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Highlights from

The European Congress of Clinical Microbiology & Infectious Diseases

29th Annual Meeting

Amsterdam 13-16 April 2019

Climate change is increasing the reach of vector-borne diseases

Take-home messages
  • Geographic reach of vector-borne diseases, such as dengue fever and chikungunya, is expanding at an alarming rate
  • Experts recommend that early anticipation and intervention of vector-borne outbreaks is necessary
  • Climatic factors may also be associated with increased levels of antimicrobial resistance
Vector-borne diseases - particularly those carried by mosquitoes - are increasing their reach and pose a considerable threat to global health

Climate change is associated with a broad number of serious adverse outcomes and infectious disease is likely to be one of them. Experts at the 29th European Congress of Clinical Microbiology and Infectious Diseases (ECCMID) warned that climate change, among other factors, may widen the geographic reach of vector-borne diseases such as dengue fever and chikungunya, and that temperature change may be associated with the incidence of antimicrobial resistance.

Vector-borne disease

In a session on climate change and infectious disease, Dr Giovanni Rezza, Director, Department of Infectious Diseases, Istituto Superiore di Sanità, Italy, warned that vector-borne pathogens - particularly those carried by mosquitoes - are increasing their geographical reach and pose a considerable threat to global health. “Globalisation is a major drive of tropical outbreaks in temperate areas, but climatic change also may play a role,” he said.

Even temperate European countries are now at risk of tropical disease outbreaks, as the pathogen-carrying insects thrive and proliferate in longer and wetter warm seasons. “[This] may influence vector density, causing a higher probability of outbreaks,” commented Dr Rezza. “If you have longer hot seasons, there may be bigger outbreaks due to the accumulation of cases over a longer period of time.”

Small clusters and outbreaks of dengue fever have been identified in southern Europe during hot seasons. Chikungunya, which was originally restricted to central Africa and Asia, has now invaded new territories that were previously disease free, such as north-eastern Italy and the Caribbean.[1] Outbreaks of west Nile virus, malaria and schistosomiasis have also been reported in temperate areas.

Other arthropods also seem to be keen on the higher temperatures and increased humidity. Tick-borne encephalitis has increased 400% in the past 30 years in endemic areas of Europe, though this is partly attributed to enhanced surveillance and diagnosis.[2]

Vector-borne disease outbreaks, including ‘tropical’ diseases in temperate areas, may become more commonplace in the next few decades, and the congress presenters made it clear that action needs to be taken. Public health agencies need to take preparatory measures, such as improving surveillance, increasing public awareness and instigating community intervention.

Antimicrobial resistance

A 30-country, observational, ecological study conducted at the Institute of Infection Control and Infectious Diseases, University Medical Center Göttingen, in collaboration with the Hannover Medical School, Germany, was also presented at ECCMID 2019. The team found that there was a novel association between antimicrobial resistance and climatic factors in Europe.

Statistical analysis and computer modelling were performed to identify the association of 6-year prevalence of carbapenem-resistant Pseudomonas aeruginosa, Klebsiella pneumoniae, multiresistant Escherichia coli and methicillin-resistant Staphylococcus aureus with seasonal temperature. The study accounted for potentially confounding factors such as socioeconomic aspects, total outpatient antimicrobial use and clinician density.

The overarching results suggest that climatic factors significantly contribute to the prediction of antimicrobial resistance in various societies and healthcare systems, and that it could also increase transmission, particularly in the case of carbapenem-resistant P. aeruginosa.

Although the study authors cautioned that a causal link is not necessarily proven, the results are consistent with previous studies, including a US study that found that a 10°C temperature increase was associated in a significant increase in antimicrobial resistance: 4.2% (P<0.0001) with E. coli and 2.2% (P<0.0001) with K. pneumoniae. These researchers postulated that the burden of antimicrobial resistance may be significantly underestimated.[3]

Based on:

Rezza G. Tropical outbreaks in temperate areas (symposium S0540). Presented on Sunday 14 April 2019.

Kaba H, Kuhlmann E et al. Novel association between antimicrobial resistance and climatic factors in Europe: a 30 country observational study (abstract 3045). Presented on Sunday 14 April 2019.


  1. Rezza G. Dengue and chikungunya: long-distance spread and outbreaks in naive areas. Pathog Glob Health 2014;108(8):349-355
  2. Semenza J C and Suk J E. Vector-borne diseases and climate change: a European perspective. FEMS Microbiol Lett 2017;365(2):244
  3. MacFadden D R, McGough et al. Antibiotic resistance increases with local temperature. Nat Clim Change 2018;8(6):510

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The content and interpretation of these conference highlights are the views and comments of the speakers/ authors.

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