Measles in Germany

[Contribution of unvaccinated siblings to a measles outbreak in Switzerland]

BACKGROUND

A measles outbreak occurred in Geneva between March and July 2003. An investigation was conducted to determine its magnitude, identify predominant modes of transmission, and assess disease outcome.

METHODS

In Switzerland, measles notification has been mandatory for physicians since 1999 and laboratories since 1988. All cases were investigated and followed up by interviewing physicians using a standardized questionnaire. Viral genotype was determined for 4 cases using a saliva specimen processed at the Robert Koch Institute, Berlin. Geographic distribution of cases and vaccination coverage were compared.

RESULTS

Overall, 54 cases were notified. Fifty-three cases were between 10 and 19 years of age. Ninety-four percent (n = 46) of 49 cases with known vaccination status were not vaccinated and none were fully immunized (2 doses). Measles complications occurred among 19% (n = 7) of the 36 patients with follow up information: pneumonia (n = 4, combined with pericarditis and hepatitis in one case) and bronchitis (n = 3). Three persons were hospitalized. No complication was reported among 3 persons partially vaccinated (1 dose). The virus belonged to genotypes D8 and D5. Five separate clusters of related cases included 74% of all cases. Transmission mainly occurred within families (43% of all cases) and school (28%). Two of the most affected areas had measles vaccination coverage well below the cantonal average.

CONCLUSION

Low vaccination coverage combined with clusters of unvaccinated household contributed to continued virus circulation and represents a threat to the canton of Geneva as new outbreaks of measles may reoccur.

Decay of passively acquired maternal antibodies against measles, mumps, and rubella viruses

The decay of maternally derived antibodies to measles, mumps, and rubella viruses in Swiss infants was studied in order to determine the optimal time for vaccination. A total of 500 serum or plasma samples from infants up to 2 years of age were tested by enzyme-linked immunosorbent assay and fluorescent-antibody testing. The decline of antibody prevalence was slowest against the measles virus. By 9 to 12 months of age, only 5 of 58 (8.6%; 95% CI, 2.9 to 19.0) infants were antibody positive for the measles virus, and only 2 had levels above 200 mIU/ml. Mumps and rubella virus antibody seropositivity was lowest at 9 to 12 months of age with 3 of 58 (5. 2%; 95% CI, 1.1 to 14.4) infants and at 12 to 15 months with 1 of 48 (2.1%; 95% CI, 0.1 to 11.1) infants, respectively. Concentrations of passively acquired antibodies decreased rapidly within the first 6 months of life. We observed no significant differences in antibody prevalence or concentration according to gender in any age group. In conclusion, MMR vaccination at 12 instead of 15 months of age could reduce the pool of susceptible subjects in infancy and support the efforts to eliminate these infections, particularly in combination with a second vaccine dose before school entry.