Report
to / Rapport au:
Health,
Recreation and Social Services Committee /
Comité de la santé, des loisirs et des services
sociaux
and Council / et au Conseil
11 April 11, 2003 / le 11 avril 2003
Submitted
by/Soumis par : Jocelyne St Jean, General Manager/Directrice générale
People
Services Department/Services aux citoyens
Contact/Personne-ressource : Robert Cushman, Medical Officer of Health/
Médecin chef en
santé publique
Public Health
and Long-Term Care / Santé publique et soins de longue durée
724-4122
ext. 23684 Robert.Cushman@Ottawa.ca
|
Ref No: ACS2003-PEO-HEA-0007 |
SUBJECT: WEST
NILE VIRUS – PREPAREDNESS AND PREVENTION PLAN, CITY OF OTTAWA
OBJET : VIRUS
DU NIL OCCIDENTAL – PLAN DE MESURES D’URGENCE ET DE PRÉVENTION, VILLE D’OTTAWA
REPORT RECOMMENDATIONS
That the Health, Recreation and Social
Services Committee recommend that Council approve funding in the amount of
$600,000 to be cost shared on a 50/50 basis with the Province for a West Nile
Virus (WNv) preparedness and prevention plan for the City of Ottawa in 2003,
including:
· Public education, particularly with respect to personal protective measures against mosquitoes and source reduction of mosquito breeding sites.
· Mosquito, bird, and human surveillance.
· Source reduction of mosquito breeding sites on City-owned properties.
· Mosquito control using a biological larvicide (Bti) in surface waters (i.e. ditches, storm water management ponds) and a chemical larvicide (Methoprene) in non-surface waters (i.e. catch basins of storm sewers) and in sewage lagoons.
· Only in circumstances where it is absolutely necessary, mosquito control using an adulticide (i.e. Malathion). Adulticide would be indicated in focal geographic areas with evidence of intense transmission in birds and human disease. The decision to adulticide rests with the Medical Officer of Health and would depend on updated risk assessments examining:
a) the level of risk to public health from the mosquito-borne virus
and
b) the risk to human health of exposure to the adulticide.
Note: “The use of adulticiding is strictly an emergency or contingency measure when a significant and immediate risk to public health exists, and all other measures of prevention or control either have been tried and shown to be inadequate, or would clearly not be effective if instituted anew.” (West Nile Virus Preparedness and Prevention Plan for Ontario 2003, Ontario Ministry of Health and Long-Term Care).
Que le
Comité de la santé, des loisirs et des services sociaux recommande au Conseil
d’approuver un financement de 600 000 $, suivant une formule de
partage égal des coûts avec la Province, en vue de la mise en œuvre d’un plan
de mesures d’urgence et de prévention du virus du Nil occidental (VNO) pour Ottawa
en 2003, qui comporterait :
·
une
campagne de sensibilisation du public, notamment en ce qui concerne les mesures de protection personnelle contre
les moustiques et de contrôle des lieux de reproduction des moustiques;
·
un
programme de surveillance des moustiques, des oiseaux et des humains;
·
le
contrôle des lieux de reproduction des moustiques sur les propriétés
municipales;
·
la
lutte contre les moustiques au moyen d’un larvicide biologique (Bti) dans les eaux de surface (fossés et
bassins de rétention des eaux pluviales) et d’un larvicide chimique (Methoprene) dans les eaux profondes
(puisards de rue des égouts pluviaux) et dans les bassins d’eaux usées;
·
seulement
si cela s’avère absolument nécessaire, la lutte contre les moustiques au moyen
d’un imagocide (Malathion), qui
serait utilisé dans des secteurs géographiques ciblés qui montrent un fort taux
de transmission de la maladie chez les oiseaux et les humains. La décision
d'utiliser un imagocide sera faite par le Médecin chef en santé publique et
sera faite en fonction d'évaluations à jour des risques portant sur :
a) le
niveau de risque pour la santé publique que pose la transmission de la maladie
par les moustiques
et
b) le
niveau de risque pour la santé humaine d’une exposition à l’imagocide.
