During 1981 there were 508 laboratory confirmed cases of ornithosis in Norway. This represents a 7-fold increase compared with previous years. Among 370 patients examined by the National Institute of Public Health, Oslo, 148 stated some contact with birds. There were also small family outbreaks and cases of ornithosis in school friends etc. where no bird exposure had occurred, suggesting that interhuman transmission might be involved. The clinical picture was that of a respiratory disease with pneumonia in more than half the cases. The clinical course was mild to moderately severe. At present we have no explanation for this change in the epidemiologic pattern of ornithosis in Norway.
The authors briefly review the incidence of some of the more important communicable diseases in Norway today. Thanks to extensive use of vaccines, effective preventive measures and useful antibiotics, many of these diseases are no longer a threat to public health, as was the rule up to the latter half of this century. However, constant vigilance is needed to sustain this positive situation.
During an epidemic of erythema infectiosum in Norway 1984-86, infection with human parvovirus B19 was diagnosed in 22 pregnant women by detection of specific IgM antibodies. Information about the outcome of pregnancy was obtained in 19 cases. 17 women delivered live babies. In two cases, spontaneous abortion occurred in week 16 of the pregnancy. In 11 cases, cord blood and serum samples were obtained from the children at an age of between six and 15 months. No specific IgM antibodies were found in cord blood. Clinical information on 16 children at two years of age revealed normal growth and development in 15 cases. One child was hyperactive and showed delayed language development. B19 IgG antibodies were detected in three children with normal growth and development. According to our findings, there was no association between infection with human parvovirus B19 in pregnancy and congenital abnormalities.
The introduction of a measles vaccination programme in Norway in 1969 using one dose of vaccine, and since 1983 two doses, was followed by a substantial decrease in the incidence of the disease. Since 1992, the annual incidence has been less than 20 cases. Small clusters and outbreaks have occasionally been observed among military personnel and unvaccinated children. This paper describes a seroepidemiological investigation of the level of immunity among 1,188 military conscripts, aged 18-28 years (mean 20.7) compared with 695 healthy 40-year-olds. The conscripts had been offered measles vaccine in infancy, in some cases also at 12-13 years of age, but they had also been exposed to wild measles virus, since the virus continued to circulate many years after the vaccination had started. The measles immunity in this group is considered to indicate the immunity level among the first 5 cohorts offered measles vaccine in Norway. The 40-year-olds had grown up in a community with no measles vaccination. Their level of immunity gives an indication of the level finally obtained when there are no vaccinations, and thus of the level that would induce herd immunity against measles in the Norwegian population. The aims of the vaccination programme must be to obtain a corresponding immunity. The results of the investigation show that the percentages with measles antibodies in the respective groups were 92.3 and 98.1. The observation of measles outbreaks among young Norwegian conscripts, as well as reports from several countries on outbreaks in university and college settings with levels of seropositivity of even more than 95%, indicate that the seropositivity in the 20-year-old group may be too low to afford protection, especially when this group is living under close conditions. Consideration should be given to the need for an intensification of the existing vaccination programme to ensure that the protection level needed for herd immunity is reached.
The study is based upon primary rubella infections detected in a collection of 7,781 serum pairs from as many pregnant women out of a total number of about 12,500 in the Oslo area of Norway in 1974. In the spring of that year, a rubella outbreak occurred. The results obtained on the serum pairs were compared and supplemented with acute serodiagnostic data obtained from the files of the virus laboratories, informations obtained from the mothers when interviewed in 1976 and from the files of application for legal abortions. From October 1973 through December 1975 a total of 118 serologically confirmed pregnancy infections were detected in the area, 94 of which took place between February and July 1974. The year following the outbreak showed scattered cases, whereas the last half of 1975 was free of cases. The pairs of the collection covered about one third of the pregnancy months occurring between February 1974 through January 1975, and the rubella infections diagnosed by seroconversion during this period indicated an attack rate for the epidemic period of 2.8% pregnancy months, and 0.35% for the post-epidemic period. 50% of the infections went unrecognised when they occurred, whereas only 17% seemed to have been subclinical. It is estimated that at least 9 children may have been born with rubella sequelae following infections during this period, when the legal abortions because of rubella in taken into consideration.