Modes of Transmission for West Nile Virus

Extract

The Winter 2003 Clinical Laboratory Science published article on West Nile Virus (WNV): An Emerging Virus in North America, was very informative, organized, and well written. Although the article clearly documents that the transmission of WNV to human occurs most commonly through the bite of an infected mosquito, I would like to comment that there have been a few reported cases whereby other modes of transmission have occurred.

There have been reports of WNV transmission to other patients due to blood product transfusions such as red blood cell, plasma, and platelet transfusion. This poses some complications due to the fact that the majority of individuals infected with WNV will show no symptoms.¹ It has been estimated that only about 1% of those infected with the virus will develop a severe form of the disease such as West Nile (WN) meningitis, WN encephalitis, or meningoencephalitis.² Thus it was recommended that all potential blood donors should be screen for the virus.¹

WNV meningoencephalitis was also diagnosed in a woman after receiving post-partum blood transfusion from a donor infected with WNV. Breast milk sample taken from her also showed WNV specific IgG and IgM antibodies. The newborn that was reported to have little outdoor exposure was also positive for WNV specific IgM antibodies. Additionally, a previously pregnant woman was admitted to the hospital with symptoms common to WNV meningoencephalitis. Serum and cerebral spinal fluid samples taken from her showed evidence of WNV specific IgM antibodies. The infant who was later delivered also showed…