Avian encephalomyelitis virus antibodies in New Zealand chicken flocks

Abstract

Extract

Madam:— Avian encephalomyelitis (AE) virus is a picornavirus which produces a clinical disease only in young chickens, especially those 2–3 weeks old. Affected birds exhibit ataxia, tremors of the head and neck and there is an average mortality of 10%. ⁽¹⁾ Clear epidemiological evidence linked the clinical form of the disease with a series of egg production drops in 1977 in several North Island multi-age laying farms, which were rearing affected batches of chickens. ⁽²⁾ Between 1980 and 1982 Howell tested pooled samples from 40 New Zealand laying chicken flocks (which had not been Ae vaccinated) using the serum neutralization (SN) test. ⁽³⁾ Neutralizing antibody levels indicative of infection with AE virus were detected in 47% of these flocks. ⁽²⁾ Recently on agar gel precipitin (AGP) test was described which appeared to offer a more convenient method for detecting antibodies. ⁽⁴⁾ We present the results obtained with this test, after assaying a selection of samples routinely submitted to the Ruakura Animal Health Laboratory during 1983–84.