Bollettino epidemiologico nazionale

Measles Increase in Italy

Marta Luisa Ciofi degli Atti e Stefania Salmaso (Infectious Diseases Unit, Laboratory of Epidemiology and Biostatistics, Istituto Superiore di Sanità, Rome) for the SPES Coordinating Group*.

*SPES Coordinating Group: Raffaele Arigliani; Antonino Bella; Guido Brusoni; Giampiero Chiamenti; Vincenzo Calia; Patrizia Carbonari; Stefano Del Torso; Michele Gangemi; Milena Lo Giudice; Vitalia Murgia; Silvana Parroccini; Alberto Eugenio Tozzi; Giovanni Vitali Rosati.

In Italy, measles vaccine became commercially available in 1976 and its administration has been recommended by the Ministry of Health since 1979. During the 1960s, immediately prior to the introduction of the vaccine, an average of 74,000 cases were notified annually, yielding a rate of 150 cases/100,000 population. Following the introduction of the vaccine, incidence has gradually decreased, with a mean incidence of 81 cases/100,000 in the 1980s and 41/100,000 in the 1990s.

The last measles epidemic in Italy occurred in 1997. Approximately 41,000 cases were reported, of which 95% were reported in children under 15 years of age, yielding an incidence rate in this age group of 473/100,000.

In 1998, the number of notified measles cases declined to 4,000, and in subsequent years has continued to decrease. In 2000, the incidence in children < 15 years of age declined to an historical low of 15/100,000. In addition to representing the lowest incidence of measles ever reported, Italy is experiencing its longest interepidemic interval, which in the past had never exceeded three years.

Although notification is statutory, measles cases are often unreported. Underreporting is more common in the south than in the north of the country. As a result, incidence rates are paradoxically lower in southern Italy, where vaccine coverage is lower, than in the north, where vaccination coverage is higher (1).

To monitor the incidence of measles and other vaccine-preventable diseases in a timely and accurate manner, a national sentinel surveillance system was launched in January 2000 (SPES) (2). This system is based on a network of primary-care paediatricians, who report cases on a monthly basis. As in statutory notification, case definition is clinical. The population under surveillance includes children enrolled in the practices of the participating paediatricians, and represents approximately 4% of the national population under 15 years of age. Feedback of results is provided monthly on a web page (www.spes.iss.it).

According to SPES results, in 2000, the monthly measles incidence did not exceed 15/100,000; in 2001, incidence had further declined to less than 5 cases/100,000 per month. However, in the first two months of 2002 the incidence has rapidly increased, reaching 20 cases/100,000 in February (Figure 1). The most affected regions were Lazio and Campania. In this latter region, which is located in southern Italy, the monthly incidence in February was 123 cases/100,000 (Figure 2). The majority of cases occurred in children of 5-9 years of age.

Despite increases in measles vaccination coverage observed in recent years, the national vaccination coverage within 24 months of age estimated in year 2000 was still lower than 80%, and it was lower than 60% in many southern regions (http://www.sanita.it/malinf/CertVacc/cop_vacc/cop_vacc.htm).

As a result of low coverage levels, a substantial number of children remain susceptible and the potential for new epidemics is high. To combat this threat, it is absolutely essential that a co-ordinated effort of Regional Health Authorities be undertaken to improve both the measles vaccine coverage for infants as well as to conduct catch-up vaccination among older children who have never been vaccinated in accordance with the recommendations provided by the Ministry of Health in 1999 (4).

According to recommendations of both the World Health Organization and the National Health Plan, it is recommended that a vaccine coverage of at least 95% be attained within the second year of life.

Strategies to perform catch-up vaccination and to offer a possible second dose differ by the level of vaccine coverage obtained within the second year of life. A distinction is made between areas with measles vaccine coverage less than 80% and those that have higher levels. In the areas with lower coverage, the vaccination of older children who remain susceptible is emphasized, which can be accomplished in two different ways:

• Use all occasions of contact with vaccine services to check the vaccine status of children under 18 years of age and offer vaccination to those who have not already been vaccinated and do not have a history of clinical measles OR

• Organize special time-limited campaigns (for example, over a fewl weeks) when vaccine is actively offered to all children over the age of two that have not been vaccinated.

In regions in which the vaccine coverage within the first two years of life exceeds 80% and the percent of susceptible under 2 years of age is less than 10%, the administration of a second dose at 5-6 years or at 11-12 years of age is recommended.

With the general increase of vaccine coverage and the declining incidence observed in Italy, it becomes ever more important to conduct surveillance for the disease. Even a single case constitutes an occasion to de5termine the vaccine status of contacts (for example, family members or classmates) and to vaccinate those determined to be susceptible.

References

1. Salmaso S, Gabutti G, Rota MC, Giordano C, Penna C, Mandolini D, Crovari P, and the Serological Study Group. Pattern of susceptibility to measles in Italy. Bulletin of the World Health Organization, 2000; 78 (8): 950-955.

2. Ciofi degli Atti ML. Sentinel Pediatric Surveillance in Italy: Results from 2000 BEN Notiziario ISS 2001; 14

3. Ministero della Sanità. Circolare n. 12 del 13 luglio 1999 “Controllo ed eliminazione di morbillo, rosolia e parotite attraverso la vaccinazione”