Please report patients with any of the following:

1. Suspected or confirmed WNV neuroinvasive disease:
   Fever (in the absence of a more likely diagnosis) in a patient with at least one of the following:

• Acute change in mental status (e.g., disorientation, obtundation, stupor, or coma), or
• Other acute central or peripheral neurological dysfunction (e.g., paresis or paralysis, nerve palsies, sensory deficits, abnormal reflexes, seizures, or movement disorders), or
• Cerebrospinal fluid (CSF) pleocytosis associated with an illness compatible with meningitis
  
  

2. WNV non-neuroinvasive disease:
   Documented fever (>38.0º C or 100.4º F) (in the absence of a more likely diagnosis) in a patient who has laboratory evidence of WNV disease:

• WNV-specific IgM antibodies in serum or CSF measured by any serologic testing method, or
• Isolation of WNV from, or detection of viral nucleic acid in, blood or CSF
  
  

3. Acute flaccid paralysis or presumed Guillain-Barré syndrome even in the absence of fever and other neurologic symptoms.
   
   
4. Suspected West Nile virus infection in patients with potential recent blood donation or transfusion histories, organ transplant recipients, laboratory or occupational exposures, pregnant women, and transplacental or breast-feeding associated exposures.

   When taking a history from a suspected WNV patient, determine if the patient received blood transfusions or organs within the 4 weeks preceding symptom onset (if so, serum or tissue samples should be retained for testing). In addition, please ask about and report any history of blood or organ donation within 2 weeks of symptom onset for persons with suspected WNV infection. Prompt reporting of these cases will facilitate follow-up including withdrawal of potentially infected blood components.

5. Asymptomatic WNV disease with laboratory evidence of WNV infection in: even in the absence of fever and other neurologic symptoms.

• A pregnant woman
• A neonate or breastfeeding infant of a WNV infected mother
• Someone who donated or received blood products in the previous month
• Someone who donated or received a tissue or organ transplant in the previous month
• Someone who has had occupational exposure to WNV (in a laboratory or through contact with infected animals)

Suspected or confirmed cases of WNV should be reported to Public Health Seattle-King County within three business days, by calling 206-296-4774.

Prevention

Counsel patients to use insect repellents containing DEET, picaridin, or lemon eucalyptus oil. People should take special care when outdoors at dusk and dawn, when mosquitoes are most active. Also ask families to check screen doors and windows for openings that might allow mosquitoes indoors.


Advise patients to decrease standing water to the greatest extent possible, particularly around the home. Mosquitoes can breed in water that is as shallow as an inch. Ways to reduce mosquito breeding include changing the water in bird baths and animal feeding troughs weekly, emptying out children's wading pools when not in use, and eliminating other sources of standing water. It is also a good idea to tip over outdoor wheelbarrows, buckets, and children's toys when not in use so that they do not collect water.