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HomeMy WebLinkAboutCOUNCIL - AGENDA ITEM - 02/24/2004 - DISCUSSION REGARDING WEST NILE VIRUS UPDATE DATE: February 24, 2004 STUDY SESSION ITEM STAFF: Tom Vosburg FORT COLLINS CITY COUNCIL SUBJECT FOR DISCUSSION Staff would like to review proposed plans for dealing with West Nile Virus in 2004. GENERAL DIRECTION SOUGHT AND SPECIFIC QUESTIONS TO BE ANSWERED 1. Should the City of Fort Collins fund and implement an Integrated Pest Management(IPM) mosquito control program to reduce the risk of West Nile virus to city residents in light of the uncertainty of the degree of threat West Nile virus will pose this year? 2. If so, does Council support implementing an IPM program that assumes extensive use of larvicide, but no use of adulticide spray? 3. If a public health emergency is declared by the Latimer County Board of Health, which option for a City response does Council support? BACKGROUND Overview of Integrated Pest Management Programs The term Integrated Pest Management (IPM) refers to a comprehensive approach to dealing with vector born diseases, rather than a limited approach focused solely on reducing the vector population. Foundation elements of an IPM mosquito control programs typically include the following elements: 1. Data gathering, mapping and reporting processes; 2. public information regarding the nature of the problem and how the general public can protect themselves; 3. training workers high in risk of exposure to mosquitoes ( i.e. park maintenance workers, natural area rangers and maintenance staff, etc...); 4. breeding site reduction (draining standing water). IPM programs may also include active mosquito control elements; including: 5. Larval control (use of granular larvicide applied to mosquito breeding sites); and 6. adult mosquito control (use of adulticide spray to kill adult mosquitoes). February 24, 2004 Page 2 The foundation elements of IPM programs are generally non-controversial. The active mosquito control elements of these programs invoke debate. Active mosquito control is expensive, and it is difficult to evaluate the effectiveness of these programs in actually reducing human infections. Mosquito control experts recommend wide spread use of larvicide as the primary focus of mosquito control programs; adulticide should only be used after larva control has been attempted and failed to adequately reduce mosquito populations. Also, while larvicides are generally accepted as being environmentally benign, many people are concerned about the safety of widespread use of adulticide spray, despite official assessments that these products pose little risk to humans. Review of 2003 Experience Fort Collins developed and implemented a IPM program to respond to West Nile virus in 2003. This IPM program was developed in cooperation with Larimer County and CSU. The State Health Department and the Center for Disease control were also involved in development of the 2003 program. The 2003 IPM program focused on the foundational elements outlined above. Few expected mosquito activity to reach a level that would require active mosquito control. Unique weather conditions (a wet spring followed immediately by a period of very high temperatures) resulted in extraordinarily high mosquito populations last year. Although the City and County began larval control measures,these measures were started very late in the season,well after significant adult mosquito populations were established. The Larimer County Health Department declared a public health emergency in response to a significant increase in human cases of West Nile Virus, and recommended that municipalities and the County implement adult mosquito control measures. The City of Fort Collins implemented a targeted,truck based spray program,and the County implemented a large scale aerial spray program. The Center for Disease Control evaluated the effectiveness of the 2003 Fort Collins and Latimer County adult mosquito control programs. Its study found no detectable difference in human infection rates between sprayed and unsprayed portions of the City. Comparison of the rate of decrease in Human West Nile cases in Larimer County to the rate of decease in other counties did suggest that the combined effect of all measures taken in Latimer county (including those by Fort Collins,Loveland and Berthoud)did appear to be related to a more rapid decrease in case rates here. However, this relationship could not be documented as scientifically defensible. A summary of the CDC review of last's year's program is included as attachment 1. Planning for 2004 Staff has coordinated with the Larimer County Department of Health,CSU and the City of Loveland in planning for 2004. In addition to staff efforts,the Natural Resources Advisory Board and the Air Quality Advisory Board formed a joint task force to review issues related to West Nile virus and to make recommendations to Council. A letter containing the task force recommendations to Council is included as Attachment 2. February 24, 2004 Page 3 It is not clear how significant a threat West Nile Virus will pose to City residents this year. A general trend exhibited by areas that have already experienced the virus for a number of years is that the second year the virus is active in an area,is the worst in terms of human cases, and that human infection rates drop off significantly in subsequent years. 