Tag: DEET

For the past several summers we have been worrying about West Nile virus. This virus was first isolated in 1937 from the blood of a patient on the West Nile province of Uganda. Not too far from where I was born. The man had fever. Initially, the outbreaks of the disease were few. But over the years the numbers have increased.

In North America, the virus was first detected in 1999. It was in New York. From there it was exported to Ontario and rest of Canada. Most cases of West Nile virus are mild and self-resolving. But one per cent of cases get infection in the nervous system.

Culex tarsalis is the blood sucking female mosquito that spreads the virus. As the summer comes and the temperature soars, the West Nile virus activity increases. Alberta Health and Wellness undertook a study of West Nile virus prevalence through June 2007. The report is posted on its website.

According to this report, Alberta experienced its first locally acquired clinical cases of West Nile virus (275 confirmed human cases) in the summer of 2003. Since then, clinical (e.g., symptomatic) infections have been detected every year, though the numbers have fluctuated.

From 2004 to 2006, there were very few clinical cases with a combined total of 51. In 2007 there was an increase in the number of infections with 320 cases and the first two deaths associated with the virus in the province. During the 2008 West Nile virus season, only one clinical infection was detected in Alberta and it is thought to be travel-related, says the Alberta Health report.

It is important to remember that for every clinical infection of West Nile virus there are many more undetected infections in humans, since majority of the infections have no symptoms and are never detected.

West Nile virus is carried by birds. Mosquitoes get infected by feeding on the blood of these birds. Infected mosquitoes then transmit the virus to humans when they bite us.

All mosquitoes need water to develop from their immature stages to adulthood. The life cycle takes less than 10 days to complete if the surrounding temperature is favorable. Once the adult mosquito is ready to fly then it looks for something to eat.

Nectar from flowers provides energy to both male and female mosquitoes. While male mosquitoes feed exclusively on nectar, the female mosquito needs blood to produce her eggs. The source of blood can be animals (including people) and birds.

It is important to control the breeding sites around your home by preventing stagnation of water (flower pots, gardening cans, wheelbarrows, puddles, tire swings, bird baths and eavestroughs) even in small quantities. Boats and gardening containers can be stored upside down.

During mosquito season you should limit your outdoor activities. Minimize exposure of your skin by wearing long pants, shirts with long sleeves, socks and shoes when outdoors. Loose clothings will keep mosquitoes away from the skin. Use insect repellents like DEET. Read the directions carefully before using DEET-based repellents especially on children, infants and yourself.

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My first article on West Nile virus was in 2003. Not much has changed in the last five years. Mosquitoes continue to threaten us every summer. Summer is a time to be free, be outdoors and have fun. But mosquitoes spoil the fun.

Every year we go through this process of reminding ourselves to protect against this horrible virus. Just like we do in winter against flu virus. The difference is there is no vaccine yet against West Nile virus.

This year the battle has already started. Alberta Government has been advertising in the media to remind us about the precautions we need to take to prevent mosquito bites. Dr. Paul Schnee, Medical Officer of Health and Gordon Wright, Health Promotion Facilitator, both from Palliser Health Region, have been relentless in reminding the doctors and the public about West Nile virus.

I thought mosquitoes would consider me their friend and spare me from their horrible stinging bites. You see, I was born and raised on the shores of Lake Victoria. A small town called Musoma, in Tanzania, East Africa. There was no shortage of mosquitoes and malaria in Tanzania. Then I moved to India to go to college. There is no shortage of mosquitoes there either. Now in Canada, I am faced with the same battle. I have been fighting mosquitoes all my life. They show no respect for me. And they show no respect to public in general.

West Nile virus was first isolated in 1937 from the blood of a patient on the West Nile province of Uganda. Not too far from where I was born. The man had fever. Initially, the outbreaks of the disease were few. But in the last 15 years the numbers have increased.

In North America, the virus was first detected in 1999. It was in New York. From there it was exported to Ontario and rest of Canada. Most cases of West Nile virus are mild and self-resolving. But one per cent of cases get infection in the nervous system.

West Nile virus is carried by birds. Mosquitoes get infected by feeding on the blood of these birds. Infected mosquitoes then transmit the virus to humans when they bite us.

