Impacts of trace metals on Ascaris sp., endoparasites of greater cane rat, Thryonomis swinderianus (Temmincks, 1827), in the tropical rainforests of Odo Ona Kekere, Oluyole Local Government of Ibadan, Oyo State, Nigeria
Authors: Elizabeth Ayodele , Bamidele Akinsanya , Lanrewaju Ogunyebi Amos , Excellence Akeredolu , Omoregie Isibor Patrick 
Published: March 2022

Background

Samples of hunted greater cane rat (Thryonomis swinderianus) were collected from Oluwo Market, Epe and Odo Ona Kekere in Oluyole Local Government Area Ibadan, Nigeria. Trace metals such as zinc, cadmium, vanadium, barium, nickel, copper, lead, cobalt, chromium, and manganese were determined in the liver, intestine, and endoparasites of T. swinderianus and the associated implications on the lipid profile, and antioxidant biomarkers were investigated.

Results

The study showed that the enteric parasites of the greater cane rat accumulated barium and zinc at a higher level than the host rat. This may be an ecotoxicological concern as the concentrations may exceed the acceptable limits in the near future if the rate of accumulation continues without remediation. The histopathological standpoint evidences indicate that the tissue alterations appear to be higher with increase in trace metal concentrations in tissues analyzed. The tissue alterations also commensurate with the intensity of the parasitic infections. Suspected cellular damage in the parasites evidenced by the high levels of cholesterol and low-lipid lipoproteins was characterized by the outstanding upregulation of SOD in the parasites above the levels detected in the liver and intestine of the greater cane rat. Furthermore, this investigation revealed that the accumulation of barium and zinc may be implicated in the oxidative stress tendencies observed in the parasites which is an early warning for the protection of the host. At the fairly higher concentrations, toxicity of these metals characterized by the oxidative stress in the parasite may be tremendous enough to eliminate the parasite and reduce their abundance in the host rats.
The deleterious impact of the multi-stress conditions in the natural habitat was evident in this study. The significantly highest concentrations of zinc and barium in the parasites than the intestines and liver of the greater cane rat may partly be implicated in the outstandingly higher cholesterol and low-lipid lipoproteins indicate dyslipidemia, which results from cellular damage due to stress. Results showed that the levels of MDA in the investigated tissues were fairly stable, the upregulated SOD in the tissues of the parasite may mitigate the parasitic infection in the host.

Conclusion

This study has demonstrated an empirical prognosis on the deleterious accumulation of barium and zinc. The results have also indicated the possibility of controlling the parasitic infection in the greater cane rat using the metal burden in the tissues of the rat to its advantage. The report has provided useful information by identifying the actual metals of concern and the associated early warning signals which necessitates proactive decisions toward sustainable conservation of the greater cane rat.