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West Nile Virus
West Nile virus is transmitted through the bite of an infected
mosquito.
Marjorie Friesen, BScPharm, SPI, Drug and Poison Information
Pharmacist,
British Columbia Drug & Poison Information Centre
West Nile virus can cause disease in humans, birds and horses.
In North America, West Nile
virus was first reported in New York City in 1999. Before this,
it was only known in parts of
Asia, Europe and Africa. By the summer of 2001, infected birds
were found in southern
Ontario. The first human case in Canada occurred the following
year. The virus has also been
detected in other provinces.
West Nile virus is transmitted through the bite of an infected
mosquito. Worldwide, more than 50
species of mosquitoes are known to carry the virus. Mosquitoes
become infected by feeding on the
blood of birds infected with the West Nile virus. Infected
mosquitoes usually prefer to take their blood
meal from birds and not humans. However, when conditions are
right, usually in late summer,
infected mosquitoes may also bite humans and other mammals.
Crows, ravens, magpies and jays are
particularly susceptible to the virus and often die when they
are infected. Human infection from
handling West Nile virus-infected birds (live or dead) has
not been reported. Monitoring programs are
in place to track the spread of West Nile virus.
The overall risk to humans of becoming ill from a mosquito
bite is extremely small. Even in areas
where mosquitoes carry the virus, less than 1% of mosquitoes
are infected.
The majority of people infected with West Nile virus experience
no symptoms at all. Some infected
people develop West Nile fever, a mild illness with symptoms
lasting only a few days. Symptoms
include fever, headache, body aches and sometimes a rash
and swollen lymph glands. Less than
1% of humans bitten by an infected mosquito will develop
an inflammation of the brain or spinal cord
(meningitis or encephalitis). Certain people, particularly
the elderly, are at increased risk of serious
health effects. Potentially serious symptoms include headache,
high fever, neck stiffness, weakness,
stupor or tremors. Anyone who experiences these symptoms
should seek immediate medical attention.
The incubation period (interval between infection and onset
of disease) is usually between two
to 14 days.
There is no specific treatment for West Nile
virus infection and no human vaccine is available. People
can protect themselves against West Nile virus by avoiding
mosquito infested areas, eliminating
stagnant water (in which mosquitoes breed) around the
home, installing window screens, wearing
protective clothing, and using a personal mosquito repellent.
Be sure to check with your pharmacist
for advice on mosquito repellents, especially for use
in children.
For more information on West Nile Virus, see
Public Health Agency
www.phac-aspc.gc.ca/wn-no/index_e.html
Health
Canada
www.hc-sc.gc.ca/dc-ma/wnv-vno/index_e.html
Saskatchewan Health
www.health.gov.sk.ca/rr_wnv_info.html
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The information in this newsletter was prepared and reviewed
by pharmacists for the Canadian Pharmaceutical Journal.
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Ask Your Pharmacist newsletter is produced through
an unconditional educational grant from APOTEX/PACE. |
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