Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Climate Change, Dengue and Aedes Mosquitoes: Past Trends and Future Scenarios
Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Background Climate change, global travel and trade have facilitated the spread of Aedes mosquitoes and have consequently enabled the diseases they transmit (dengue fever, Chikungunya, Zika and yellow fever) to emerge and re-emerge in uninfected areas. Large dengue outbreaks occurred in Athens in 1927 and in Portuguese island, Madeira in 2012, but there are almost no recent reports of Aedes aegypti, the principal vector, in Europe. A dengue outbreak needs four conditions: sufficient susceptible humans, abundant Aedes vector, dengue virus introduction, and conducive climate. Can Aedes aegypti establish themselves again in Europe in the near future if they are introduced? How do the current and future climate affect dengue transmission globally, and regionally as in Europe? This thesis tries to answer these questions.

Methods Two process-based mathematical models were developed in this thesis. Model 1 describes a vector’s ability to transmit dengue – vectorial capacity – based on temperature and diurnal temperature range (DTR). Model 2 describes vector population dynamics based on the lifecycle of Aedes aegypti. From this model, vector abundance was estimated using both climate as a single driver, and climate together with human population and GDP as multiple drivers; vector population growth rate was derived as a threshold condition to estimate the vector’s invasion to a new place.

Results Using vectorial capacity, we estimate dengue epidemic potential globally for Aedes aegypti and in Europe for Aedes aegypti and Aedes albopictus. We show that mean temperature and DTR are both important in modelling dengue transmission, especially in a temperate climate zone like Europe. Currently, South Europe is over the threshold for dengue epidemics if sufficient dengue vectors are present. Aedes aegypti is on the borderline of invasion into the southern tip of Europe. However, by end of this century, the invasion of Aedes aegypti may reach as far north as the middle of Europe under the business-as-usual climate scenario. Or it may be restricted to the south Europe from the middle of the century if the low carbon emission – Paris Agreement – is implemented to limit global warming to below 2°C.

Conclusion Climate change will increase the area and time window for Aedes aegypti’s invasion and consequently the dengue epidemic potential globally, and in Europe in particular. Successfully achieving the Paris Agreement would considerably change the future risk scenario of a highly competent vector – Aedes aegypti’s – invasion into Europe. Therefore, the risk of transmission of dengue and other infectious diseases to the mainland of Europe depends largely on human efforts to mitigate climate change.

Abstract [sv]

Bakgrund Klimatförändringar tillsammans med en ökad frekvens av globala resor och handel har gynnat spridningen av Aedes-myggor och möjliggjort att de sjukdomar som de överför (dengue feber, Chikungunya, Zika och gul feber) etablerar sig i tidigare oinfekterade områden. Det två största utbrotten av dengue i Europa inträffade i Aten 1927 och på den portugisiska ön Madeira 2012 orsakades av Aedes aegypti, men i de allra flesta delar i Europa finns inga rapporter om Aedes aegypti. Ett utbrott av dengue kräver att fyra villkor uppfylls: tillräckligt mottagliga människor, rikligt med Aedes-vektorer, introduktion av dengue-virus, och ett gynnsamt klimat. En stor fråga idag är om Aedes aegypti kan etableras igen i Europa i ett förändrat klimat, och hur nuvarande och framtida klimatförhållanden möjligör dengue smittspridning globalt och regionalt i Europa. Denna avhandling försöker svara på dessa frågor.

Metoder Två processbaserade matematiska modeller utvecklades i arbetet med denna avhandling. En av modellerna beskriver vektorns förmåga att överföra dengue – vektorkapaciteten – baserat på temperatur och dyngstemperaturens varation (DTR). Den andra modellen beskriver vektorpopulationens dynamik baserat på myggans livscykel. Myggornas populationsdynamik och populationstäthet uppskattades med en modell baserat på enbart klimat, samt en modell baserat på klimat, mänsklig befolkning och BNP. Vektorgruppens tillväxthastighet härleddes som ett tröskelvärde för att uppskatta vektorernas invasionsbenägenhet till nya områden i takt med att klimatet förändras.

Resultat Med hjälp av vektorkapacitetmodellen uppskattade vi den epidemiska potentialen av dengue smittad av Aedes aegypti globalt och i Europa av Aedes aegypti och Aedes albopictus. Vi visar att den genomsnittliga temperaturen och DTR båda är viktiga för dengue myggornas kapacitet att starta epidemier, särskilt i tempererade klimatzoner, så som Europa. För närvarande är Syd-Europa tillräckligt gynnsamt för dengueepidemier vissa tider på året om myggpopulationerna är tillräckligt stora. Vi visat att Aedes aegypti möjligen kan etablera sig längs Europas södra utkanter idag. I slutet av detta århundrade kan invasionen av Aedes aegypti nå så långt norrut till mitten av Europa om vi inte begränsar klimatutsläppen mer än vad vi gör idag. Om vi följer klimatavtalet från Paris 2015 där den globala uppvärmningen begränsar till under 2 grader kan invasionen troligtvis förhindras, eller i vilket fall kraftigt begränsas i Europa.

