West Nile virus (WNV) is a mosquito-borne disease that can cause fever, headache, body aches, joint pain, rash, and sometimes more severe symptoms such as meningitis or encephalitis. Most people who are infected with West Nile virus do not feel sick, but about 1 in 5 develop mild symptoms and about 1 in 150 develop serious illness. There is no vaccine or specific treatment for West Nile virus infection, so prevention is the best way to avoid getting sick.
 |
| West Nile Virus(Illustration) |
How is West Nile virus transmitted?
West Nile virus is mainly spread by the bite of an infected mosquito. Mosquitoes become infected when they feed on birds that carry the virus. The virus then multiplies in the mosquito's body and can be passed on to other animals or humans through its saliva.
West Nile virus is not transmitted from person to person or from animal to person, except in very rare cases of blood transfusion, organ transplant, breastfeeding, or pregnancy.
Where and when does West Nile virus occur?
West Nile virus is found in many parts of the world, including Africa, Asia, Europe, the Middle East, and North America. In the United States, West Nile virus was first detected in New York City in 1999 and has since spread to all 48 contiguous states and the District of Columbia.
West Nile virus activity varies from year to year and depends on many factors such as weather, mosquito population, bird migration, and human behavior. Generally, West Nile virus activity peaks in late summer and early fall, when mosquitoes are most abundant and active. However, West Nile virus can be transmitted any time mosquitoes are biting, which can be as early as spring or as late as winter in some areas.
What are the symptoms of West Nile virus infection?
Most people (about 80%) who are infected with West Nile virus do not develop any symptoms and may not even know they have been exposed.
Some people (about 20%) develop mild symptoms that usually last for a few days to a few weeks. These symptoms may include:
- Fever
- Headache
- Body aches
- Joint pain
- Nausea
- Vomiting
- Diarrhea
- Rash
- Fatigue
- Loss of appetite
These symptoms are similar to those of other viral infections and may not be recognised as West Nile virus infection. However, if you have been bitten by mosquitoes and develop these symptoms, you should see your doctor and mention your possible exposure to West Nile virus.
A small number of people (less than 1%) develop severe symptoms that affect the central nervous system, such as:
- High fever
- Stiff neck
- Confusion
- Disorientation
- Seizures
- Coma
- Paralysis
- Tremors
- Muscle weakness
These symptoms may indicate a serious condition such as meningitis (inflammation of the membranes around the brain and spinal cord) or encephalitis (inflammation of the brain). These conditions can be life-threatening and require immediate medical attention.
Severe symptoms usually appear between 2 and 14 days after being bitten by an infected mosquito, but can occur as late as 21 days after exposure.
People who are at higher risk of developing severe symptoms include:
- People over 60 years old
- People with weakened immune systems due to certain medical conditions or treatments
- People with certain chronic diseases such as diabetes, hypertension, kidney disease, or cancer
However, anyone can get sick from West Nile virus infection, so everyone should take steps to prevent mosquito bites and reduce their risk of exposure.
How is West Nile virus diagnosed and treated?
 |
| Diagnosing West Nile Virus(Illustration) |
West Nile virus infection is diagnosed by testing blood or cerebrospinal fluid (CSF) for the presence of antibodies or genetic material of the virus. These tests are usually done at specialised laboratories and may take several days to get the results.
There is no specific treatment for West Nile virus infection. Most people with mild symptoms recover on their own without any complications. They can take over-the-counter pain relievers, anti-inflammatory drugs, or antihistamines to relieve their symptoms and drink plenty of fluids to prevent dehydration.
People with severe symptoms may need to be hospitalised and receive supportive care such as intravenous fluids, oxygen therapy, respiratory support, or medications to control seizures or inflammation. In some cases, they may need rehabilitation to recover from neurological damage caused by the infection.
The mortality rate for people who develop severe symptoms is about 10%, but it can be higher for certain groups such as the elderly or those with underlying medical conditions.
How can West Nile virus infection be prevented?
The best way to prevent West Nile virus infection is to avoid mosquito bites and reduce mosquito breeding sites. Here are some tips to protect yourself and your family from West Nile virus:
- Use insect repellent that contains DEET, picaridin, IR3535, oil of lemon eucalyptus, or para-menthane-diol when you go outdoors, especially during dawn and dusk when mosquitoes are most active. Follow the product label instructions and reapply as needed. Do not use repellent on babies under 2 months old or oil of lemon eucalyptus on children under 3 years old.
- Wear long-sleeved shirts, long pants, socks, and shoes when you are outdoors. You can also treat your clothing and gear with permethrin, a type of insecticide that kills or repels mosquitoes. Do not apply permethrin directly to your skin.
- Install or repair screens on windows and doors to keep mosquitoes out of your home. Use air conditioning if you have it.
- Empty or cover any containers that can hold water, such as buckets, barrels, flower pots, bird baths, pet bowls, tires, or toys. Mosquitoes lay their eggs in stagnant water and can breed in very small amounts of water. Change the water in birdbaths and pet bowls at least once a week.
- Clean and chlorinate swimming pools, hot tubs, and fountains regularly. If they are not in use, drain them or cover them tightly.
- Report any dead birds or animals to your local health department or animal control agency. They may be tested for West Nile virus and help monitor the spread of the virus in your area. Do not touch or handle dead birds or animals with bare hands.
By following these simple steps, you can reduce your risk of getting West Nile virus infection and enjoy the summer without worrying about mosquitoes.
For more information about West Nile virus, visit the Centers for Disease Control and Prevention website or the World Health Organisation website.
