Effect of unfavourable storage conditions on the viability of marketed fowl typhoid vaccines: rural area scenario

Abstract

Poultry farming in the rural areas of Nigeria plays a major role in the sustenance of the dwellers and contributes to the total national income of the country. Protecting the birds from fowl typhoid is of dire importance. Vials of a marketed fowl typhoid vaccine were subjected to variable storage conditions namely;:daily freeze-thaw cycles, room temperature, 40 ºC, 85% relative humidity (RH) and refrigeration (with fluctuating power) for three weeks. Biochemical tests were carried out on the vaccine samples before storage to confirm the presence of live 9R viable Salmonella before commencement of the stability studies. The stability of the vaccines was assessed by performing these studies: percent (%) viability, pH, FTIR spectroscopy and ninhydrin test. For the % viability, the daily freeze-thaw cycle samples had the highest number of viable cells, while the refrigerated samples had the least, after three weeks of storage. The pH showed a slight increases for all the extreme storage conditions. The FTIR spectroscopy showed slight shifts in the peaks of all the spectra after three weeks indicating imminent loss of viability. The results show a gradual loss of viability of the vaccines kept under unfavorable conditions. Stringent measures need to be taken to ensure adequate storage of the vaccines to prevent loss of viability that may lead to infection with fowl typhoid.

Keywords: fowl typhoid, vaccine, Salmonella gallinarum, viability, stability, storage