5 Things You Should Know about West Nile Virus

West Nile Virus infects many Amerians every year, sometimes resulting in death. This article highlights the sources of West Nile infection.

Since its introduction to the United States in 1999, West Nile virus has become a serious threat to public health. Despite growing public awareness of its existence, West Nile virus remains mysterious to many of those at risk of infection. Here are five facts about this potentially deadly virus, and what you can do to protect yourself.


1. West Nile virus is primarily transmitted by mosquito bites.


The vast majority of human infections occur when a person is bitten by an infected mosquito. As mosquitoes draw blood into their digestive systems, West Nile virus has open access to the host's bloodstream, through which it can enter a person's body and establish an infection. Mosquitoes carry West Nile virus after biting infected birds, which carry large amounts of virus in their blood and thus transmit infection to mosquitoes at high rates. Because of this, ecological factors such as climate, which influences mosquito breeding, as well as bird migration patterns can directly influence the risk of infection in a given geographical area. 


2. West Nile virus is not typically contagious between humans.


While West Nile virus can infect human hosts, the human immune system is able to limit the amount of virus circulating in blood, instead concentrating the infection to certain organs. This means there is limited capacity for human body fluids to carry and transmit the virus to other people. However, there is always a small risk of human-to-human spread of any blood-borne pathogen. People whose immune systems are weakened by medication, cancer, or HIV infection should take extra precautions if they may be exposed to potentially infectious fluids.


3. West Nile virus can infect the brain.


The brain is typically protected from infection by the presence of the blood-brain barrier, a special collection of cells that prevent pathogens in the blood from accessing brain tissue. However, West Nile virus is one of the few viruses that are somehow able to bypass or break through the barrier. Because of their high susceptibility to the virus, infected brain cells become prone to serious neurological injury and inflammation, often resulting in death. 



4. West Nile virus only causes serious disease in a small number of people.


Fortunately, most people who are infected with West Nile virus do not end up with brain infections. While the biological reasons for this are unclear, many people with West Nile infections never develop any noticeable symptoms, while others develop a serious but limited flu-like illness that they eventually recover from. In fact, West Nile virus infects the brain in less than 1 percent of cases involving otherwise healthy people, though rates are higher in the elderly, children, and persons with compromised immune systems. 


5. Prevention is critical.


There are no FDA-approved vaccines for West Nile virus, and no specific treatments beyond symptom management for those who develop serious illness and can use test for the specific protein. Therefore, limiting exposure to mosquitoes is currently the most effective way to avoid becoming infected. During warmer months, care should be taken to wear insect repellent and protective clothing if work or recreation require extended amounts of time outdoors. Many communities may also attempt to limit mosquito populations with the use of insecticides and habitat destruction, including draining stagnant ponds where mosquito eggs can be found. 


While West Nile virus can cause serious health issues, most people can limit their risk by avoiding mosquito bites and maintaining proper immune function. A balanced diet, regular exercise, and sufficient sleep are recommended to strengthen the body's immune system and protect against viral infections before they occur.

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