Measles surveillance in France—a disease subject to mandatory reporting from 1945 to 1985—has been conducted since 1985 by the Sentinelles network, established by Inserm U444, based on weekly reports of clinical measles cases seen in private practice by volunteer physicians. The national incidence extrapolated from the data fell from nearly 300,000 cases per year in 1985 to fewer than 5,200 cases in 2002 (95% CI: 1,300–9,000). At the same time, an increase in the age of cases was observed, with the proportion of patients over 10 years of age rising from 13% in 1985 to 48% in 1997. Measles vaccination coverage in 2001 was 84% at 24 months, with disparities by department and lower rates in the southern half of France. In the Provence-Alpes-Côte d'Azur (PACA) region, vaccination coverage by department was 84% in the Alpes-Maritimes, 82% in the Bouches-du-Rhône and the Var, 76% in the Vaucluse, and 59% in the Alpes-de-Haute-Provence. Data are not available for the Hautes-Alpes. Current epidemiological conditions therefore remain conducive to the occurrence of outbreaks, with the main at-risk populations being unvaccinated children aged one to thirteen, adolescents, and infants under one year of age. However, France, like other European countries, has committed, in accordance with the objectives of the World Health Organization (WHO), to a policy of measles elimination to be achieved by 2010. This report presents the results of the investigation into measles cases that occurred in the PACA region, which aimed to document the intensity of viral circulation in this region and to study the feasibility of a prospective surveillance system, in order to guide the implementation of control measures, particularly vaccination efforts. The investigation of measles cases took place in several phases: - a response to the alert from La Timone Hospital in Marseille, including individual interviews of reported cases (initiated on May 20); - an active search for additional cases in Marseille and surrounding cities involving various healthcare providers and institutions (hospitals, clinics, the General Council, SCHS, SOS Médecins, Médecins du Monde, school health services . . .—initiated on May 29); - a retrospective search for serologically confirmed measles cases in the PACA region since January 2003, involving the main laboratories in France performing anti-measles IgM testing (initiated on June 2); - a survey of general practitioners in the main towns of three departments (Marseille, Avignon, and Digne-Les-Bains) where the virus was actively circulating (initiated on June 19); - a retrospective survey of general practitioners, pediatricians, and homeopaths in an area between Manosque and Digne, where, following telephone interviews with laboratory technicians, numerous cases of measles had been reported (initiated on June 27). The cases investigated were patients identified by hospital laboratories, clinical laboratories, and physicians, who provided the requested information. These cases met the following definitions: Biologically confirmed case: a case in which serological detection of specific anti-measles IgM antibodies was positive. Epidemiologically confirmed case: a clinical case in a person who had contact with a biologically confirmed case within 7 to 18 days before the onset of symptoms. Clinical case: a case for which a diagnosis was made by the attending physician. The following variables were collected: case identification, department of residence or arrondissement for Marseille, date of the first serological test for biologically confirmed cases or date of clinical diagnosis for clinical cases, hospitalization, occurrence of complications, vaccination status, and reason for non-vaccination. The various phases of the investigation identified 259 cases, of which 138 could be documented: 74 were biologically confirmed, 2 epidemiologically confirmed, and 62 clinically confirmed. The Sentinelles network detected no cases in the region during the six-month period. Thus, the case detection rate for the PACA region was 3.1 cases per 100,000 inhabitants. The most affected department was Alpes-de-Haute-Provence with a rate of 39.4 cases per 100,000 inhabitants, followed by Vaucluse and Bouches-du-Rhône, with 6.4 cases and 2.5 cases per 100,000 inhabitants, respectively. Characteristics of documented cases: Description by time, place, and person: the first cases were recorded starting in the first week of January, and the last reported case occurred in July, with a peak in April. Three departments accounted for 96% of the identified measles cases: Alpes-de-Haute-Provence (40%), Bouches-du-Rhône (33%), and Vaucluse (23%). The male-to-female ratio was 1.1. The average age was 15 years [ranging from 11 months to 57 years] across the entire region, and 11 years in Alpes-de-Haute-Provence, 20 years in Bouches-du-Rhône, and 14 years in Vaucluse. Vaccination status: it was known for 69 cases (50%), of which 60 had not been vaccinated, 8 had received only one dose (between 1 and 15 years of age), and one clinical case, aged 17, who was reported to have received 2 doses. The main reasons cited for non-vaccination were parental refusal and the use of homeopathy. Clinical characteristics: 18% of documented cases were hospitalized. The reasons