Nota : « L’utilisation d’un imagocide
est strictement une mesure d’urgence ou de prévoyance qui ne doit être
envisagée que lorsqu’il existe un risque considérable et immédiat pour la santé
publique et que toutes les autres
mesures de prévention ou de lutte se sont révélées inadéquates ou seraient
manifestement inefficaces si elles étaient appliquées de nouveau. » (tiré
du West Nile Virus Preparedness and
Prevention Plan for Ontario 2003, Ministère de la Santé et des Soins de
longue durée de l’Ontario)
WNv first appeared in the Western Hemisphere in 1999. In Canada, the first human cases were recorded in 2002. In Ontario, there were 307 confirmed and 83 probable WNv human cases reported. No human cases have been reported in the City of Ottawa. No human vaccine yet exists for WNv and treatment of the severe form of the illness is limited. For more details on the history of the disease, please see Annex 1.
Given the spread of West Nile virus throughout North America last year, most experts presume that the spread of the disease will continue. It is considered likely that human cases of WNv will occur in Ottawa in 2003. Because the spread of West Nile virus is unpredictable and can cause serious illness or death, it is important to act now. In this age of global travel and evolving diseases, governments need to remain focused on the goal to protect human health. Protection of the environment is also important, and the City’s WNv plan addresses environmental concerns by emphasizing front-end larviciding in an effort to reduce the potential requirement for adulticiding at a later date.
The provincial strategy for WNv, as outlined by the Ontario government, is a 7-point plan for WNv. This provincial plan includes new lab testing capabilities, tracking the virus, public education, mosquito control, early warning, community exposure study and research. Funding for municipal West Nile efforts will be cost-shared on a 50/50 basis with the Province. The provincial strategy makes it clear that implementation of the WNv strategy will be at the municipal level under the direction of the Medical Officer of Health. The City of Ottawa will work in co-ordination with the Province, and in some areas, will supplement the Province’s strategy. The City’s plan is similar to what is being organized in other cities in Ontario.
DISCUSSION
A local WNv control strategy has four main pillars – public education, source reduction of mosquito breeding sites, surveillance, and mosquito control.
The Ministry of Health and Long Term Care is
currently working on new educational materials that are expected to be released
soon. The City of Ottawa will make these materials available to the public at
Client Service Centres, Ottawa Public Library Branches, childcare centres and
seniors’ residences, and on the City’s website. Discussions have been held with
the National Capital Commission (NCC) and, as in previous years, the NCC will
post WNv information at their public properties.
The City of Ottawa is also developing its own public awareness campaign to be disseminated shortly and that will complement the provincial strategy. During the past two summers, the City has conducted a WNv public information campaign, including media briefings and the dissemination of pamphlets. This season, the City will increase the scope of its WNv campaign and is currently investigating other methods of information distribution.
Information included in the campaign will include
measures to increase personal protection as well as measures to
reduce/eliminate mosquito breeding sites around the home and property. Personal
protection measures include staying inside at dawn and dusk in
mosquito-infested areas and using mosquito repellants. Health Canada has revised its guidelines on
the use of the mosquito-repellant ingredient DEET (N, N-diethyl-m-toluamide)
for adults and children. Such information will be included as part of our
campaign.
To target mosquito breeding sites, residents will be urged to store tires inside; change birdbath water frequently; and protect containers from holding standing water. Other recommendations will be to: store small boats and canoes upside down; construct sumps so that water does not stand, or screen opening to prevent mosquito entrance; drain plastic covers on lawn chairs; and clean eavestroughs and rain gutters.
The public will be encouraged to keep swimming pools, spas and hot tubs chlorinated, re-circulating systems operating, and if not in use, covered tightly to keep rainwater from accumulating on the cover. Residents will be encouraged to remove pool covers early in this spring and turn on the re-circulating system to remove any ‘standing water’ condition in the pool.
