A multiagency approach to reducing West Nile virus risk in Richmond County, Georgia, in 2015.
Augusta is the principal city of the Augusta-Richmond County Metropolitan Statistical Area, which as of 2012 had an estimated population of 580,270, (1) making it the third-largest city and the second-largest metro area in the state after Atlanta. Augusta is located about halfway up the Savannah River on the fall line, which creates a number of small falls on the river. The city marks the end of a navigable waterway for the river and the entry to the Georgia Piedmont area.
The Richmond County Mosquito Control program is a part of the Richmond County Environmental Health office. It is a small program with one full-time and 4 seasonal workers that was established in 1983 in response to the emergence of a large nuisance mosquito problem. Some limited surveillance was done in the county in response to West Nile virus (WNV), but the program worked to create partnerships with other county and local agencies, as well as with the Georgia Department of Public Health (GDPH), with the intent to expand the program into a fully functioning, integrated pest management operation. Some surveillance was done by the state entomologist in response to either complaints or WNV cases beginning in 2004. In 2007, the mosquito control program hired a seasonal mosquito surveillance technician for the year. Because of the benefits to the program associated with mosquito surveillance, in 2014 the Richmond County Mosquito Control program joined forces with the Phinizy Center for Water Sciences, a local nonprofit water quality research organization in order to trap mosquitoes at sites across the county and identify them to species. These data helped determine locations of disease-carrying mosquitoes during the 2015 WNV season, allowing mosquito control to prioritize their control efforts, reducing the risk of viral transmission in Richmond County. (2) The GDPH supported these efforts with free mosquito identification and training classes for the researchers at Phinizy Swamp, as well as providing use of the GDPH emergency mosquito surveillance trailer with its complement of mosquito surveillance equipment. (3)
West Nile virus is a mosquito-borne viral pathogen that was introduced into the United States in 1999. Within 4 years following its initial detection in New York, WNV was detected in states from the East and West coasts as well as in Mexico and Canada. (4)
West Nile virus is maintained in birds. It occasionally infects humans who are bitten by mosquitoes that have been feeding on birds. Most people (approximately 80%) infected with WNV do not develop symptoms. About one in five infected people experiences a milder illness, often termed "West Nile fever," characterized by fever, headache, muscle weakness or myalgia, arthralgia, and sometimes rash. Less than one percent of persons infected with WNV develop neurologic illness (West Nile neurologic disease (WNND)) in the form of meningitis, encephalitis, or possibly acute flaccid paralysis. Approximately 3% to 15% of WNND cases are fatal. Risk of WNND is associated with increasing age and the presence of underlying medical conditions.
The presence of WNV in Georgia was first confirmed in July 2001 when an American crow from Lowndes County tested positive for the virus. Since then, human cases, equine cases, positive birds, and positive mosquito pools have been detected every year within the state.
Since 2012, human cases have been reported every year in Richmond County (Table 1). Since mosquito control is a small program, it was determined that an interagency approach was needed to better target mosquito control to reduce mosquito populations and reduce the risk of WNV transmission. High risk areas are defined as areas with a human WNV case or a WNV positive mosquito pool.
In 2015, Richmond County Mosquito Control created a 5-step action plan for responding to a potential WNV outbreak:
Step 1: Identify a 2-block area on all sides of the high risk area without identifying case location (Figures 1 and 2). For human cases, the street name is obtained from the GDPH District Epidemiologist. (Note: The state of Georgia is divided into 18 public health districts of varying size based on population.)
Step 2: Mosquito surveillance and identification is provided by the Center for Water Science at Phinizy Swamp. When a WNV positive case is detected, trapping equipment will be positioned to establish 2 locations on each side of the positive site. Traps will be set every 2 weeks, and selected species will be sent for virus testing after identification. This will continue until the end of the year.
Step 3: Realign the spray areas to include WNV positive locations. Use a thermal fogger in overgrown yards and unoccupied houses. If any mosquito pools test positive for WNV, reevaluate the spray areas and patterns. Add an additional spray event in the early morning to control daytime biters (Table 2).
Step 4: Conduct a neighborhood survey (Figure 3) to locate any other mosquito habitats that can be eliminated or treated, working with code enforcement, animal control officers, and deputies from the marshalls' department to write citations if necessary. Once completed, reevaluate the spray areas with any new information and make any necessary adjustments.
