West Nile advisory issued by AHS


"The following advisory about West Nile was sent to all municipalities in the South Region by Alberta Health Services."

 Alberta Health Services (AHS) would like to remind Albertans to protect themselves against West Nile virus (WNv) infection. We are heading into the part of the summer that is most favourable for the type of mosquito that spreads WNv infection – Culex Tarsalis. 

There are many types of mosquitoes and while all of them can be a nuisance, not all of them carry disease. It’s typically later in the summer when Culex Tarsalis increases in number. 

WNv is transmitted to humans primarily through the bite of an infected mosquito. WNv was first confirmed in Alberta in July 2003. Since then, the Alberta government conducts surveillance for WNv in humans through the Notifiable Diseases Reporting System. Veterinarians and animal health laboratories report cases of WNv identified in horses. 

The period of greatest risk of WNv transmission to humans by mosquitoes usually occurs between mid-July and mid-August. The majority of WNv activity occurs in southeastern Alberta. The risk of WNv depends on: 

 The number of Culex mosquitoes that have successfully survived the previous winter 

 Weather conditions in the spring and early summer affecting the spread of WNv from mosquitoes to birds, horses and humans 

 The amount of WNv circulating in these same Culex mosquito populations 

 Standing water, such as lakes, ponds, pools where mosquitoes like to breed 

 The proximity of human populations to WNv-infected mosquito populations 

 Individual human factors such as age and overall health 

Any exposure to mosquitoes brings a risk of WNv, so it’s important to avoid being bitten at all. Whenever outdoors for any reason, all Albertans should take these simple steps to prevent bites and protect themselves from WNv: 

 Wear a long-sleeved, light-colored shirt, long pants, and a hat 

 Use insect repellent with DEET or icaridin (also known as picaridin): 

1. For children younger than 12 years old, pay special attention to the percentage based on age. For complete details about this, visit MyHealth.Alberta.ca

2. For babies less than six months old, do not use any insect repellent. Instead, protect them with full-coverage clothing and a hat. 

 Insect repellant should be applied after sunblock 

 Consider staying indoors at dawn and dusk, when mosquitoes are most active 

 Remove standing water around your yard - or change the water daily - such as bird baths, dog dishes, etc. 

After being bitten by a mosquito carrying the virus, humans can develop West Nile Non-Neurological Syndrome (formerly known as West Nile fever) or the more serious West Nile Neurological Syndrome. Severe neurological illness associated with the virus is rare, but the risk increases with age and for those who are immune-compromised. The greatest risk appears to be for those who are on anti-rejection medication following organ transplant. 

Symptoms of Non-Neurological Syndrome can be uncomfortable, including fever, chills, nausea, vomiting, fatigue, skin rash, swollen glands and headache. For individuals who do develop Neurological Syndrome, symptoms can be much more severe, including tremors, drowsiness, confusion, swallowing problems, high fever, unconsciousness, paralysis and even death. 

Remember, WNv can affect anyone; one in five people who do become infected become ill. 

Albertans can learn more about West Nile virus and the precautions necessary to reduce risk at www.fightthebite.info or by calling Health Link at 811.

Click here for information on confirmed cases of West Nile virus cases in Alberta since 2003.