2003 was the second year of West Nile virus activity in Latimer County, so if this general pattern holds true, Fort Collins should expect lower levels of human cases in 2004. However, the Center for Disease Control warns that conditions in the West are very different than those in the East, where patterns have been established. Enough exceptions to this rule have been demonstrated that it may not be prudent to expect a decreased third year infection rate in planning the City's response for 2004. Revised IPM Plan for West Nile Virus Based on input from the NRAB/AQAB joint task force, the Latimer County Department of Health and mosquito control contractors, staff is recommending that the City implement an IPM program that maintains all of the foundational program elements that were implemented last year (public information, employee training, etc.....), but that we also begin a more extensive larval control program very early in the season. This program would involve applying larvicide to as many mosquito breeding sites in and around Fort Collins as possible. The larvicide would be applied using a variety of methods, included helicopter and manual application. Three or more applications would be required through out the season to provide on-going protection. To be effective,the larval control program should include a buffer area outside the city limits to limit the number of mosquito hatching outside the city and then flying in. Staff has developed a proposed larvicide program area in coordination with the Loveland mosquito control program. This program area and its relationship to Loveland's control area is illustrated by the map included as attachment 4. Staff estimates that providing mosquito trapping,larval control and public information services for this area would cost between $200,00 and$250,000 for the 2004 mosquito season. Staff also recommends that the City's limited financial resources for active mosquito control be directed larval control, and that we do not use adult mosquito control in our 2004 IPM program. Staff notes that a number of Homeowners' Associations privately contract with mosquito control contractors to spray for adult mosquitoes, so some spraying for adult mosquitoes will likely to continue to take place within the city. Options for Responding to a Public Heath Emergency Although staff is confident that the proposed larvicide oriented IPM program will significantly reduce the number of adult mosquitoes in Fort Collins, there is a possibility that extraordinary conditions could lead the Latimer County Board of Health to declare a Public Heath Emergency with a recommendation to implement adult mosquito control again in 2004. The City will have a number of options of how to respond to such an event: February 24, 2004 Page 4 Option 1: Do not implement adult mosquito control, but instead increase public education activities regarding personal protection measures. Option 2: Fund and administer a truck based,targeted adult mosquito control program similar to last year's program. Option 3: Allow County or State agencies to design, fund and administer an adult mosquito control program without active City administrative or financial involvement. Staff recommends Option 1 as the City's response in the event that the Larimer County Board of Health declares a public health emergency again in 2004. Staff is concerned that it is likely that any such declaration will come late in the season, and that it will be too late to effectively implement adult mosquito control. The CDC's evaluation of last year's program(which was similar to Option 2)did not demonstrate that the late season adult control was effective in decreasing human infection rates. Staff also notes that both the State and the County have the authority to implement Option 3, with or without the consent or participation of the City. Regional Coordination and Cost Sharing The proposed 2004 IPM will be coordinated with the Larimer County,CU and other municipalities. Public information campaigns will be coordinated between each entity, and Latimer County will continue to coordinate data collection and reporting for the region. The City has worked with Loveland to design the coverage of the two cities larval control programs to provide complete coverage between the two cities. However, few opportunities exist share the substantive cost of the larval control program. The City of Loveland already has a funded, on-going mosquito control program that includes the use regular use of adult mosquito control spray. As a result, it would be difficult for the City to administer a joint program with Loveland. Larimer County is not planning to fund or implement any larval control or adult mosquito control this year, so there is no opportunity to share costs with the County. Senator Allard is attempting to secure federal funds to assist Colorado with mosquito control, but it is not clear if these efforts will be successful. Next Steps If Council supports the staff recommendation to fund and implement the proposed larvicide based IPM program for 2004, staff will proceed with selecting a vendor and implementing the program. Larvicide application activities could be expected to begin in April of 2004. ATTACHMENTS 1. Summary of CDC study of Fort Collins and Larimer County 2003 mosquito control programs. 2. Recommendation of the NRAB/AQAB Joint West Nile Virus task force. 3. Map of proposed 2004 Fort Collins larval control program boundaries RECOMMENDATION FORT COLLINS WEST NILE VIRUS TASK FORCE DATE: February 18, 2004 TO: City of Fort Collins Mayor and Council Members FROM: Fort Collins West Nile Virus Task Force SUBJECT: Recommendations Regarding West Nile Virus Control Measures The West Nile Virus (WNV) Task Force is a 11-member group comprised of scientific experts, members of the air quality and natural resources advisory boards, and citizens. The task force voluntarily convened for the purpose of drafting recommendations for safe, effective, and acceptable responses to a possible a WNV outbreak in 2004. Beginning in December of 2003, the task force met three times to discuss the human health and environmental ramifications of various control methods to minimize WNV effects. Based on its scientific expertise, reviewing the scientific literature, and examining other cities'WNV management programs, the task force presents the following recommendations for Council consideration: 