A WNv survey was conducted with Ottawa residents by Health Canada in July 2002 to explore public awareness of West Nile virus. Roughly 500 respondents completed the survey. The survey report, entitled West Nile virus: A Survey about Awareness, Attitudes, and Practices of City of Ottawa Residents, found that about 60 % of respondents had items around their homes that collected water, and that more than 70% of them drained these items. The majority of adult respondents reporting using mosquito repellants when mosquitoes started biting (about 73%), with most using DEET-containing products. Significantly fewer urban parents reported using repellent on their children compared to parents who lived in rural areas.
Source Reduction of mosquito breeding
sites (City-owned property)
Just as private property owners will be encouraged to reduce or eliminate mosquito breeding sites, the City of Ottawa plans to monitor potential breeding sites on City property and encourage public agencies to do the same. City staff will investigate the status of City parks and ditches and decide how best to reduce or eliminate their potential as mosquito breeding sites.
Environmentally sensitive areas will not be drained or altered in any way.
Effective May 1, 2003, WNv human illness will be reportable under the Health Protection and Promotion Act, meaning physicians must report cases suspected, possible and confirmed cases to the Medical Officer of Health, who then reports the cases to the Ministry of Health and Long-Term Care. A new case definition of human WNv illness has been put forward to the West Nile Virus National Steering Committee, soon to be adopted as the national standard. The definition gives clinical and laboratory criteria for suspected, possible and confirmed cases. The Medical Officer of Health in Ottawa will provide detailed communications to local physicians, hospitals and medical clinics on the new WNv case definition, and encourage a high index of suspicion and WNv testing on all suspicious cases. Fortunately, this year, human WNv testing will be more readily accessible and results available more quickly as the Province has improved its human testing capabilities.
Surveillance of dead crows is thought to play an important role in predicting outbreaks of the disease. There is some evidence from Halton, Ontario and Chicago, Illinois that human cases tend to increase shortly after a dramatic increase in dead crow sightings. Given the important role of such surveillance, the City of Ottawa plans the following:
· The public is encouraged to report dead crow sightings to 580-2400 (City Call Centre) starting May 5, 2003. Dead crows found on roads and presumably killed by vehicles should also be reported, as these birds may have become vulnerable to traffic due to WNv infection. Dead crow sightings will be mapped geographically using the City’s GIS technology. People should not report sightings of other types of dead birds.
· The Canadian Cooperative Wildlife Health Centre (University of Guelph) will receive dead crows from across the Province. The centre will receive dead crows from May 5 forward, accepting no more than four dead crows per week from Ottawa.
· Ottawa Public Health plans to hire a person who will be responsible for picking up dead crows reported by the public to the City’s Call Centre at 580-2400. The public is urged to wait for pick-up and not to touch the bird. Pick-ups are to occur weekdays and weekends starting May 5, 2003.
The City of Ottawa has developed experience in mosquito surveillance from previous years. Mosquito surveillance is important for two reasons – to track the population of the disease vector and to monitor the effectiveness of mosquito control measures.
Adult mosquitoes are collected in traps; larvae are counted by dipping in surface waters. Mosquito surveillance will be done on different species of bird-biting and human-biting mosquito larvae and adult mosquitoes.
Based on the Province’s mosquito surveillance protocol, Ottawa is required to set up 5 mosquito traps over a 20-week period, emptying these traps every two weeks and sending specimens to Brock University for WNv testing. Because it is felt that 5 traps are not sufficient, Ottawa Public Health will supplement this work by increasing the number of traps set up in Ottawa.
The Canadian Food Inspection Agency has made WNv in horses an immediately notifiable disease under its legislation. Equine WNv cases will be reported to the provincial Ministry of Health and Long-Term Care by the Ministry of Agriculture and Food. A vaccine now exists for equine WNv.
