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.