Prevalence of antibody to the hepatitis A virus in a large institution for the mentally retarded

[Prevalence of anti-HAV antibodies and efficacy of pre-vaccine detection at institutions for mentally retarded of the city of Alicante]

OBJECTIVE

The aim of this study was to investigate the prevalence and efficacy of the anti-HAV antibodies detection in institucions for mentally retarded people in the city of Alicante.

DESIGN

Prevalence study.

SETTING

Two institucions for mentally retarded people in the city of Alicante.

PARTICIPANTS

One hundred and seven residents and seventy seven in care of them.

MEASUREMENTS AND MAIN RESULTS

We have investigated the anti-HAV antibodies prevalence by enzymeinmunoanalysis of microparticle test. The efficacy of the anti-HAV antibodies detection before the vaccination has been studied by calculating the threshold of prevalence with the following formula: unit cost of detection + (1 - X) x unit cost vaccination anti-HAV negative subjects = unit cost vaccination.

RESULTS

The global prevalence of anti-HAV antibodies was 56.5% (95% CI, 49-63.7). The prevalence of the residents was 55.1% (95% CI, 45.2-64.7) and 58.4% in care of them (95% CI, 46.6-69.5). Among the sociodemographic variables evaluated only the age was associated with the prevalence of anti-HAV antibodies (p < 0.001). The unit cost of prevaccination detection of anti-HAV antibodies was calculated as 998 pesetas and the unit cost of the vaccination as 3595, obtaining a prevalence anti-HAV threshold of 27.8%.

CONCLUSIONS

The prevalence of anti-HAV antibodies in this collective studied is similar to the prevalence of anti-HAV antibodies of the spaniard population. The direct vaccination without a previous marker study is recommended to people under the age of 31 in this population group.

Prevalence of hepatitis A in an institution for the mentally retarded in an intermediate endemicity area: influence of age length of institutionalization

OBJECTIVE

This study aimed to examine the prevalence of antibodies against hepatitis A (anti-HAV) in a population of institutionalized mentally retarded persons compared with that of institutionalized non-mentally retarded persons in an area with moderate endemicity of HAV infection.

METHODS

The study population was a group of mentally retarded persons aged between 10 and 30 years, institutionalized in one residence in Madrid, Spain. A group of non-mentally retarded subjects in the same age range was chosen as controls. Information about demography and duration of institutionalization was obtained by the investigator. Four drops of whole blood were obtained from each person by finger-stick, collected on filter paper, air-dried and stored at +4 degrees C until antibody determination. Eluates were tested by an ELISA method.

RESULTS

A total of 314 institutionalized subjects were included: 157 mentally retarded (mean age and mean duration of institutionalization were 24.4+/-3 and 9.7+/-5 years respectively) and 157 non-mentally retarded (mean age and mean duration of institutionalization were 19.2+/-5 and 4.6+/-3 years respectively). The prevalence of anti-HAV antibody was 54% (95% confidence interval (CI) 50-58) in mentally retarded and 22% (95% CI 19-25) in non-mentally retarded [P<0.001; odds ratio (OR): 4.2 (95% CI 2.5-7)]. In both groups, these differences were not statistically significant for anti-HAV antibody prevalence between persons institutionalized for >5 years compared with those institutionalized for < or = 5 years.

CONCLUSIONS

There results indicate that in an area of moderate endemicity the institutionalized mentally retarded are at increased risk of having acquired hepatitis A infection compared to the non-mentally retarded. In these institutionalized persons, regardless whether they are mentally retarded or not, prevalence is not influenced by age or length of stay in institutions.

Immune globulin and vaccine therapy to prevent hepatitis A infection

The hepatitis A virus is usually transmitted person-to-person due to fecal-oral exchange of virus. Approximately 30,000 infections are reported each year in the United States, with the actual incidence being much greater. Prophylaxis with immune globulin has had a minimal impact on the overall incidence of hepatitis A. The recent availability and proven efficacy of a hepatitis A vaccine offers the hope that the incidence of infection may be substantially reduced. Pre- and postexposure prophylaxis should be targeted to individuals at increased risk of either acquiring infection, transmitting infection, or developing fulminant hepatitis, or to help control epidemics. This article reviews the current literature and discusses recommendations for pre- and postexposure prophylaxis against hepatitis A virus.