To demonstrate why larviciding is necessary, it is important to understand the WNv transmission cycle. Bird-biting mosquitoes (i.e Culex) breed in standing water such as birdbaths and storm sewers starting in May, after which their population increases steadily over the season. Bird infections increase along with the increases in the numbers of Culex mosquitoes. At a certain level of infection in birds, another type of mosquitoes (i.e. Aedes, which breed in places like ditches) begin transmitting the virus from birds to humans. If the infection threshold in birds is not met, human infections are more likely to be prevented. That is why it is crucial to larvicide Culex mosquitoes early in the season as a measure to prevent bird infections, and thus transmission to humans later on.
The fact that the WNv virus must reach a critical level in mosquito and bird populations before humans become infected may explain why human infections aren’t generally reported until August and September. Weather needs to be regularly monitored because it influences mosquito life cycles.
“The use of
adulticiding is strictly an emergency or contingency measure when a significant
and immediate risk to public health exists, and all other measures of
prevention or control either have been tried and shown to be inadequate, or
would clearly not be effective if instituted anew.” (West Nile virus
Preparedness and Prevention Plan for Ontario 2003, Ontario Ministry of Health
and Long-Term Care).
The City of Ottawa will be sending out a Request for Proposals to retain the professional services of a suitable firm that will conduct WNv surveillance and mosquito control as needed. Public Health will direct, administer, and monitor the project and the work of the contractor. A Technical Advisory Committee (TAC) consisting of representatives of various City departments will be formed to act as a resource group for the project.
There are environmental implications regarding the use of chemical larvicides and adulticides.
There is an important distinction to be made between the cosmetic use of pesticides and non-cosmetic use. Non-cosmetic use involves pesticide application on lawns and gardens. The City of Ottawa, under direction from City Council (Dec. 2002), is currently engaged in a three-year strategy to encourage residents to reduce or eliminate the cosmetic use of pesticides on their lawns and gardens. As well, the City has prohibited cosmetic pesticide use on public properties such as parks and boulevards.
Like antibiotics, pesticides should be used only when necessary, and where the indications for their use are clear. The overuse of pesticides not only leads to pest resistance, but also poses health and environmental risks. Because some non-cosmetic pesticide use has become necessary to protect public health in the prevention of WNv illness, Ottawa residents are strongly encouraged to reduce or eliminate their cosmetic use on lawns and gardens. The City’s pesticide reduction campaign will provide residents with advice on alternatives to pesticides on residential properties.
Non-cosmetic pesticide uses, which include agriculture and the protection of human health, were exempted in the City’s pesticide reduction strategy. Pesticide use for mosquito control to prevent human WNv illness is a good example of a non-cosmetic use that is justified on the basis of protecting human health.
RURAL IMPLICATIONS
The larvicide Methoprene will be applied in storm sewers, which are more commonly found in urban areas as compared to rural areas. Concerns have been raised in the media about the potential for mosquito breeding at a sewage lagoon in Munster. Sewage lagoons can be treated with Methoprene for mosquito control.
The Medical Officer of Health and staff at Ottawa Public Health have had ongoing discussion on WNv with the Ontario Ministry of Health and Long-Term Care, other Medical Officers of Health in Ontario, the Medical Officer of Health for Gatineau and other City departments such as Transportation, Utilities and Public Works and Corporate Communications. Public Health has also been in recent contact with the National Capital Commission.
A Public Health representative met with the City’s Environment Advisory Committee to present the WNv Preparedness and Prevention Plan on April 10, 2003.
FINANCIAL IMPLICATIONS
All WNv activities conducted in the City of Ottawa are cost shared on a 50/50 basis with the Province of Ontario. An exact funding amount is not known at this time because the City awaits proposals from companies; the proposals will include cost estimates.
It is estimated that for 2003, the upset limit for this work would be $600,000, for which the City would pay half and the Province would pay half. The final costs will reflect the number and frequency of mosquito control applications.
The budget pressures identified are not presently included in the Public Health and Long Term Care operating budget and would require Council direction. If approved, the funding would come from the City-wide Reserve Fund. This Reserve Fund is a component of the $50 million minimum tax-supported reserve fund balance directed by Council. The City’s Notice By-law requires that the budget amendment be advertised prior to the Corporate Services and Economic Development Committee meeting where amendment is introduced.
