Experimental Ascaris suum infection in Yankasa lambs: Parasitological and pathological observations

Abstract

The effects of experimental Ascaris suum infection in Yankasa lambs were investigated. Twenty four (24) Yankasa lambs aged 6-8 months were purchased and randomly divided into two groups (1 and 2). The lambs in group 1, consisting of 16 animals, were orally infected with 1500 infective A. suum eggs daily for seven consecutive days while those in group 2, consisting of 8 animals were maintained as non-infected/control group. All the experimental animals were closely monitored for 10 weeks, during which faecal samples were collected and analysed; and biochemical parameters of the blood samples were also evaluated. A total of seven animals (six from the infected and one from the control group) were humanely sacrificed on days 7, 14, 28 and 56 post-infection (p.i.) for larval/worm recovery, gross and histopathological examinations of organs. The values of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) from animals in the infected group increased significantly (P<0.05) on day 14 p.i. The animals from the infected group were observed to have a significant increase in the mean values of creatinine and urea on day 28 p.i. All liver samples from the sacrificed infected animals showed varying degrees of diffuse whitish areas of necrosis. Similarly, histopathology revealed different levels of mononuclear cellular infiltration in the liver of the sacrificed infected animals. In two of the infected animals, the kidneys were congested. By comparison, the corresponding organs from animals in the control group were normal. Eight (8) A. suum larvae were recovered from the lungs of one infected animal sacrificed on day 28 post-infection. However, no egg was detected in the faeces of the lambs. It is concluded, based on the findings of this study that A. suum is infective to Yankasa lambs but is only slightly pathogenic to the lambs and did not develop to patency.

Keywords: Ascaris suum, Histopathology, Lambs, Larvae, Pathology