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West Nile Virus Activity: States of New York, New Jersey,
Connecticut, Massachusetts, Rhode Island, New Hampshire, Maryland, Pennsylvania,
Vermont, Virginia, North Carolina and the District of Columbia (Washington)
Updated: October 23, 2000
Following last year's West Nile virus outbreak in New York City (NYC) and
surrounding counties in September, Health Canada's Travel Medicine Program
has been closely monitoring West Nile virus activity in the States of New
York, New Jersey, Connecticut, Massachusetts, Rhode Island, New Hampshire,
Maryland, Pennsylvania, Vermont, Virginia, North Carolina and the District
of Columbia (Washington). This year, the West Nile virus has been detected
in dead birds and mosquitoes in a number of counties in these states and in
32 horses: eight in New York, 15 in New Jersey, six in Connecticut, one in
Pennsylvania, one in Massachusetts and one in Rhode Island. To date, 18 human
cases, including one death, have been confirmed: nine cases on Staten Island,
NYC; three cases in Brooklyn, NYC; one case in Queens, NYC; four cases in
New Jersey in Jersey City, Cliffside Park, Little Falls and Bayonne; and one
case in Connecticut. One death has been reported; an 82-year-old man in Little
Falls, New Jersey. Illness has been reported in nine individuals age 61 or
older and seven people between 37 and 54 years of age. The age of one person
is not available. Three persons are in hospital, and 14 individuals are recovering
at home.
Although infected dead birds and/or positive mosquito pools have been reported
by a number of counties in New York, New Jersey, Connecticut, Massachusetts,
Rhode Island, New Hampshire, Maryland, Pennsylvania, Vermont, Virginia, North
Carolina and in the District of Columbia (Washington), it is likely that the
virus is now more widespread in those States and the District than the reports
suggest.
Culex pipiens, Culex restuans and Culex salinarius mosquitoes,
which are dusk-to-dawn biters, and Aedes japonicus and Aedes
triseriatus mosquitoes, which are daytime biters, have been shown to
be infected.
Last September, New York City experienced the first confirmed outbreak of
West Nile virus ever reported in North America. Sixty-two human cases were
confirmed with 7 deaths, including one Canadian who travelled to New York
City. Historically, West Nile virus is found in Africa, Asia, southern Europe
and the former USSR.
In spite of active surveillance, West Nile virus has not been detected in
Canada to date. It is difficult to predict whether the virus will move into
northern ecologies in Canada where appropriate mosquitoes are well-established.
Nevertheless, Health Canada and provincial, territorial and municipal authorities
have implemented surveillance programs to identify the presence of West Nile
virus in dead birds, sentinel chickens and mosquitos before disease is detected
in humans. At this time, provinces bordering areas in the United States where
infected dead birds have been found are intensifying surveillance. For more
information, go to http://www.phac-aspc.gc.ca/wnv-vwn/index.html.
West Nile virus is spread to humans through the bite of an infected mosquito.
A mosquito becomes infected by biting a bird that carries the virus. The virus
is not known to spread from person-to-person nor from bird-to-person. Symptoms
in the vast majority of individuals can be unapparent to mild. Three to 12
days following the bite of an infected mosquito, symptoms may range from a
slight fever headache and mild flu-like illness to rapid onset of severe headache,
high fever, stiff neck, muscle weakness, and disorientation. Fatalities usually
occur in the elderly and immunocompromised. Illness is more severe in adults
than in children.
Due to the appearance of West Nile virus in a number of dead birds and in
both dusk-to-dawn and day-time biting mosquitoes, Canadians travelling to
the States of New York, New Jersey, Connecticut, Massachusetts, Rhode Island,
New Hampshire, Maryland, Pennsylvania, Vermont, Virginia, North Carolina and
the District of Columbia (Washington) are encouraged to use personal protection
measures at all times while outside to avoid being bitten. To reduce your
exposure to mosquitoes, consider the following measures:
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remain in well-screened or completely enclosed, air-conditioned areas;
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wear light-colored clothing with full-length pant legs and sleeves; and
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use insect repellent on exposed skin.
The use of insect repellent on exposed skin is strongly recommended. Of
the insect repellents registered in Canada, those containing diethyltoluamide
(DEET) are the most effective. Although the concentration of DEET varies from
product to product, repellency rates are largely equivalent. In general, higher
concentrations protect for longer periods of time, but there is little advantage
in the duration of repellence with DEET concentrations > 50%, and
there may be additional risk of toxicity with higher concentrations. New microencapsulated
products containing 33% DEET are registered in Canada, and they should provide
8 hours of protection.
Children and DEET
In rare instances, application of insect repellents with DEET has
been associated with seizures in young children (only 14 cases over 30 years
of DEET use and billions of applications every year). The actual concentration
of DEET varies among repellents and can be as high as 95%; however, repellents
with DEET concentrations of 10% are very effective and should last 3 to 4
hours. Therefore, in children, DEET <= 10% should be applied sparingly
to exposed surfaces only and washed off after the children come indoors.
The likelihood of adverse reactions can be minimized by the following
precautions:
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apply repellent sparingly and only to exposed skin;
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avoid applying high concentration products;
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avoid applying repellents to portions of children's hands that are likely
to contact the eyes or mouth;
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never use repellents on wounds or irritated skin; and
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wash repellent-treated skin after children come indoors. If a reaction
to insect repellent is suspected, wash treated skin and seek medical attention.
In Canada, DEET products are not recommended for use in children < 2
years of age. For more information, go to: http://www.pmra-arla.gc.ca/english/consum/insectrepellents-e.html
In the U.S., Canadians can call the New York City West Nile Information
Line at 1-877-WNV-4NYC (1-877-968-4692) Information can also be obtained from
the New York City Department of Health web site at http://www.ci.nyc.ny.us/
Sources: New York State Department of Health, New York City Department
of Health, New Jersey Department of Health and Social Services, Connecticut
Department of Environmental Protection, Massachusetts Department of Public
Health, Rhode Island Department of Environmental Management, New Hampshire
Department of Health and Human Services, Maryland Department of Health and
Mental Hygiene, Pennsylvania Department of Health, Vermont Department of Health,
Virginia Department of Health, North Carolina Department of Health and Human
Services, and the Government of the District of Columbia.
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