Dane particles and associated DNA-polymerase activity in saliva of chronic hepatitis B carriers

Horizontal transmission of hepatitis B virus

Meta-analysis of seroprevalence surveys shows that horizontal transmission of hepatitis B virus (ie, that occurring without apparent parenteral, sexual, or perinatal exposure) is common in areas endemic for the virus. It occurs especially in pre-adolescent children. In developed countries, where endemicity of hepatitis B virus is low, horizontal transmission (probably via saliva or open wounds) may occur in households with a persistent carrier, but it is less efficient a means of infection than is sexual or perinatal transmission. Horizontal transmission also seems possible in pre-school day-care centres in developed countries, despite the small numbers of carriers in such places.

Hepatitis B virus infection in dentists and dental students in Greece

The prevalence of hepatitis B virus (HBV) markers in 416 dental students, 115 dentists, and 329 members of the general population was studied in Athens. Markers were present in 36 students (8.7%), 34 dentists (29.6%), and 74 controls (22.5%). Four students (1.0%), 3 dentists (2.6%), and 6 controls (1.8%) were carriers of hepatitis B surface antigen (HBsAg). The prevalence of HBV infections increased with age significantly faster in the dental profession than in the general population, showing an increased risk. Of 22 dentists in practice for more than 20 years, 12 (54.5%) had HBV markers and 4 (18.2%) reported a clinical hepatitis infection. These data show that members of the dental profession should also be included in the national hepatitis B vaccination program.

Diagnostic virology using electron microscopic techniques

This chapter illustrates the development of the use of electron microscopy in viral diagnosis. The field covered is confined to medical viral diagnosis, but parallel developments have taken place in both veterinary and botanical fields and techniques derived from both these sources are also included where relevant. It is reported that the scanning transmission mode of operation, which can induce image contrast changes electronically, may enhance studies with unstained sections and perhaps facilitate thin section immune electron microscopy (IEM). The application of negative stain IEM has been particularly useful for the study of the antigenic nature of some of the newly discovered noncultivable viruses. Viral antigens can also be detected in thin sections of infected cells by IEM with suitably labeled specific antibodies. Confirmation of viral infection by electron microscopy on tissues originally processed for light microscopy is also frequently useful.