding drugs continuously. 

 Hudson and Pino (1952) and Pino, Rosen- 

 blatt and Hudson (1954) found that enheptin 

 prevented or delayed sexual maturity in 

 chickens and turkeys. When fed in the 

 ration to chickens, it produced complete - 

 sexual involution or inhibition in both 

 males and females. In young birds, sex- 

 ual development did not take place, while 

 in older ones the testes, ovary and oviduct 

 atrophied. The effect was less marked in 

 turkeys, altho 0.1% enheptin in the ration 

 reduced the level of reproductive perform- 

 ance. This effect was found to be due to 

 inhibition of gonadotropin secretion by the 

 pituitary, and could be counteracted, at 

 least in part, by simultaneous administra- 

 tion of gonadotropic hormone. Shellabar- 

 ger and Schatzlein (1955) found that enhep- 

 tin caused rats to have larger thyroid 

 glands and to accumulate less iodine than 

 normal rats. They suggested that these 

 antithyroid properties might explain why 

 enheptin inhibits the secretion of pituitary 

 gonadotropin in the chicken. 



Grumbles, Boney and Turk (1952) 

 and Cooper and Skulski (1957) compared 

 enheptin with acetylenheptin. The former 

 found that 0. 1% enheptin in the feed reduced 

 production, fertility and hatchability in tur- 

 keys, but that acetylenheptin had no such 

 effect. The latter found that enheptin de- 

 creased spermatogenesis and egg produc- 

 tion and increased embryo mortality when 

 fed to chickens at preventive levels. Acet- 

 ylenheptin was less toxic. It had no effect 

 on egg production, fertility or embryo 

 mortality, and reduced sperm production 

 only slightly. 



According to Cuckler, Porter and Ott 

 (1957), 0.1% nithiazide in the feed did not 

 interfere with growth, maturation or re- 

 production of chickens or turkeys. 



The nitrofuran, furazolidone (NF-180, 

 Furoxone), was found by McGregor 

 (1953a, 1954), Horton-Smith and Long 

 (1955, 1956) and Costello and DeVolt (1956) 

 to suppress histomonosis when fed at the 

 rate of 0. 01 to 0. 04% in the feed. Even 

 with the higher doses, however, some re- 

 lapses occurred after medication was 

 stopped, and slight lesions were found in 

 treated birds killed during the experiments. 



Cooper (1956) reported that feeding 

 0. 02% furazolidone to pullets for 12 weeks 

 had no effect on body weight, egg produc- 

 tion, fertility or hatchability, but Cooper 

 and Skulski (1955, 1956) found that feeding 

 this drug to cockerels and roosters re- 

 duced the number of spermatozoa and de- 

 creased weight gains. 



Control : Histomonosis can be pre- 

 vented by good management. Turkeys 

 should be kept separate from chickens, 

 since chickens are carriers. Young tur- 

 keys should be kept separate from adults. 

 The same attendants should not care for 

 chickens and turkeys. Persons who go 

 from one flock to another should take care 

 not to carry the infection on contaminated 

 shoes or equipment. 



Young birds should be raised on hard- 

 ware cloth, and the droppings should be 

 removed regularly. When the poults are 



