ArticlesWest Nile encephalitis epidemic in southeastern Romania
Introduction
Mosquito-borne West Nile fever (WNF) is an endemic febrile illness in Africa, the Middle East, and southwestern Asia. The flavivirus has also been isolated in Australia and sporadically in Europe but fewer cases in human beings have been recognised. Clinical features are acute fever with severe myalgia, arthralgia, and headache, conjunctivitis, prominent lymphadenopathy, and a roseolar rash, complicated, occasionally, by meningitis or encephalitis.1, 2, 3, 4, 5 Outbreaks with hundreds of cases were reported from Israel in 1950–57. In 1974, an epidemic in a 2500 km2 area of central South Africa produced tens of thousands of infections.6, 7 Except for a small outbreak in southern France in 1962, WNF has not been a public-health threat in Europe.8 Between July and October, 1996, an epidemic of WNF with mainly neurological infections occurred in Bucharest and the lower Danube valley of southeastern Europe. We described after a field investigation from Sept 28 to Oct 11, 1996, the epidemic, its transmission patterns, and its likely source.
Section snippets
Methods
Romania is divided by the Carpathian range into a region of mountains and high plains to the northwest and a large plain to the south, with the Danube river forming most of the southern border with Bulgaria. Bucharest, the capital city, consists of six administrative sectors and is surrounded by the Ilfov District (figure 1). The national and Bucharest municipal populations were about 23 million and 2·3 million, respectively, in 1996.
In mid-August, 1996, unusually high numbers of acute
Results
Of 835 patients admitted to hospital with suspected central-nervous-system infection and reported under the surveillance system, 767 (92%) met the definition of WNF cases. Appropriate blood, cerebrospinal fluid, and necropsy samples were available from 441 patients, among whom WN encephalitis was serologically confirmed in 352 (80%). In addition, among 68 patients who did not meet the case definition, 41 (60%) had laboratory-confirmed or probable infection. A total of 393 patients had
Discussion
Although WNF is recognised in Africa, Asia, and Europe, encephalitis cases have been reported previously only from Israel, India, and Pakistan.1, 2, 3, 4, 5, 6, 7, 11, 12 Transmission of WN virus in at least 11 European countries (France, Cyprus, former Czechoslovakia, Greece, Italy, Portugal, Romania, Spain, Turkey, former Yugoslavia, and Russia) has been surmised from animal and human serosurveys and by the occasional isolation of the virus from human, horse, wild bird, mosquito (Aedes
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