'Tis the season to be eaten alive. And while most mosquito bites are little more than itchy nuisances to be treated with After Bite or calamine lotion, some can be significantly more dangerous.
Toronto Public Health blames the warmer-than-usual temperatures for the record-high number of mosquitoes with West Nile virus across the city.
Two human cases of the virus have been identified in Toronto, two in Winnipeg and another in Windsor. The Winnipeg and Windsor cases are considered mild and were discovered by Canadian Blood Services after blood donations, CBC reports.
Here are ways to identify when a mosquito bite becomes a bigger problem than just an itch you can't stop scratching.
Also see: How to keep mosquitoes away
It's an Allergy
If you're sensitive to mosquito bites, you'll likely experience some itchy lumps on your skin and even fluid-filled blisters.
Allergic reactions exhibit more severe symptoms, possibly including mild nausea, cramps, diarrhea, or significant swelling larger than 10 centimetres in diameter at the site of the bite, MayoClinic.com reports. These symptoms should be treated by a doctor promptly.
Large localized reactions (LLR) can also include rashes and painful or swollen joints, NHS Choices reports.
Systemic reactions (SR) include difficulty breathing, rapid heartbeat, hives, swelling of the lips or throat, dizziness and confusion. These reactions require a 911 call.
If you speculate that you're allergic to mosquito bites, ask your physician for a simple skin test.
If the red area around your mosquito bite continues to grow in size, becoming more swollen and painful, and/or drains pus, the bite is infected. Seattle Children's Hospital instructs parents of children with infected bites to treat the spot three times a day by washing the sore, treating it with an antibiotic ointment, then covering the area with a fresh Band-Aid.
More serious infections can be identified by worsening redness and drainage, by a fever, or by red streaks extending out from the bite. In these cases, antibiotics are likely needed.
Also see: Natural remedies for garden pests
It's West Nile virus
How do you know if you were bitten by a mosquito carrying the West Nile virus? Most people don't exhibit symptoms at all, Health Canada reports. Those who do, often experience mild flu-like symptoms within two to 15 days of being bitten.
Individuals with weaker immune systems, however, are at risk for significantly greater health effects, like meningitis and encephalitis.
"In these cases, symptoms could include the rapid onset of severe headache, high fever, stiff neck, vomiting, drowsiness, confusion, loss of consciousness, muscle weakness, and paralysis. Severe cases of illness due to West Nile virus can be fatal," Health Canada warns.
There is no specific treatment for a West Nile virus infection, reports the U.S. government organization Center for Disease Control and Prevention In mild cases, people experience uncomfortable symptoms that pass on their own. In more severe cases, patients need in-hospital care that includes intravenous fluids.
It's always preferable to prevent bites rather than treat them.
WedMD recommends insect repellents containing DEET as a bite-avoidance strategy. Cover up with long sleeves and pants, spray your clothes as well as your body, skip the outdoor activities from dusk to dawn, drain standing water around your home, and install screens in all your doors and windows for your best chance at avoiding bites this summer.
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