Contributed Papers: Oral Presentations
Mixed Cocciodiosis Control: Drugs and Vaccines |
Higher incidence
of Eimeria spp. field isolates sensitive to diclazuril
and monensin after live coccidiosis vaccination with
Paracox™-5
H.W. Peek and W.J.M. Landman
w.landman@gdvdieren.nl
Animal Health Service Ltd., P.O. Box 9,
7400 AA Deventer, the Netherlands
Abstract
Twenty Eimeria
spp. field isolates originating from Danish, German,
Greek, Italian, Portuguese and Rumanian broiler farms
were subjected to anticoccidial drug sensitivity testing.
The anticoccidial drugs tested were diclazuril (Clinacox®)
and monensin (Elancoban®) at a concentration of
1.1 mg/kg and 103 mg/kg respectively. The assay was
performed in experimental battery cages. Broiler chickens
fed with anticoccidial drugs were infected with a
defined number of sporulated oocysts of the Eimeria
spp. field isolates. An infected unmedicated control
group was given the same inoculum and served as positive
control while an uninfected unmedicated group was
used as negative control. Coccidial lesion scores,
oocysts shedding and weight gain were used as parameters.
Based on the percentages of reduction of mean lesion
scores of the infected medicated birds compared to
the infected non-medicated chicks, the results show
that resistance is common amongst European coccidiosis
field isolates, especially E. acervulina (68 and 53%
resistance for diclazuril and monensin, respectively).
Resistance is less frequent amongst E. maxima (38
and 50% resistance to diclazuril and monensin, respectively)
and E. tenella isolates (23 and 38% resistance to
diclazuril and monensin, respectively). Statistical
analysis by the Chi-Square test showed a highly significant
influence of the coccidiosis prevention program (live
coccidiosis vaccination with Paracox™-5 versus
anticoccidial drugs in feed) on the sensitivity pattern
of Eimeria spp. field isolates to both diclazuril
(P = 0.000) and monensin (P = 0.001). When looking
at coccidia species and anticoccidial drug level,
a significant effect of vaccination on the sensitivity
profile of E. acervulina to monensin (P = 0.018),
E. tenella for diclazuril (P = 0.007) and E. maxima
to diclazuril (P = 0.009) was found – thus,
in half of the cases. The present study shows that
sensitivity to the anticoccidial drugs diclazuril
and monensin is more frequent in Eimeria spp. field
isolates originating from broiler farms where a coccidiosis
vaccination policy was followed.