Slutsats Ett varmare klimat kommer att öka antalet geografiska områdena i Europa som är gynnsamt för Aedes aegypti. Det kommer även öka tidsfönstret för vektorernas epidemiska potential globalt, och i synnerhet för Europa. En framgångsrik implementering av klimatavtalet från 2015, som riktar sig mot att begränsa uppvärmingen till under 2 grader, skulle väsentligt minska risken för en framtida invasion av dengue, zika och chikungunya i Europa. Därför beror risken för dengueöverföring och andra infektionssjukdomar i södra Europa till stor del på mänskliga ansträngningar för att med utsläppsminskningar av växthusgaser kontrollera klimatförändringen.

Place, publisher, year, edition, pages
Umeå: Umeå universitet , 2018. , p. 100
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 1931
Keyword [en]
dengue, mathematical modelling, vectorial capacity, DTR, Aedes aegypti, Aedes albopictus, climate change, Europe, vector invasion, abundance
Keyword [sv]
dengue, matematisk modellering, vektorkapacitet, DTR, Aedes aegypti, Aedes albopictus, klimatförändring, Europa, vektor invasion
National Category
Public Health, Global Health, Social Medicine and Epidemiology
Research subject
Epidemiology
Identifiers
URN: urn:nbn:se:umu:diva-143764ISBN: 978-91-7601-798-2 (print)OAI: oai:DiVA.org:umu-143764DiVA, id: diva2:1172083
Public defence
2018-02-02, Hörsal D, Tandläkarhögskolan, By1D, 9 tr, Norrlands universitetssjukhus, Umeå, 09:00 (English)
Opponent
Supervisors
Available from: 2018-01-12 Created: 2018-01-09 Last updated: 2018-01-31Bibliographically approved
List of papers
1. Vectorial capacity of Aedes aegypti: Effects of temperature and implications for global dengue epidemic potential
Open this publication in new window or tab >>Vectorial capacity of Aedes aegypti: Effects of temperature and implications for global dengue epidemic potential
2014 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 3, article id e89783Article in journal (Refereed) Published
Abstract [en]

Dengue is a mosquito-borne viral disease that occurs mainly in the tropics and subtropics but has a high potential to spread to new areas. Dengue infections are climate sensitive, so it is important to better understand how changing climate factors affect the potential for geographic spread and future dengue epidemics. Vectorial capacity (VC) describes a vector's propensity to transmit dengue taking into account human, virus, and vector interactions. VC is highly temperature dependent, but most dengue models only take mean temperature values into account. Recent evidence shows that diurnal temperature range (DTR) plays an important role in influencing the behavior of the primary dengue vector Aedes aegypti. In this study, we used relative VC to estimate dengue epidemic potential (DEP) based on the temperature and DTR dependence of the parameters of A. aegypti. We found a strong temperature dependence of DEP; it peaked at a mean temperature of 29.3°C when DTR was 0°C and at 20°C when DTR was 20°C. Increasing average temperatures up to 29°C led to an increased DEP, but temperatures above 29°C reduced DEP. In tropical areas where the mean temperatures are close to 29°C, a small DTR increased DEP while a large DTR reduced it. In cold to temperate or extremely hot climates where the mean temperatures are far from 29°C, increasing DTR was associated with increasing DEP. Incorporating these findings using historical and predicted temperature and DTR over a two hundred year period (1901–2099), we found an increasing trend of global DEP in temperate regions. Small increases in DEP were observed over the last 100 years and large increases are expected by the end of this century in temperate Northern Hemisphere regions using climate change projections. These findings illustrate the importance of including DTR when mapping DEP based on VC.

