Declining prevalence of antibodies to hepatitis A virus infection in Iceland

Seroprevalence and susceptibility to hepatitis A in the European Union and European Economic Area: a systematic review

Most of the European Union (EU) and European Economic Area (EEA) is considered a region of very low hepatitis A virus (HAV) endemicity; however, geographical differences exist. We did a systematic review with the aim of describing seroprevalence and susceptibility in the general population or special groups in the EU and EEA. We searched databases and public health national institutes websites for HAV seroprevalence records published between Jan 1, 1975, and June 30, 2014, with no language restrictions. An updated search was done on Aug 10, 2016. We defined seroprevalence profiles (very low, low, and intermediate) as the proportion of the population with age-specific anti-HAV antibodies at age 15 and 30 years, and susceptibility profiles (low, moderate, high, and very high) as the proportion of susceptible individuals at age 30 and 50 years. We included 228 studies from 28 of 31 EU and EEA countries. For the period 2000-14, 24 countries had a very low seroprevalence profile, compared with five in 1975-89. The susceptibility among adults ranged between low and very high and had a geographical gradient, with three countries in the low susceptibility category. Since 1975, EU and EEA countries have shown decreasing seropositivity; however, considerable regional variability exists. The main limitations of this study are that the studies retrieved for analysis might not be representative of all EU and EEA publications about HAV and might have poor national representativeness. A large proportion of EU and EEA residents are now susceptible to HAV infection. Our Review supports the need to reconsider specific prevention and control measures, to further decrease HAV circulation while providing protection against the infection in the EU and EEA, and could be used to inform susceptible travellers visiting EU and EEA countries with different HAV endemicity levels.

Seroprevalence of Toxoplasma gondii in Sweden, Estonia and Iceland

Toxoplasmosis is a disease caused by the intracellular protozoan parasite, Toxoplasma gondii which infects up to one-third of the world human population. Toxoplasmosis in neonates and immunocompromised patients can lead to severe disease and death. We investigated the prevalence and risk factors for T. gondii infection in Iceland, Sweden and Estonia, and tested the hypothesis that T. gondii infection causes systemic inflammation and protects against atopy. Blood samples were collected from 1277 randomly selected subjects. The presence of T. gondii IgG antibodies was determined by an ELISA method and levels of Hs-CRP by immunoturbidimetric assay. The prevalence of T. gondii antibodies was 54.9% in Tartu, 23% in Uppsala and 9.8% in Reykjavik (p<0.0001). The risk of positive T. gondii antibodies increased with the number of siblings and with age in Sweden. T. gondii infection was associated with asthma related symptoms and increased Hs-CRP (p = 0.02). No association was found with IgE-sensitization and lung function. We concluded that risk factors for T. gondii infection suggested that soil exposure was 1 of the mechanisms in all 3 countries and a meat-associated infection route is a risk in Sweden.

The effects of socioeconomic development on worldwide hepatitis A virus seroprevalence patterns

BACKGROUND

Hepatitis A virus (HAV) infection confers long-term immunity, so mathematical analysis of age-specific seroprevalence in populations can reveal changes in the infection rate over time. HAV transmission is related to access to clean drinking water, personal hygiene and public sanitation.

METHODS

We used an SIR (susceptible-infectious-recovered) compartmental model with age structure to fit a time-dependent logistic function for HAV force of infection for 157 published age-seroprevalence data sets. We then fit linear regression models for socioeconomic variables and infection rate.

RESULTS

The proportion of the population with access to clean drinking water, the value of the human development index (HDI), and per capita gross domestic product (GDP) are all inverse predictors of HAV infection rates. Declining infection rates were observed in 65.6% of the surveys. Discussion This work demonstrates the utility of HAV seroprevalence studies to reveal patterns of change in force of infection and to assess the association between socioeconomic risk factors and transmission rates.

IgG antibodies against microorganisms and atopic disease in Danish adults: the Copenhagen Allergy Study

BACKGROUND

Seropositivity to food-borne and orofecal microorganisms (hepatitis A virus, Helicobacter pylori, and Toxoplasma gondii ), which are considered to be markers of poor hygiene, has been reported to be associated with a lower prevalence of atopy. In contrast, colonization of the gut with Clostridium difficile, a potential intestinal bacterial pathogen, in early childhood may be associated with a higher prevalence of atopy.

OBJECTIVE

The objective of this study was to investigate the association between atopy and exposure to 2 groups of food-borne and orofecal microorganisms: (1) markers of a poor hygiene and (2) intestinal bacterial pathogens.

METHODS

A cross-sectional population-based study of 15- to 69-year-olds living in Copenhagen, Denmark, was carried out in 1990 to 1991. Atopy was defined as a positive test result for specific IgE to at least 1 of 6 inhalant allergens. Exposure to microorganisms was assessed as IgG seropositivity to microorganisms.

RESULTS

Seropositivity to 2 or 3 markers of poor hygiene (hepatitis A virus, H pylori, and T gondii ) was associated with a lower prevalence of atopy (adjusted odds ratio, 0.5; 95% CI, 0.3 to 0.8). In contrast, seropositivity to 2 or 3 intestinal bacterial pathogens (C difficile, Campylobacter jejuni, and Yersinia enterocolitica ) was associated with a higher prevalence of atopy (adjusted odds ratio, 1.7; 95% CI, 1.2 to 2.6).

