Infection with anthroponotic Cryptosporidium parvum does not fully protect the host against a subsequent challenge with C. hominis.

Cryptosporidium hominis and Cryptosporidium parvum are the major Cryptosporidium species that infect humans. Earlier studies in gnotobiotic piglets, model susceptible to both, showed that piglets recovered from infection with C. hominis were fully protected against challenge with same species but incompletely protected against C. parvum challenge. In the present study, piglets were infected with C. parvum first, and after recovery were re-challenged with C. parvum or C. hominis. Again, full protection was only observed when piglets were challenged with the homologous parasite strain. Although the two species are genetically/antigenically almost identical, they do not confer complete protection against each other.

Growing support for gay and lesbian equality since 1990.

Since 1991, public acceptance of gays and lesbians has grown dramatically. We use two approaches to examine changing attitudes in U.S. survey data. First, we conduct cohort analyses showing that both generational replacement and period effects are having impacts. Since 1991, older, less accepting generations of Americans have been dying and being replaced by younger, more tolerant Americans, and all age groups have been becoming more tolerant. Second, we pool cross-sectional, time series survey data to show that there has been a broad, dramatic increase in virtually every group's acceptance of gays and lesbians over time.