Place, publisher, year, edition, pages
San Francisco: Public Library of Science, 2014
National Category
Public Health, Global Health, Social Medicine and Epidemiology
Identifiers
urn:nbn:se:umu:diva-87872 (URN)10.1371/journal.pone.0089783 (DOI)000332483600022 ()24603439 (PubMedID)
Available from: 2014-04-15 Created: 2014-04-14 Last updated: 2018-01-10Bibliographically approved
2. Climate change and Aedes vectors: 21st century projections for dengue transmission in Europe
Open this publication in new window or tab >>Climate change and Aedes vectors: 21st century projections for dengue transmission in Europe
Show others...
2016 (English)In: EBioMedicine, ISSN 0360-0637, E-ISSN 2352-3964, Vol. 7, p. 267-277Article in journal (Refereed) Published
Abstract [en]

Warming temperatures may increase the geographic spread of vector-borne diseases into temperate areas. Although a tropical mosquito-borne viral disease, a dengue outbreak occurred in Madeira, Portugal, in 2012; the first in Europe since 1920s. This outbreak emphasizes the potential for dengue re-emergence in Europe given changing climates. We present estimates of dengue epidemic potential using vectorial capacity (VC) based on historic and projected temperature (1901–2099). VC indicates the vectors' ability to spread disease among humans. We calculated temperature-dependent VC for Europe, highlighting 10 European cities and three non-European reference cities. Compared with the tropics, Europe shows pronounced seasonality and geographical heterogeneity. Although low, VC during summer is currently sufficient for dengue outbreaks in Southern Europe to commence–if sufficient vector populations (either Ae. aegypti and Ae. albopictus) were active and virus were introduced. Under various climate change scenarios, the seasonal peak and time window for dengue epidemic potential increases during the 21st century. Our study maps dengue epidemic potential in Europe and identifies seasonal time windows when major cities are most conducive for dengue transmission from 1901 to 2099. Our findings illustrate, that besides vector control, mitigating greenhouse gas emissions crucially reduces the future epidemic potential of dengue in Europe.

Place, publisher, year, edition, pages
Elsevier, 2016
Keyword
Dengue, Vectorial capacity, Aedes aegypti, Aedes albopictus, Temperature, Climate change
National Category
Public Health, Global Health, Social Medicine and Epidemiology
Identifiers
urn:nbn:se:umu:diva-118643 (URN)10.1016/j.ebiom.2016.03.046 (DOI)000377459700039 ()27322480 (PubMedID)
Funder
EU, FP7, Seventh Framework Programme, 282589
Note

This study is part of the DengueTools project funded by the European Union Seventh Framework Programme FP7/2007-2013 under grant agreement no. 282589.

Originally included in thesis 1 as submitted manuscript.

Available from: 2016-03-28 Created: 2016-03-28 Last updated: 2018-03-16Bibliographically approved
3. Estimating past, present and future trends in the global distribution and abundance of the arbovirus vector Aedes aegypti
Open this publication in new window or tab >>Estimating past, present and future trends in the global distribution and abundance of the arbovirus vector Aedes aegypti
(English)Manuscript (preprint) (Other academic)
National Category
Public Health, Global Health, Social Medicine and Epidemiology
Identifiers
urn:nbn:se:umu:diva-143762 (URN)
Available from: 2018-01-09 Created: 2018-01-09 Last updated: 2018-01-10Bibliographically approved
4. Climate change may enable Aedes aegypti mosquitoes infestation in major European cities by 2100
Open this publication in new window or tab >>Climate change may enable Aedes aegypti mosquitoes infestation in major European cities by 2100
(English)Manuscript (preprint) (Other academic)
National Category
Public Health, Global Health, Social Medicine and Epidemiology
Identifiers
urn:nbn:se:umu:diva-143763 (URN)
Available from: 2018-01-09 Created: 2018-01-09 Last updated: 2018-01-10Bibliographically approved

Open Access in DiVA

fulltext(5164 kB)275 downloads
File information
File name FULLTEXT03.pdfFile size 5164 kBChecksum SHA-512
43d5b1593ef1019d1b62d82969f969cad511a5f1d96469b32607b15146838bb62cac2ae079b24edf6e010f4213b2ae1fcdc6c5aa7199881983176095578211bf
Type fulltextMimetype application/pdf
spikblad(149 kB)31 downloads
File information
File name SPIKBLAD01.pdfFile size 149 kBChecksum SHA-512
265e56b43ecda6a0f2acf4f67b9d415e7fd49311bad316ddd245f60011ae69b562ca02b1e5cfa38e375d7371224ce8538ee8280ab6a5e9596cc3148e49d2b68a
Type spikbladMimetype application/pdf
errata(127 kB)7 downloads
File information
File name ERRATA01.pdfFile size 127 kBChecksum SHA-512
d7aee9ac7a51ea70652d7e6d79e4423ea44e3c991b81629cc621fabcc4646c6d84141aeec4c1c4f0242ff6ff8a66205ed72625f677dfcca4c0abfe01e47c2add
Type errataMimetype application/pdf

Search in DiVA

By author/editor
Liu-Helmersson, Jing
By organisation
Epidemiology and Global Health
Public Health, Global Health, Social Medicine and Epidemiology

Search outside of DiVA

GoogleGoogle Scholar
Total: 275 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 1318 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf