Epidemiology of hepatitis E virus infection

Abstract

Hepatitis E is an acute, icteric, self-limiting disease, which is spread widely in many tropical and subtropical countries where it occurs both in the form of epidemics of variable magnitude or sporadically. Hepatitis E affects young adults, rather than children, and causes a high mortality rate, particularly in pregnant women. In industrialized countries this disease occurs occasionally as imported sporadic cases. The aetiological cause of hepatitis E is a virus, hepatitis E virus (HEV), which is temporally classified as a member of the Calicivirus family, although its genomic composition is unique. There are experimental data as well as epidemiological observations allowing us to assume that hepatitis E may be a zoonosis as HEV is pathogenic for some domestic and wild animals. Recently, serological assays based on the use of recombinant or synthetic antigens were developed and applied to determine the prevalence of antibody to HEV (anti-HEV) in various epidemic and non-epidemic settings. In suspected hepatitis E cases, anti-HEV seropositivity was detected at an elevated rate but the overall seroprevalence of anti-HEV in normal human populations of endemic areas appeared to be unexpectedly low. A low but constant presence of anti-HEV seropositivity was observed also in non-endemic industrialized countries. In some of these countries, anti-HEV seropositivity was accumulated in groups of patients with various liver and non-liver pathologies and certain groups at risk for blood-borne infections.

Hepatitis E virus infection in selected Brazilian populations

“…The distribution of HEV infection by sex has pointed to higher values in males than in females; this is probably the result of more involvement of males in risky situation (Balayan 1997). Our seroprevalence results from males blood donors were higher (4%) than those found in pregnant women (1%), although the difference was not statistically significant (p=0.05).…”

“…It is not known why the overall seroprevalence of anti-HEV in normal human populations of endemic areas are low or why a low but constant presence of anti-HEV is observed in normal human populations of non-endemic industrialized countries (Balayan 1997). It is also unknown why in endemic and nonendemic areas, individuals with risk of parenteral (Thomas et al 1997).…”

“…In epidemic situations, as well as in sporadic cases, the group between 15 and 40 years of age shows the highest attack rate, however, pediatric cases have been reported in some parts of the world (Balayan 1997). In areas where almost 100% of children are infected with HAV by 5 years of age, very few are infected with HEV until adolescence and young adulthood (Purcell 1996).…”

“…The infection has been shown to occur in both epidemic and sporadic forms and to be primarily associated with the ingestion of fecally contaminated drinking water (Balayan 1997). HEV and hepatitis A virus (HAV) infections share some clinical and epidemiological proprieties: both are transmitted via fecal-oral route, the diseases are self limited, and the prevalence of antibodies is closely related to the level of sanitation.…”

“…In develop countries outbreaks have not been recognized, however, sporadic cases have been identified in Mediterranean countries and in the United States, mostly imported from endemic areas (Balayan 1997). In endemic areas, seroepidemiological studies have shown that anti-HEV antibodies in normal human populations appear to be unexpectedly low.…”