For 2004, these costs would need to be included in the budget development process as a new budget pressure.
1. Public Health, People Services Department will implement decisions resulting from consideration of this report.
2. The Medical Officer of Health will provide public updates on the
status of WNv in Ottawa throughout the 2003 season.
Annex 1 – History of the Disease in North America
West Nile virus (WNv) can cause illness and death in many species of birds and mammals, including humans.
WNv first appeared in the Western Hemisphere in 1999, causing 61 human cases of encephalitis in New York City, resulting in 7 deaths. In 2000, there were 21 U.S. human cases (2 deaths) in three states. By 2001, the illness had spread to 11 states. The United States experienced a marked increase in the number of reported human cases in 2002 (4,008 laboratory-confirmed humans and 263 human deaths in 39 states). The northern American states had more human cases than the southern states in 2002, with a concentration of cases near the Great Lakes in locations such as Illinois and Ohio.
In Canada, the first human cases were recorded in 2002. In Ontario, there were 307 confirmed and 83 probable WNv human cases reported, including 17 deaths.
No human cases have been reported in the City of Ottawa. However, 4 birds in the City of Ottawa did test positive for the virus in 2002, and one horse in Ottawa was confirmed positive. No mosquitoes have tested positive for WNV in Ottawa; a very limited number of mosquitoes were trapped and tested here in 2002 due to provincial testing protocol.
For people infected with West Nile virus, there are three levels of manifestation of the illness. Figures below are based a sero-survey (testing blood to look for exposure) that was carried out in Queens, New York in 1999. A similar sero-survey is being planned this year in Halton region (Oakville/Burlington), which saw high levels of WNv illness in 2002.
· 80 per cent of those infected have no symptoms and are not aware they have been infected.
· About 20 per cent have a mild illness that is called West Nile Fever. Typical symptoms of West Nile Fever can include: tiredness, headache, muscle aches, rash, nausea, vomiting, eye pain and fever. People generally recover without having lasting effects.
· Approximately one of every 150 people (0.7%) infected with the virus will develop serious illness with neurological symptoms. While all age groups may be at risk for the disease, the risk of having more severe disease increases with age. Symptoms of WNv Neurological Manifestations may include fever, headache, stiff neck, disorientation, tremors, muscle weakness/paralysis and coma. The disease sometimes manifests itself as a polio-like illness.
A recent study examined 64 WNv cases admitted to 7 hospitals in the Toronto, Peel and Halton regions, and found that “the WNv outbreak of 2002 resulted in unexpectedly serious morbidity and mortality.” Of the 64 cases of documented WNv infection, 57 suffered from WNv encephalitis and/or neuromuscular weakness. Sixteen of the patients studied required intubation and mechanical ventilation as a result of a depressed level of consciousness, inability to safely handle secretions, or paralysis of respiratory muscles, while 9 others suffered disabling muscle weakness of one or more limbs. Difficulty swallowing was commonly noted. Ten patients died (18 % of those with neurological manifestations). Only 20% of the survivors could be discharged home without additional support. It is believed that many people experiencing severe neurological deficits from WNv illness will suffer chronic, possibly permanent deficits. In the study, patients were predominantly active independent middle aged and elderly people, and they became ill in August and September.
The incubation period (time from mosquito bite to first symptoms) for WNv ranges from 3 to 14 days. No human vaccine yet exists for WNv. Treatment of the severe form of the illness is limited and there is no cure.
WNv is transmitted from infected birds to humans by mosquito bites. The presence of the virus in a community is maintained through a bird-mosquito chain. Humans are not naturally part of the life cycle of the virus, and are therefore called ‘incidental hosts.’
There are other rare forms of human WNv
transmission - through human blood and organs, through maternal milk, from
mother to fetus, and to laboratory workers through accidental needle injection. The Centers for Disease Control and
Prevention in Atlanta have issued a warning to wild game hunters to use
prophylactic measures when handling animal carcasses.