West Nile Virus

West Nile virus is found in the wild bird population.  A mosquito gets infected by feeding on the blood of an infected bird.  An infected mosquito can then bite a person or animal and give them West Nile virus.  Not all mosquito types carry West Nile virus or bite humans.

How do you get West Nile virus?

West Nile virus is spread to humans mainly when an infected mosquito bites them. In a small number of cases, West Nile virus has been spread through blood transfusions, organ transplants, breastfeeding or in pregnancy from the mother to her baby. The virus is not spread by person to person contact such as drinking from the same cup.

Only about 20% of people with West Nile virus have symptoms. Symptoms usually appear two to 15 days after a mosquito bite from an infected mosquito. Symptoms may last several weeks. Some effects may be severe and permanent, including death for a small number of people. 

Signs and symptoms of West Nile virus

Most people have mild symptoms that include:

  • Fever
  • Headache
  • Nausea
  • Vomiting
  • A rash on the chest, stomach or back
  • Body aches

Some people may have severe symptoms including:

  • A stiff neck
  • Confusion
  • Tremors
  • Muscle weakness
  • High fever
  • Severe headache
  • Numbness
  • Sensitivity to light

Seniors and people with weakened immune systems have the highest risk of developing severe illness from West Nile virus.

Less than 1% of people with West Nile virus develop other serious illnesses such as meningitis and encephalitis.  Meningitis is swelling of the lining of the brain or spinal cord.  Encephalitis is swelling of the brain.  These conditions can cause lasting illness or death.

Read about West Nile virus in French (PDF, 22 KB) |  Arabic (PDF, 106 KB) |  Mandarin (PDF, 304 KB)  | ​ Spanish (PDF, 69 KB)

Talk to your doctor if you have think you symptoms of West Nile virus.

West Nile virus in humans is confirmed by a blood test or by testing the fluid around the brain and spinal cord.  Test results take one to two weeks.

There is no specific treatment or vaccine for West Nile virus.

Here are some things that you can do to prevent West Nile virus:

  • Remove standing water from:
    • Bird baths
    • Old tires
    • Unused containers
    • Flower pot saucers
    • Swimming pool covers
    • Wading pools
    • Clogged gutters and eavestroughs
    • Clogged drainage ditches
    • Small containers
    • Unused children’s toys
    • You should remove standing water at least once every seven days.  Mosquitoes lay their eggs in very shallow standing water.  If you remove the standing water they cannot lay eggs. 
  • Report standing water on public or private property.
  • Avoid mosquito-infested areas.  They like weeds, tall grass and bushes.
  • Avoid cologne, perfume and scented body lotion when going outdoors.
  • Wear long-sleeved shirts, long pants, hats, socks and shoes; tuck your pants into socks.
  • Repair damaged doors and window screens so mosquitos cannot get inside.
  • Avoid spending time outdoors from evening until early morning, when mosquitoes are most active.
  • Use an insect repellent that contains DEET for your family members that are older than six months of age.

Mosquito control

Mosquitoes breed in standing water and tend to stay close to their breeding site throughout their life.  If the number of breeding areas can be reduced, we can reduce the number of mosquitoes and West Nile virus in our community.

Standing water surveillance starts on April 1 each year and continues until October 31, under Hamilton’s Standing Water By-law No. 03-173  (PDF, 61 kB).  We do not investigate complaints outside of these dates.

If you want to report standing water:

We accept complaints for standing water that is more than 2 ½ cm deep at the deepest point with no movement of the water.  If water has been treated to prevent insects from breeding, it is not considered standing water. Treatment may include continuous movement of the water or appropriate pesticide treatment or other actions approved by the Medical Officer of Health.

Public land complaints

We follow up on public land complaints within five business days. The City looks for mosquito larvae at several hundred surface water sites from June to the fall each year.  We treat sites when necessary to reduce or eliminate the amount of mosquitoes developing in the water.  This helps control the mosquito population in Hamilton.

