Understanding West Nile Virus

The West Nile virus belongs to the Flaviviridae family of viruses. This virus, which is also a part of the Japanese encephalitis antigenic complex of viruses, can be found in both temperate and tropical areas of the globe.

The virus is said to primarily to infect birds but is also transmitted to other animals such as horses, cats, dogs, rodents, rabbits as well as humans.

The West Nile virus is said to originate from various remote areas such as Africa, West Asia, Eastern Europe and the Middle East. The virus was discovered to have been documented to reach North American shores in 1999.

Prior to that, no documentation of the West Nile virus has been found anywhere in the Western Hemisphere. Experts believe that the virus found in the US and Canada might have come from virus strains that originated in the Middle East.

The main carriers of the West Nile virus are wild birds. But it is certain species of mosquitoes that actually spread it to other animals as well as humans. The virus is transferred when a mosquito bites a bird infected with the West Nile virus.

The virus then enters into the mosquito’s bloodstream and circulates until the virus settles on the salivary glands of the mosquito. When the mosquito bites another animal or human, the virus is transmitted into the host’s bloodstream where it may cause illness.

And when the West Nile virus enters the host’s bloodstream, it multiplies and moves towards the brain through the blood. The virus then tries to cross the brain and blood barrier where it begins to infect the brain tissues or its linings. It is then that the tissues become inflamed and the symptoms come up.

And because mosquitoes are more active during warm weather, the West Nile virus transmission is usually higher during the summer. The time it takes for the symptoms to show up after being bitten by an infected mosquito may take from two to 14 days.

But not all humans or even animals react similarly to the West Nile virus. There are other people who might be bitten but would not necessarily display the symptoms that come with the West Nile virus infection.

Aside from mosquitoes, there are other cases where the virus may be spread from human to human. Blood transfusions of infected blood may also be a means of transmission of the infection. Organ transplants may also be a possible source of transmission.

Breastfeeding can transmit the virus from mother to baby as well as during the stages of pregnancy. But this is considered only in rare cases as the chances of such transmission are still being evaluated.