[The TT virus: review of the literature]. / Le virus TT: revue de la littérature.

OBJECTIVE: To review the literature on the TT virus. METHODS: The literature review was based on articles identified through MEDLINE between Jan. 1, 1997, and August 15, 1999. RESULTS: In 1997, a new DNA virus, designated TTV, was isolated and seemed to be associated with non A-G post-transfusion hepatitis. The virus was identified using a polymerase chain reaction (PCR) because serology was not routinely available. At least 16 genotypes were identified. Depending on the PCR technique used, the prevalence of infection ranged from 17% to 71% in a group of sera tested. The prevalence rate ranged from 1.2% to 62% among blood donors, from 0.5% to 83% among hemophiliacs and from 1% to 71% in cases of chronic hepatitis. The current hypothesis is that routes of infection were parenteral and orofecal. The pathogenesis of this virus, if it really exists, is not yet clearly established. It has been postulated that some interaction may exist between the TT virus and the hepatitis C virus. The use of interferon seems to decrease the TT viremia, according to results obtained outside the context of clinical trials. CONCLUSION: The pathogenesis of the TT virus needs to be rapidly established for transmission prevention and therapeutic intervention.

Family size and social utility: income distribution dominance criteria.

"This paper generalizes previous results on income distribution dominance in the case where the population of income recipients is broken down into groups with distinct utility functions. The example taken here is that of income redistribution across families of different sizes. The paper first investigates the simplest assumptions that can be made about family utility functions. A simple dominance criterion is then derived under the only assumptions that family functions are increasing and concave with income and the marginal utility of income increases with family size."