The Journal of Lancaster General Hospital • Spring 2017 • Vol. 12 – No. 11212

“Earth is not a platform for human life. It’s a living being.“We’re not on it but part of it. Its health is our health.”

—ThomasMoore*

INTRODUCTIONInfarnorthernSiberialiesamassivesubdivision

called the Yamalo-Nenets, a permafrost region thatextendswell north of theArcticCircle. TheNenets(whichmeans “man” in thenative language) are thenomadic inhabitants of the region, and “Yamal,”looselytranslated,meansthe“endoftheworld.”TheNenetsaresustainedbythelocalreindeerpopulation,estimated to be the largest herd in the world, andreindeeraresacredtothepeopleoftheregion.Fromreindeer thepeoplederive food, clothing, and tools,andtheyuse the thickhides to formshelters.Nenetherderstravelupto1,000kmwiththereindeerherdsannuallyalongancientmigrationroutes.1

The climate in Yamalo-Nenets is brutal.Historically, winter temperatures reach –50°C, andsummertimetemperaturesinthesouthernregionsonlybrieflyreach15°C(59°F).However,climatologistsindi-catethatRussiaiswarmingat2.5timestherateoftheworldaverage.InJuly2016theYamalo-Nenetsregionexperienced a heat wave that was unprecedented inbothmagnitudeandduration.Temperaturesreachedapeakof95°F,andtheypersistedabove80°Fformanyweeks.Theresultwasarapidthawingofmanythou-sandsofsquaremilesoffrozentundra.2

As decades-old reindeer carcasses thawed,microbesthathadbeenfrozenandwell-preservedwerereleased,andadiseasethathadnotbeenseenintheregionsince1941wasresurrected.Whatfollowedwasamassiveoutbreakofreindeeranthrax,whichkilledanestimated2,300reindeer inonlya fewweeks,asaffectedanimalsdiedwithinonlytwotothreedays.Thesporeformofanthraxcansurviveindefinitelyin

frozensoil,andBacillus anthraciswaseasilycultivatedfromnewlythawedcarcassesaswellasthenewlysick-enedanimals.

Aregionalalarmwassoundedwhena12-year-oldNenetboydiedofanthrax,atleast90moredeerherd-ersweresickened,andmorethan20werehospitalized.Astateofemergencywasdeclared,andthespecterofRussianpublichealthofficialsinyellowHazmatgarbandquarantinetentsappearedininternationalnewsfeeds.HundredsofNenetswereevacuated.Veterinaryteamsrestartedamassiveanthraximmunizationpro-gram for the regional herd, which had been haltedoveradecadeagoduetolackofreporteddisease.Bylate2016,Russianofficialsconsideredculling250,000reindeertotrytohalttheepidemic.

In the even further northern reaches of theSiberiantundraliesthetownofZashiversk,stillunderpermafrost.There,150yearsago,amassiveoutbreakofsmallpoxkilled40percentoftheregion’spopula-tion. Could the frozen corpses in shallow woodengraves serve as a source for the future reappearanceofsmallpox,adiseaseofficiallydeclarederadicatedin1977?3

To investigate this possibility, wooden gravesfrom the 1840s were unearthed, and samples fromfrozen corpses were examined. While fragments ofthesmallpoxvirusgenomewererecoveredbyRussianandFrenchresearchers,todatenoviabletransmissiblesmallpox virushasbeen identified in frozenhumanremains.4

Theserarereportsofso-called“zombieInfections,”admittedly hyperbolic, nonetheless highlight a starkreality:thatchangingclimateandinfectiousdiseaseshavealwaysbeenlinked.

GLOBAL WARMING AND CLIMATE CHANGEThe knowledge that climatic conditions

affect human illness is centuries old. The Roman

Zombie infections and other infectious disease complications of Global WarminG

Joseph M. Kontra, M.D.LG Health Physicians Infectious Diseases

*Americanspiritualwriter,b.1940

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aristocracytooktheirsummersathighercoolereleva-tions inparttoavoidseasonaloutbreaksofmalaria(“bad air”).The foodprocesses of salting, smoking,and currying ofmeats began in temperate climatesduetoanunderstandingoftheassociationbetweenfoodspoilageanddiarrhealdisease.

Climate change in the modern world is theresult of accumulating greenhouse gases, mainlycarbondioxideandmethane,andtheresultanttrap-pingofreflectedinfraredradiationfromtheearth’ssurface.As a result of the increasing concentrationof greenhouse gases, the global mean temperatureis rising and the trend is accelerating (Fig. 1). TheIntergovernmentalPanelonClimateChange(IPCC)predictsanaverageincreaseof1.8°Cto5.8°Cacrosstheglobebytheendofthe21stcentury.5Changesinambienttemperaturecanaffectboththegeographicrangeofpathogensaswellastheincidenceandsea-sonalprevalenceofdisease.Thisholdstruenotonly

for themicrobes themselves, but for the insect andanimalvectorsthatparticipateinthechainoftrans-missionofzoonoticinfections.6

