Absence of nonpercutaneous transmission of hepatitis C virus in a colony of chimpanzees

Transmission of hepatitis C virus by saliva?

Saliva can contain a range of infectious agents and, despite several antimicrobial mechanisms, transmission of these can occur. Hepatitis C virus (HCV) is of increasing importance, and HCV is transmitted by unknown routes as well as by the percutaneous route and sexual contact. Contact with blood or other body fluids may be responsible, as may be receipt of unscreened blood or blood product transfusions. HCV-RNA can be detected by the polymerase chain reaction which also shows that HCV may be present in the saliva of HCV-infected patients. This might provide an argument for the possible transmission of HCV via contaminated saliva. Epidemiological studies however, suggest that the infective capacity of HCV viral particles in saliva is low, but it has not been possible to determine their infective potential. Moreover, HCV-specific receptors have not been defined on oral epithelial cells, nor has the role of host defence mechanisms been determined. New experimental animal models and the recently described infectious HCV pseudoparticles, capable of simulating HCV replication in vitro, could be useful in establishing any role of saliva in the transmission of HCV infection.

Hepatitis C virus infection: Review and implications for the dentist

OBJECTIVE

The purpose of this report was to review the current literature on hepatitis C virus infection, with particular attention to the aspects of interest for dental health care staff.

MATERIAL AND METHODS

The authors searched original research and review articles on specific aspects of hepatitis C virus infection, including articles on virology, epidemiology, transmission, diagnosis, natural history, extrahepatic manifestations, therapy and oral aspects of hepatitis C virus infection. The relevant material was evaluated and reviewed.

RESULTS

Hepatitis C virus is an RNA virus that is present throughout the world and has major geographic variations. The virus, transmitted mainly by means of blood contact, causes chronic hepatitis in up to 80% of cases and may give rise to hepatic cirrhosis and hepatocellular carcinoma in a significant proportion of patients. Although it is of limited efficacy, interferon alpha is currently the drug of choice in the treatment of the infection. Hepatitis C virus infection is associated with a number of extrahepatic manifestations that may include oral diseases such as lichen planus or sialadenitis. Although there are documented cases of nosocomial transmission to health care workers after percutaneous exposure, the prevalence of hepatitis C virus among dental staff members is probably similar to that in the general population.

CONCLUSION

Hepatitis C virus infection is a relatively common infection worldwide (1.4% in the US general population) that causes significant chronic hepatic disease. The dentist is thus likely to face a growing number of patients with a diagnosis of hepatitis C virus infection. For this reason it is essential for dental health care workers to be aware of the principal features of the disease and of its oral and dental implications.

Analysis of hepatitis C virus-inoculated chimpanzees reveals unexpected clinical profiles

The clinical course of hepatitis C virus (HCV) infections in a chimpanzee cohort was examined to better characterize the outcome of this valuable animal model. Results of a cross-sectional study revealed that a low percentage (39%) of HCV-inoculated chimpanzees were viremic based on reverse transcription (RT-PCR) analysis. A correlation was observed between viremia and the presence of anti-HCV antibodies. The pattern of antibodies was dissimilar among viremic chimpanzees and chimpanzees that cleared the virus. Viremic chimpanzees had a higher prevalence of antibody reactivity to NS3, NS4, and NS5. Since an unexpectedly low percentage of chimpanzees were persistently infected with HCV, a longitudinal analysis of the virological profile of a small panel of HCV-infected chimpanzees was performed to determine the kinetics of viral clearance and loss of antibody. This study also revealed that a low percentage (33%) of HCV-inoculated chimpanzees were persistently viremic. Analysis of serial bleeds from six HCV-infected animals revealed four different clinical profiles. Viral clearance with either gradual or rapid loss of anti-HCV antibody was observed in four animals within 5 months postinoculation. A chronic-carrier profile characterized by persistent HCV RNA and anti-HCV antibody was observed in two animals. One of these chimpanzees was RT-PCR positive, antibody negative for 5 years and thus represented a silent carrier. If extrapolated to the human population, these data would imply that a significant percentage of unrecognized HCV infections may occur and that silent carriers may represent potentially infectious blood donors.