for hospitalization were related to diagnostic difficulties, particularly with differential diagnoses of severe toxic dermatitis and primary HIV infection, in cases presenting severe clinical presentations such as skin lesions affecting more than 90% of the body surface area (3 cases) and severe deterioration of general health (2 cases). Few serious complications and no fatal complications were reported; the most frequently encountered were pneumonia (2 cases), neurological signs (without encephalitis) (2 cases), mild gastrointestinal disturbances (9 cases), and otitis (1 case). These patients were unvaccinated or had unknown vaccination status. It should be noted that one of the measles cases was a woman who was three months pregnant; the outcome of the pregnancy was not reported. Microbiological description: of the 74 biologically confirmed cases, four samples (3 urine, 1 throat swab) were sent to the CNR for genotyping. Two samples were positive. The results of strain typing identified genotype D7. The feasibility of establishing a prospective surveillance system for measles cases involving all clinicians in the PACA region showed that among the GPs surveyed, 53% (or 89% of respondents) are willing to report any suspected case of measles using a reporting form. Once the form was duly completed by them, it could be sent or transmitted by fax for 71% of GPs, by telephone for 19% of GPs, and by mail for 3% of GPs. It should be noted that 45 of the GPs surveyed (75% of respondents) agreed to perform a saliva sample collection. This part of the survey also made it possible to assess GPs’ communication practices. Information on the means of communication used by GPs was collected: 64% of GPs have an internet connection, but not all of them use their email regularly. Email is used by 35% and fax by 75% of the GPs who responded to the survey. The measles epidemic that ravaged the PACA region during the first half of 2003 was likely characterized by local outbreaks and thus by spatial heterogeneity across the region’s various departments. The occurrence of clusters of measles cases was facilitated by low vaccination coverage in pockets of non-immune populations. Indeed, this low coverage, especially in the Alpes-de-Haute-Provence, allowed the virus to continue circulating, resulting in insufficient control of the disease among the pediatric population. In other departments where vaccination coverage is higher but still insufficient, a shift in cases from childhood to adolescence and adulthood was observed. The average age of cases observed in the investigation was 11 years in the Alpes-de-Haute-Provence, 14 years in the Vaucluse, and 20 years in the Bouches-du-Rhône, which is consistent with what is typically described. The decline in the number of cases, which began in May and June, can be explained, on the one hand, by the seasonal nature of measles in France, where the disease is more common during the first half of the year, and on the other hand by the closure of schools for summer vacation, preceded by teachers’ strikes that may have contributed to interrupting virus transmission in the region. These various investigations highlight the limitations of the current measles surveillance system in France. Indeed, starting with the five measles cases identified in Marseille, a total of 259 cases were ultimately recorded through the investigation. Without the alert issued by the Timone University Hospital, these cases—though underestimated—would likely have gone unnoticed. Early case detection requires the implementation of an enhanced surveillance system in France: currently, the Sentinelles network does not meet this objective, and case reporting by laboratories remains limited to serologically confirmed cases only. The implementation of a system comprising mandatory reporting for measles and a mechanism to perform biological confirmation tests for clinical cases—widely used by other countries in the WHO European Region—now appears appropriate, even if it requires significant investment in raising awareness among physicians to limit underreporting of cases. The primary means of communication used by general practitioners remain the landline (with or without an answering machine) and/or the cell phone. However, in our investigation, 40% could not be reached despite these efforts. Email, a fast and economical method, is used by only 35% of the GPs who responded to the survey, and fax by 71%. According to an Ipsos report, contacting a large number of general practitioners, whether for a survey or an alert, is complicated. A broader review of the methods for contacting healthcare professionals in the context of an alert or survey should be undertaken, and discussions should be initiated with certain institutions (medical associations, unions, etc.) that possess comprehensive directories of these professionals’ addresses, either to enable file sharing or so that these institutions can disseminate alert messages through their networks. In conclusion, measles remains a current concern, and vaccination efforts must be strengthened if we are to prevent these outbreaks and aim to eliminate the disease by 2010. This goal can only be achieved with the participation of policymakers, healthcare professionals, and the general public. (R.A.)