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The arrival of mosquitoes has never been anybody's favorite sign that the long winter is finally over, but since the arrival of the West Nile virus in Canada, these tiny creatures are not just an annual annoyance anymore.
To help deal with this threat to the Canadian public, Health Canada will be working closely with First Nations, to help prevent the spread of the virus within Native communities.
The feds will partner with First Nations to co-ordinate surveillance, testing, education, and methods of preventing the spread of West Nile during the coming mosquito season.
The West Nile virus has been around for decades, and was first identified and isolated in the West Nile region of Uganda in 1937. The virus first shows up in birds, and can be spread to humans if they are bitten by a mosquito that has been infected by feeding on a bird that carries the virus.
Over the years, there had been outbreaks of the virus in Egypt, Israel, South Africa, and in parts of Europe. And then, in mid-August 1999, the bodies of dead crows were found on the grounds of the Bronx Zoo in New York City. The West Nile virus had arrived in North America.
Soon people within the city began to experience symptoms similar to encephalitis, an inflammation of the brain. By the end of the year, the virus has spread to Long Island, downstate New York, to New Jersey, and to Connecticut, and had killed at least 5,000 birds.
In total, 62 cases of West Nile virus were reported in humans that year. Of those, seven people died, including one person in Toronto who had visited New York.
By the end of 2000, the virus has spread as far as the Canada/U.S. border. The first case of West Nile virus in Canada was confirmed on Aug. 22, 2001 in a dead bird found in Windsor-Essex County in southern Ontario, and it began to spread from there.
According to Dr. Harvey Artsob, chief of zoonotics diseases and special pathogens for the population and public health branch of Health Canada, the cases of West Nile virus reported in Canada and the United States in 2002 made it the largest mosquito-transmitted epidemic ever documented in North America, and the largest West Nile epidemic ever documented anywhere in the world.
To date, there have been 325 human cases of West Nile virus confirmed in Canada. In three of those cases-including two in Alberta-it is believed the people contracted the virus while traveling.
All told, a total of 18 deaths have been linked to the virus, including four deaths where the virus itself was listed as the primary probable cause of death.
While the number of positive cases of human contraction of the virus has been limited to Quebec and Ontario, dead birds have tested positive for the virus as far east as Nova Scotia and as far west as Saskatchewan.
In Ontario, at least two of the birds testing positive were found on First Nations. And while no one can predict where the virus will show up this year, it is likely to continue to spread, possibly reaching into Alberta and British Columbia this summer.
"The pattern of West Nile over the years since it incursion in '99 certainly has been for spread of the virus from the initial four statesthat were involved in 1999 through 12 states, and then at the end of last year 44 states, and it finally made it's way to the West Coast," Artsob explained. "So I guess, in brief, the answer is, yes we do expect the virus will probably keep expanding its range. But we still have so many questions we're asking about West Nile, and we're not certain that every area that we saw West Nile activity last year, that the virus activity will recur."
Many people who contract the West Nile virus have no symptoms, while others become mildly ill. In mild cases, the symptoms can include fever, headache, body aches, a mild rash, or swollen lymph glands.
In others, especially those with weakened immune systems, the virus can cause more serious health effects, including meningitis-inflammation of the lining of te brain or spinal cord-or encephalitis, and can be fatal. In these severe cases, symptoms could include rapid onset of a severe headache, high fever, a stiff neck, nausea or vomiting, drowsiness, difficulty swallowing, confusion, loss of consciousness, lack of co-ordination, muscle weakness and paralysis. Last year a number of additional symptoms were added to the list, including movement disorders, muscle degeneration, and symptoms similar to that experienced in Parkinson's disease and poliomyelitis.
While in the past, statistics have shown that about 80 per cent of people contracting the virus won't have any symptoms, while about 20 per cent develop mild symptoms and less than one per cent develop more serious symptoms, new research has shown those numbers may need modifying.
