Newcastle disease (ND) is a very common and economically important disease of poultry. There is no drug for treatment of the disease during an outbreak in poultry flocks, and prevention by vaccination is one of the recommended control measures. However, post vaccination outbreaks have been observed on many occasions in chicken flocks and one of the causes has been attributed to possible failure of vaccine to confer immunity. This study was designed to evaluate the potency of ND vaccines available in Ibadan, Nigeria.
Haemagglutination (HA) technique and elution phenomenon were employed to evaluate the potency of ND vaccines randomly selected in Ibadan. A total of 45 vaccines comprising 9 brands and 5 different strains were selected for potency test. The vaccine brands included ‘Vireo 116’ (n=10), ‘ABIC’ (n=5), ‘Biovac’(n=9), ‘Nobilis’(n=3), ‘NVRI’(n=12), ‘R2B’ (n=2), ‘BAL-ND’ (n=2), ‘Forte dodge’(n=1) and ‘Jovac’ (n=1), while the vaccine strains in the brands included Lasota, B1, Clone, Komarov, Hitcher, and an unknown strain.
Thirty-five of the 45 (77.8%) ND vaccines tested had more than 4 HA titer (>64) and were therefore regarded as potent. All the 15 (100%) ND Lasota vaccine strain, 7 out of 10 (70%) ND Komarov strain, 4 out of 5 (80%) ND clone and 5 out of 8 (62.5%) ND B1 strains were potent. None of the ND brand ‘R2B’ vaccine as well as Hitchner strain from ‘Nobilis’ brand was potent, but all 5, 2, 1 and 1 vaccines tested from brands ‘ABIC’, ‘BAL-ND’, ‘Fort dodge’ and ‘Jovac’ respectively were potent. Similarly, 9 of 10, 6 of 9, 2 of 3 and 9 of 12 vaccine strains tested from brands ‘Vireo 116’, ‘Biovac’, ‘Nobilis’ and ‘NVRI’ were respectively potent
The occurrence of ND vaccines that are not potent in this study may be contributing to post vaccination failure. It is advisable to subject vaccines to potency test before use.
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