Các tác nhân Một số virus đã được xác định gần đây nhưng không có khả năng gây ra bệnh gan lâm sàng. "Viêm gan siêu vi G" hoặc "Viêm gan GB''là một loại virus như flavivirus với chuỗi 20-30% tương đồng với HCV. Mặc dù có thể truyền truyền, nó không phải là cảm thấy kết quả trong bệnh lâm sàng và không còn cảm thấy là một virus viêm gan. | 29. EMERGING HEPATITIS VIRUSES Other hepatitis viruses non-A non-B non-C G. L. Davis Evidence that agents other than the commonly described hepatotrophic viruses can cause hepatitis comes from the observation of multiple distinct episodes of serologically uncharacterized hepatitis in some patients and the persistence of some cases of post-transfusion hepatitis despite elimination of hepatitis B and C from the donor pool. Additionally most cases of non-A non-B hepatitis are also due to HCV. THE AGENTS Several viral agents have been identified recently but these are unlikely to cause clinical liver disease. The Hepatitis G or Hepatitis GB is another flavivirus-like virus with 20-30 sequence homologous to HCV. Though probably transfusion transmitted it is not felt to result in clinical disease and is no longer felt to be a hepatitis virus. The SEN and TT viruses are common in patients with hepatitis B and C as well as the general population. Although solid evidence that they cause hepatitis is lacking it does appear that they may be responsible for some cases. TRANSMISSION INCUBATION PERIOD CLINICAL FEATURES All 3 of the above-mentioned agents are common in transfusion recipients and patients with other forms of parenterally transmitted hepatitis suggesting that the routes of transmission may be similar. It still remains unclear how prevalent these infections are and whether they account for an appreciable proportion of patients if any with cryptogenic hepatitis and cirrhosis. THERAPY Interestingly retrospective testing of HCV co-infected subjects has shown that all 3 agents respond to interferon. Nonetheless since liver disease as a result of these infections has not been proven treatment should not be considered. LABORATORY DIAGNOSIS The lack of widely available serological markers for these infections has prevented identification of patients outside of research surveys. The studies reported to date have screened serum samples with either RT-PCR amplification of the