[Detection and significance of HCV RNA in saliva, seminal fluid and vaginal discharge in patients with hepatitis C]

To investigate the transmission of HCV infection through family contact, we detected HCV RNS in body fluids (saliva, seminal and vaginal discharge) of 16 serum HCV RNA positive patients (including 7 men and 9 women) and in sera of their family members. The positive rates of HCV RNA in the body fluids were 31.25% (5/16) in saliva, 57.14% (4/17) in seminal fluid and 22.22% (2/9) in vaginal discharge, respectively. Among the family members in our series, all were negative for both anti-HCV and HCV RNA, despite two spouses positive for HCV RNA. This result strongly suggested the potential possibility of the transmission of HCV infection through the family contact.

Risk factors in community-acquired chronic hepatitis C virus infection: a case-control study in Italy

AIMS/METHODS

A case-control study was carried out in Italy to assess the risk factors associated with chronic hepatitis C virus infection. Five hundred consecutive chronic anti-hepatitis C virus positive cases and 500 sex and exactly age-matched anti-hepatitis C virus negative/HBsAg negative controls entered the study. Information was collected through an interviewer-administered questionnaire. The adjusted Odds Ratios linking hepatitis C virus infection and risk factors were estimated by conditional multiple logistic regression. Demographic and socio-economic characteristics were similar in cases and controls. Seventy-five percent of patients were aged over 40: males were prominent in the group < or = 40, while the number of females increased with age.

RESULTS

As expected, drug addiction and blood transfusion emerged as independent risk factors: blood transfusion in all ages and in both sexes, drug addiction only in subjects under 41 years and mostly in males. Other risk factors independently associated with hepatitis C virus infection were: previous use of non-disposable needles, previous tuberculosis, and prolonged hospitalization before 1970. A history of sexually-transmitted diseases was not associated.

CONCLUSIONS

This study shows that the great spread of hepatitis C virus in Italy may have occurred several years ago through parenteral routes which are not now operating. Modern hygienic and sanitation measures have significantly controlled exposure to the infection, which in the younger generations is confined to high-risk groups such as drug addicts.

Hepatitis C: progress and problems

The hepatitis C virus (HCV), a single-stranded RNA virus, is the major cause of posttransfusion hepatitis. HCV isolates differ in nucleotide and amino acid sequences. Nucleotide changes are concentrated in hypervariable regions and may be related to immune selection. In most immunocompetent persons, HCV infection is diagnosed serologically, using antigens from conserved regions. Amplification of RNA may be necessary to detect infection in immunosuppressed patients. Transmission by known parenteral routes is frequent; other means of spread are less common and may represent inapparent, percutaneous dissemination. Infection can lead to classical acute hepatitis, but most infected persons have no history of acute disease. Once infected, most individuals apparently remain carriers of the virus, with varying degrees of hepatocyte damage and fibrosis ensuing. Chronic hepatitis may lead to cirrhosis and hepatocellular carcinoma. However, disease progression varies widely, from less than 2 years to cirrhosis in some patients to more than 30 years with only chronic hepatitis in others. Determinants important in deciding outcome are unknown. Alpha interferon, which results in sustained remission in selected patients, is the only available therapy. Long-term benefits from such therapy have not been demonstrated. Prevention of HCV infection by vaccination is likely to be challenging if ongoing viral mutation results in escape from neutralization and clearance.

Hepatitis C virus: historical perspective and current concepts

Over the past 30 years, hepatitis C has emerged from shadowy enigma to important public health problem. The existence of the etiological agent of this disease was first appreciated two decades ago but significant progress in its understanding had to await its molecular characterization within the past 5 years. The virus is a member of the family Flaviviridae and is the cause of approximately 20% of clinical viral hepatitis in the United States. While the control of the transmission of hepatitis C virus in blood and blood products has been nothing less than spectacular, the control of community-acquired hepatitis C will be a major challenge to the scientific and medical communities.