Private land complaints

We follow up on private land complaints within five business days.  The City investigates and enforces private land complaints that fall within the scope of Hamilton’s Standing Water By-law No. 03-173.

Notice of application to larvicide City of Hamilton surface waters for West Nile Virus mosquito control 

The City of Hamilton, Public Health Services is conducting ongoing monitoring of mosquito larvae (immature mosquitoes) in standing surface water within the City of Hamilton boundaries on City land. When such monitoring indicates that there is a need for mosquito control, application of larvicide may be required in order to prevent larval development into vectors of West Nile Virus. Application of larvicide may commence as early as June 1st, 2016 and end as late as October 31th, 2016.

The larvicide Bacillus thuringiensis subspecies israelensis - Bti (product names: VectoBac 200G- reg. no. 18158 and VectoBac 1200 liter - reg. no. 21062) and the larvicide Bacillus sphaericus strain 2632 - Bs (product name: VectoLex CG - reg. no. 28008) will be applied to identified standing surface water. The application of these products will be carried out under permit from the Ontario Ministry of the Environment and Climate Change.

Notice of application to larvicide public catch basins for West Nile Virus mosquito control 

As early as June 1, 2016 and as late as October 31st, 2016 the City Of Hamilton will be conducting a larviciding program under the authority of the local Medical Officer of Health to control larval mosquitoes in order to prevent their development into vectors of West Nile Virus. The mosquito growth regulator methoprene, pellet formulation (product name: Altosid Pellets - methoprene 4.25%, reg. no. 21809) and briquette formulation (product name: Altosid XR – reg. no. 27694)  will be placed into catch basins of storm drains on city streets and on selected publicly owned properties within the City of Hamilton. The larvicide Bacillus sphaericus (product name:  Vectolex WSB - reg. no. 28009) will be placed into catch basins of storm drains on city streets and on selected publicly owned properties within the City of Hamilton.  The application of these products will be carried out under permit from the Ontario Ministry of the Environment and Climate Change.

All control products will be applied by licensed applicators or trained technicians of GDG Canada Inc. (GDG Environment) under contract with the City of Hamilton. For more information about the West Nile virus program, including dates of completed treatment rounds throughout the summer, please check this page regularly.

For more information call 905 546-CITY (2489)
519 residents call 519 647-2577
Campbellville residents call 905 634-2971

The City of Hamilton is committed to reducing the risk of West Nile virus within our community by using strategies with the least negative impact on human health, nature and the environment.  We do many things to control West Nile virus such as:

  • public education
  • reducing mosquito breeding sites and standing water on City land
  • enforcing Hamilton's Standing Water By-law No. 03-173
  • surveillance for West Nile virus in mosquitoes
  • monitor for West Nile virus in humans 

Adult mosquito control

We have a contingency plan for using an ultra-low volume insecticide called malathion to control the adult mosquito population.  This could be used if the Medical Officer of Health determines that it is needed to decrease the risk of West Nile virus to human health.  Spraying to control adult mosquitoes has not yet been required in Hamilton or any other municipality in Ontario for West Nile virus control. 

If we are going to use malathion, Public Health Services will notify residents in the affected areas a minimum of 48 hours before application. Notification will be through the media such as newspapers, television, radio or door-to-door notices.

Sign up for the Adult Mosquito Control Registry

If you want to receive personal advance notification of plans to apply malathion in your area because of health-related concerns, sign up for the adult mosquito control registry.  Let Public Health Services know your:

  • Name
  • Preferred method of contact - phone, fax or email
  • Contact information – phone, fax and/or email

You can submit this information to Public Health by:

We will use an automated system to electronically contact each person registered on the adult mosquito control registry by their chosen method of phone, email, fax or a combination of these to notify them of any adulticiding plans in their area. 

Personal information collected for the purpose of administering the Adult Mosquito Control Registry is being collected under the authority of the Health Protection and Promotion Act, R.S.O. 1990, c. H.7. If you have any questions regarding this collection,  contact the West Nile Virus program, Public Health Services, City of Hamilton, 110 King Street West, Hamilton, Ontario, L8P 4S6 or by Phone: 905-546-2424 ext. 3576.

