Objective: To confirm the occurrence of an outbreak of viral meningitis in 1996 in the province of Tucuman, Argentina, and to study the outbreak's epidemiological characteristics.
Methods: We analyzed information from the National Epidemiological Surveillance System of the Ministry of Health (MOH) of Argentina for 1994-1998 that had been provided by the MOH's Bureau of Epidemiology. We calculated incidence rates using population estimates for the years 1994-1998 developed by the National Statistics and Census Institute, based on the 1991 census. We studied frequencies with contingency tables, using the chi-square method with Yates' correction. Results were considered significant when P < 0.05.
Results: We confirmed the occurrence of an outbreak of 189 cases of viral meningitis between 11 February and 18 May 1996. The incidence of cases in Tucuman province increased between 1995 and 1996, from 0.5 to 19.3 cases per 100 000 person-years. That 1996 rate in Tucuman was significantly higher than what was seen in the rest of the country (2.8 cases per 100 000 person-years). Of the 189 cases, 142 of them (75.1%) occurred in children less than 9 years old. Out of 111 samples studied, 65 of them (58.6%) were enterovirus-positive. Through reverse transcription-nested polymerase chain reaction, enteroviruses were found in 66.3% (53/80) of the cases studied by this method, versus in only 29.6% (24/81) of the cases studied through viral isolation. In the 22 samples that were serotyped, echovirus type 4 was identified in 15 of them (68%): 5 by isolation, 3 by sequencing, and 7 by both methods. During the Tucuman outbreak, at least 56% of the cases were hospitalized. This viral meningitis outbreak shows the capacity of enteroviruses to spread and cause disease.
Conclusions: The use of molecular methods makes it possible to rapidly diagnose the etiological virus and to better control an outbreak. Recognizing this outbreak in Tucuman sooner could have averted the majority of the hospitalizations and the indiscriminate use of antibiotics.