1. The City of Fort Collins should adopt an integrated pest management (IPM) approach toward WNV control in 2004. IPM methods combine all natural factors, together with compatible cultural, chemical, and supportive measures, rather than simply relying on chemical controls. To address WNV in Fort Collins, the task force recommends a specific IPM approach consisting of the following elements: a) Development and promotion of a campaign to reduce mosquito larvae in waters on private property, including public service announcements educating residents on where mosquitoes breed and effective source control measures starting in early spring; b) Initiation of citizen action by providing small larvicide pellets called "Dunkits" to residents, as was done in the City of New Orleans; c) Strong emphasis on personal citizen responsibility for protection from mosquitoes through frequent, easy to understand public service announcements stressing personal protection, particularly in July and August; d) Proactive and effective communication with the media and neighborhood organizations about control measures undertaken by the City to maximize the effectiveness of these measures; e) Control of mosquito populations through coordinated and appropriately-timed (spring through summer) larvicide applications to wetlands, catch basins, and other breeding grounds. WNV Task Force Recommendation 1 February 18, 2004 RECOMMENDATION FORT COLLINS WEST NILE VIRUS TASK FORCE 2. Fort Collins should work with Larimer and Weld counties to develop a regionally coordinated IPM approach. Loveland, Greeley, and Boulder County are all committed to larvicide treatments; however, the effectiveness of the Cities' programs requires that Larimer and Weld counties also participate. 3. The City should develop a detailed GIS database to identify and map most small water bodies where mosquitoes breed in order to develop a long-term IPM program for mosquito control. 4. The City should develop and maintain a long-term monitoring program to track the occurrence of WNV. The Fort Collins WNV Task Force recommendations are based on the best available information, scientific studies and professional experience, summarized as follows: • WNV is here to stay but future outbreaks should become less severe than in 2003. Usually the greatest virus outbreak severity occurs in the second year. However, there have been exceptions, such as outbreaks that occurred in Pennsylvania. Hence, Fort Collins cannot assume the 2004 WNV season will be less extreme. • The Culex mosquito that carries the WNV breeds in accumulations of standing water from April through to the first frost in the fall. • Adult mosquitoes can travel up to five miles/night in search of a blood meal. This distance can increase to 18 miles on a windy night. Thus, a city control program by itself, without comparable control efforts in Weld and Larimer counties, will not completely control the exposure of Fort Collins residents to mosquitoes. • Larvicides can effectively reduce mosquito numbers, but the effectiveness is related to the number of water bodies treated in a region. When ALL water bodies are treated, as in Cheyenne, Wyoming, larval control measures are extremely effective. • Fort Collins, Larimer, and Weld counties, do not have wetlands and small, standing water bodies mapped in sufficient detail for maximum larvicide effectiveness. This problem is made worse by pools such as animal water bowls and even flower pot saucers in backyards, a potentially significant source of mosquitoes. • The larvicides methoprene and BTI commonly used for mosquito control last as long as 150 days after application and are extremely specific in targeting mosquito larvae. Although still uncertain, it appears few other non-target species are susceptible to these larvicides. Non- WNV Task Force Recommendation 2 February 18,2004 RECOMMENDATION FORT COLLINS WEST NILE VIRUS TASK FORCE biting midges (chironomids), an important fish food, are susceptible. However, at low dosages the long-term effect on aquatic organisms is thought to be negligible. • Spraying for adult mosquitoes is expensive and there is a strong public perception that larvicides are much safer than adulticides. The results of a Center for Disease Control (CDC) study of Fort Collins' adulticide spraying program (Roger Nasci, 2004) showed the spraying was possibly effective in reducing mosquito numbers in the sprayed areas, at least temporarily. However, the CDC study failed to conclude that adulticide spraying curtailed transmission of WNV to humans. The study showed the peak of virus transmission to humans occurred well before spraying began. In addition, the study showed there were no significant differences in the numbers of reported human cases in sprayed and unsprayed areas following the spraying program. • The chemicals that are typically used to kill adult mosquitoes are pyrethroids, a class of compounds that may have deleterious non-target effects. Their application definitely causes concerns among a large number of citizens. • An active monitoring program, including dead bird counts and the numbers and infection rates of adult mosquitoes is essential to track both the spread of the virus and th q p e effectiveness of control actions. Thank you for considering the WNV Task Force's recommendations. Please feel free to contact the task force members for any additional information on this important public health issue. Respectfully submitted, Jill Baron, PhD. Will Clements, PhD. Randy Fischer, NRAB Boris Kondratief, PhD. Eric Levine, citizen Greg McMaster, PhD. Chester Moore, PhD. Sarah Rathburn, PhD. Ryan Staychoke, NRAB Ellen Wohl, PhD. Nancy York, AQAB WNV Task Force Recommendation 3 February 18,2004 PROPOSED 2004 FORT COLLINS MOSQUITO LARVA CONTROL AREA MY � rrr w a Li 1 `� .�■.� ,< ,r�' ml Mai 1 1 IILI A�� 1.�■�■Y 'yY �� 111L,1 a Y 1 v ■� WI f "k, a1® T '�l l { H Pon MEN UMPKIMM �