j West Nile Virus Program Final Report - 2005.......~.:=......-.... IIIIIIII.=-""-==- a West Nile Virus Mosquito BIle ProI8ctIon FACT SH~ET ~Nili.~...aodllogll""",,~-,IIICIucIIIf~_8fICI"""""". T"8dr8_""'-"~b8twMoIdutlltndd8\ool'l n ~_.,.... v..'on..- """"*'8~,'*"' WId_ 1rItIIII0I"'"'*""8flCldoar_Ml~-*..~ ~, DftT(~~CIc8I"'08fICI8;pOMII.... FOIOw HI8II'Ic c..ws.pmciiifttsoalty 1N8CM<...,., -,-- Group Information Sessions l..,..'11 ;; ' W.""'ltomM, ec".,"'.~.,heoi1h "","o.cx._""i_q o~odd_., ""obo.i...w N"'... FcI,O<"~Q_"",,,,,,,,,,,,,p"'20,,- Co~i"""'S-Dopo"_"'3&3-o:I'~l.. ')OIt s "8 ~ "' FG<_""--, '""".coiin.c,af_c-..y HooIt+Is-._~"::lJ3.62'31 _, ':IOO,IDII'- 1-800.667.1.1\::-..... <'0 errw;::b2 t 10W101'" -=-=..:=.:: 2"'2,-_ S 1011... 0..12,...... t Nile ~~~ reduce the ris\l ] COUNTY OF LAMBTON COMMUNITY HEALTH SERVICES DEPARTMENT Environmental Health & Prevention Services 160 Exmouth Street Point Edward, Ontario N7T 7Z6 Telephone: (519) 383-8331 Toll free: 1-800-667-1839 Fax: (519) 383-7092 Email: chsd@county-iambton.on.ca www.lambtonhealth.on.ca Revised 07.2006
I TABLE OF CONTENTS EXECUTIVE SUMMARY 3 INTRODUCTION 6 BACKGROUND............ 6 TRANSMISSION...... 6 PUBLICHEALTHPREPAREDNESSANDPREVENTIONPLAN 7 HUMAN SURVElL LANC E 9 CHSD ACTIVITIES..... 9 EQUINE SURVElL LANC E 9 CHSD ACTIVITIES 10 DEAD BIRD SURVEl LLANC E 10 CHSDACTIVITIES.... 11 MOSQUITO SURVEl LLANCE 12 CHSD ACTIVITIES..... 13 MOSQUITO CONTR0 L 16 SOURCEREDUCTION 16 CHSD ACTIVITIES 16 LARVAL CONTROL.. 17 PUBLICE DUC AT ION 18 CHSD ACTIVITIES 18 RAPID RISK FACTOR SURVEILLANCE SURVEY (RRFSS) 20 RRFSS RESULTS 20 CONC LUSIONS 24 RECOMMENDATIONS 25 L County of Lambton West Nile Virus Annual Report 2005 1
EXECUTIVE SUMMARY Introduction The West Nile virus (WNV) is a mosquito-borne "flavivirus". The virus was first isolated and identified in an infected person from the West Nile province of Uganda in 1937. The first WNV outbreak in the Western Hemisphere occurred in New York City in the summer of 1999. In Ontario, 2002 has been the most prominent infection year, with close to 400 human cases and 19 deaths reported. Since then, 2005 has shown the second highest activity level, with 101 human cases and eight deaths reported. WNV is spread to humans through the bite of an infected mosquito. A mosquito becomes infected by biting a bird with the virus. The WNV is amplified over time through a bird-mosquito-bird cycle of transmission. The goal of Lambton County's WNV surveillance program is to reduce the risk of transmission to humans through the development and delivery of a comprehensive program. The program consists of the following components: public education, source reduction, larval control in catch basins, and mosquito, bird, human and equine surveillance. Many people infected with WNV will not experience symptoms or will only have mild symptoms including fever, headache, swollen lymph nodes, skin rash and/or muscle aches (West Nile Non- Neurological Syndrome). In some cases, WNV may cause encephalitis (West Nile Neurological Syndrome). Encephalitis can result in the rapid onset of severe headache, high fever, stiff neck, confusion, coma and very rarely death. Although individuals with weaker immune systems and those over the age of 50 are at greater risk of severe illness, WNV can cause complications for people of any age and health status. The Ministry of Health and Long Term Care (MOHLTe) developed a comprehensive WNV Preparedness and Prevention Plan for 2005. The plan was based on local health units undertaking a risk assessment pertinent to their jurisdiction. Surveillance, public education and mosquito control activities in Lambton County were structured around this plan and adapted to local circumstances. Human and Equine Surveillance Two human cases were confirmed in Lambton County in 2005. On October 7th,the Community Health Services Department (CHSD) was notified of Lambton's first case, a 77 year old male from Corunna. The individual died shortly after hospitalization. On October 19t\ a second human case was reported. A 56 year old male from contracted the virus and is currently hospitalized (as of December 2005). These are the first human cases reported in Lambton County since a Petrolia man was diagnosed in 2002. Two positive horses were also reported in Lambton in 2005. The first positive horse was located near Thedford and was reported in early September. The second occurred in early October and was located near Wilkesport. Neither horse had been vaccinated and both died from the disease. Bird Surveillance Birds are hosts in the WNV transmission cycle. Bird mortality data may be utilized for the early detection of WNV activity in an area and for predicting the risk of human infection. s and blue jays are particularly susceptible to the virus and have high death rates when infected. Therefore, CHSD recorded all dead bird sightings, but only dead crows and blue jays were sent to the laboratory for County of Lambton West Nile Virus Annual Report 2005 3
