Because the virus utilizes the circulatory system as a means of dissemination to the target organ such as the central nervous system, exposure to blood from other sources could lead to infection. It has been reported that in some cases infection can lead to hematospermia (blood in the ejaculate) and this has resulted in transfer of the virus to the sexual partner. In fact the virus may be secreted in other fluids such as saliva and urine even without blood as has been shown with West Nile Virus present in urine.
The natural hosts of this virus remain to identified. Natural hosts usually show no signs of disease and are important in maintaining the transmission cycle in the wild. Whether certain birds or small mammals are important in this natural cycle remain to be seen.