Disease category Vector-borne diseases Borreliosis (Lyme disease) Crimean-Congo hemorrhagic fever Chikungunya fever Dengue fever Human granulocytic anaplasmosis Leishmaniasis Malaria Q fever Rift Valley fever Tick-borne encephalitis (TBE) Tularemia Viral hemorrhagic fevers West Nile fever Yellow fever Rodent-borne diseases Hantavirus infections Plague Food-borne diseases Water-borne diseases Campylobacteriosis Cholera Cryptosporidiosis Enterovirus infections Giardiasis Leptospirosis Naegleria fowleri infections Norovirus infections Rotavirus infections Salmonellosis Vibrio species Respiratory diseases Legionellosis Severe acute respiratory syndrome 29 30 27 29 29 — — 29 29 29 29 29 29 28 29 29 29 29 29 29 — 27 — — — 29 — — — — — — 28 29 25 (86) 25 (83) 10 (37) 5 (17) 5 (17) 12 (41) 12 (41) 2 (7) 21 (72) 9 (31) 5 (17) 15 (54) 2 (7) 17 (59) 18 (62) 1 (3) 23 (79) 24 (83) 4 (15) 16 (55) 19 (68) 2 (7) 29 28 27 29 29 24 27 28 26 26 29 23 25 27 27 25 27 25 27 28 26 23 25 24 25 27 22 24 26 27 24 — 27 21 25 (86) 22 (79) 8 (30) 15 (52) 11 (38) 7 (29) 15 (59) 8 (29) 11 (42) 4 (15) 19 (63) 12 (52) 3 (12) 19 (70) 6 (22) 17 (68) 15 (56) 1 (4) 19 (70) 19 (68) 14 (54) 3 (13) 10 (40) 12 (50) 8 (32) 15 (56) 6 (27) 6 (25) 7 (27) 16 (60) 9 (38) 16 (59) 1 (5) Semenza et al. about numbers of outbreaks within the previ‑ ous 10 years and whether they believed that some of these outbreaks were attributable to climate change. For endemic insect‑, tick‑, and rodent‑ borne diseases, experts were also asked to indicate whether they had observed changes in seasonality and geographic, alti‑ tudinal, or latitudinal distributions. The sur‑ vey instrument also included questions about planning, preparedness, and surveillance. Likert scale responses were summarized as positive (agree strongly or agree somewhat that climate change will affect disease), negative (disagree strongly or disagree somewhat that climate change will affect disease), or neither agree nor disagree. To assess the reliability of expert responses, two successive interviews with different individuals were conducted over a span of 3 years. Countryl‑evel data were pooled to compute summary statistics for the 2007 and 2009/2010 surveys, and a two‑sample test of equality of proportions was applied to compare the proportions of respondents with positive and negative responses between the two survey rounds. We used a less stringent level of significance (α = 0.1) to capture minor changes between the two survey rounds. Accuracy of the responses was assessed with data from the peer‑reviewed literature and submissions to the United Nations Framework Convention on Climate Change (UNFCCC 2010). Analysis and presentation of the data were performed with ESRI software ArcGIS, version 10.0 (Environmental Systems Research Institute Inc., Redlands, CA, USA). Results Government officials from each of the 30 EEA countries completed a survey questionnaire in 2007, and officials from 29 of 30 countries completed questionnaires in 2009/2010 (non‑ response, Lichtenstein). Different national infectious disease experts were interviewed for the two survey rounds, with an 89% con‑ cordance in their assessments; 18 infectious diseases were evaluated in both rounds and Table 1. Infectious diseases likely to be affected by climate change based on survey responses by infec­ tious disease experts representing EEA countries in 2007 and 2009/2010. 2007 responses 2009/2010 responses Total (n) Positive [n (%)] Total (n) Positive [n (%)] —, no data for 2007; the list of pathogens was expanded in 2009/2010. There is some overlap between disease cate­ gories (not mutually exclusive). Data are based on the following survey question: “Future infectious disease risk in a changing climate; which infectious diseases do you think climate change will most affect in your country?” Responses were recorded on a Likert scale with five response options: agree strongly; agree somewhat; neither agree nor disagree; disagree somewhat; disagree strongly. The first two responses (agree strongly and agree somewhat) were grouped to reflect a positive response. ap­Values for 2007 compared with 2009/2010. 386 ovlume 120 | number 3 | March 2012 • Environmental Health Perspectives p-Valuea 1 0.91 0.56 0.048 0.07 — — 0.33 0.93 0.32 0.46 0.1 0.58 0.20 0.1 0.29 0.63 0.83 0.42 0.18 — 0.82 — — — 0.91 — — — — — — 0.47 0.74 for only 2 (chikungunya and dengue fever) did the proportion of countries reporting an impact change significantly (p < 0.1). The majority of country representatives indicated that they believed climate change would have an impact on all major categories of infectious diseases (vector,‑ water,‑ food,‑ and rodent‑ borne) (Table 1). Diseases with a low or nonexistent disease burden in Europe (e.g., plague, yellow fever, cholera) were ranked rather low (ECDC 2010a). Here we discuss the results by infectious disease category, planning and preparedness, and surveillance activities. For simplicity, summary estimates are reported for the 2009/2010 survey unless otherwise noted. Vector-borne diseases. Individual vector‑ borne diseases judged by national experts to be likely affected by climate change in the future included Lyme borreliosis (79%), West Nile fever (70%), and tick‑ borne encephali‑ tis (TBE; 63%) (Table 1). About one‑fourth of respondents also attributed outbreaks or increases in the incidence of these diseases dur‑ ing the last decade to climate change (30%, 25%, and 22% for Lyme borreliosis, West Nile fever, and TBE, respectively). Other vectorb‑orne disease outbreaks (e.g. , leishma‑ niasis, hantavirus infections; data not shown) tend to occur in low numbers or infrequently, which makes attribution to climate change dif‑ ficult and limits interpretation. The data for 2009/2010 were mapped by pathogen and country. Potential effects of future climate change on Lyme borreliosis were of concern to respondents from almost all countries except for officials from three Mediterranean countries (Italy, Malta, and Greece) and two Atlantic countries (Ireland and Iceland) (Figure 1A). Respondents in northern and central Europe thought climate change is likely to affect TBE, and respon‑ dents in southern Europe expected effects on West Nile fever (Figures 1B and 2A). A larger number of respondents in 2009/2010 than in 2007 felt that climate change would affect chikungunya (52% vs. 17%, p = 0.048) and dengue fever (38% vs. 17%, p = 0.07) in their countries (Table 1, Figure 2B,C). Experts also reported an increase in the geographic distri‑ bution and seasonality of several insect,‑ tick‑ , and rodentb‑orne diseases in their countries in the previous decade (Table 2). Countries of the northeast reported expan‑ sion in the geographic distribution of tick‑ borne diseases (Lyme borreliosis and TBE) (Figure 1A,B), whereas countries of the south reported expansion in the distribution of mos‑ quito‑borne diseases (e.g. , West Nile fever; Figure 2A). Both local range contraction and range expansion were reported in the case of leishmaniasis in Portugal (Table 2). Food- and water-borne diseases. A large proportion of the experts indicated that they believed that water‑borne diseases would