West Nile virus statistics in Hamilton

The following table provides year-over-year surveillance data for the number of positive dead birds, positive mosquito pools, human cases, human deaths related to West Nile virus and horse cases.

Type of surveillance

2011

2012

2013

2014

2015

2016

Positive mosquito pools

31

33

12

7

9

23

Human cases

2

20

5

0

2

2

Human deaths related to West Nile virus

0

1

0

0

0

0

Horse cases

0

1

1

0

0

0
Other 0 0 0 0 0 1 Crow*

*Note: One crow from Hamilton was tested by Canadian Wildlife Health Cooperative and found positive for West Nile Virus on August 25, 2016. Routine surveillance or routine testing of dead birds is not currently conducted in Hamilton as part of the West Nile Virus program

The following table provides the number of positive mosquito pools in an area. Positive mosquito pools indicate a group of female mosquitos of the same species.  The number of mosquitoes in a pool ranges from one to 50.  There can be several pools in one trap.

Area

Positive mosquito pools

Ancaster

0

Dundas

1

Flamborough

1

Glanbrook

1

Central Mountain

1

East mountain

1

West mountain

0

Lower Central Hamilton

5

Lower East Hamilton

5

Lower West Hamilton

0

Lower Stoney Creek

6

Upper Stoney Creek

2

Total

23

Positive mosquito pools indicate a group of female mosquitos of the same species.  The number of mosquitos in a pool ranges from one to 50.  There can be several pools in one trap.

Number of positive mosquito pools

Date collected

Date reported positive

Area

1 July 26, 2016 July 28, 2016 Lower Central Hamilton
2 August 3, 2016 August 5, 2016 Lower Stoney Creek
1 August 9, 2016 August 11, 2016 Glanbrook
1 August 9, 2016 August 11, 2016 Lower Central Hamilton
1 August 16, 2016 August 17, 2016 Lower East Hamilton
1 August 16, 2016 August 17, 2016 Lower Stoney Creek
1 August 16, 2016 August 17, 2016 Flamborough
1 August 23, 2016 August 25, 2016 East Mountain
1 August 23, 2016 August 25, 2016 Lower East Hamilton
1 August 23, 2016 August 25, 2016 Lower Stoney Creek
1 August 23, 2016 August 25, 2016 Lower Central Hamilton
1 August 23, 2016 August 25, 2016 Central Mountain
1 August 30, 2016 September 1, 2016 Lower East Hamilton
1 August 30, 2016 September 1, 2016 Dundas
1 August 30, 2016 September 1, 2016 Upper Stoney Creek
1 August 30, 2016 September 1, 2016 Lower Stoney Creek
1 September 7, 2016 September 9, 2016 Upper Stoney Creek
1 September 7, 2016 September 9, 2016 Lower Central Hamilton
1 September 13, 2016 September 15, 2016 Lower East Hamilton
1 September 13, 2016 September 15, 2016 Lower Central Hamilton
1 September 13, 2016 September 15, 2016 Lower Stoney Creek
1 September 20, 2016 September 21, 2016 Lower East Hamilton

The following table provides the number of larvicide applications year-over-year. The catch basin colour shows up as a painted dot on the city street catch basins when they receive a treatment.  A 4th round of treatment is applied based on a rise in positive mosquito results.

Application of larvacide

2011

2012

2013

2014

2015

2016

Catch basin colour

1

 

June 16 - 29

June 18 - 29

June 24 - July 9

June 13 - 22

June 18 - 27

June 30 - July 12

Green

2

July 6 - 18

July 10 - 20

July 15 - 29

July 4 - 14

July 9 -19

July 27 - August 8 

Purple

3

July 28 - August 10

August 1 - 15

August 5 - 19

July 25 – August 2

July 30 -  August 7

August 24 - September 7

Blue

4

August 17 - 24

August 20 - September 11

None applied

None applied

None applied

 

TBD