Epidemiological survey and follow‐up of transfusion‐transmitted virus after an outbreak of enterically transmitted infection

Abstract

An outbreak of enterically transmitted hepatitis occurred during 1996 among students at a vocational school. Viral fragments homologous to transfusion-transmitted virus (TTV) were detected in faeces. To elucidate the endemic status, an epidemiological survey and case follow-up after the outbreak were carried out. During and after the outbreak, virus carriers among staff were, respectively, 32.1% and 31.3% in serum, and 24.6% and 18.2% in faeces. After the last outbreak, attacks were still occurring among new students with an incidence of 2.4% in 1997 and 2.3% in 1998. There was also a small-scale outbreak in 1998 with a prevalence of 17.9%. On follow-up at 6 and 18 months after onset, alanine aminotransferase (ALT) elevation was found in 29.7% and 13.9% of patients. At 6 months, viral fragments were detected in serum in 78.1% and 46.7% of patients, with and without ALT elevation, respectively. At 18 months the corresponding figures were 55.6% and 19.2%, respectively. At the 18-month follow-up, viral fragments were detected in faeces in 29.6% and 19.3% of patients with and without ALT elevation. In conclusion, this disease might be transmitted from asymptomatic virus carriers. According to the laboratory data, both parenteral and non-parenteral transmissions are involved, and the faecal-oral route might be more important.

TT virus infection in Italy: prevalence and genotypes in healthy subjects, viral liver diseases and asymptomatic infections by parenterally transmitted viruses

“…No correlation emerged between TTV and HIV infections. The similar prevalence of the virus in populations with different demographic and epidemiological characteristics could be explained by the transmission of TTV through routes other than the parenteral one; in keeping with an environmental spreading, TTV‐DNA sequences were isolated from saliva, semen and stools of viraemic patients [15–19] and phylogenetic analysis did not show genetic divergence between animal and human isolates of TTV, suggesting the existence of animal reservoirs of the virus [20,21].…”

TT virus-related acute recurrent hepatitis

“…Only a few data are available on the follow-up of TTV-infected patients. Kangxian et al [9] followed up a series of 381 patients with enterically transmitted TTV infection and found that ALT levels remained elevated for 6 months after the onset of the disease in 29.7% of the patients, and for 18 months in 13.9% of the patients.…”