Extreme Weather Events: ENSOOneofthemostsignificantlydisruptiveclimate

eventscausedbyglobalwarmingistheperturbationintheElNiñoSouthernOscillation(ENSO),whichresults inextremeweathereventsoverawidearea.ClimaticcyclesofElNiño(seasurfacetemperaturesintheeasternPacificOceanthatareaboveaverage)andLaNiña(belowaverageseasurfacetemperaturesin the central and eastern PacificOcean), stronglyaffectregionaltemperaturesandrainfall.Variationsin the amplitude, duration, and distribution ofENSO events can lead to major, sometimes mas-sive anddisruptive, heatwave-drought-flood cycles.More extreme variations in weather conditions,includingseverestormsaswellasmorefrequentand

Fig. 1. Line plot of global mean land-ocean surface temperature index, 1880 to present, with the base period 1951-1980. The dark blue line is the annual mean and the gold line is the five-year running mean. [This is an update of Fig. 1A in Hansen et al. (2006).] The graph shows an overall long-term warming trend. (NASA Goddard Institute for Space Studies — http://data.giss.nasa.gov/gistemp/graphs/)

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non-seasonal hurricanes and typhoons, are conse-quences of global warming as well. The resultingeffects onhealth anddisease, especially in impov-erished regions with poor water, sanitation, andhealthcareinfrastructurecanbedevastating.7

Infections Associated with Extreme Weather EventsTropical storms and hurricanes in Central

America and across the southern United Stateshave increased substantiallyover the last20years,with attendant increases in weather-related deathsandmassive socio-economicdisruption.8 Increasedratesoffecal-oralgastrointestinalinfections,vector-borneillnesses,skinandsofttissueinfections,andrespiratoryinfectionshaveallbeenassociatedwithsuchdisasters.Flood-relatedoutbreaksofbacterialdiseases that have been identified include typhoidfever,cholera,shigellosis,enteropathogenicE.coli,non-typhoidal salmonella, and leptospirosis. Therisk of fecal-oral viral infections such as hepatitisAandEisalsoincreasedinassociationwithrainyseason floods. Parasitic diseases such as GiardiaandCryptosporidiumarealsoconsequencesoftheflooding that results from these extreme weatherperturbations.

Further,displacedandcrowdedpopulationsarealso at risk for outbreaks ofmeasles,meningococ-calmeningitis, influenza,andMRSAinfection.9Adetailed study in Peru compared health care dataafterasevereElNiñoseasonwithbaselinedata.Foreach 1°C increase in temperature, hospital admis-sions increased by 8 percent. Diarrheal diseaseadmissions predominated, and increased by over6,200casespost-ElNiño.10

Evendroughtconditionscanbeassociatedwithan increase in infectiousdiseases.Underaridcon-ditionswherewater sourcesare scarce,mosquitoesandbirdscanbebroughtintoproximity,facilitatingtransmissionofWestNilevirustobirds,andthentohumans.Inaddition,thepoorsanitationthatcanaccompanydroughtconditionscan facilitate trans-missionof enteric infections, aswasdemonstratedby a drought-related epidemic of cholera in Kenyain2009.11

Climate Change and Zoonotic DiseasesChangesinprecipitationandambienttempera-

turescandirectlyaffecttheincidenceandprevalenceof vector-borne infections, through host-pathogeninteractions as well as ecosystem changes. Rising

temperatures can allow for the survival of patho-gens in previously hostile environments. Ambientwarming can also result in a shortened pathogenincubationperiod,andanincreaseinmicrobeden-sity within the vector.12 Increasing temperatures,humidity, rainfall, and flooding also favor vec-tor breeding, while shortening their life cycle andexpandingtheirhabitatrange.

Arthropod-bornediseasesareperhapsthemostnotable infectiousdiseases tobeaffectedbyglobalwarming. These burgeoning epidemics have beenparticularlyfacilitatedbytheunrelentingexpansionof the range ofAedes aegypti, the critically impor-tantmosquito vector formultiple viral pathogens.Itsgeographicrange isheavily influencedbyvaria-tions in temperature, humidity, and precipitationthatresultfromtheweatherpatterndisruptionsofglobalwarming.Inonlythelastfewyearsitsrangehasexpanded fromtheMexicanborderup toSanFranciscoonthewestcoastandPennsylvaniaontheeastcoast.13

Dengue and chikungunyaarearbovirusesthatpro-duce acute febrile illnesses associated with severemusculoskeletalpain(Dengueisknownbylocalsinendemicareasas“breakbonefever”).WhilenotasnewsworthyintheUnitedStatesaszikavirus,aboutonethirdoftheworld’spopulationlivesindengueendemicareas,withover400millioninfectionsesti-matedtooccurannually.14

The intercontinental spread of these diseaseshas in part been attributed to increased ambienttemperatures and the increase in water breedinghabitatsthataccompanymoreprolongedandpersis-tentrainyseasonsrelatedtoElNiño.15

Chikungunyavirus,whichhadbeenendemicinAsia and Africa for decades, spread suddenly anddramatically from India to the Americas in late2013,causinganexplosiveepidemic.Itisnowesti-matedtoberesponsiblefor1.7millioncasesin45countries.16Thoughchikungunyaislesslethalthandengue,itsdebilitatingpost-infectiousmusculoskel-etalpaincanlastformonths.

