Abstract: The aims of present research were to determine the concentration of micro minerals, including Cu, Zn, Co and Fe in hydatid cyst fluid, comparing micro minerals composition between fertile and infertile cysts and determining the correlation between values in cysts, serum and liver tissue. A total of 2,550 slaughtered sheep were examined carefully for hydatid cyst infection. Blood samples, hydatid cysts fluid and liver samples were taken from 100 infected sheep and gravidity was diagnosed in aid with microscopic examination. Potentiometric Striping Analyzer (PSA) and atomic absorption spectroscopy were used for measuring the micro minerals concentration as well. Results showed that the concentration of mentioned micro minerals in gravid cyst fluid and its related sheep serum were significantly higher than that non-gravid ones. So, a significant and positive correlation between some micro minerals (zinc, cobalt and iron) concentration of gravid cyst fluid and related sheep serum was observed too (p<0.05).
INTRODUCTION
Hydatid disease is a problem in many parts of the world particularly in rural communities. Echinococcosis is an infectious disease of food animals and human caused by the larval (metacestode) stage of the cestode species, Echinococcus granulosus (cystic echinococcosis or hydatid disease) (Gottstein, 1992; Morakote et al., 2007). The final/intermediate cycles of E. granulosus include: dog/sheep; dog/horse; dog/cattle; dog/pig; dog/reindeer and wallaby/dingo (Eckert and Thompson, 1988). Cystic echinococcosis (hydatidosis) produces clinical disease in human and economical losses to the livestock industry. The larva dwells in the viscera of intermediate hosts; it has the form of a fluid-filled cyst, bounded by a cyst wall. The hydatid fluid contains host proteins as well as parasite excretion/secretion products. The cyst wall comprises an innermost germinal layer of live parasite tissue, which synthesizes an outer, carbohydrate-rich laminated layer. The latter structure is unique to the genus Echinococcus and its biosynthesis represents a major metabolic activity of the germinal layer; it plays a key role in the establishment and persistence of infection by preventing the access of host cells to the live parasite. The germinal layer also gives origin, through budding towards the interior of the cyst, to the larval worms or protoscoleces. These stages are capable of infecting dogs and maturing to adult worms; for this reason, the cysts containing protoscoleces are said to be fertile or gravid (Thompson, 1995). Determining the requirement of parasite to micronutrient and the effect of cyst (fertile and infertile) on copper, zinc, cobalt and iron status in sheep infected naturally with Echinococcus granulosus were mentioned in this research.
MATERIALS AND METHODS
This research was conducted from March 2006 to June 2007 on 2,550 slaughtered sheep. Blood samples were taken before slaughtering and cyst fluid with liver samples were collected from infected sheep. At laboratory, cyst fluids were centrifuged for detecting hydatid sands by microscopic examination. Finally, 50 fertile and 50 infertile cysts were diagnosed. Liver and blood samples were also collected from 50 healthy sheep to compare the data. The concentration of copper, zinc and iron were measured by atomic absorption spectroscopy Analytical methods for atomic absorption spectroscopy (Perkin-Elmer, 1981b) Atomic Absorption Spectroscopy (AA or AAS) is one of the commonest instrumental methods for analyzing for metals and some metalloids and cobalt concentration by Potentiometric Striping Analyzer (PSA) (Baldwin and Marshall, 1999). The data were analyzed by using 1-Way Analysis of Variance (ANOVA) for comparing micro minerals concentration between fertile and infertile cysts and also between serum and liver samples of infected sheep. For determining the relationship between micro minerals concentration in cysts and serum or liver the Pearson Correlation were used at the level of p<0.05 (Sigma Stat for windows, version 2.1).
RESULTS AND DISCUSSION
The concentration of copper, zinc, cobalt and iron in fertile cyst were significantly higher than that infertile cyst (p<0.001). These data were analyzed by using ANOVA with aid of supplemental tests such as Tukey and Dunnet at the level of p<0.001 (Table 1). Measuring the mentioned micro minerals in serum showed a significant differences between values in serum of sheep that affected by fertile cyst compared to infertile ones (Table 2). The concentration of these micro minerals in serum of former sheep (affected by fertile cyst) was significantly higher than that later (p<0.001). The correlation of micro minerals concentration in cysts and also in serum of sheep was carried out by using Pearson correlation test with aid of Tukey test. Results showed that a positive and significant correlation exists between zinc and iron concentration in fertile cyst fluids (r = +0.345, p = 0.0294) and between serum concentration of zinc and cobalt (r = +0.328, p = 0.0388) in sheep with fertile cyst. Liver concentration of copper, zinc, cobalt and iron in healthy and naturally affected sheep with hydatidosis were measured are shown in Table 3. The data showed that liver concentration of copper was significantly lower and zinc concentration was higher than that healthy sheep (p<0.05).
| Table 1: | Comparison of Cu, Zn, Co and Fe concentration in fertile and infertile hydatid cysts of sheep |
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| *: p<0.001 | |
| Table 2: | Comparison of Cu, Zn, Co and Fe concentration in serum of sheep affected by fertile and infertile hydatid cysts |
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| *: p<0.001 | |
| Table 3: | Concentration of Cu, Zn, Co and Fe in liver samples of sheep affected by hydatid cysts |
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| *: p<0.05 | |
| Table 4: | Schematic form of micro minerals concentration in different samples |
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The amount and proportion of mineral elements in all animal tissues varies widely. Four broad types of function for minerals exist; structural, physiological, catalytic and regulatory. These biological functions are important, but in the second quarter of the 20th century minerals have been found to regulate cell replication and differentiation; for example, calcium influences signal transduction and zinc influences transcription, adding to long-established regulatory roles, such as that of the element iodine as a constituent of thyroxin. Minerals can act as catalysts in enzymatic and hormonal systems, as integral and specific components of the structure of metalloenzymes or as less specific activators within those systems (Underwood and Suttle, 1999). Hydatid cyst fluid is clear or pale yellow, has a neutral pH and contains sodium chloride, proteins, glucose, ions, lipids and polysaccharides. The fluid is antigenic and may also contain scolices and hooklets. In present research the concentration of copper in fertile and infertile cyst fluids and iron in their related sheep serum were higher than that other mentioned micro minerals (Table 4). However, Sultan Sheriff et al. (1984) have showed that the concentration of zinc in hydatid cyst fluid is higher than that others; Sr, Cu, Fe, Cd, Ni, Cr and Co (Sultan Sheriff et al., 1984). The serum and cyst fluid levels of selenium, zinc and copper in patients and sheep with hydatid cysts were investigated earlier. They reported there is a decrease in Se and Zn and a rise in Cu in sera of patients with hydatid disease. Similar results were reported in infested sheep as related to the healthy control animals (Ozen et al., 1992). But based on our study the concentrations of four mentioned micro minerals in sheep sera that affected by fertile hydatid cyst were higher than that sheep with infertile cyst. To this view, sheep hydatidosis may alter micro minerals status and raise their serum concentration. Copper and zinc in liver of sheep that affected by hydatid cyst were lower and higher than that healthy sheep, respectively. These findings showed a negative effect of hydatidosis on hepatic copper concentration, that is a major site for copper reserving. Due to this hydatidosis could increase the copper concentration of serum via liver copper depletion and may interfere with determining the normal blood copper level in epidemic areas. On the other hand, gravid cysts need more copper for their growth and binding the drug (Scolecidal) with copper may enhance its efficacy.