What is the West Nile virus?
WNV is classified as a member of the genus Flavivirus in the Flaviviridae family, which contains more than 70 viruses, with approximately 40 of them being human pathogens (e.g. Dengue fever viruses, tick-borne encephalitis virus, Japanese encephalitis virus, Yellow fever virus, etc.)
Where did it appear for the first time?
The virus was isolated -for the first time- from a febrile woman in 1937 in West Nile province in Uganda,.
How is it transmitted?
Transmission occurs mainly through infected mosquito bite. Less common ways of transmission are: solid organ transmplantation from an infected donor, blood transfusion, from a mother to her fetus, through breast feeding, through infected animals handling. It is not transmitted from human to human. It is not transmitted through social contant, cough droplets or sexual contact.
Which is the role of birds, equines and humans in the transmission cycle?
Birds are the reservoirs of the virus.
Humans and equines are dead-end hosts of the virus.
Which are the clinical manifestations of the disease in humans?
The disease runs usually subclinically without any symptom, but in a few cases it may cause Central Nervous System symptoms/signs (encephalitis/meningitis).
Is there an effective primary preventive method?
No. There is not a vaccine for the protection of humans against the virus.