Similarly,thealarmingspreadofthegeographicrangeofzika virus fromBrazil throughSouthandCentral America and into the United States hasbeenassociatednotonlywithcomplexenvironmen-tal,biological,andsocioeconomicfactors,butwithprolongationofthemosquitoseason(averagenum-berofdaysofactivemosquitovectoractivity).17Thedevastating obstetrical and neonatal consequences

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ofzikainfectioninpregnantwomenhavebeenwelldescribed.

About half of the world’s population livesin regions at risk for malaria. The World HealthOrganization (WHO) estimated that 212 millioncases of malaria with 429,000 deaths occurredin 2015.18 As ambient temperatures rise, thePlasmodiumparasite replicates faster.This acceler-ated life cycle results in ahigher infectionburdeninthevectormosquitoes,renderingtheirbitemoreinfectious. Furthermore, the warmer temperaturesalsostimulatetheinfectedmosquitoestotakebloodmealsmorefrequently.Theheatandmoreintenserainy seasons associated with El Niño events areexpected to further exacerbate the hyper-endemicnatureofmalariainaffectedregionsoftheworld.19

The outbreak of hantavirus in the in the early1990sinthefourcornersregionoftheSouthwesternUnited States is another example of how climatedisruption can lead to emergence of an infectiousdisease.20 The heavy El Niño rains that followedyears of drought resulted in an explosion of plantgrowth and a dramatic rise in the population ofdeermicethatcarrythevirus.Thesubsequentexpo-sureofhumanstomousedroppingsresultedintheexplosive 1993outbreak ofHantavirus PulmonarySyndrome. Hantavirus infections have now beenreportedinmorethan30states.

Later in that same decade, another emerginginfectiousdiseaseappearedafterasequenceofheatwave, drought, and flood. In 1999 the mosquito-borne African West Nile virus arrived in NorthAmerica for the first time.Theoutbreakbegan inNew York City, killing nine people and infectinghundreds, and then spread rapidly in the immu-nologicallynaiveU.S.populationovertheensuingyears. The wide spectrum of illness ranged fromasymptomatic infection, to self-limited asepticmeningitis, to devastating polio-like meningoen-cephalitis.Todatealmost2,000peoplehavediedofWestNileVirusinfection,andthediseaseremainsendemicintheUnitedStates.21

Mosquitoes, however, are not the only insectvectortobeimpactedbyclimatechange.Epidemicsoftick-borneillnessessuchasLyme diseasehavebeenfacilitatedbythemilderwintersofglobalwarming.Theecologyandepidemiologyofhuman infectionwithBorrelia burgdorferii is complex, and is relatedtothegeographicrangeanddensityofIxodesticks,

theirhostmammals,aswellastheirinfectionbur-den with Lyme spirochetes. Climate change hasresulted in more favorable overwintering condi-tions and a resultant increase in survival of boththe pathogenwithin infected ticks, as well as thewhite-taileddeeranddeermousehostsinvolvedinthelifecycle.22

The web of events leading to the 2014 Ebolaoutbreak inwesternAfrica is a bitmore complex,but here, too, climate change has played a role.Certainly, the progressive deforestation of theregion over decades has caused displacement ofmany animal species from their preferred habitatsand therefore an increased likelihood of contactwithhumans.TheprecipitousriseinhumanEbolainfectionsin2014,however,followedaheat-drought-raincyclethatleadtoanabundanceoffoodsuchasfruit, bringing bat vectors in close proximity withprimates.Infectedprimate“bushmeat,”consideredafoodstapleby localpopulations,servedtotrans-mitthedeadlydiseasetohumans.23

CONCLUSIONSGlobalwarminghasresultedinanunrelenting

rise in theearth’smean temperature, and is accel-eratingat analarming rate.Warmingof theearthhas caused a disruption of normal global weatherpatterns resulting in a variety of extreme weatherconditions.Thesephenomenahavebothdirectandindirecteffectsonhumaninfectiousdiseases.

While theproblemsoutlined in thispaperareindeed pervasive, the devastating consequencesof global warming and extremeweather events gofar beyond just infectious diseases. Famine, politi-caluprisings,massmigrations,andsocio-economicupheaval can also be consequences of climatechange.Itwillbelefttogovernmentsandnationstotryandaddress,andhopefullybegintoreverse,thecomingglobalcatastrophe.

In December 2015, the United States joinedrepresentativesofmorethan190countriesindraft-ing the ParisClimateAgreement, which has beenratifiedby125parties as of thiswriting.OnNov.4, 2016 theAgreement entered into force.24 If thecurrent change in our political environment doesnotreversethiseffort,theagreementcallsformiti-gationofgreenhousegasestobeginin2020.Letushopethatwedonothavetofacetheconsequencesofitsfailure.

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JosephM.Kontra,M.D.LGHealthPhysiciansInfectiousDiseases2106HarrisburgPike,Suite301Lancaster,PA17601Phone:717-544-3517JMKontra@lghealth.org