2002 Poultry Science Association, Inc.
Effect of Anticoccidials and
Antibiotics on the Control of
Blackhead Disease in
Broiler Breeder Pullets
J. Hu1and L. R. McDougald
Department of Poultry Science,
University of Georgia, Athens, Georgia 30602
Broiler chicks inoculated with both Histomonas and cecal coccidia developed moderately severe
blackhead disease. Antibiotics tested at normal feed or water additive levels had little effect on
Histomonas lesions or weight gains. Bacitracin at 100, 200, or 300 g/ton reduced liver lesion scores
(P < 0.05) but had no other positive effects. Apramycin at 300 ppm in water reduced liver lesion
scores (P < 0.05), but did not improve cecal lesions or weight gains. Penicillin (100 ppm),
chlortetracycline (100 ppm), tylosin (110 ppm), and sarafloxacin (40 ppm) in water did not improve
liver or cecal blackhead lesions. Weight gains were improved relative to infected controls by
treating with penicillin, tylosin, or sarafloxacin (P < 0.05).
Five anticoccidials (salinomycin, diclazuril, nicarbazin, roxarsone, and lasalocid) were tested
at common use levels in two trials. Results were similar in both trials; liver lesion scores in the
nicarbazin treatment were reduced (P < 0.05) compared with controls and other medicated groups,
and the number of birds positive for liver lesions was lower (P < 0.05). Otherwise, anticoccidials had
shown by oocyst counts) varied among products but was not correlated with severity of blackhead
lesions. These results suggest that the effect of cecal coccidia on susceptibility of chickens to
Histomonas meleagridis is not a simple function of mechanical damage to the cecal mucosa.
Key words: antibiotic, anticoccidial, blackhead disease, Eimeria tenella, feed additive, Histomonas
2002 J. Appl. Poult. Res. 11:351–357
DESCRIPTION OF PROBLEM
90 to 100% mortality in turkeys but is relatively
mild in chickens [1, 2]. However, recent out-
in the southeastern United States have been se-
1To whom correspondence should be addressed: firstname.lastname@example.org.
vere, creating a significant deterrent to the pro-
duction of broiler hatching eggs and table eggs
[3, 4]. Outbreaks of blackhead in breeder and
layer pullets are characterized by extensive mor-
tality, morbidity, poor uniformity, and reduced
tality from blackhead depends on Histomonas
HU AND MCDOUGALD: BLACKHEAD DISEASE IN CHICKENS 357
larity to other organic arsenic products with
known antihistomonal activity, roxarsone is
sometimes given in the water during blackhead
outbreaks in chickens. In this study, we did not
observe evidence that roxarsone was of benefit
in prevention of blackhead at the normal feed
additive level of 45 g/ton.
CONCLUSIONS AND APPLICATIONS
1. Some of the tested antibiotics had beneficial effects on weight gains in infected chickens;
however, none was effective in reducing the lesions or other pathology of H. meleagridis at
2. High levels of some products (300 g/ton of bacitracin or 300 ppm of apramycin) reduced liver
lesion scores but had no other positive benefits.
3. Lesions and other signs of blackhead were not reduced by most anticoccidials, regardless of
the effectiveness of control of cecal coccidia.
4. Nicarbazin (0.0125% in feed) gave significant reduction in liver lesion scores in two trials. The
reason for this improvement was not clear.
REFERENCES AND NOTES
1. Lund, E. E. 1969. Histomoniasis. Adv. Vet. Sci. Comp. Med.
2. McDougald, L. R. 1997. Protozoa: Other protozoan diseases
of the intestinal tract. Pages 890–899 in Diseases of Poultry. 10 ed.
B. Calnek, H. J. Barnes, C. W. Beard, L. R. McDougald, and Y. M.
Saif, ed. Iowa State University Press, Ames, IA.
3. Homer, B. L., and G. D. Butcher. 1991. Histomoniasis in
Leghorn pullets on a Florida farm. Avian Dis. 35:621–624.
4. McDougald, L. R. 2000. New developments in research on
blackhead disease in chickens. World’s Poult. Sci. J. 16(8):46–48.
5. McDougald, L. R., and J. Hu. 2001. Blackhead disease (His-
tomonas meleagridis) aggravated in broiler chickens by concurrent
infection with cecal coccidiosis (Eimeria tenella). Avian Dis.
6. Bradley, R. E., and W. M. Reid. 1966. Histomonas melea-
gridis and several bacteria as agents of infectious enterohepatitis in
gnotobiotic turkeys. Exp. Parasitol. 19:91–101.
7. Springer, W. T., J. Johnson, and W. M. Reid. 1970. Histo-
moniasis in gnotobiotic chickens and turkeys: Biological aspects of
the role of bacteria in the etiology. Exp. Parasitol. 28:383–392.
8. McDougald, L., and R. B. Galloway. 1973. Blackhead dis-
ease: In vitro isolation of Histomonas meleagridis as a potentially
useful diagnostic aid. Avian Dis. 17:847–850.
9. Petersime Incubator Co., Gettysburg, OH.
At present, no products are approved for
treatment of blackhead infections in chickens
or turkeys. Only nitarsone (4-nitrophenylarsonic
acid, 0.0175%) is used in feed for prevention of
blackhead. Exposure of chickens to the cecal
worm vector (Heterakis gallinarum) can be re-
duced by frequent worming with effective prod-
10. SAS Institute Inc. 1994. Version 6. SAS Institute Inc.,
11. Reid, W. M. 1962. Now it’s blackhead in broilers. Broiler
Business Magazine, Watt Publishing Co., Mount Morris, IL. Sept.,
titis in chickens in Uttar Pradesh. Indian J. Anim. Sci. 71:30–31.
13. Reid, W. M. 1967. Etiology and dissemination of the black-
head disease syndrome in turkeys and chickens. Exp. Parasitol.
14. Hegngi, F. N., J. Doerr, T. S. Cummings, R. D. Schwartz,
G. Saunders, A. Zajec, C. T. Larsen, and F. W. Pierson. 1999.
The effectiveness of benzimidazole derivatives for the treatment and
prevention of histomoniasis (blackhead) in turkeys. Vet. Parasitol.
15. McDougald, L. R., G. F. Mathis, and B. P. Seibert. 1990.
Anticoccidial efficacy of diclazuril against recent field isolates of
Eimeria from commercial poultry farms. Avian Dis. 34:911–915.
16. McDougald, L. R., J. M. Gilbert, L. Fuller, A. Rotibi, M.
Xie, and G. Zhu. 1992. How much does roxarsone contribute to
coccidiosis control in broilers when used in combination with iono-
phores? J. Appl. Poult. Res. 1:172–179.
17. Chapman,H.D., andS.H.Fitzcoy.1996. Effectofroxarsone
and bacitracin methylene disalicylate on the development of immu-
nity to Eimeria in broilers given a live coccidiosis vaccine. Poult.