Effects of Schistosoma mansoni infection on inorganic elements in the snail Biomphalaria glabrata

Alterations in Lipids and Minerals in Relation To Larval Trematode Infections of Nerita Polita Marine Snails

Marine snails provide an important source of vitamins, proteins, minerals, and essential fatty acids, and their mucus has a therapeutic significance. Parasitic infection of larval trematodes in these snails affects their nutritional value. The present study aimed to screen Nerita polita marine snails for the prevalence of cercarial infections and to evaluate the changes in lipids and some minerals in the infected as well as non-infected ones. Snails were collected randomly from February 2018 to January 2019 from the Red Sea Obhor bay, Jeddah city, Saudi Arabia. The amount of triglycerides, cholesterol, and phospholipids in the Digestive Gland Gonad Complex (DGG), hemolymph, and Snail Conditioned Water (SCW) of non-infected and infected Nerita polita snail was estimated using a spectrophotometer. Minerals content such as Ca, Zn, Pb, Na, Mn, Mg, K, Fe, Cu, and Cd, in the DGG and shell in the infected and non-infected snails were analyzed using an Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES). Two types of cercariae were detected, ocellate furcocercus cercaria (Trichobilharzia regent) and xiphidiocercaria (Litorina saxatilis VII). The study showed that there is a fl uctuation in the concentration of lipids and minerals between increase and decrease in DGG, hemolymph, shell, and SCW in infected snails. The nutritive value of the snails is affected with infection through the decrease of some lipids and minerals in infected snails. Further qualitative studies are needed.

Surges in trematode prevalence linked to centennial-scale flooding events in the Adriatic

The forecasts of increasing global temperature and sea level rise have led to concern about the response of parasites to anthropogenic climate change. Whereas ecological studies of parasite response to environmental shifts are necessarily limited to short time scales, the fossil record can potentially provide a quantitative archive of long-term ecological responses to past climate transitions. Here, we document multi-centennial scale changes in prevalence of trematodes infesting the bivalve host Abra segmentum through multiple sea-level fluctuations preserved in brackish Holocene deposits of the Po Plain, Italy. Prevalence values were significantly elevated (p < 0.01) in samples associated with flooding surfaces, yet the temporal trends of parasite prevalence and host shell length, cannot be explained by Waltherian facies change, host availability, salinity, diversity, turnover, or community structure. The observed surges in parasite prevalence during past flooding events indicate that the ongoing global warming and sea-level rise will lead to significant intensification of trematode parasitism, suppressed fecundity of common benthic organisms, and negative impacts on marine ecosystems, ecosystem services, and, eventually, to human well-being.

Heavy metal concentrations in the freshwater snail Biomphalaria alexandrina uninfected or infected with cercariae of Schistosoma mansoni and/or Echinostoma liei in Egypt: the potential use of this snail as a bioindicator of pollution

In spite of using aquatic snails as bioindicators for water pollution, little attention has been paid to the effect of parasitism upon the concentration of heavy metals (Al, Cd, Cu, Fe, Mn, Pb and Zn) in these organisms. The present study therefore aimed to compare the concentrations of heavy metals in trematode-infected Biomphalaria alexandrina collected from Kafer Alsheikh and Menofia provinces, Egypt, with uninfected snails from the same sites, in order to assess the effect of parasitism on the use of these snails as bioindicators. The concentrations of heavy metals in the soft parts and shells of snails were measured by flame atomic absorption spectrometry. The results showed that the heavy metal profile in snails infected with Echinostoma liei was very different from that in snails infected with Schistosoma mansoni. The total concentration of heavy metals in E. liei-infected snails collected from Kafer Alsheikh or Menofia province was greater than in uninfected snails. In contrast, the total concentration of heavy metals in S. mansoni-infected snails was reduced compared with uninfected snails. In conclusion, the status of snails with respect to parasitic infection must be taken into consideration when these snails are used as bioindicators.

Effects of Schistosoma mansoni and Schistosoma haematobium infections on calcium content in their intermediate hosts

Flame atomic absorption spectrometry was performed to determine the alteration of calcium concentration in the soft parts and shells of Biomphalaria alexandrina and Bulinus truncatus due to the infection with Schistosoma mansoni and S. haematobium, respectively. The results showed significant lowering in the calcium content of the shells of cercariae shedding B. alexandrina and B. truncatus relative to the calcium content in the shells of uninfected ones. In contrast, the calcium content in the soft parts of cercariae shedding snails was higher than in the soft parts of uninfected snails; the differences were statistically significant. Generally, calcium content was significantly higher in the shells than in the soft parts of the snails, regardless infected or uninfected. The results obtained and the hypothesis of hypercalcification in shells of infected snails were discussed.