Safety and efficacy studies of Newcastle Disease vaccines in very young African local ecotype chicks and in commercial pullets

Abstract

Two Good Clinical Practice studies are described. Firstly, the safety and efficacy of live, attenuated LaSota and
l-2 Newcastle Disease (ND) vaccines and inactivated, adjuvanted ITA-NEW ND vaccine were evaluated in eightday old local ecotype chicks. For all vaccines safety and efficacy were satisfactory and serological titres
exceeded the putative protective level of >2
3
before 14 days post-vaccination. The vaccinated groups displayed
no significant differences. The data suggest that these vaccines are effective in very young village poultry.
Secondly, in 35 day-old ISA-Brown pullets, MSD a 10x field dose formulation of Clone 30 vaccine, was
compared to I-2 after a heat-stress test approximating to local conditions of delivery and use (24h, 32.3oC, in the
dark). By 14 days post-vaccination, the heated MSD vaccine and heated I-2 titres exceeded 23
but the response
of the heated MSD group was significantly higher than the heated I-2 group. Non-heated MSD induced a very
rapid and higher response than those induced by the heated vaccines, as by 7 days post-vaccination, a 2
3 titre
was reached and exceeded (GMT 4.0). The 10x normal field dose approach to conferring thermotolerance to live
vaccines appears to be a simple, cheap and pragmatic method for use in hot climates.