CONCLUSION

Exposure to markers of poor hygiene was associated with a lower prevalence of atopy, whereas exposure to intestinal bacterial pathogens was associated with a higher prevalence of atopy. These findings raise the hypothesis that different groups of food-borne and orofecal microorganisms may have different effects on the risk of atopy.

Safety and immunogenicity of a combined hepatitis A and hepatitis B vaccine in young healthy adults

BACKGROUND

A combination of hepatitis A and hepatitis B monovalent vaccines could offer advantages for disease control programs in terms of convenience, compliance and cost.

METHODS

Under randomized, double-blind conditions, 156 healthy young adults were divided into 3 groups to receive 1 of 3 lots of a combined hepatitis A/hepatitis B vaccine administered at months 0, 1, and 6. Safety and immunogenicity were assessed after each dose.

RESULTS

Transient and predominantly mild reactions were reported by slightly more than half the vaccinees; no serious adverse effects were relate to vaccination. One month after dose 2, all subjects had converted to the hepatitis A component. Geometric mean titers (GMTs) of antibodies of hepatitis A virus varied from 4415 to 4882 mIU/ml in the three groups. For hepatitis B, most vaccinees (73%-92%) had protective levels of antibodies to hepatitis B virus (anti-HBs) after the second dose, and all were sero-protected after the booster. Anti-HBs GMTs at month 7 ranged from 1917 to 3298 mIU/ml.

CONCLUSIONS

No statistically significant differences were observed between vaccine lots. The combined hepatitis A/hepatitis B vaccine was safe and clinically well tolerated and induced immune responses quantitatively similar to those obtained with the respective monovalent vaccines.

Prevalence of antibodies against hepatitis A virus among new immigrants in Israel

Israel, located in a region endemic for hepatitis A virus (HAV), recently absorbed a large population of immigrants who came from the former USSR. To assess the risk of high morbidity in this population a serosurvey of HAV antibodies was undertaken. Serum samples were collected from 965 new immigrants, of whom 664 came from the European, non-endemic region, and 301 from the Asian and Caucasian endemic regions of the former Soviet Union. They were compared to 240 Israelis. Each population was divided into six age groups: 1-9, 10-19, 20-29, 30-39, 40-49, and 50 years of age and older. The Asian/Caucasian immigrants and the Israeli population were found to share similar characteristics. In both groups, antibodies to HAV (anti-HAV) were present in the 1-9-year-old age group and reached maximum prevalence (90% and 86.7%, respectively) in the 20-29-year-old age group. In contrast, among the European immigrants anti-HAV was first found in the 10-19-year-olds and peaked (93%) in the age group of 50 years and older. It is concluded that immigrants originating from the European part of the former USSR may require vaccination against hepatitis A.

Immunogenicity and safety in adults of hepatitis A virus vaccine administered as a single dose with a booster 6 months later

An inactivated vaccine against hepatitis A was administered as a single 1,440 enzyme-linked immunosorbent assay (ELISA) units dose at month 0 with a booster at month 6 to 200 subjects divided into two age groups: group 1, 20-39 years (n = 134) and group II, 40-62 years (n = 66). At day 15, the seropositivity rates were 90% and 77% in groups I and II, respectively. At month 1 the seropositivity rate was 97% in both groups. At month 6 the seropositivity rates were 94% and 88% in groups I and II, respectively. One month after the booster, at month 7, 100% in both groups had become seropositive. The vaccine was well tolerated and did not cause any severe reactions. The results indicate that a single high vaccine dose offers protection against hepatitis A virus (HAV) for at least 6 months in the majority of cases where rapid vaccination is required even in travellers of older age. A booster dose will ensure long-term protection.

Current seroepidemiological status of hepatitis A with a comparison of antibody titers after infection and vaccination

The overall prevalence of anti-hepatitis A virus antibodies was 49.6% in 385 inhabitants in Honda City, Japan in 1991. An approximately 50% prevalence rate occurred between 40 and 49 years of age. The prevalence of anti-HAV antibodies was significantly lower in 1991 than in 1982 in the age groups 20 to 29 years and 30 to 39 years (p < 0.01), suggesting there has been no significant HAV infection since 1982. In addition, anti-HAV antibody titers of sera from convalescent hepatitis. A patients were compared with those from seropositive healthy subjects and from healthy subjects following administration of a lyophilized inactivated hepatitis A vaccine or immune serum globulin. Titers after vaccine administration were considerably higher than after immune serum globulin and, although lower than those obtained after natural infection, should be sufficient for protection against hepatitis A virus.

Prevalence of hepatitis A virus infection among sewage workers in Singapore

To determine whether or not occupational exposure to sewage is associated with a higher seroprevalence of hepatitis A virus (HAV) infection, 600 sewage workers in Singapore were tested for total (IgG and IgM) antibody to HAV by enzyme immunoassay. Using logistic regression with stepwise procedure, the adjusted seroprevalence of sewage workers was 2.2 times higher than that of another non-occupationally exposed population group. Seroprevalence was significantly correlated with age and educational levels, the association being independent of the occupational association. The epidemiological data in the study show that sewage workers have an increased occupational risk of acquiring HAV infection and should be protected by active immunization.