Bollettino epidemiologico nazionale

Rubella Epidemiology in Italy

Antonietta Filia

School of Hygiene and Preventive Medicine

University of Rome “Tor Vergata”

The primary objective of rubella vaccination programs is to prevent the occurrence of congenital rubella. Three approaches are possible: (a)selective immunization of adolescent girls and/or women of childbearing age; (b) universal vaccination of infants and young children; or (c) a combination of the previous two strategies (1).

Rubella vaccine was introduced in Italy in 1972. Initially, immunization was targeted at pre-adolescent girls, but following the introduction of the combined measles-mumps-rubella (MMR) vaccine in the early 1990s, universal vaccination of all infants was recommended. The national immunization program currently recommends MMR vaccine at 12–15 months of age. Immunization of pre-adolescent girls also continues to be recommended until high levels of coverage are achieved in infants (2).

Rubella immunization coverage is not routinely assessed in Italy, but studies performed in the 1990s have shown that 90% of children vaccinated against measles received combined MMR vaccines (3). Coverage of rubella vaccine in infants is therefore considered to be similar to that of measles and was estimated at 53% in 1998 (3), and 76% in 2001 (source: Ministry of Health). Coverage levels vary greatly between regions however, and in 2001 ranged from 47% to 91%. No recent rubella coverage data are available for pre-adolescent girls.

The impact of rubella immunization can be evaluated by monitoring disease incidence and susceptibility levels in the population. Systems for monitoring disease incidence in Italy include the national disease notification program and the pediatric sentinel surveillance network (SPES) (4).

Rubella became a notifiable disease in Italy in 1970. Figure 1 shows the number of annual reported rubella cases from 1976 to 2001. Epidemics occur approximately every 4 years; the last one occurred in 1997, with approximately 35,000 reported cases. Between 1998 and 2001, disease incidence declined, with a maximum of 5500 reported cases per year. However, SPES data reveal an increased incidence in 2002. From 2000 to 2002, incidence was higher in Central and Southern Italy, with most cases occurring in children between 10 and 14 years of age.

Table 1 shows the mean age of reported cases and the incidence in women of childbearing age by five year periods from 1976 to 1996. As can be seen, a shift has occurred in the mean age of rubella infection; nevertheless, the incidence in women of childbearing age has slightly declined.

As far as susceptibility levels are concerned, a serosurvey performed in Italy in 1996 showed that over 30% of children between ages 2 and 14 years, and 9% of those over age 14 years were seronegative. Mean susceptibility rates among women of childbearing age were 10% between ages 15 and 19 years and 7% between ages 20 and 39 years, with higher rates in the South (5).

Congenital rubella syndrome (CRS) was notifiable in Italy between 1987 and 1991 (Figure 1). The number of reported cases ranges from 8 cases in 1987 to 76 cases in 1989 (source: ISTAT). Since 1992 incidence data are no longer available; nevertheless, hospital discharge diagnoses indicate that congenital rubella cases still do occur in Italy (29 cases in 1999, and 11 in 2000).

Low levels of rubella immunization coverage have reduced but not interrupted circulation of rubella virus, and, as a result, congenital rubella cases may still occur in Italy. Serological surveys have shown that susceptibility rates are indeed high in both the general population and in women of childbearing age.

To interrupt rubella transmission, uniformly high levels of coverage in infants must be achieved and sustained. In fact, if vaccination coverage is inadequate, the disease continues to circulate in the community with a shift of infections toward higher age groups. In the case of rubella, this is of great concern as it may lead to an increased number of infections during pregnancy and an increased number of congenital rubella cases (6).

Aside from universal vaccination of infants, selective immunization of schoolgirls should continue until sufficiently high infant coverage rates are reached.

References

• Weekly Epidemiological Record WHO 19 May 2000, 75, 161-172
• Ministero della Sanità. Circolare n°12 del 13 luglio 1999. Controllo ed eliminazione di morbillo, parotite e rosolia attraverso la vaccinazione.
• Salmaso S, Rota MC, Ciofi degli Atti M, Tozzi A, Kreidl P, and the ICONA Study Group. Infant immunization coverage in Italy: estimates by simultaneous EPI cluster surveys of regions. Bull. WHO 1999; 77(10): 843-51.

• Ciofi degli Atti ML, Salmaso S, Bella A, Arigliani R, Gangemi M, Chiamenti G, Brusoni G, Tozzi A, e SPES Study Group. Pediatric Sentinel Surveillance of vaccine preventable diseases in Italy. Pediatr Infect Dis J, 2002; 21(8):763-8

• Gabutti G, Rota MC, Salmaso S., Bruzzone BM, Bella A., Crovari P, and the Serological Study Group. Epidemiology of measles. mumps and rubella in Italy.Epidemiol. Infect. (2002), 129:543-550

• Edmunds WJ, van de Heijden OG, Eerols M, Gay NJ. Modelling rubella in Europe Epidemiol Infect. 2000 Dec; 125 (3):617-34