|Personal protective measures
for humans include:
- Installation of screens (16-18 mesh) on the windows and
doors of homes and commercial buildings.
- Minimizing time spent outdoors between dusk and dawn.
- Wearing shoes, socks, long pants (trousers), and a
long-sleeved shirt when outdoors for long periods of time, or at times when mosquitoes are
- The use of mosquito repellents (particularly those
containing N,N-diethyl-metatoluamide (DEET),
diethyl phthalate, diethyl carbate or ethyl hexanediol), applied according to directions,
when it is necessary to be outdoors for long periods or at times when mosquitoes are most
active. When using repellents:
- It is important to cover the skin evenly (including behind the
ears), as mosquitoes
will find and bite untreated areas;
- Repellents may often be sprayed on outer clothing in
addition to skin;
- In general, protection may be expected for up to six hours
after application of DEET (shorter times after application of other
- Care must be taken when applying DEET as it may damage
synthetic materials including plastics, rayon, spandex, as well as leather and painted or
- Precautions when using repellents include: (W175.Nov01.wnv2)
- Keep repellents away from the eyes,
nostrils and lips;
- Do not inhale or ingest repellents;
- Do not apply to children's hands that
are likely to come into contact with their eyes or mouth;
- Minimise use in pregnant and nursing
- Never use on wounds or irritated skin;
- Avoid application of products containing
greater than 30% DEET to the skin, especially for children;
- Wash treated skin after coming indoors;
- In the event of a suspected reaction to
the repellent, wash treated areas of skin and consult a
- The use of permethrin
- Replacing outside lights around homes with yellow "big
bulbs" or sodium vapour lights that are less attractive to
mosquitoes than are standard bulbs.
- Use window shades at night to avoid attracting mosquitoes in towards
The following information regarding precautions to be taken in field
collection of dead animals, laboratory manipulation of the West Nile virus and
handling of potentially infectious clinical specimens is taken directly from the Health Canada "Biosafety Advisory West Nile Virus (June 2001, Revised June 2003)
[Reproduced with the permission of the Minister of Public Works and
Government Services Canada, 2004]
|Precautions for the field collection of dead birds and other animals:
Persons involved in collecting dead birds and other animals should follow the recommendations of the Occupational Health Advisory West Nile Virus, Revised May 29, 2003:
- precautions for mosquito avoidance (i.e. wearing long sleeved shirts, full length trousers, socks, light coloured clothing, high boots) and the use of
repellants (i.e. 20-30% DEET) should be implemented
- when possible, minimize outdoor activities where and when (e.g. dusk, night, dawn) mosquitoes are likely to be encountered
- bare-handed contact should be avoided when handling dead animals and birds and precautions should be taken to avoid direct contact with excretions
- rubber/nitrile/latex/vinyl/PVC gloves and double plastic bags turned inside out over hands can be used to collect dead birds
- cut-resistant gloves can be worn under rubber/nitrile/latex/vinyl/PVC gloves to avoid cuts or puncture wounds from bills, claws, or instruments during
handling and dissection of birds and other animals
- hands should be washed after handling dead birds
Precautions for the handling of suspect specimens in animal necropsy suites:
- where practical, animal carcasses should be manipulated in a certified biological safety cabinet
- larger carcasses should be manipulated using equivalent protective measures (e.g. splash protection on eyes, protective solid-front gowns with tight
fitting wrists, rubber/latex/vinyl/PVC gloves, and respiratory
protection1 (NIOSH certified N-95 to N-100 respirator filter mask, half or full face,
depending on splash protection)
Precautions for the handling of human and animal (including avian) suspect clinical specimens:
- potentially infected human and animal clinical specimens (e.g. blood, serum, CSF, tissues) may be handled in a Containment Level 2
facility2 using Containment Level 3 operational
practices2 as outlined below
- blood collection should be carried out using standard universal
precautions3 (e.g. wearing gloves, hand washing, avoiding needle sticks)
- sorting of mosquitoes for species identification, where possible and practical, may be performed in a Containment Level 2
- certified biological safety cabinets should be used for laboratory manipulations of suspect clinical specimens
- centrifugation of clinical specimens (e.g. for serum separation) should be carried out using sealed centrifuge cups or rotors that are loaded and
unloaded in a biological safety cabinet
- aliquots used for serology should be heat inactivated at 56° C for 30 minutes
- PCR testing may be performed in a Containment Level 2 facility1 using Containment Level 3 operational
Precautions for virus isolation and laboratory manipulation of the WN virus:
- virus isolation and propagation should be performed in a Containment Level 3
facility2 using Containment Level 3 operational
- animal studies should be performed in a Containment Level 3 animal facility1 using Containment Level 3 operational
- studies involving infected mosquitos should be performed in a Containment Level 3 facility2 using Containment Level 3 operational
Dead birds and sera to be tested (eg. sera collected from sentinel chickens) should be packaged adequately and labelled and shipped as “Diagnostic
Shipping, packaging and transport of the WN virus and suspect clinical specimens and sera should follow the Transportation of Dangerous Goods Regulations, Transport Canada.
- Further biosafety information may be obtained from the Office of Laboratory Security, Population and Public Health Branch, Health Canada at (613) 957-1779 or fax (613) 941-0596.
- Further occupational health and safety information is available in the Occupational Health Advisory, Occupational Health and Safety Agency, June 24, 2003.
- Containment Standards for Veterinary Facilities, Agriculture and Agri-Food Canada, Publication No. 1921, July 1996.
- Laboratory Biosafety Guidelines, Health Canada, 1996.
- Preventing the Transmission of Bloodborne pathogens in Health Care and Public Service Settings, Canada Communicable Diseases Report - Supplement Vol. 23S3, May 1997.
[Source: Biosafety Advisory West Nile Virus, Health Canada, (June 2001, Revised June
2003) & Reproduced with the permission of the Minister of
Public Works and Government Services Canada, 2004.]
- A study undertaken in Mississippi in 2002 found that the use of
personal protection including staying inside during peak mosquito
biting times, avoiding areas which were apparently mosquito-infested,
wearing long sleeves and long pants did appear to reduce the risk of
WNV infection. (P48.4.w9)
- Public education is important to provide information about personal
protective measures which they can use and why they should use them. (D71)
REASONS WHY PERSONAL PROTECTION MAY NOT BE UTILISED FULLY
There are a variety of reasons why personal
protection may not be utilised fully. These include:
- Incorrect perceptions of risk: lack of understanding that this
disease continues to be a problem, lack of recognition that is a
threat in the local area, lack of understanding that older persons,
rather than children, are most at risk from the disease.
- Incomplete understanding of transmission routes and overriding
importance of transmission by mosquito bite.
- Unwillingness to reduce time spent outdoors between dusk and dawn
due to conflicts with e.g. social interactions and physical activity
such as outdoor sports.
- Regular application of insect repellents may be considered
- There may be concerns regarding the use of products containing DEET,
particularly for use on children.
- A recent review of the evidence available fount that "the
evidence does not support increased risk in young children"
and that the available data were reassuring also regarding safety
of use during pregnancy and lactation. (J257.169.w1)
- Incomplete acceptance of personal responsibility for protection:
perception that public control of mosquitoes should be sufficient for
- Economic or physical barriers to activities such as replacing or
repairing damaged insect screens.
- Individuals who are homeless present special challenges as they
have extensive outdoor exposure and limited financial resources to
engage in personal protection; individuals in residences lacking
effective window screens also have an increased risk of exposure
to mosquito bites and should be targeted for assistance with
- It is not easy to change personal behaviours.