[Mumps in a urban area of the Community of Madrid. Vaccination status, diagnosis and intervention measures].

OBJECTIVES

To describe the epidemiological situation of an epidemic of mumps, to calculate the risk of catching the illness depending on the vaccine strain used and to evaluate the diagnostic performance of the serologic determination.

DESIGN

Longitudinal observational study. The incidence of mumps between January 1999 and June 2000 was calculated. Case-control study of outbreaks evaluated the risk of catching the disease depending on the vaccine strain.

SETTING

Health Area 4 in the Community of Madrid.

PARTICIPANTS

Residents and students from schools in the district.Interventions. Epidemiological vigilance. Serologic determination of IgM and titration of IgG. In outbreaks, people exposed were vaccinated after assessment of their vaccine status.

MEASUREMENTS AND MAIN

RESULTS

The rate of incidence in the first 27 weeks of the year 2000 for the 1-4 year-old age group was 334.7/105, against 12.2 in 1999. In children under 5 vaccinated with the Rubini strain there was a significantly greater risk of suffering illness than in those vaccinated with the Jeryl-Lynn strain (OR, 6.28, 95% CI, 1.43-38.50). The amount of cases confirmed serologically (specific IgM positive) was 22.22%. The mean of the logarithms of the IgG titres was significantly higher (p < 0.001) in IgM-negative patients with epidemiological confirmation (4.05, 95% CI, 3.18-4.28) than in IgM-negative cases without any epidemiological link (2.58; 95% CI, 2.33-2.84).

CONCLUSIONS

We emphasise the increase of mumps incidence in the school population (fundamentally in the under-5s), which parallels an increase in outbreaks. The results suggest that the Rubini strain is less efficacious. The possibility of using alternative methods to IgM detection (IgG titration) as a diagnostic tool in a population with high vaccination coverage is posed.