Figure 50. West Nile Virus Infections 2003

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1 121 WestNileVirus There are two reasons for looking at countybased statistics for West Nile virus both are relatedtoconcernsvoicedbygarfieldcountyresidents.first,inpublicmeetings,focusgroups, andinterviews,citizenshaveexpressedtheconcernthatbirdsappearedtobefewerinnumber incertainareasofgarfieldcountythanremembered.birdsarethereservoirhostforwestnile virus.theymaybecomeillanddieasaresultoftheviralinfection. Second,manyofthesymptomsassociatedwithhumanWestNilevirusinfectionmimicthose reported by Garfield County residents and attributed to exposures related to natural gas industryactivities. WestNileviruswasfirstobservedinColoradoin2002.Itwasnotuntil2003,however,before the virus had a significant WesternSlope presence.the coincidenceof the presence of this virusandthebeginningsofthesurgeinnaturalgasindustryactivitiesonthewesternslope makeitimportanttoconsiderthepossibilitythatwestnilevirusinfectioncouldbethecauseof someofthehumanphysicalsymptomsandanimalimpactsthathavebeenreportedbygarfield Countyresidents.Atthispoint,itwouldbeextremelydifficulttoeitherruleoutWestNilevirus asthecauseofatleastsomeoftheseimpactsortoproveconclusivelythatitwasthevirusand notexposuretovolatileorganiccompoundsorothertoxicantspresentintheenvironmentasa resultofnaturalgasactivity. NaturalHistoryofWestNileVirus( WestNilevirusismaintainedinabirdmosquitobirdcycle.Mosquitoesareinfectedbyfeeding onaninfectedbird;virusisthentransmittedtoanewhostwhenthemosquitobitesaperson orotheranimal.humansandhorsesarethemostfrequent, deadend hosts(i.e,theycannot infectothermosquitoes).virusesareprevalentfrommaytoseptember,whenmosquitoesare mostabundant. West Nile virus infection has been detected in more than 70 wild bird species.the highest deathratesareseenamongbirdsinthecorvidfamily.horsesaresusceptibletoinfectionwith West Nile virus and can die as a result of the infection.other clinical signs include lack of coordination or muscle control, weakness of limbs, and inability to rise.other mammalian speciesmaybesusceptibletoinfectionwiththisvirus(e.g.,therehavebeenreportsofinfection indogs). MostpeoplewhoareinfectedwithWestNilevirusdonotbecomeillandhavenosymptoms. Forthosewhodobecomeill,theonsetofsymptomsoccurs515daysafterbeingbittenbyan infected mosquito.the clinical symptoms of West Nile virus infection range from a flulike syndrome(westnilefever)tomeningitisandencephalitis.thesymptomsofwestnilefever have been reported to last significantly longer than the usual flu. Individuals who have developed West Nile fever report not feeling well for many months after the onset of the illness.insomecases,infectionwiththevirusresultsininflammationofthebrain,resultingin either meningitis or encephalitis. In these cases, symptoms begin with a high fever and headachethatmayprogresstostiffneck,disorientation, tremors, coma and death. Severe infections have resulted in longlasting neurological syndromesthatresemblepolio.

2 122 CommunityHealthRiskAnalysisofOilandGasIndustryImpactsinGarfieldCounty ThefollowinggraphsandmapsillustratethetimetrendsforWestNileVirusinColoradofrom 2002through2007(ColoradoDepartmentofPublicHealthandEnvironment).Informationis providedforbothhumanandanimalinfections.itisimportanttonotethatthenumbersfor humancasesrepresentonlythosethatwereclinicallyvalidated(eitherbybloodtestsorbythe factthattheindividualwashospitalizedasaresultoftheirinfection).becauseofthetendency ofindividualssuffering flulike symptomsnottobetestedforwestnilevirus(duetocostor unavailability of the test) and to either be treated by their doctors or to treat themselves symptomatically, it is very likely that theactual numbersof individuals who developed West Nile Fever were much higher than those listed in the official records (CDPHE; Figure50.WestNileVirusInfections 2003 Number of validated cases Total deaths Total Cases Encephalitis Meningitis Fever 5 0 Delta Garfield Mesa Montrose County 2003 Colorado cases: Fever = 2325; Meningitis = 288; Encephalitis = 234; Total Cases = 2947; Deaths = 63

3 Total deaths Total Cases Encephalitis Meningitis Fever Number of validated cases Delta Garfield Mesa Montrose County 2004 Colorado cases: Fever = 250; Meningitis = 22; Encephalitis = 29; Total Cases = 291; Deaths = 4 Figure51.WestNileVirusInfections Number of validated cases Total deaths Total Cases Encephalitis Meningitis Fever 5 0 Delta Garfield Mesa Montrose County 2005 Colorado cases: Fever = 85; Meningitis = 13; Encephalitis = 8; Total Cases = 106; Deaths = 2 Figure52.WestNileVirusInfections 2005

4 124 CommunityHealthRiskAnalysisofOilandGasIndustryImpactsinGarfieldCounty Figure53.WestNileVirusInfections Total deaths Total Cases Encephalitis Meningitis Fever Number of validated cases Delta Garfield Mesa Montrose County 2006 Colorado cases: Fever = 280; Meningitis = 34; Encephalitis = 31; Total Cases = 345; Deaths = 7 Figure54.WestNileVirusInfections 2007 Number of validated cases Total deaths Total Cases Encephalitis Meningitis Fever 10 0 Delta Garfield Mesa Montrose County 2007 Colorado cases: Fever = 459; Meningitis = 43; Encephalitis = 53; Total Cases = 555; Deaths = 6

5 125 Figure55.ColoradoWestNileVirusHumanCases 2002 Figure56.ColoradoWestNileVirusHumanCases 2003

6 126 CommunityHealthRiskAnalysisofOilandGasIndustryImpactsinGarfieldCounty Figure57.ColoradoWestNileVirusHumanCases 2004 Figure58.ColoradoWestNileVirusHumanCases 2005

7 127 Figure59.ColoradoWestNileVirusHumanCases 2006 Figure60.ColoradoWestNileVirusHumanCases 2007

8 128 CommunityHealthRiskAnalysisofOilandGasIndustryImpactsinGarfieldCounty Figure61.ColoradoWestNileVirusSurveillanceMap 2002 Figure62.ColoradoWestNileVirusSurveillanceMap 2003

9 129 Figure63.ColoradoWestNileVirusSurveillanceMap 2004 Figure64.ColoradoWestNileVirusSurveillanceMap 2005

10 130 CommunityHealthRiskAnalysisofOilandGasIndustryImpactsinGarfieldCounty Figure65.ColoradoWestNileVirusSurveillanceMap 2006 Figure66.ColoradoWestNileVirusSurveillanceMap 2007