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In April 1985 a national immunisation survey was conducted in which sera were collected from almost 3000 randomly selected children throughout New Zealand. The sera collected were from about 1000 new school entrants (mean age 5 years), 1000 standard 3 students (mean age 10 years), and 1000 form 4 students (mean age 15 years). The sera were tested for diphtheria and tetanus immunity and antibody to pertussis by enzyme-linked immunosorbent assay (ELISA) tests. The percentage of those immune to diphtheria decreased with age from 73.1% in the 5 year olds to 53.7% in the 15 year olds. The percentage of those immune to tetanus decreased with age from 66.9% in the 5 year olds to 54.6% in the 10 year olds but then increased to 64.0% in the 15 year olds. While more than 71.0% of the 10 and 15 year olds had measurable antibody to pertussis, only a low 54.4% of the 5 year olds did. The proportion immune to diphtheria and tetanus in both Maoris and Europeans was approximately similar in all three age groups. More Maoris (78.9%) than Europeans (66.1%) had antibody to pertussis. When the data had been standardised for age and ethnic group the percentage with antibody to pertussis and immunity to diphtheria was highest in the southern region, while for tetanus immunity the percentage immune was highest in the northern and southern regions. We conclude that a sizeable pool of new school entrants (mean age 5 years) without antibody to pertussis is accumulating at a time when pertussis still persists.(ABSTRACT TRUNCATED AT 250 WORDS)

In April 1985 a national immunisation survey was carried out, during which sera were collected from approximately 3000 randomly selected children throughout New Zealand. The sample comprised approximately equal numbers of new school entrants (mean age 5 years), standard 3 pupils (mean age 10 years) and form 4 students (mean age 15 years). This collection of sera was tested for antibody to hepatitis A virus, a marker of past infection with this virus, by means of a sensitive ELISA test. Prevalence of infection was found to be less than 1% in the 5 year olds, about 3% in the 10 year olds, and about 9% in the 15 year olds. Amongst the 10 and 15 year olds, but not the 5 year olds, Maori children were approximately three times more likely to have been infected than European children. Children resident in the eastern part of the North Island had a higher risk of infection than other children, even after controlling for ethnic distribution.

During the three years 1985 to 1987 an increasing number of methicillin-resistant Staphylococcus aureus (MRSA) strains were identified in New Zealand each year. A total of 66 strains of MRSA were identified among isolates received from 418 patients and health personnel. The majority (337/418, 80.6%) of the isolates were from two independent large outbreaks of MRSA. All strains of MRSA were sensitive to vancomycin, rifampicin and fusidic acid. An overseas origin, usually Australia, was identified for 48.4% of strains. The majority of isolates were from patients whose host defences had been breached. Postoperative and cutaneous wounds were the commonest sites of acquisition.

In April 1985 a national immunisation survey was conducted, in the course of which blood samples were collected from approximately 3000 randomly selected children throughout the country. The study sample comprised approximately 1000 new school entrants, 1000 standard three pupils, and 1000 form four students. The sera were tested for morbilli antibody using an ELISA technique. Twenty-one percent of the five year olds lacked antibody, suggesting that an overall immunisation rate of about 80% is being achieved. Fourteen percent of the 15 year olds lacked antibody, suggesting that this rate of immunisation is partially interfering with the circulation of the wild virus. We conclude that a sizeable pool of susceptible adolescents is accumulating at a time when some wild virus activity still persists, and anticipate a shift in the peak age of measles infection from the 5-9 to the 10-15 age group. This unfortunate side effect of the national immunisation programme could be minimised by improving immunisation uptake in young childhood. Suggestions are made as to how this could be achieved.

Between 1982 and 1986 virus infections were identified in 16,372 cases. These identifications were based on virus isolation and/or serological evidence of infection by the main virus diagnostic laboratories at Auckland, Waikato, Christchurch and Dunedin hospitals, and at the National Health Institute. The most frequent virus identifications reported were herpes simplex (46.7%), rotavirus (11.8%), respiratory syncytial virus (5.7%), and adenovirus (5.6%). During this period of surveillance, the most prominent feature has been the high incidence of herpes simplex which reached a peak in 1983 but which has abated only slightly since. Significant trends and virus outbreaks or epidemics were detected with the regular reporting of monthly virus identifications in the New Zealand Virus Report (NZVR); these included a measles epidemic in Auckland in 1984/85, major influenza A outbreaks in 1983, 1985 and 1986, the respiratory syncytial virus epidemic in the winter of 1986, the increased incidence of rotavirus predominantly in young infants and children during the winter months, outbreaks of enterovirus type 71 and parainfluenza type 3 infections in 1986, and rubella in 1984.

Enzyme-linked immunosorbent assay (ELISA) tests were developed to detect IgG antibodies to diphtheria, tetanus, and pertussis in a healthy New Zealand population. Sera from 551 healthy persons aged 6-65 years from different areas in New Zealand were tested. Immunity to diphtheria decreased steadily from 97.1% in the 6-9 age group to 47.6% in the 60-65 age group. Immunity to tetanus varied from 88.6% in the 6-9 age group to 83.3% in the 20-29 age group, whence the level decreased with age to 57.1% in the 60-65 age group. In the teenage and adult groups more than 87.6% have antibodies to pertussis while in the 60-65 group it was 66.7%. There was great variation in the level of measurable antibody to pertussis in all age groups.

In April 1985 a national immunisation survey was conducted, in the course of which blood samples were collected from 3000 randomly selected children throughout the country. There were 1000 new school entrants (mean age 5 years), 1000 standard 3 pupils (mean age 10 years), and 1000 form 4 students (mean age 15 years). The sera were tested for hepatitis B surface antigen, antibody to hepatitis B surface antigen, and antibody to hepatitis B core antigen, by ELISA. The prevalence of infection rose with age until by 15 years of age 13.1% of the study population (8.2% of the European and 42.0% of the Maori children) were marker positive. At all ages, Maori children were five times more likely to be positive for any marker, and approximately thirteen times more likely to be positive for antigen (actively infected), than the European children. Even when the data had been standardised for age and race, children resident in the eastern North Island were still almost three times more at risk than children in the South Island. Children in the remaining areas of the North Island were at approximately equal degrees of risk, intermediate between the high and low endemic areas mentioned. We conclude that universal childhood immunisation is necessary to control horizontal transmission of heptatis B virus in New Zealand.

Enzyme linked immunosorbent assay (ELISA) tests were used to measure IgG antibody levels to Bordetella pertussis whole-cell and to pertussis toxin in a healthy New Zealand population. The percentage of individuals with measurable antibody to B pertussis whole-cell increased from 47.3% in the 5 year olds to 93.0% in the 40-49 age group, from which the percentage with antibody dropped to 88.7% in the 50-65 age group. The percentage of persons with antibody to the toxin increased with age from 17.5% in the 5 year olds to 67.0% in the 40-49 age group, from which the percentage of individuals with antibody dropped to 45.4% in the 50-65 age group. Similarly, the percentage of persons with antibody to both B pertussis whole-cell and pertussis toxin increased with age from 15.5% in the 5 year olds to 63.0% in the 40-49 age group, and then the percentage with antibody to whole-cell and toxin dropped to 45.4% in the 50-65 age group. The percentage of individuals with antibody to pertussis toxin is generally markedly lower than the percentage of persons with antibody to B pertussis whole-cell across the age range. Suggestions are made as to how to improve herd immunity for pertussis.