The current epidemiology of hepatitis A infection in South Africa: implications for vaccination

Testing stored sera from various categories of individuals has shown that among the Black population hepatitis A virus (HAV) infection is universal and most adult Black subjects are immune. Infection probably occurs early in life, consistent with the epidemiological pattern seen in the developing world. By contrast, seroprevalence of HAV infection in adult White subjects increases with age, reflecting an epidemiological pattern seen in the developed world. White subjects working in a virological laboratory and White medical students had comparatively low seroprevalences of HAV infection and could therefore represent groups at risk. Hepatitis A vaccine is likely to be available in South Africa in the near future and could be offered to these groups. Pre-vaccination immunity screening would be a cost-effective strategy.

Survival of hepatitis A virus on human hands and its transfer on contact with animate and inanimate surfaces

The survival of hepatitis A virus (HAV; strain HM175) on the hands of five volunteers was determined by depositing 10 microliters of fecally suspended virus on each fingerpad and eluting the inoculum after 0, 20, 60, 120, 180, and 240 min. The amount of virus recovered from each fingerpad at 0 min was approximately 6.0 x 10(4) PFU. At the end of 4 h, 16 to 30% of the initially recoverable virus remained detectable on the fingerpads. HAV inocula (10 microliters; approximately 1.0 x 10(4) PFU) placed on fingerpads or 1-cm-diameter metal disks were used to determine virus transfer to clean surfaces upon a 10-s contact at a pressure of nearly 0.2 kg/cm2. When the inoculum was dried for 20 min, virus transfer from fingerpad to fingerpad, fingerpad to disk, and disk to fingerpad ranged from 2,667 to 3,484 PFU, while 0 to 50 PFU could be transferred after 4 h of drying. Elevation of the contact pressure alone from 0.2 to 1.0 kg/cm2 resulted in an approximately threefold increase in the amount of virus transferred. Incorporation of friction (10 half turns of the finger during 10 s of contact) with the low and high levels of pressure gave two- and threefold increases in the PFU of virus transferred, respectively. Pressure and friction were found to significantly affect HAV transfer (F = 33.98; P less than 0.05), irrespective of the mode of transfer used. No statistically significant interaction was observed between mode of transfer and pressure or friction. The findings of this quantitative study suggest that human hands may play an important role in the direct as well as the indirect spread of HAV.

Effect of relative humidity and air temperature on survival of hepatitis A virus on environmental surfaces

Stainless steel disks (diameter, 1 cm) were contaminated with fecally suspended hepatitis A virus (HAV; strain HM-175) and held at low (25% +/- 5%), medium (55% +/- 5%), high (80% +/- 5%), or ultrahigh (95% +/- 5%) relative humidity (RH) at an air temperature of 5,20, or 35 degrees C. HAV survival was inversely proportional to the level of RH and temperature, and the half-lives of the virus ranged from greater than 7 days at the low RH and 5 degrees C to about 2 h at the ultrahigh RH and 35 degrees C. In parallel tests with fecally suspended Sabin poliovirus (PV) type 1 at the low and ultrahigh RH, all PV activity was lost within 4 h at the low RH whereas at the ultrahigh RH it remained detectable up to 12 h. HAV could therefore survive much better than PV on nonporous environmental surfaces. Moreover, the ability of HAV to survive better at low levels of RH is in direct contrast to the behavior of other enteroviruses. These findings should help in understanding the genesis of HAV outbreaks more clearly and in designing better measures for their control and prevention.

Safety and immunogenicity of an inactivated hepatitis A candidate vaccine in healthy adult volunteers

The reactogenicity and immunogenicity of a formaldehyde-inactivated hepatitis A vaccine have been investigated. Three different dose levels of vaccine (180, 360 and 720 ELISA units) were administered to healthy volunteers according to a 0, 1, 2 and 12 month schedule. The vaccine was safe and well tolerated. Reactions observed following vaccination were essentially mild and were not dependent upon the quantity of antigen administered. All subjects had measurable titres of anti-HAV antibodies after the full vaccination course; the immune response to the vaccine was dose-related. Antibody titres in vaccinees at month 13 were between 60- and 190-fold higher than those observed in a group of subjects given anti-HAV immunoglobulin.

