Subclinical hemorrhagic enteritis (HE) has become more of a concern in the turkey industry than classical HE. The subclinical version, which tends to strike birds 6 to 12 weeks of age, leads to immunosuppression and mild enteritis. Damage to the gut wall allows Escherichia coli to penetrate the bloodstream, and immunosuppression reduces the bird's ability to fight off the infection.

Prevention is key
There are no good treatments for HE, so the best approach is to prevent the disease through good management and proper vaccination, Radu advises.“I emphasize proper vaccination,” Radu says, “because it’s been theorized that if HE vaccines are given improperly or administered at the wrong time, the result is suboptimal immunity, which allows subclinical HE to occur.”

Vaccination
Turkeys should be vaccinated against HE by 6 weeks of age, before they are moved to the grower/finisher barn, Radu says. The exact age to vaccinate depends on the maternal antibody levels passed on to poults and the timing of field challenge by the HE virus, he continues.  Poults from breeders with moderate levels of HE antibodies should not be vaccinated before 4 weeks of age because levels of maternal antibodies may interfere with the vaccination response, he says.

“In a situation of early field challenge, these poults should be vaccinated at 4 weeks of age and again at 5 weeks of age, but poults from breeders with moderate levels of HE antibodies that are challenged at a later age may only need one vaccination around 5 weeks of age,” Radu says.