"Although it is still the case that most people who contract West Nile virus show no symptoms or mild flu-like illness, we must remember that disease and fatalities do occur in all age groups, but particularly the elderly and those with weakened immune systems. Anyone in an area where West Nile virus is active is at some risk."
A West Nile virus fact sheet on the Health Canada Web site lists the groups who have a higher risk of developing serious health effects after contracting the virus. These groups include people over 40, people with chronic diseases, such as cancer, diabetes, alcoholism or heart disease, and people that require medical treatment such as chemotherapy that may leave them with weakened immune systems.
That list concerns Ruby Jacobs, director of health services for the Six Nations of the Grand First Nation. Six Nations is located in southern Ontario, the region of Canada where the first West Nile outbreaks occurred, and is the country's most populous First Nations community.
According to a recent study looking at the health of members of the Six Nations community, there are high percentages of the population with diabetes, cancer and cardiovascular disease.
"There ar high numbers in all of those areas. Our study actually said around 49 per cent either have or will have diabetes. And the whole statistics were just horrendous. . . many people are involved in those kinds of diagnosis. And you know, the state of health is one major factor in whether you catch disease or not," she said.
"We don't want to scare people, but people, even with the SARS [Severe Acute Respiratory Syndrome] we've stated the vulnerable folks need to be extra cautious, so we'll be doing the same here," she said.
The West Nile virus has been a concern for Six Nations for a while. The community took part in bird surveillance last year, with about seven birds picked up for testing. The bird surveillance will continue again this year. In fact, one dead crow has already been picked up and sent to be tested for the virus.
This year, work will also be done to monitor the mosquito population, to try to identify areas where the insects reproduce.
Six Nations will also be focusing on educating its members, and increasing their awareness of ways they can work to reduce the spread of the virus, Jacobs explained.
"We've got these things you can do in your environment to reduce the reproduction of mosquitoes. Like emptying out stagnant water in any kind of a receptacle around your property, and making sure your house has got proper screens on and so on, to prevent entry into the houses. And then for yourself, there's personal things you can do . . . like wearing proper clothing at peak times like dusk and dawn, where you'd wear long pants and socks and shirts and that so that they couldn't bite you," she said.
"We're working with Health Canada, the environmental health office, very closely on this. All the components that will be concerned in our community, like probably health, health services staff and the environmental staff, are all working together in a collaborative effort to reduce the reproduction," Ruby Jacobs said.
As for chemical means of controllin mosquito populations, such as larviciding, which targets mosquito breeding sites, and adulticiding, which involves spraying or fogging insecticide to kill flying adult mosquitoes, those options are being looked at by a consultation advisory group working with the environmental health office.
Insecticides have never been used by the community in the past, Jacobs said.
"When you spray or use any kind of those insecticides or things, you have to watch out what it does to the full ecosystem. So there's concerns for unforeseen impacts and problems arising as a result of using a chemical. So all of those are, those are under review. But we're working on the education and awareness component, and the personal component about what you can do yourself to prevent it."
Health Canada will be working to educate people about what they can as individuals do reduce to their risk of becoming infected. They will also be providing the most up-to-date information about the virus and surveillance results on the Health Canada Web site, at http://hc-sc.gc.ca.
Health Canada will be co-ordinating nation-wide surveillance of the virus, which will involve testing of dead birds-especially members of the crow family-suspected of being infected, as well as monitoring mosquito populations, and infection in horses and in humans.
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The department will work with Canadian Blood Services and Hema Quebec to help ensure the Canadian blood supply is free of the virus. Private industry is working to develop a test for screening donated blood for the virus, and Artsob expects that test should be in place by July.
The blood agencies are working to stockpile blood and blood products, gathering them from donors before this year's mosquito season begins.
The federal department is working to provide the provinces with the ability to more quickly diagnose infected people.
"Health Canada's national microbiology laboratory is actively supporting efforts to provide faster test results this year. The faci
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