[The effect of emissions from a mercury-processing metallurgy plant on the intensity of experimental Fasciola hepatica infection in sheep].

A group of 14 improved Valashka lambs, aged 4 months, body weight 14-16 kg, were used in the experiment studying the effect of subchronic heavy metal intoxication on the course of experimental fasciolosis (Fasciola hepatica). The animals were divided into two groups, each of 7 lambs, 3 lambs--ewes and 4 lambs--rams. Each animal in group I was given orally for 27 days gelatinous capsules containing heavy metal emissions of the following composition: 4.5 mg Hg, 2.9 mg Pb, 147.8 mg Cu, 9.8 mg Zn, 0.9 mg Cr and 0.04 mg Cd per animal and day. Group II served as control. On Day 27, when the administration of heavy metals ceased, each animal in both groups received 250 F. hepatica metacercariae. The animals were sacrificed on Day 110 post infection, their liver necropsied and parenchymatous organs and muscles taken to examine the content of heavy metals. The heavy metal concentrations are presented in Tab. I. In the emission-intoxicated group, the maximum permissible reference level of mercury in the kidneys, liver and muscles was exceeded on the average by 1.94, 0.87 and 0.020 mg Hg/kg, respectively. Cu exceeded the reference level only in the liver, with 261.3 mg Cu/kg. In the kidneys and muscles, Cu was below the reference levels. An analogous situation was with Zn, Cr, and Cd. The F. hepatica infection mean intensity in this animal group was 38.3 +/- 3.01 specimens (min. 34 - max. 46 specimens). In control group, the heavy metal levels were several times lower than the reference values and the infection mean intensity was 27 +/- 5.4 (min. 19 - max. 35 specimens). In subchronically intoxicated animals, the reference values for mercury were exceeded and so were partially those of copper in the parenchymatous organs and muscles. The F. hepatica infection mean intensity also increased, compared with control. The results have proved the negative effect of the metal emissions on the animal immune system, which was manifested by the increased infection intensity.