Tuesday, September 4, 2012

West Nile Virus


Laura Uselding, MD
From the desk of Dr. Uselding:

As we think about the end of summer, we often conjure up images of squeezing in the last summer vacation, barbeques, shorter days, and getting ready for everyone’s favorite time, back to school. This year, however, anyone watching or reading the news should also be thinking about the threat of West Nile Virus. In general, West Nile Virus is a mosquito borne virus that is transmitted through the bite of an infected mosquito. Mosquitoes carry this virus after they bite an infected bird. Once infected, humans cannot spread this virus through person-to-person contact; however, there have been a very small number of cases reported where an infected mother passed the virus to her unborn baby or to a nursing child through breast milk. The incubation period for West Nile Virus ranges from 2-14 days.

The CDC noted that this year, the West Nile Virus is showing earlier and greater activity in the United States than in years past and it is projected that 2012 will have the largest number of West Nile Cases thus far. The majority of the cases are reported in Texas (over 35%), followed by South Dakota, Mississippi, Oklahoma, Louisiana, and Michigan. Just this past week, the CDC reported a steep rise in the number of West Nile Virus cases, and since early to mid-August, the CDC reported an increase of over 40%. Locally, as of August 28, 2012, there were 2,740 cases of mosquitoes infected with West Nile Virus reported in Illinois. The top three counties with infected mosquitoes included Cook (1,953 cases), DuPage (376 cases), and Will (77cases) counties.

Clinical Symptoms

Most people (80%) infected with the virus have no clinical signs or symptoms.

Some people (20%) will experience mild symptoms called West Nile Fever. These symptoms include:

 fever

 headache

 body aches

 fatigue

 red rash on the trunk of the body

 swollen lymph nodes

Less than 1% of those infected will develop severe symptoms, which include:

 severe headache

 high fever

 neck stiffness

 disorientation

 confusion

 seizures

 coma

 muscle weakness

 paralysis

Individuals older than 50 years of age and immune-compromised people are at highest risk for severe disease.

Treatment

The West Nile Virus causes a viral infection and there is no specific treatment. In patients who have milder symptoms, care is mostly supportive, and we recommend rest, fluids, ibuprofen, and acetaminophen. In more severe cases, we hospitalize patients and support them with IV fluids, breathing assistance, pain control, and nursing care.

Ways to Protect Your Family


Despite the fact that everyone is at risk for mosquito bites, which means all of us run the risk of West Nile Virus exposure, there are several things you can do to help minimize your exposure to mosquitoes

1. Minimize your time outdoors during dusk and dawn when mosquitoes are most active.

2. Protect yourself if you have to go outside during these peak times by wearing long pants, long sleeve shirts, socks, and shoes. You can help protect infants by using mosquito netting on strollers and infant carriers.

3. Utilize a mosquito repellent. We recommend a mosquito repellent with 7-10% DEET for children over 1 year of age. It is important to follow directions on the bottle, and to shower after use.  This should only be applied once per day. 

4. Install tight fitting screens in your home and check for repairs. Try to keep doors and windows shut especially at night.

5. Reduce or eliminate standing water around your home. You should always keep children’s wading pools empty and on their sides when they are not being used. Remove water from empty flowerpots and buckets, change water in bird baths every 3-4 days, and keep gutters clear of debris as any container holding water for more than 4 days can become a breeding ground for mosquitoes.

6. If you have a backyard pond utilize aeration, larvae eating fish, or Bacillus thuringiensis israelensis (bacteria that eat mosquito larvae) to minimize mosquito breeding. These tools are available at garden supply stores.

7. Never touch a dead bird with your hands as birds may carry West Nile Virus. Contact your local health department for instructions on reporting and deposing of the body.

References:

American Academy of Pediatrics. (2012, August 27). Possible largest United States West Nile Virus outbreak. Retrieved from http://aapredbook.aappublications.org/site/news/

Centers for Disease Control and Prevention. US Department of Health and Human Services, Centers for Disease Control and Prevention. (2005). CDC West Nile Virus fact sheet. Retrieved from website: http://cdc.gov

http://www.healio.com/infectious-disease/emerging-diseases/news/online/%7B7A770FDA-F669-4535-877B-DF8610A0AA11%7D/CDC-reports-40-increase-in-West-Nile-virus-cases-since-last-week

US Geological Survey. US Department of the Interior, US Geological Survey. (2012). West nile virus mosquito 2012. Retrieved from website: http://diseasemaps.usgs.gov/wnv_il_mosquito.html




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