Carboxymethylated and acetylated xerogel derivatives of Plectranthus esculentus starch protect Newcastle disease vaccines against cold chain failure.

Developing vaccine stabilizers from local natural sources is desirable especially if the stabilizer would enhance the ability of the antigen to withstand frequent failures in cold chains. The study was undertaken to formulate immunogenic live Newcastle Disease (ND) LaSota vaccines stabilized with modified native starches for use at cold and ambient temperatures and to assess the immunogenicity of the starch stabilized vaccines in vaccinated chickens. Native starch extracted from the tubers of Plectranthus esculentus (Family, Lamiaceae) was modified by carboxymethylation and acetylation/xerogel formation and used as vaccine stabilizers of ND LaSota virus with/without buffers/bulking excipients. Cold Chain Failure (CCF) was simulated by storing the vaccines at 5 ± 2 °C for one month then at 37 ± 1 °C for 96 h. The stability of the samples were evaluated in comparison with peptone stabilized ND vaccines using pH, residual moisture, XRD, reconstitution time, mean embryo infective dose (EID50) and haemagglutination (HA) tests. Haemagglutination inhibition was used to evaluate the efficacy of the vaccines in conferring positive serum antibody titers (≥23 log2) in vaccine-naïve 2-week old broilers that were orally administered a single dose of the vaccines kept at 37 ± 1 °C for 96 h and bled weekly over four weeks. Temperature, pH, moisture content and amorphousness impacted vaccine stability. Peptone stabilized vaccines were significantly less stable and most affected by temperature changes with 1.2log10EID50 loss while buffered/bulked trehalose, carboxymethylated and acetylated/xerogelized starch stabilized vaccines were most stable (0.2-0.5log10EID50 loss in titer) after 96 h in CCF. Buffered trehalose stabilized vaccine (TVB) had lower HA titres than peptone and starch stabilized vaccines containing D-mannitol and Na2HPO4. Antibody titres of vaccinated broilers were between 3.3 ± 1.398 and 8.35 ± 2.678. All the vaccines were immunogenic (HI ≥ 23) and developed HI titres (≥24) considered to be protective. Carboxymethylated and acetylated/xerogel derivatives of P. esculentus starch have a great potential as vaccine stabilizers especially in areas prone to CCF.

A pilot study for targeted surveillance of bovine spongiform encephalopathy in Nigeria.

Bovine spongiform encephalopathy (BSE), popularly known as 'mad cow disease', led to an epidemic in Europe that peaked in the mid-1990s. Its impact on developing countries, such as Nigeria, has not been fully established as information on livestock and surveillance has eluded those in charge of this task. The BSE risk to Nigeria's cattle population currently remains undetermined, which has resulted in international trade restrictions on commodities from the cattle population. This is mainly because of a lack of updated BSE risk assessments and disease surveillance data. To evaluate the feasibility of BSE surveillance in Nigeria, we carried out a pilot study targeting cattle that were presented for emergency or casualty slaughter. In total, 1551 cattle of local breeds, aged 24 months and above were clinically examined. Ataxia, recumbency and other neurological signs were topmost on our list of criteria. A total of 96 cattle, which correspond to 6.2%, presented clinical signs that supported a suspect of BSE. The caudal brainstem tissues of these animals were collected post-mortem and analysed for the disease-specific form of the prion protein using a rapid test approved by the International Animal Health Organization (OIE). None of the samples were positive for BSE. Although our findings do not exclude the presence of BSE in Nigeria, they do demonstrate that targeted sampling of clinically suspected cases of BSE is feasible in developing countries. In addition, these findings point to the possibility of implementing clinical monitoring schemes for BSE and potentially other diseases with grave economic and public health consequences.

Variations in haematological parameters and erythrocyte osmotic fragility of pigs during hot-dry and harmattan season in Northern Guinea Savanna zone of Nigeria.

Experiments were performed with the aim of investigating the effect of season on haematological parameters and erythrocyte osmotic fragility (EOF) of pigs. A total of 23 local pigs including males, non-pregnant and non-nursing females, aged 9 to 12 months were used for the study, ten animals were used during the hot-dry season and thirteen during the harmattan season. Blood sample was taken from each animal for the determination of EOF and other haematological parameters as well as total protein. The PCV value of 39.7±1.9 % obtained during the hot-dry season was significantly higher than 32.00 ± 0.9 % obtained during the harmattan season. Total leucocyte count of 18,836.5±1727.1 obtained during the harmattan season was higher than the value 15,920.00±1119.1 recorded during the hot-dry season. The neutrophil:lymphocyte ratio value was significantly higher during the harmattan season, with a value of 0.61±0.0 than the recorded value of 0.43±0.0 during the hot-dry season. The percentage haemolysis values obtained during the harmattan season at NaCl concentration of 0.5-0.9 % with a value of 92.03±0.02 % respectively were significantly higher than those recorded during the hot-dry season. In conclusion, the haematological values showed that harmattan season was more stressful to pigs than the hot-dry season in the Northern Guinea Savanna zone of Nigeria.