West Nile Virus: Epidemiology, Clinical Presentation, Diagnosis, and Prevention

Abstract

West Nile virus was recognized in the United States for the first time in 1999, when it caused an epidemic of encephalitis and meningitis in New York City, NY. Since then, the disease has been steadily moving westward, and human cases were recognized in 39 states and the District of Columbia in 2002. The infection is caused by a flavivirus that is transmitted from birds to humans through the bite of culicine mosquitoes. Most infections are mild, with symptoms primarily being fever, headache, and myalgias. People older than 50 years are at highest risk of severe disease, which may include encephalomyelitis. In 2002, 5 new modes of transmission were recognized: blood product transfusion, organ transplantation, breast-feeding, transplacental transmission, and occupational exposure in laboratory workers. The transmission season was long, with cases occurring into December in some parts of the United States. Currently, there is no specific drug treatment or vaccine against the infection, and avoiding mosquito bites is the best way to protect against the disease.

Transmission of Tropical and Geographically Restricted Infections during Solid-Organ Transplantation

“…WNV was first detected in the Western Hemisphere in 1999 during an epizootic outbreak among birds and horses and a meningitis and encephalitis epidemic in humans in the New York City area (70,292,323). Over the next 5 years, the virus spread across states of the continental United States, north into Canada, and southward into the Caribbean Islands and Latin America (212).…”

Transmission of donor illness by stem cell transplantation: should screening be different in older donors?

“…Blood product transfusion, transmission through solid organ transplantation and transplacental transmission have been recognized as modes of transmission. 47,18,19 No reports are available with regard to transmission through stem cell transplantation.…”

Investigation of West Nile Virus in Cerebrospinal Fluid and Blood Samples of Patients with Initial Diagnosis of Central Nervous System Infection and Comparison of Results

“…Batı Nil virüsü insanlarda, subklinik enfeksiyondan ölüme kadar uzanan farklı klinik tablolara sebep olmaktadır (1) . İnsanda görülen BNV enfeksiyonlarının büyük bir kısmı (%80) asemptomatik seyreder.…”

“…BNV, enfekte insanların 1/5'inde (%20) Batı Nil Ateşi denilen; genellikle 3-6 gün süren ani ateş yükselmesi, baş ağrısı, sırt ağrısı, miyalji, hâlsizlik, anoreksi, bulantı, kusma gibi semptomlarla karakterize, sıklıkla yaygın lefadenopatinin eşlik ettiği kendini sınırlayan grip benzeri klinik tablo oluşturur (2) . Nörolojik tutulumun olmadığı BNV ile enfekte olguların tamamı iyileşirken, SSS hastalığı olanlarda uzun süren morbidite ve %10'u aşan mortalite görülmüştür (1) .…”

“…Ancak tek başına menenjit veya ensefalit olguları da bildirilmiştir (1) . Ciddi SSS enfeksiyonu olgularında yüksek ateş, baş ağrısı, kas zayıflığı, ense sertliği, uyuşukluk, konfüzyon, koma, kas titremeleri, konvülziyonlar görülür ve nihayetinde akut flask paralizi oluşur (7,8) .…”