Population seroprevalence of human papillomavirus types 6, 11, 16, and 18 in men, women, and children in Australia.

BACKGROUND: Representative population-based data on human papillomavirus (HPV) epidemiology are important for public health decision making but are difficult to obtain. Seroepidemiology is a valuable tool, although the relationship between HPV infection and seropositivity is incomplete. METHODS: We obtained a large representative sample using residual diagnostic test serum samples obtained from individuals aged 0-69 years (1247 samples from male patients and 1523 samples from female patients) in Australia. Serum antibody levels to HPV types 6, 11, 16, and 18 were measured using an immunoassay. RESULTS: Overall, seroprevalence of HPV types 6 and 16 was higher than seroprevalence of HPV types 11 and 18. Among female patients, peak HPV seropositivity occurred among those who were 30-39 years of age for types 6, 16, and 18 (22%, 22%, and 10.5%, respectively) and among those who were 40-49 years of age for HPV 11 (11.8%). Among male subjects, peak HPV seropositivity occurred among those who were 40-49 years of age for types 6 and 11 (15.4% and 9.1%, respectively) and among those who were 50-59 years of age for types 16 and 18 (14.3% and 8.2%, respectively). No cases of HPV seropositivity were detected in individuals <10 years of age. CONCLUSIONS: Australian seroepidemiological data, showing differing age-specific patterns of HPV seropositivity in male and female patients, are likely to be generalizable to other developed countries and add to other data supporting completion of HPV vaccination before adolescence.

The impact of a new universal infant and school-based adolescent hepatitis B vaccination program in Australia.

We compared the results of two national serosurveys in Australia to evaluate the impact of universal infant vaccination and school-based programs for adolescents. Immunity improved significantly overall, especially in 1-year-olds (40.0% versus 86%; p<0.0001); in adolescents it was significantly higher in regions with established school-based programs (56.6% versus 38.8%; p=0.0008). 6.1% of 1-59-year-olds were positive for HBcAb and 0.7% for HBsAg. We have demonstrated successful implementation of universal infant hepatitis B vaccination in Australia and that school-based programs for adolescents are effective. This experience should be applicable to low prevalence countries in northern Europe which have not implemented universal hepatitis B immunisation.

European seroepidemiology network 2: Standardisation of assays for seroepidemiology of varicella zoster virus.

BACKGROUND: The aim of the European Sero-Epidemiology Network (ESEN2) is to harmonise the serological surveillance of vaccine-preventable diseases in Europe. OBJECTIVE: To allow comparison of antibody prevalence in different countries by standardising results into common units. STUDY DESIGN: For varicella zoster virus (VZV), a reference laboratory established a panel of 148 samples, characterised by indirect enzyme-immunoassay (ELISA), indirect immunofluorescence, and complement fixation test. Fifty-seven samples were also studied by the fluorescence antibody to membrane antigen test. The geometric mean of the antibody activity (GMAA) obtained from four ELISA determinations was used to characterise each sample of the panel as positive (GMAA: >100 mIU/ml), equivocal (GMAA: 50-100 mIU/ml) or negative (GMAA: <50 mIU/ml) for antibody to VZV (anti-VZV). Thirteen laboratories, using five different ELISA tests, tested the panel. RESULTS: Agreement with the reference laboratory was above 85% in all cases, and the R(2) values obtained from regression analysis of the quantitative results were always higher than 0.87. Finally, the regression equations could be used to convert national values into a common unitage. CONCLUSION: This study confirmed that results for anti-VZV obtained by different ELISA methods can be converted into common units, enabling the comparison of the seroprevalence profiles obtained in the participant countries.

Immunity to diphtheria and tetanus in Australia: a national serosurvey.