analysis. CHSD received a total of 376 dead bird sightings throughout the County in 2005. Eight birds (5 crows, 3 blue jays) tested positive for WNV in 2005 (see following table). Location, date and type of positive bird found in Lambton County in 2005 Date Found June 21st August 4th August 5th August II th August Ith August 19th August 22nd August 24th Type of Bird Area Sombra Corunna Mooretown Courtright Forest In 2005, the first positive bird confirmation occurred earlier than usual. In previous years, positive birds were not diagnosed until August in Lambton County. Hot weather may have amplified the virus faster in the mosquito population causing birds to be infected earlier. Mosquito Surveillance Mosquitoes are the vectors in the WNV transmission cycle. An understanding of the mosquito population is an important component of a WNV prevention and control plan. Mosquito traps were set up weekly across Lambton County. A total of 28 trapping locations were used in 2005, capturing approximately 18,300 mosquitoes. This represents a dramatic increase compared to 2004, when 5,800 mosquitoes were captured at 35 locations. Sustained hot, dry and humid weather conditions may have contributed to this increase. In 2005, three mosquito pools tested positive for the WNV in Lambton County. This is equal to the number of positive pools found in 2004. Two positive pools were found in Corunna in August and one was found in Wyoming in early September. All mosquito species that tested positive for the virus were Culex pipiens, the primary vector for amplifying and transmitting the WNV. Mosquito Control Larval surveillance provides information about the presence and abundance of mosquito populations, identifies areas of high risk and triggers control measures. In 2005, the County of Lambton entered into an agreement with the St. Clair Parks Commission (SCPC) to provide larval monitoring and larvicide applications to catch basins located on municipal property. Catch basins were treated three times between June and August and approximately 13,800 catch basins were treated during each application. In 2004, catch basins were only treated twice. Eliminating breeding sites is the simplest and most effective way to reduce the number of mosquitoes. CHSD public health inspectors were responsible for investigating stagnant water complaints on private property. In 2005, there were 41 complaints reported to CHSD. These complaints primarily consisted of unmaintained swimming pools and vacant lots. In most cases, property owners responded to the initial warning and eliminated the stagnant water. Nine complaints were received concerning municipal properties. Follow-up letters were sent to municipal clerks to increase awareness of these problem areas and to help municipalities prioritize source reduction activities. County of Lambton West Nile Virus Annual Report 2005 4
Public Education Public education is a critical component of the WNV control program. Educating the public about the importance of personal protection and source reduction is essential for minimizing the impact of the virus on the human population. The public education campaign began early in 2005, with the first WNV presentations being held in March. The campaign focused on educating the rural population, particularly horse owners, on the importance of horse vaccinations. Specific activities included: advertising, sending out information packages to veterinarians, developing a fact sheet on WNV horse vaccinations, and conducting presentations for agricultural organizations. WNV awareness was also increased by developing and distributing magnetic signs to municipal public works offices throughout Lambton County. These signs were placed on public works vehicles throughout the summer to encourage the public to "Cover Up" and to "Clean Up" to protect themselves from mosquitoes. As part of the Rapid Risk Factor Surveillance Survey (RRFSS), Lambton residents were asked several questions about WNV to examine public knowledge and opinions. Nearly 100% of respondents were aware that WNV is spread by MagneticTruckSigns infected mosquitoes. Approximately 45% of individuals had made more of an effort to avoid mosquitoes since hearing about WNV. However, perceived risk of illness from WNV was low, with only 25% of respondents reporting that they felt at risk. Only 30% of respondents knew that larvicides had been used in Lambton in 2005. Most were unsure whether larvicides or adulticides had been used to control WNV in Lambton. Almost 80% of respondents were strongly or somewhat supportive of the use of larvicides to control the spread of WNV, while less than half of respondents indicated support for the use of adulticides for this purpose. Conclusion ~t Nile '--'-==-~ 'educe the risl< 1$1"1113.8.u1 1-800_"'_11:1' -... Jt COVER UP and avoid mosquitoes Jt CLEAN UP and reduce stagnant water To date, our knowledge of the West Nile virus is too limited to make predictions about its future impact. In 2005, the number of human cases increased for Lambton County and infections were again found in horses, birds and mosquitoes. The hotter summer in 2005 may be linked to earlier infection rates in birds, repeat positive mosquito pools at one location and the occurrence of two human cases for the first time since 2002. Further research should be conducted to determine how weather patterns influence WNV activity. The following report describes the findings from the WNV program conducted in Lambton County by CHSD in 2005 involving surveillance activities, mosquito control measures, public education and future recommendations. County of Lambton West Nile Virus Annual Report 2005 5