Clinical Characteristics of the West Nile Fever Outbreak, Israel, 2000

Abstract

West Nile (WN) virus is endemic in Israel. The last reported outbreak had occurred in 1981. From August to October 2000, a large-scale epidemic of WN fever occurred in Israel; 417 cases were confirmed, with 326 hospitalizations. The main clinical presentations were encephalitis (57.9%), febrile disease (24.4%), and meningitis (15.9%). Within the study group, 33 (14.1%) hospitalized patients died. Mortality was higher among patients >70 years (29.3%). On multivariate regressional analysis, independent predictors of death were age >70 years (odds ratio [OR] 7.7), change in level of consciousness (OR 9.0), and anemia (OR 2.7). In contrast to prior reports, WN fever appears to be a severe illness with high rate of central nervous system involvement and a particularly grim outcome in the elderly.

Skin Manifestations of West Nile Virus Infection

“…In 19 hospitalized patients in the New York epidemic, Weiss et al [11] found truncal rash in 3 patients (16%) and Asnis et al [5] in 2 out of 8 patients (25%), whereas Nash et al [3] reported a rash in 11 patients out of 59 (19%). In the 2000 West Nile fever outbreak in Israel [12], a macular rash was recorded in 51/233 (22%) of the hospitalized patients, but the study from Romania noted only 5% [13, 14]. When clinical data are available, the rash is described as a nonpruritic, ‘roseola-like’ or maculopapular rash on the chest, back and arms, which lasts 1 week [3, 5, 6].…”

“…Neurological complications include meningitis, encephalitis, meningoencephalitis, myelitis, cranial neuropathies, optic neuritis, ataxia or polyradiculitis [1,2,3,4,5,6]. Overall death rates for patients admitted to hospital during recent outbreaks ranged from 4 to 14% but were higher in older patients [1, 3, 9]. …”

West Nile encephalitis

“…Since the 1990s the clinical epidemiology of West Nile virus seems to have changed, with increasing frequency and severity of outbreaks, including urban disease (table). 2–4 13…”

“…In recent outbreaks about two thirds of patients admitted to hospital had encephalitis (with or without signs of meningeal irritation), while one third had meningitis. 2 3 23 Severe generalised muscle weakness was common feature in the New York outbreak in 1999 and in subsequent outbreaks in the United States 23. In some patients this affects only the limbs, but in others respiratory and bulbar musculature are affected and patients require ventilation.…”

“…West Nile virus also occurs in Africa, parts of Asia, and southern Europe, with recent outbreaks in Romania, Russia, and Israel (fig 1). 2–4 Unpublished evidence is reported to show that birds in the British Isles may also have antibody to the virus 5. The recent outbreaks of West Nile virus have drawn attention to the devastating potential of mosquito-borne neurogenic flaviviruses to spread (see box 1 for details) 6…”