OBJECTIVE: To determine immunity to tetanus and diphtheria in the Australian population. DESIGN AND SETTING: Analysis, using double antigen enzyme immunoassays, of a representative sample of sera (1950 samples tested for diphtheria and 2884 for tetanus) collected opportunistically from Australian laboratories between July 1996 and May 1999. MAIN OUTCOME MEASURE: Immunity to diphtheria and tetanus, defined as negative (susceptible) when the antitoxin level was < 0.01 IU/mL, positive (immune) when it was > or = 0.1 IU/mL, and low positive (partially immune) when it was in the range 0.01-< 0.1 IU/mL. RESULTS: About 99% of children aged 5-9 years had diphtheria and tetanus antitoxin levels > or = 0.01 IU/mL (immune or partially immune). Antitoxin levels declined with age and generally more markedly for diphtheria than tetanus. For subjects aged 50 years and over, less than 60% were immune or partially immune to diphtheria and less than 75% to tetanus. Men and women had similar diphtheria antitoxin levels, while women had lower levels of tetanus antitoxin compared with men of the same age, with the difference being most marked in the age group > or = 70 years (37% v 60%; P < 0.001). CONCLUSIONS: Immunity in children appears to be good, but adults, especially older people, may not be adequately protected. Recent changes to the Australian Standard Vaccination Schedule should improve immunity in cohorts now aged < 50 years. However, additional efforts are required to protect those over 50 years (especially travellers), who are most susceptible.

National serosurvey of poliovirus immunity in Australia, 1996-99.

OBJECTIVE: To measure immunity to poliovirus types 1, 2 and 3 in the Australian population. METHODS: Sera were collected opportunistically from laboratories around Australia between 1996 and 1999. A representative sample by age and gender was tested for neutralising antibodies to poliovirus types 1, 2 and 3. A titre of > or = 8 was considered antibody positive and indicative of immunity. RESULTS: Of the 1,813 sera tested, 82% were antibody positive for poliovirus type 1 and 88% were positive for type 2. Immunity to type 3 poliovirus was lower overall (74%) and especially in school-aged children and young adults. For all three poliovirus types, there were more females immune than males and immunity peaked in the 2-4 years age group. The proportion of the population immune to all three types was 59%, and 3% were negative for all three types. CONCLUSIONS AND IMPLICATIONS: This is the first national serosurvey for immunity to poliovirus in Australia. Herd immunity is probably sufficient to prevent generalised outbreaks due to type 1 and 2 poliovirus, but this may not be the case for type 3. However, localised outbreaks of any poliovirus type could still occur following reintroduction unless uniformly high levels of vaccination coverage are maintained. Ongoing serosurveillance is required following the recent change back to inactivated polio vaccine.

Hepatitis C prevalence--a nationwide serosurvey.

Hepatitis C is the most commonly notified disease in Australia. In 1998 the Hepatitis C Virus Projections Working Group (HCPWG) estimated that there were approximately 210,000 people who had been infected by hepatitis C virus (HCV) in Australia by 2001. Population-based serosurveys are required to validate this estimate. Here we estimate HCV prevalence on the basis of HCV antibody seroprevalence in the Australian national serosurvey. Between 1996 and 1998, 2,800 sera opportunistically collected from pathology laboratories throughout Australia were tested for HCV antibody. National HCV notifications reported from 1991 through 1998 were also assessed. Eighty-one sera were HCV antibody positive, giving an age standardised prevalence of 2.3 per cent (95% CI 1.8%-2.9%). The 20-24 year age group had the highest HCV prevalence, 5.3 per cent (95% CI 3.3%-8.1%) and the male to female ratio was 1.8:1.0. Approximately 111,000 HCV notifications were received from 1991 through 1998. HCV prevalence estimated by the serosurvey is approximately three times higher than cumulative HCV notifications. Age and sex distributions of seroprevalence are broadly consistent with cumulative notification data. These distributions are consistent with the majority of HCV infections in Australia being transmitted by injecting drug use. Very low age specific seroprevalence estimates in the over 50 years age group indicate that there is not a large pool of undiagnosed infection in this age group. The serosurvey provides an estimate of Australian HCV prevalence and baseline data to determine incidence trends, both of which are required for health-care planning.