Step 5: Continue the public awareness program. This includes media events, health fairs, and a family emergency planning day.
The non-WNV positive areas continued to be sprayed as needed and were monitored for other complaints. Surveillance in these areas is done every 2 weeks.
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Typically, Richmond County has very few WNV human cases. The first human case was reported in 2004; the first case in Georgia was reported in 2001. However, since 2012, there have been cases reported every year in Richmond County. Mosquito surveillance had been a missing component of the Richmond County Mosquito Control Program. The creation of a partnership with the Phinizy Center for Water Sciences has resulted in better focused mosquito control efforts. In 2015, the first WNV case in Richmond County was reported in July, and a second case reported soon after. A third case was reported the following month. All 3 cases were less than 10 miles from one another. Culex quinquefasciatus, Georgia's primary WNV vector, flies approximately a half mile in search of a blood meal. In an effort to reduce the risk of WNV in the area between and around the 3 case sites, Richmond County Mosquito Control implemented their 5-step response program.
The 2015 area surveillance in the high risk area (Figure 2) collected 12 different mosquito species, including Culex quinquefasciatus (Table 3). Twenty-five mosquitoes sampled from one pool tested positive for WNV (Table 4). Although the number of WNV cases in Richmond County has historically not been high, the ability to better target mosquito control has helped reduce risk of disease transmission.
Although complaints by residents can provide some information on the presence of mosquito problems in a given area, surveillance allows the targeting of areas where vector populations are high. Surveillance and viral testing also provides a means of determining the effectiveness of control efforts. Although some level of surveillance was done in Richmond County almost every year starting in 2004, it was primarily performed once a month. More frequent surveillance is needed to support targeted mosquito control efforts.
The collaboration with the Phinizy Center has changed mosquito control operations and saved Richmond County money. Identifying areas of the county with disease-carrying species helps to accomplish the primary mission of aiding public health by reducing the number of vector species and reducing the risk of disease transmission.
The current goal is to increase public education programs with civic clubs, churches, schools, homeowners' associations, and public events. Outreach to the public is the best method of reducing mosquito habitats for the better health of the citizens of Richmond County, especially with the recently identified potential risks presented by the Zika virus.
Figure 3. Neighborhood survey following surveillance and treatment of area of concern. A MULTIAGENCY APPROACH TO REDUCING WEST NILE VIRUS RISK IN RICHMOND COUNTY, GEORGIA, IN 2015 Date and time: October 20, 2015 10 am to 3 pm People involved: * 5 from Mosquito Control * 1 from Environmental Health as observer * 1 from Center for Water Sciences (trapping and identification) * 5 from Augusta/Richmond County Code Enforcement * 3 from Richmond County Marshal's department * 6 from Richmond County Sheriff's department * Animal control was on standby due to personnel shortage. 142 Properties surveyed (Figures 1, 2): * 32 houses on Bandler Rd * 49 houses on Circular Dr * 15 houses on Harold Dr * 17 houses on Sanders Rd * 26 houses on Martin Rd * 3 houses on Ivey Rd Age of houses in survey area: * 80% of the houses in the survey area were built between 1944 and 1952. * All houses are located within a 180-acre area divided equally on both sides of a major 4 lane highway. * All houses on both sides are similar in age and maintenance. * Construction materials range from brick to lap board and T-11. Most carports are aluminum. * Almost all houses have crawl spaces which are well known as mosquito habitats.
The Phinizy Center for Water Sciences
The Phinizy Center for Water Sciences was established to provide leadership to balance sustainable watersheds and economic vitality through solutions-based research, education, and public involvement (http://phinizycenter. org). The Phinizy Center manages the Phinizy Swamp Nature Park, a 1,100-acre nature park in the city of Augusta. The park contains wetlands and woodlands and has a campus for water research and environmental education. As the wetlands at Phinizy Swamp Nature Park obviously have the potential to contribute to mosquito problems in Richmond County, the scientists at the Phinizy Center are intimately involved in efforts to address the risks.
(1.) US Census Bureau. Quick Facts; Richmond County, Georgia. US Census Bureau website. Available at: https://www.census.gov/quickfacts/table/ PST045215/00,13245. Accessed May 31, 2016.
(2.) Mirshak M. Phinizy Center, Richmond County Mosquito Control join efforts to identify mosquito species [internet]. The Augusta Chronicle. August 9, 2015. Available at: http://chronicle.augusta.com/ news/metro/2015-08-09/phinizy-center-richmondcounty-mosquito-control-join-efforts-identify-mosquito#. Accessed May 31, 2016.
