COMPLIANCE INFO_1991-2019 - Laserfiche WebLink

Home Browse Search

Hepatitis B envelope antigen (HBeAg) also appears in serum at the time that HBsAg is first detected. It persists for less time than HBsAg in the majority of patients. HBeAg is a reliable and sensitive marker for the presence of high levels of virus, and therefore a high degree of infectivity. HBsAg -positive individuals who are HBeAg positive are highly infectious; they have a higher absolute number of infectious viral particles in their serum. As HBeAg disappears from the serum, antibody to it (anti -HBe) develops. This seroconversion generally occurs at the peak of clinical symptoms and suggests that the dis- ease is on the wane. Persons who progress to the chronic HBsAg carrier state do not seroconvert from HBeAg to anti - HBe during this phase of acute infection. The persistence of HBeAg by radioimmunoassay for more than 10 weeks is asso- ciated with the carrier state and with chronic -persistent or chronic -active hepatitis. In addition to HBsAg and HBeAg, there is HBcAg, or core antigen, the 27 -nanometer nucleocapsid core found in the nuclei of liver cells infected with HBV. Under normal conditions, it is not found free in serum. However, anti - HBc is found in serum, appearing 2 4 weeks after HBsAg is first detected. The final serologic marker of HBV infection is anti - HBs. It does not arise until the convalescent period. In all but a few cases, anti -HBs is not detectable in serum until HBsAg has disappeared and recovery is complete. Therefore, anti -HBs is a marker of recovery and immunity. Hepatitis B infection is commonly spread by the parenteral route or by intimate sexual contact. Serologic markers of prior hepatitis B infection are common among drug addicts, medical personnel and dialysis patients. Only about 50% of persons with acute type B hepatitis give a history of known parenteral exposure, even after close and thorough questioning. In these cases, inapparent parenteral spread may have occurred, such that the virus entered the body through a tiny insignificant break in the skin or mucous membrane.-- HBV does not seem capable of crossing the intact skin. Experimental studies have shown that the virus has extremely low infectivity by oral, nasal or respiratory routes. Health care professionals who handle open containers of blood frequently are at an increased risk of contracting hepatitis B compared to the general population. Several surveys have confirmed this increased risk. In one, 26% of blood bank workers demonstrated serologic markers indicative of previous HBV infection. In contrast, only 14% of den- tists, 10% of intensive care nurses, and 4% of hospital wor- kers with no patient contact have evidence of prior hepati- tis B. Before surrogate testing began, 5% of all volunteer blood donors had HBV markers indicating prior exposure to HBV. BIOSAFETY - INFAGT - 0491 - PAGE 2