Comparison of effects of two contagious Bovine Pleuropneumonia vaccines on Lung lesions and Seroprev Alence in Cattle kept under the Maasai ecosystem

Abstract

Contagious bovine pleuropneumonia (CBPP) is a disease of major economic importance in many countries in sub Saharan Africa. Routine vaccination remains the preferred option for control of the disease. The purpose of the present study was to evaluate the effect of two live attenuated TA4 Mycoplasma mycoides mycoides small colony (MmmSC) vaccines: a modified vaccine cultured in a buffered growth media and a conventional vaccine cultured in unbuffered media on the prevalence of CBPP in cattle in the Maasai ecosystem. The study population consisted of cattle under pastoral production system in Loita, Mara and Osupuko divisions of the greater Narok District. Approximately eighty thousand (80, 000) cattle in 458 participating herds were randomly allocated such that half received either the conventional vaccine or modified vaccine in February/ March 2007. Data including age, sex and geographical location were recorded in a data base. An abattoir study was conducted 9 to 15 months post vaccination in 4 slaughterhouses in Dagoretti to compare prevalence of lung lesions suggestive of CBPP and MmmSC antibodies in a randomly selected sample of the two study groups. Thorough examination of 424 lungs from cattle vaccinated with either the conventional (227) or modified (197) vaccines did not reveal any lesions suggestive XVI of CBPP. Antibody prevalence was investigated by complement fixation test (CFT) and competitive enzyme linked immunosorbent assay (cELlSA). The seroprevalence estimated by cELlSA were 17% and 11.3% in the conventional and modified groups respectively while CFT estimates were 6.3% and 1.3%. However, a statistically significant association between vaccine type and antibody prevalence was only demonstrated by CFT (P = 0.024). Univariate logistic regression analysis showed that period post vaccination (P = 0.058), division (P = 0.009) and vaccine type (P = 0.076) were significantly associated with presence of MmmSC. This study did not find convincing evidence to show any difference in the protection provided by conventional and modified vaccines 9 to 15 months following vaccination. Both vaccines could be equally effective in preventing development of disease.