Schistosomes live up to 30 years in humans, but in mice can live for the life of the animal, which is 12-30 months.  Of course, the intensity of infection affects this, since a heavily infected mouse will die from granulomatous schistosomiasis, but mice tolerate light infections (20-50 cercariae) well and are "permissive" hosts for S. mansoni.  JPCaruso, PhD, 1983, Veterinary Parasitology, University of Georgia, USA

There is a very good point mentioned by (Cheever et al., 2002):

“The chronicity of schistosome infections in humans is obviously not reproducible in most animal models. Although one may predict that in some respects a week or two in the life of a mouse may be equivalent to a year in humans, the calculation of equivalent times is uncertain”

And I think it is a good review for murine schistosomiasis.

Cheever, A. W., Lenzi, J. A., Lenzi, H. L., & Andrade, Z. A. (2002). Experimental models of Schistosoma mansoni infection. Memórias do Instituto Oswaldo Cruz, 97(7), 917-940.

Dear Godfrey

I agree with Dr Caruso. In fact, the mice mortality will depend on the infectious number of cercariae you innoculated. However, if you want to test the schistosomicidal activity of a drug, start your test after 40 days after infection, when the adult parasite will be mature and the oviposition will have begun.

Good lucky in your experiment!

Best regards

Hudson 

Dear Godfrey:  The life expectancy of mice varies widely depending on the strain and a variety of other factors (below).  Quoting from the excellent review by Cheever et al (2002) that Dr. Harith Al-Warid suggested above, "A/J mice incur this complication (i.e. mortality) early in infection and at low infection intensities (Dean et al. 1981, Colley & Freeman 1983) while C57BL/6 and BALB/c mice are unusually resistant to death after infection."  Therefore, longevity of S. mansoni-infected mice depends on the infectious dose, host genotype (especially in the MHC genes) and overall health of the mouse.  I agree with Dr. Alves-Pinto that if drug-testing, you should start your test 40 days or so after infection with a small number of cercariae (e.g. 20 or so).  I'd also use a mouse strain relatively resistant to mortality from S. mansoni.

Dear Godfrey:

Acute infections in mice: below 6 weeks.

Chronic infections in mice: over 12 weeks

Nature Reviews Immunology 2, 499-511 (July 2002) | doi:10.1038/nri843

If you require chronic infections of S. mansoni, see the best amount of cercariae for infection, I suggest below 60 cercariae and strain mice (CD1). As indicated earlier comments, mouse strain influences much about it. Taking intoaccount these two variables (strain mice and number of cercariae to infection) you will get chronic infections in mice for yours experiments.

Good luck with your tests.

It can survive for more than 30 weeks.