All mosquitoes need water to develop from their immature stages to adulthood. The life cycle takes less than 10 days to complete if the surrounding temperature is favorable. Once the adult mosquito is ready to fly then it looks for something to eat.

Nectar from flowers provides energy to both male and female mosquitoes. While male mosquitoes feed exclusively on nectar, the female mosquito needs blood to produce her eggs. The source of blood can be animals (including people) and birds.

It is important to control the breeding sites around your home by preventing stagnation of water (flower pots, gardening cans, wheelbarrows, puddles, tire swings, bird baths and eavestroughs) even in small quantities. Boats and gardening containers can be stored upside down. These are just a few examples.

During mosquito season you should limit your outdoor activities. Minimize exposure of your skin by wearing long pants, long sleeves, socks and shoes when outdoors. Loose clothings will keep mosquitoes away from the skin. Use insect repellents like DEET. Read the directions carefully before using DEET-based repellents especially in children, infants and yourself.

Remember, Culex tarsalis is the mosquito that spreads the virus here. The Culex is just out and is now active. It comes to us from July to September (first freeze). Now is the time to start really watching for this one, says Gordon Wright, Palliser’s Health Promotion Facilitator. There is no sign of the virus yet, but we are assuming it will be here soon, says Wright.

Start reading the preview of my book A Doctor's Journey for free on Amazon. Available on Kindle for $2.99!

Dear Dr. B: The mosquito season is going to be here soon. How can I control mosquitoes around my home and how can I protect myself?

Answer: At this time of the year, it is quite appropriate to worry about mosquitoes. Mosquitoes carry many diseases worldwide. In North America, the real concern is the role of mosquitoes in spreading the West Nile disease. West Nile virus is carried by birds. Mosquitoes get infected by feeding on the blood of these birds. Infected mosquitoes then transmit the virus to humans when they bite us.

All mosquitoes need water to develop from their immature stages to adulthood. The life cycle takes less than 10 days to complete if the surrounding temperature is favorable. Once the adult mosquito is ready to fly then it looks for something to eat.

Nectar from flowers provides energy to both male and female mosquitoes. While male mosquitoes feed exclusively on nectar, the female mosquito needs blood to produce her eggs. The source of blood can be animals (including people) and birds.

According to Health Canada website, the female mosquito may live for as long as three weeks during the summer, and any female that lives long enough to feed on blood more than once has the potential to transmit blood-borne diseases from one animal or person to another. Although most mosquito species breed in clean water in the wild, many of the species that breed near your home tolerate polluted water. Most of the 75 mosquito species found in Canada survive the winter as dormant fertilized eggs.

The Health Canada website has many helpful suggestions on how to protect your home and yourself from mosquitoes. I will summarize that information here.

Certain species of mosquitoes breed around the home in containers like bird baths and eavestroughs. It is important to control the breeding sites around your home by preventing stagnation of water (flower pots, gardening cans, wheelbarrows, puddles, tire swings) even in small quantities. Boats and gardening containers can be stored upside down.

Cover any garbage, recycling or composting containers, to prevent water from accumulating in them. Empty your rain barrel if the water is more than a week old. Keep your swimming pool aerated, cleaned and chlorinated, even if it is not being used. Dump any water that collects on your swimming pool cover. For more ideas visit http://www.pmra-arla.gc.ca/english/consum/mosquitos-e.html

How to protect yourself?

During mosquito season (May to September for most of Canada), you should limit your outdoor activities between dusk and dawn, when mosquitoes are the most active. Minimize exposure of your skin by wearing long pants, long sleeves, socks and shoes when outdoors. Loose clothings will keep mosquitoes away from the skin. Use personal insect repellents. Very useful information on this subject is available in Health Canada’s fact sheet, Safety Tips on Using Personal Insect Repellents found at www.westnilevirus.gc.ca.

DEET-based repellents (considered to be most effective) at various concentrations offer different protection times. For example: 30 per cent concentration will provide six hours of protection compared to five per cent concentration which provides only two hours of protection from mosquito bite. Read the directions carefully before using DEET-based repellents especially in children and infants.

Enjoy your summer but don’t forget the sun screen and insect repellent.

Start reading the preview of my book A Doctor's Journey for free on Amazon. Available on Kindle for $2.99!