The prevalence of antibody to hepatitis A virus in Singapore

Sera collected from 1, 630 healthy children and adults aged between six months and 55 years during the period 1984 to 1985 were tested for hepatitis A virus (HAV) immunoglobulin G antibody by enzyme immunoassay. The over all antibody prevalence rate was 31.8%. It increased from 0% in children under five years old to 15.5% in adolescents and young adults (15 to 24 years) and reached the highest level of 88.2% in adults over 55 years of age. No statistically significant differences in the overall prevalence by sex and ethnic group were observed. None of the 938 samples tested for HAV immunoglobin M antibody was positive. Compared with the data in 1975, the survey showed that the level of exposure of Singapore children to HAV was declining as the result of vast socio-economic progress made during the past decade.

Prevalence of hepatitis A virus antibody among Navajo school children

Previous studies of the prevalence of immunity to hepatitis A (anti-HAV) in the United States have used urban settings or institutions for the mentally handicapped. In a rural setting among normal children, a serologic investigation of prevalence of anti-HAV was conducted in a boarding school adjacent to the Navajo reservation. The results show rates of anti-HAV that are the highest reported at the ages tested in any subpopulation in the United States, comparable only with those in developing countries.

Hepatitis A and hepatitis B virus infection in children and adolescents in north-east Italy

The sera of 722 children and adolescents without overt liver disease were tested for hepatitis B surface antigen (HBsAg), antiHBs and anti-hepatitis B core anti-HBc; 658 of the sera were also tested for anti-hepatitis A virus anti-HAV. Except for the "passive" antibody peak observed in babies, the anti-HAV age-specific prevalence was negligible until the age of 3; it then increased, reaching 35% by the age of 15. Serological evidence of HBV was present in 16% of the subjects: this prevalence was almost constant at all ages. The HBsAg carrier rate was highest in children under 5 years of age (7.6%) and decreased with age. However, only one HBsAg carrier was under 1 year of age. Anti-HBs age-specific prevalence increased progressively from 2.7% to 11.4%. Anti-HBc alone was present in 4.1% of the subjects. No significant sex differences were found in the prevalence of HBV serum markers or in the HBsAg carrier rate. Neither HAV nor HBV infection was significantly influenced by place of residence or socioeconomic status. It is concluded that in this area both HAV and HBV are endemic, but while HAV is mainly acquired at school, most of the HBV infections occur within the household. The results suggest that not only perinatal transmission, but also intrafamilial horizontal infection, plays a role in HBV spread among infants.

Viral hepatitis A and B in hemodialysed patients

In 113 hemodialysed patients, 167 hospitalized patients, and 143 outpatients the frequency of HAV and HBV markers were studied by testing HBsAg, anti-HBs, anti-HBc, HBeAg, anti-HBe, and anti-HAV. The hemodialysis patients in a dialysis-center had significantly more often HBV markers (85.7%) than those maintained on home-dialysis (46.5%). 29.9% of the hospitalized patients and 32.1% of the outpatients had HBV markers. By the anti-HBc test up to 41% of additional HBV infections could be detected.--The prevalence of anti-HAV was very high in all groups. Significant differences between the hemodialysis patients and the control groups existed only in the age groups up to 39 years.--The frequencies of HAV and HBV markers were related to age, duration of dialysis treatment, transfusional frequency, and transaminases. The HBV appeared as the clinically important hepatitis agent in dialysis.

An outbreak of hepatitis A in an institution for the mentally retarded

From December 1977 until April 1978 a hepatitis A outbreak occurred in an institution for the mentally retarded. The institution housed 311 residents and had a staff of 308. The outbreak was studied by enzyme-linked immunosorbent assays for hepatitis A antigen and antibodies, and by liver function tests in serum. When the investigations started, 13 residents and one staff member were ill and already seropositive; 34 of the 182 residents that were seronegative at that time and 12 of the 223 seronegative staff members subsequently developed disease. Out of the 60 cases 32 were asymptomatic; 19 cases with jaundice were seen. Normal human immunoglobulin was administered to a large part of the seronegative group, but the effect is difficult to interpret as the immunoglobulin was often given after the presumed time of infection and failed to protect. Elevated liver enzyme levels were demonstrated in 38 of 60 patients.