Bollettino epidemiologico nazionale

SIMINEWS

Stefania Salmaso. Antonino Bella. Barabara D Mei. and Donatella Mandolini

Laboratory of Epidemiology and Biostatistics

The SIMI Project (System for the Surveillance of Infectious Diseases). which began in 1996. was designed to improve the quality of the existing infectious disease surveillance system and encourage timely reporting and utilization of data. The project has focused on computerized reporting of Class II diseases (25 common communicable diseases such as vaccine-preventable childhood illnesses and salmonellosis for which confirmed cases must be individually notified on a standard form) and two of the four Class III diseases (tuberculosis and mycobacteriosis) which require submission of additional documentation. At present. sixteen of the country’s 21 regions have joined the system and regularly send data. Sicily. Calabria. Sardinia. and Abruzzo have indicated an interest in participating but do not yet have monthly computerized data entry systems compatible with SIMI. and although Lombardy initially participated in the system. but has not provided data since 1999.

Reports of the activities and recent findings of SIMI have been published periodically as a supplement to the Notiziario of the Istituto Superiore di Sanità. These reports. entitled SIMINEWS. are meant to disseminate information of the data collected by the system and to provide updates on initiatives related to specific infectious diseases. Starting in January 2002. the SIMINEWS will be published within the BEN. Periodically tables of standardized rates will be published based on SIMI data. and epidemiologic analyses of infectious diseases deemed to be of particular interest will also appear.

To facilitate epidemiologic comparisons of the data. the summary table contains incidence rates for 14 selected class II diseases for 1999 (the most recent year for which the official Ministry of Health surveillance reports are available) and for 2000. More detailed information for 1999 and 2000 can be obtained at the SIMI web site www.simi.iss.it under “Data Banks”; the 1999 data are also accessible through the Ministry of Health website www.sanita.it/malinf). This report will be limited to those diseases which have not previously been specifically covered in previous SIMINEWS publications.

The rates have been standardized to allow comparison between the regions. which differ in the age distributions of their populations. The direct method was used to calculate standardized rates. with the age distribution of the Italian population from the 1991 census used as the reference population. Case reports for which information was not available for purposes of age standardization were excluded from the analysis.

In 1999. there were a total of 174.845 notifications. of which 1304 (0.74%) were excluded because they did not contain information on age. In 2000. 1093 of the 162.217 notifications (0.67%) were excluded for this same reason. In general. the two years can be considered comparable because of the similarity in number of cases reported. Disease-specific data are shown in Table 1.

Trends and commentary on the most frequently reported diseases:

Gonorrhea and Syphilis: The number of notifications for these two sexually transmitted diseases is extremely low (in 1999. 287 and 321 cases. respectively. were notified to the Ministry of Health from the entire country). and between 1976 and the present. the national incidence have been reduced 10-fold (trend data are also available on the SIMI web site). While a certain reduction may be plausible. the exceptionally low incidence suggests a major under-notification that is on the order of 100%-150%. In this context. the regions with the highest rates are Emilia Romagna. Tuscany. and the autonomous provinces of Bolzano and Trento. but these higher rates most likely reflect a higher sensitivity of the reporting system rather than an increased risk of these diseases. Nonetheless. it appears that there has been an increase in the 2000 rates compared with 1999 rates in some areas of the country.

Brucellosis: Campania. Basilicata and Puglia reported the highest incidence of brucellosis. Of note. the rate in Molise has decreased since 1999. The distribution of brucellosis cases by age suggests that the transmission of this zoonosis is for the most part via consumption of contaminated foods and thus represents an indicator not only of the level of veterinary monitoring but also local differences in risks associated consumption of various foods (available on SIMINEWS. March 2000). Such differences in food-associated risks may also explain regional differences in incidence rates for hepatitis A and typhoid fever. which are elevated in those regions experiencing high rates of brucellosis.

Hepatitis A(HAV) and Typhoid Fever: These two infections share the same modes of transmission. even though HAV may also be transmitted person-to-person and the infective dose is far less than that required for transmission of typhoid fever.  The highest rate of HAV in 2000 was reported in Emilia Romagna. followed by Puglia (which nonetheless experienced a decrease between 1999 and 2000). Campania. and Liguria. both of which experienced increases). The high rate reported in Emilia-Romagna likely reflects the higher sensitivity of the reporting system in the region. The highest rates of typhoid fever were reported in Puglia. Campania. Basilicata. and Lazio.

Scarlet fever: This condition showed considerable inter-regional variability. with a range in rates from 2.6 per 100.000 in Campania to 160.5 per 100.000 observed in Emilia-Romagna. Given the controversial nature of the epidemiology of this condition. which presents certain diagnostic difficulties compared with other rash illnesses. these wide variations require further evaluation.

Additional detail on specific problems. a more in-depth vision of the situation regarding specific infectious diseases. and previous issues of SIMINEWS can be found at the SIMI web site.

Comment:

The SIMI site was developed to disseminate data on the incidence of several reportable diseases that are collected as part of the SIMI surveillance network. This experimental network was designed to electronically transmit data from the district or local health agency level directly to the national level in a timely fashion.

The standardization of the methods and the ease of integrating data collected into regional data systems is ensured by the data collection procedures and by training courses in the participating areas. SIMI permits the sharing of data on the incidence of the diseases in the system within a few months of their collection.

On the site. it is also possible to consult the data bank to obtain tables tailored to individual needs. For example. the number of cases and case rate for a given disease can be examined by age. sex. region. and specified time interval.

Recently. the site has been further enhanced as a result of the addition of data from a variety of other sources. including from ISTAT (the Italian National Statistics Institute). the Ministry of Health. and from other special disease-specific surveillance systems. For certain infectious diseases. the recently added infectious diseases section provides general information about the disease from the infectious disease unit of the ISS and presents graphs of disease trends from 1976 to 1998 and tables reporting the number of cases each year by sex during the same period. In the infectious diseases page. there is also a specific area dedicated to AIDS that. in addition to providing the above-mentioned tables. also has a link to the all of the “Update on Notified AIDS Cases in Italy” publications in Italy from 1995 to 2001.

Yet another recently introduced section is dedicated to vaccinations. It contains information on the trends in notifications of several vaccine-preventable diseases in Italy and the incidence of adverse events. It also contains results of the national childhood vaccine coverage survey (ICONA) conducted in 1998 and a section with vaccine related news on topics such as the use of thimerisol in vaccines.