(3.) Georgia Mosquito Control Association. Georgia Emergency Surveillance Trailer Protocols. Georgia Mosquito Control Association Website. Available at: http://www.gamosquito.org/resources/Georgia EmergencyMosquitoSurveillanceTrailerUseProto cols.pdf. Accessed May 31, 2016.
(4.) Centers for Disease Control and Prevention. West Nile virus [internet]. CDC website. Available at: http://www.cdc.gov/westnile/. Accessed May 31, 2016.
Rosmarie Kelly, PhD, MPH
Oscar P. Flite III, PhD
R. Chris Rustin, DrPH, MS, REHS
Dr Kelly is a Public Health Entomologist with the Vector-Borne & Zoonotic Diseases Team Environmental Health Section, Georgia Department of Public Health, Atlanta, Georgia.
Mr Koehle is with the Environmental Health Section of the Richmond County Department of Public Health, Augusta, Georgia.
Dr Flite is the Chief Executive Officer and Senior Scientist, Phinizy Center for Water Sciences, Augusta, Georgia.
Dr Rustin is with the Jiann-Ping Hsu College of Public Health, Georgia Southern University, Statesboro, Georgia.
Table 1. Human Cases of WNV: Georgia statewide and Richmond County, 2001-2015 * Year Georgia Richmond Statewide County 2001 6 2002 36 2003 55 2004 23 2 2005 24 1 2006 11 2007 55 3 2008 12 2009 6 2010 14 2011 25 2012 117 4 2013 20 1 2014 13 2 2015 15 3 * Data from GDPH Arboviral Surveillance and Richmond County Mosquito Control records. Table 2. Spray and Trapping Schedule Date Procedure 8/25/2015 First morning spray (7:45 to 8:45) 8/27/2015 Evening spray (6:30 to 7:30) 8/31/2015 Baseline trapping at 4 selected sites 9/1/2015 Morning spray 9/3/2015 Evening spray 9/4/2015 Mosquito pools from baseline sent for testing * 9/8/2015 Morning spray 9/10/2015 Evening spray 9/15/2015 Morning spray 9/15/2015 First trapping of regular series (every 2 weeks) 9/17/2015 Evening spray 9/17/2015 Mosquito pools from regular series sent for testing * 9/22/2015 Morning spraying cancelled due to rain 9/24/2015 Evening spray * Virus testing conducted by University of Georgia College of Veterinary Medicine as part of the Southeastern Cooperative Wildlife Disease Study (http://vet.uga.edu/scwds). Table 3. Mosquito Surveillance Data From a High Risk Area Species 08/31/15 09/02/15 09/09/15 Aedes albopictus 115 113 88 Aedes vexans 1 16 Anopheles crucians complex Anopheles quadrimaculatus 2 2 Culex erraticus 27 Culex nigripalpus 1 Culex quinquefasciatus 6 19 2 Culex salinarius 69 30 Ochlerotatus triseriatus 1 4 Orthopodomyia signifera Psorophora columbiae 1 Psorophora ferox Grand Total 122 236 139 Species 09/23/15 10/14/15 Species total Aedes albopictus 98 65 479 Aedes vexans 2 19 Anopheles crucians complex 4 4 Anopheles quadrimaculatus 13 4 21 Culex erraticus 2 29 Culex nigripalpus 2 3 Culex quinquefasciatus 147 38 212 Culex salinarius 3 779 881 Ochlerotatus triseriatus 3 8 16 Orthopodomyia signifera 2 2 Psorophora columbiae 2 2 5 Psorophora ferox 1 1 Grand Total 275 900 1,672 Table 4. Richmond County Mosquito Surveillance Results, 2004-2015 Year WNV test Results Yearly Negative Positive total 2004 17 17 2006 373 373 2007 1,395 7 1,402 2008 1,906 1,906 2009 841 841 2010 212 212 2011 384 384 2012 4,992 4,992 2013 2,272 2,272 2014 111 111 2015 747 25 772 Grand Total 13,250 32 13,282
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|Author:||Kelly, Rosmarie; Koehle, Fred; Flite, Oscar P., III; Rustin, R. Chris|
|Publication:||U.S. Army Medical Department Journal|
|Date:||Oct 1, 2016|
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