Pathological changes in paratuberculosis vis-à-vis serum micronutrient status in spontaneously affected goats

The present study was undertaken to evaluate histological and histochemical alterations in paratuberculous lesions vis-a-vis the serum micronutrient status in spontaneously affected goats. Pathological studies, using routine and special staining techniques, were carried out in 8 paratuberculous morbid goats. Serum samples from 10 infected and 10 uninfected goats were used for comparing micronutrient status. Pathological studies revealed wide spectrum of lesions varying from paucibacillary to multibacillary types. Histopathologically, the multibacillary lesions in the intestines and MLNs were characterized by extensive infiltration of epithelioid macrophages containing numerous acid fast bacilli (AFB) while the paucibacillary lesions were characterized by small macrophage granulomas with a few AFB, surrounded by numerous lymphocytes. Histochemically, the multibacillary paratuberculosis showed abundant calcium and iron deposits, positivity for acid mucopolysaccharides was in the areas with severe inflammatory zones, however, no variation was noted in copper deposition in tissue sections in uninfected and affected goats. The mean serum iron level in the infected goats was lower and differed significantly (P<0.05) from the uninfected controls. The mean values of the other minerals viz: zinc, copper, manganese and copper did not differ significantly. The study revealed a positive correlation of mycobacterial load to tissue iron levels, and a negative correlation with serum iron levels.