Experimental studies on anaemia in sheep infected with Dictyocaulus filaria.

The pathogenesis of Dictyocaulus filaria induced anaemia was experimentally investigated. Nineteen Dorset-Muzaffarnagri male lambs were divided into two groups of 13 and six. The lambs in the former group received a primary infection dose of 2000 D. filaria infective larvae, whereas animals in the latter group were kept as uninfected controls. The haematological alterations and faecal larval output were monitored weekly until day 220 post-infection. The infection caused an increase in erythrocyte sedimentation rate (ESR) and total leukocyte count (TLC). However, a decrease in packed cell volume (PCV), haemoglobin, total erythrocyte count (TEC) and blood pH was observed in acute infection. The shape and size of the erythrocytes, serum bilirubin level, mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentration (MCHC) remained unaffected In carriers, except for TEC, the values of these parameters returned to near-normal levels. The analysis of the results suggests that the infected animals developed a normocytic normochromic anaemia which persisted during the later stage of infection.