[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.


CONCLUSIONS
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.
Delaporte
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Direction générale de la santé, Département de l'action sociale et de la santé, Avenue de Beau-Séjour 22, case postale 166, CH-1211 Genève 4, Suisse. elisabeth.delaporte@etat.ge.ch
Wyler-Lazarevic
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CA
Richard
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JL
Sudre
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P
D000293:Adolescent; D000328:Adult; D002648:Child; D018563:Disease Notification; D004196:Disease Outbreaks; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D008457:Measles / Q000453:epidemiology* / Q000635:transmission / Q000821:virology; D008458:Measles Vaccine; D008459:Measles virus / Q000235:genetics; D035781:Siblings; D013557:Switzerland / Q000453:epidemiology
D008458:Measles Vaccine