West Nile Virus

Overview

West Nile virus (WNV) is the predominant cause of mosquito-borne illness in the United States. Transmitted primarily through the bite of an infected mosquito, West Nile cases tend to rise during mosquito season, which spans from summer through fall. Currently, there are no vaccines or specific treatments available for curing West Nile in people.

Most people infected with the virus don’t experience symptoms. About 1 in 5 will develop a fever and other mild symptoms, while around 1 in 150 may experience a severe, sometimes life-threatening illness. To reduce the risk of West Nile, focus on preventing mosquito bites.

What is West Nile Virus?

West Nile virus is transmitted through mosquito bites. While most infected people do not experience any symptoms, around 1 in 5 will develop flu-like symptoms, such as fever, headache, and body aches. In rare cases, the virus affects the nervous system, leading to serious inflammation of the brain or spinal cord (encephalitis or meningitis). Named after the West Nile district in Uganda where it was first discovered, the West Nile virus continues to be a health concern due to its potential severity.

West Nile Virus Symptoms

Most people infected with West Nile virus do not experience any symptoms and may never know they were infected. However, about 1 in 5 people develop a mild, flu-like illness known as West Nile fever, with symptoms that can include headache, body aches, fever, swollen lymph glands, and skin rash on the torso.

In rare cases, particularly in older adults or those with weakened immune systems, the virus can cross the blood-brain barrier, leading to severe complications involving the nervous system. This severe form of West Nile virus may cause high fever, intense headache, stiff neck, disorientation, extreme lethargy, stupor, or unresponsiveness, seizures, muscle weakness, coma, paralysis, and tremors.

Since many of these West Nile virus signs and symptoms can also be associated with other health conditions, it is important to seek medical attention for proper diagnosis and treatment.

West Nile Virus Causes

West Nile virus is transmitted to humans primarily through the bite of an infected female mosquito. These mosquitoes acquire the virus by feeding on infected birds, with crows and jays being the most frequently associated species. However, there are over 110 other bird species that are also carriers of the virus.

It is important to note that the West Nile virus does not spread from person to person in typical circumstances. There have been a few rare instances of transmission through organ transplants, although the exact risk associated with receiving an organ from an infected donor remains unclear, as not all organ donors undergo testing for the virus.

On the other hand, blood donations are routinely screened for West Nile virus, and the likelihood of contracting the virus through a blood transfusion is significantly lower than the risks associated with needing a transfusion in the first place.

West Nile Virus Diagnosis and Tests

If an individual thinks they or their family members might have West Nile virus, it is important to reach out to a healthcare provider. Diagnosis generally includes assessment of symptoms, reviewing any recent exposure to mosquitoes that could carry the West Nile virus, and laboratory testing of blood or spinal fluid. The healthcare provider can order tests to confirm the West Nile virus or identify other possible infections with similar symptoms, helping ensure the correct diagnosis and treatment are received.

Treatment and Vaccine Required for West Nile Virus

There are no antiviral medications available to treat West Nile virus. It is possible to manage mild symptoms at home with over-the-counter (OTC) medications, similar to those for a cold or flu. In cases of serious neurological symptoms, healthcare providers will monitor the condition in a hospital setting.

Treatments for this disease may include supplemental oxygen or mechanical ventilation to assist with breathing, antiseizure medications for seizure management, tube feeding for individuals unable to eat independently, corticosteroids to reduce inflammation, and intravenous (IV) fluids to maintain hydration.

Preventive Measures for West Nile Virus

Currently, there is no vaccine to prevent West Nile virus, so reducing the risk relies on protection from mosquito bites. Here are effective ways to minimise exposure:

Avoid Peak Mosquito Hours: Mosquitoes are most active at dawn and dusk. Try to stay indoors during these times when possible.

Use Insect Repellent: Apply EPA-registered insect repellent to exposed skin and clothing before going outside. Look for products proven to be effective against mosquitoes.

Wear Protective Clothing: When outdoors, wear lightweight, long-sleeved shirts and long pants to cover as much skin as possible.

Eliminate Standing Water: Regularly empty or clean any items that may collect water, like birdbaths, flowerpots, or clogged gutters, as these are prime mosquito breeding areas.

Keep Mosquitoes Out: Use screens on doors and windows or keep them closed to prevent mosquitoes from entering.

Take Precautions When Outdoors Overnight: If sleeping outdoors, keep windows closed if possible, or use a mosquito net for added protection.

Myths and Facts Related to West Nile Virus

Here is a list of the most popular myths and facts related to West Nile virus:

Myth 1: There is Nothing I Can Do to Prevent West Nile Virus
Fact: Individuals can take several proactive steps to reduce their risk of West Nile virus infection. Regularly apply mosquito repellent containing DEET when spending time outdoors, especially during peak mosquito activity hours from dusk to dawn.
Additionally, minimising mosquito breeding sites around the home by eliminating standing water where mosquitoes can lay eggs can help. Also, one can inspect the yard weekly for containers that collect water, change water in bird baths frequently, and ensure gutters are clean and free-flowing.

Myth 2: Children are the Most At Risk for Severe Illness from West Nile Virus
Fact: While children should certainly take precautions against mosquito bites, individuals over the age of 60 are at the highest risk for developing severe complications from West Nile virus. Most reported cases of severe illness and fatalities occur in older adults, highlighting the importance of protective measures for this age group as well.

Myth 3: Only Individuals With Pre-Existing Health Conditions Need to Worry About West Nile Virus
Fact: Healthy, active older adults who spend time outdoors are also at risk for severe illness from West Nile virus. Age is a significant risk factor and being over 60 increases the likelihood of developing severe disease if infected. When engaging in outdoor activities it is crucial to use mosquito repellent and take other preventive measures.
By understanding these myths and facts, individuals can better protect themselves and their families from the risks associated with the West Nile virus. Taking personal responsibility through preventive actions is essential for reducing exposure and potential infection.

Myth 4: Repellents Containing DEET are Not Safe
Fact: DEET must be used with caution, specifically for children, as they may experience irritation or other reactions from prolonged skin exposure or accidental ingestion. When people use DEET products with moderate concentrations according to the manufacturer’s instructions, they generally consider them safe. Always follow recommended guidelines to minimise any risks and ensure effective protection against mosquitoes.

Myth 5: As Long as There is a Mosquito Control Program in the Area, There is No Need to be Concerned About Applying Repellent
Fact: Although mosquito control activities can significantly reduce the mosquito population, they do not eliminate every mosquito in an area. This means that relying solely on these measures may not provide complete protection from mosquito bites. Therefore, personal protection strategies remain crucial.