Evaluation of Some Fowl Pox, Gumboro and Newcastle Disease Vaccines Marketed in Nigeria
The quality of live commercial fowl pox (FP), Gumboro disease (GD) and Newcastle disease (ND) vaccines manufactured by four laboratories and on sale in Nigeria were tested. One of the nine vaccines yielded Aspergillus sp., two Salmonella sp. and three Escherichia coli when grown on culture media. All the four ND vaccines and one of the three FP vaccines tested contained the recommended virus titre. None of the two GD vaccines tested contained the recommended virus titre. Two of the three FP vaccines were able to protect 100% of vaccinated chicks challenged with a virulent FP virus. All chicks vaccinated orally (PO) or intramuscularly (IM) with Two of the three vaccines had pox lesions when challenged while only 17% of chicks had pox lesions following IM vaccination with one of the three FP vaccines. Two weeks post vaccination (PV) only 17% and 33% of the chicks vaccinated with two of the three GD vaccines had precipitin antibodies (PAb) in their sera while 100% of the chicks vaccinated with one of the three GD vaccines had PAb. All the three GD vaccines caused reduction in body weight gain and atrophy of the bursa of Fabricius when administered at one or 10 times the normal dose. The haemagglutination inhibition (HI) antibody titre of ND vaccinated chicks was highest two weeks PV and in chicks vaccinated intraocularly with 10 times the normal dose. Only 50%, 56% and 78% of chicks vaccinated with three ND vaccines were protected when challenged with a local virulent ND virus. Live viral vaccines are therefore possible sources of bacterial and fungal infections for poultry in Nigeria. Some commercial vaccines contain low virus titres, are poorly immunogenic or pathogenic even at recommended dose therefore are unable to protect all vaccinated chicks when exposed to virulent viruses. The aforementioned factors are some of the likely causes of outbreaks of FP, GD and ND in vaccinated flocks in Nigeria. There is the need to routinely reassess the quality of all commercial poultry vaccines and maintain their quality by proper handling, transportation and storage. Vaccines should also to be properly administered by poultry farmers.
Keywords: Safety, Poultry vaccines, Potency.