Identification
of Coccidia Species in Broiler Chickens in Argentina
Hernán González1, Mauricio
De Franceschi2 and Hebe Barrios1
1Departament of Basic Science, 2Departament of Technology.
Luján National University. Ruta Nacional 5
y Avenida Constitución. 6700. Luján.
Argentina. sip@mail.unlu.edu.ar.
We need not to assert that
coccidiosis is highly prevalent in poultry production.
Therefore, it is important to determine the presence
and the frequency of the species present in any region.
The identification of species depends on the ability
to use traditional diagnostic methods. The development
of molecular techniques in different studies requires
simple techniques for DNA extraction. The identification
of coccidia in broiler chickens in the provinces of
Buenos Aires and Entre Rios was made using conventional
methods, and the presence of Eimeria sp. was confirmed
using molecular biology. In both provinces, 63 samples
of 74 farms were positive for presence of coccidia,
whereas the remaining 11 were negative. All seven
species were present in variable percentages. Characteristic
lesions of Eimeria acervulina and ovoid oocysts were
present in all 59 positive samples (93.65%). Typical
ovoid oocysts of Eimeria maxima and typical lesions
in the jejunum-ileum were present in 34 samples (53.97%).
Eimeria mitis was present in 24 farms (38.10%), where
it produced typical sub spherical oocysts before 93
hours post-inoculation. Eimeria tenella was confirmed
in 15 samples based on oocyst size and typical lesions
in the cecum (hemorrhages, coagulated blood in the
lumen, and thickened cecal mucosa). Eimeria praecox
was conclusively identified in 14 samples (22.22%)
by the typical oocysts present in the feces 84 hours
post-inoculation. Lesions in the lower small intestine
of 5 samples (7.94%) were typical of Eimeria brunetti,
and Eimeria necatrix was present in 5 farms (7,94%).
Finally, the high prevalence of Eimeria acervulina
and Eimeria maxima was related to the high incidence
of mild clinical and subclinical cases. The conventional
methods are not adequate for a definitive identification
for the differentiation between Eimeria acervulina
and Eimeria mitis. The low incidence of Eimeria praecox,
Eimeria brunetti, and Eimeria necatrix warrants the
reconsideration of the inclusion of these species
in the specific immunogen for broiler vaccination.
The presence of Eimeria DNA, generated by the amplification
of regions ITS1 using primers EF1 and ER1, and ITS2
with primers WW2 and WW4r developed in the University
of Melbourne, confirm the presence of these species
in our country. It is concluded that the methodology
used may be the starting point for the identification
of specific primers aiming at the development of vaccines
based on native strains.