Outcomes of Schistosoma mansoni infection in outbred albino mice exposed to Larvin contaminant.

The present study tested the hypothesis that mice exposed to Schistosoma mansoni and treated with the insecticide Larvin have an increased risk of accelerated liver damage. To investigate this hypothesis, adverse effects resulting from treatment with Larvin were compared between S. mansoni-exposed and nonexposed outbred albino mice. The effects of concurrent treatment with Larvin on the progress and outcomes of S. mansoni infection were assessed via macroscopic and microscopic examination of liver and spleen, evaluation of several hematological, biochemical and hepatic enzymes parameters, and effect on worm burden. Oral administration of 1/5 and 1/10 LD(50) of Larvin to S. mansoni-exposed mice induced (1) hepatomegaly and splenomegaly; (2) prominent lymphocytic aggregation in liver replacing large areas of bridging necrosis; (3) increased serum level of bilirubin and alanine aminotransferase-aspartate aminotransferase enzymes; (4) decreased serum level of albumin and total proteins; and (5) decreased RBC, hemoglobin content, leukocyte, and lymphocyte counts. No significant effect on worm burden or oviposition was noted as a result of Larvin treatment compared to controls. All doses used in mice either for infection with S. mansoni cercariae or treatment with Larvin resulted in dose dependent alterations in hepatic functions of the tested mice. These alterations were most profound in mice exposed to S. mansoni and receiving Larvin treatment. The present findings support our hypothesis and show that concurrent S. mansoni infection with exposure to Larvin adversely affect liver functions and seriously alter hematological, biochemical, and hepatic enzymes parameters in outbred albino mice. These findings warrant further investigation and reinforce the need to minimize exposure to insecticide in both natural field settings and the broader environment.

Vaccination of mice with a 30 kDa Schistosoma antigen with and without human adjuvant induces high protection against S. mansoni infection.

A 30 kDa antigen was characterized as a hydrophobic polypeptide containing 16 amino acids and evaluated as a potential candidate vaccine against infection by Schistosoma mansoni. CD1 albino mice immunized at 0, 14, and 21 days with 25 or 50 microg of the 30 kDa antigen per mouse with and without alum developed high levels of IgG antibodies (predominantly IgG2a and IgG2b isotypes). When immunized mice were infected with 200 S. mansoni cercariae, the highest protection levels (61% and 65% reduction in worm burden in two separate experiments) were obtained using the 50-microg antigen without alum adjuvant. The granuloma size decreased to 10%, a non-significant level in mice immunized using alum adjuvant. The results demonstrate the ability of the 30 kDa antigen with and without alum adjuvant to protect mice against S. mansoni infection.