Birds and Spread of West Nile Virus

Although the primary carriers of the West Nile virus have been known to be mosquitoes, it has been the infected avian population that has brought about its spread in many parts of the globe. 

Since there are a number of bird species that migrate annually to escape the winter season, this process has been seen to have contributed to the spread of the virus to different locations on the globe.

The West Nile virus is mainly found in both tropical and temperate regions. Its transmission has been due to a cycle of mosquitoes infecting birds and the other way around. The cycle begins when infected mosquitoes bite on an unsuspecting bird from which the virus is spread through the blood. The bitten bird then becomes a carrier of the virus.

As the infected bird travels long distances from one location to another, it becomes an important component from which the West Nile virus spreads. As the birds arrive at another location and bitten by another mosquito, the virus is again transferred to the mosquito and becomes a carrier of the virus. The cycle can go on and on among mosquitoes and birds and can greatly increase the incidence of the virus transmission from place to place.

The West Nile virus multiplies faster on infected birds and therefore easily transmits the virus to mosquitoes. Other mammals are considered as dead-end infections when bitten by mosquitoes carrying the West Nile virus since they do not further transmit the virus when bitten by mosquitoes.

Despite being considered as dead-end infections, pet animals such as cats and dogs may still carry the risk of incubating the virus and pass it along to mosquitoes. Human to human transmission of the West Nile virus can be more associated mainly from direct blood contact than by any other means.

The West Nile virus can also be fatal to most bird species. The virus has also been found to be a cause for a number of fatal avian epidemics in recent years. In North America, the virus has affected quite a number of bird species, with the American crow proving to be the most affected of species. Recent tests have shown that the West Nile virus is 100 percent lethal to crows that have led to increasingly higher mortality rates in the crow population.

With the same findings, scientists and experts have found a link between the increased American crow deaths to a progressing spread of the West Nile virus. In this way, scientists and experts have considered the American crow as an initial indication to alert of an impending or possible epidemic of the virus in a certain area.

This incidence can act as an early warning feature that will allow experts to be more prepared to handle and prevent the further development of any West Nile virus epidemic on humans before they ever approach critical levels.

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