Counting Eimeria Before They Hatch
By Rosalie Marion
Bliss February 7, 2007
Agricultural Research Service (ARS) scientists have developed a rapid
system for identifying which of several Eimeria species are present on a
particular farm. Eimeria are single-celled protozoans that cause
coccidiosis, a major intestinal disease of chickens.
Coccidiosis makes it difficult for the chickens to absorb feed and
gain weight, resulting in economic losses of more than $600 million annually
for U.S. poultry producers.
Distinguishing between the Eimeria species that commonly infect
chickens has been a challenge because their egglike oocysts are nearly
identical in appearance. Producers have commonly used anticoccidial compounds
that kill multiple Eimeria species at once, regardless of how many may
actually infect a farm. But the Eimeria species targeted by these
all-in-one anticoccidial drugs develop resistance to the compounds. The new
technique can help producers fine-tune which drugs or vaccines to use in a
particular poultry facility.
Jenkins and molecular biologist
Miska, both with the
Animal Parasitic Diseases Laboratory in Beltsville, Md., developed a method
that involves isolating Eimeria oocysts from poultry litter. Combining
this process with PCR (polymerase chain reaction) technology enables
researchers to identify which Eimeria species are present.
The new method will enable poultry producers to quickly determine
which of seven Eimeria species are present on a farm. That knowledge
will help them use just the right combination of vaccine and anticoccidial
treatment to protect their flocks.
The system was described in the journal Avian
more about this research in the February 2007 issue of Agricultural
ARS is the U.S. Department of
Agriculture's chief scientific research agency.