West Nile virus – Response plan 2011

Alberta's response plan

Purpose of the plan

To minimize the risk of West Nile virus (WNV) infection to humans.

Key components

Provincial Coordination

Provincial committee

An interdepartmental committee has met each year since 2003 to prepare a provincial response plan to address potential WNV risks in Alberta. At the end of the WNV season, the committee also produces an annual report to summarize Alberta’s response.

Ongoing coordination

The Government of Alberta will continue to evaluate Alberta’s WNV response plan within the context of what is happening in the province as well as nationally and internationally. Alberta Health and Wellness will participate in the national meetings that address WNV in Canada.

Communications

Specific objectives

To inform Albertans of the potential consequences of a WNV infection, about the steps they can take to prevent being bitten by mosquitoes and the most effective means of reducing the risk of infection.

Albertans notified

Alberta Health Services will inform Albertans of the evidence of WNV in the province when there is confirmation of the virus in humans.

Evidence of WNV cases in Alberta will be posted on the Alberta Health and Wellness website.

Messages to the public

Information about WNV and the steps people can take to protect themselves will be made available to Albertans in the following ways:

• Alberta Health Services will implement a public awareness campaign that will remind Albertans about the simple steps they can take in the summer to protect themselves, and direct them to reliable information through the WNV Fight the Bite website
• Albertans can also call Health Link Alberta for more information.

Humans

All cases reported

Under the authority of the Public Health Act, human cases of WNV infection are reported to public health officials in Alberta.

The milder form of the infection, West Nile Non-Neurological Syndrome (formerly known as West Nile Fever) and the more serious form of the disease known as West Nile Neurological Syndrome are both reported to Medical Officers of Health, Alberta Health and Wellness, Public Health Agency of Canada and if necessary, to Canadian Blood Services.

Blood supply protected

Alberta Health Services will notify Canadian Blood Services when it is suspected that an individual has WNV and there is a history of either donating or receiving blood or blood products. Measures will then be taken by Canadian Blood Services to prevent the possibility of WNV transmission through blood.

Physicians alerted

Once WNV is confirmed in Alberta in a person who does not have a history of travel to an area with WNV, physicians will be notified of this information through the local Medical Officer of Health. Physicians will also be asked to consider WNV when someone presents with specific symptoms and ensure laboratory testing is ordered as appropriate.

Laboratory testing

All WNV testing in Alberta will be carried out by the Provincial Laboratory for Public Health.

Prevention stressed

Alberta Health Services will implement a public awareness campaign will remind Albertans of WNV and the measures they can take to protect themselves and their families.

Messages to the public

Alberta Health and Wellness will monitor and report on the number of cases of WNV human infections in Alberta on an ongoing basis.

• The numbers of cases of WNv will be posted on the Alberta Health and Wellness WNV website.

Mosquitoes

Role in surveillance

There will be no mosquito surveillance in Alberta in 2011.

The mosquito surveillance plan was initiated in 2003 with the objectives of performing West Nile virus testing on mosquito pools in different areas of the province, determining the presence of West Nile virus in mosquitoes, and to assist in determining the point where transmission from mosquitoes to humans is of greatest risk.

Since its arrival in Alberta, the virus has exhibited a consistent pattern of occurrence. Information collected from 2003 to 2008 indicates the period of greatest risk of WNv transmission to humans is between mid-July and mid-August. This is related to the presence and activity of the mosquito Culex tarsalis. The success of this mosquito acting as a transmitter of the virus is dependent on consistent warm weather from early June through mid-August.

Messages to the public

Alberta Health Services will provide messaging to the public on personal protective measures will occur in the summer to coincide with the period of greatest risk of WNv infection.

Birds

Role in surveillance

Alberta is no longer conducting WNV surveillance in wild birds. The surveillance program was originally designed to provide an early warning system to alert the public and officials to the presence of the WNV. Since its arrival in Alberta in 2003, the virus has exhibited a consistent pattern of occurrence, so there is no need to submit individual dead birds for testing.

WNv expected in 2011

Similar to the past seven years, limited bird mortality is likely to occur largely in the Grassland Natural Region of southeastern Alberta where conditions are most favourable for development of the Culex tarsalis mosquito, the only mosquito that appears to be effectively transmitting the virus in Alberta.

The number of dead birds infected with WNV has declined significantly since 2003. However, the populations of birds such as crows and magpies have not declined. It is likely that these birds, as well as other bird species exposed to the virus, adapted to the presence of WNV in the ecosystem and developed protective immunity.

Messages to the public

Information on how to handle dead birds and answers to frequently asked questions are available on the Alberta Health and Wellness website and the Alberta Sustainable Resource Development’s, Fish and Wildlife website.

Horses

Role in surveillance

Cases of WNV in horses will be monitored, used to identify the presence of the virus and provide information to alert the public.

Low risk / serious illness

Although the risk of an individual horse becoming infected with WNV is very low, a small proportion of horses infected with WNV will develop varying degrees of clinical disease. Up to 35 per cent of these sick horses will die or have to be euthanized because of complications resulting from the illness.

Reporting

Under Alberta's Animal Health Act, WNV is a notifiable disease and anyone knowing or suspecting WNV infection in a horse must report the occurrence to the Chief Provincial Veterinarian’s Office within 24 hours. During regular business hours call 780-427-3448 or 24 hour emergency toll-free 1-800-524-0051.

Information for owners

Alberta Agriculture and Rural Development and the Alberta Veterinary Medical Association provide information to veterinarians informing them of the surveillance and reporting protocols.

Information is available for horse owners about the precautions they can take to minimize the risk of WNV to their animals. This includes steps that can be taken to reduce exposure to mosquitoes that may carry WNV (e.g., reducing mosquito breeding sites, ensuring barns have screening in good repair, applying repellents containing DEET, regularly changing water in water tanks etc).

Horse owners are advised to consult their veterinarian regarding the use of vaccination to prevent WNV in their horses.

Messages to the public

Alberta Agriculture and Rural Development provides a fact sheet, articles in Agri-News, public information spots on “Call of the Land” and materials for various stakeholder publications.

Information regarding any positive cases will be posted on the Chief Provincial Veterinarian website.