General Studies
Spread of Disease
Thermal Stress
CLIMATE CHANGE AND SPREAD OF DISEASE

Abstracts

General Studies

Patz, J. A., P. R. Epstein, T. A. Burke and J. M. Balbus. 1996. "Global climate change and emerging infectious diseases," Journal of the American Medical Association, Vol. 275, No. 3, January 17, pp. 217-223.
ABSTRACT: Climatic factors influence the emergence and reemergence of infectious diseases, in addition to multiple human, biological, and ecological determinants. Climatologists have identified upward trends in global temperatures and now estimate an unprecedented rise of 2.0 degrees C by the year 2100. Of major concern is that these changes can affect the introduction and dissemination of many serious infectious diseases. The incidence of mosquito-borne diseases, including malaria, dengue, and viral encephalitides, are among those diseases most sensitive to climate. Climate change would directly affect disease transmission by shifting the vector's geographic range and increasing reproductive and biting rates and by shortening the pathogen incubation period. Climate-related increases in sea surface temperature and sea level can lead to higher incidence of water-borne infectious and toxin-related illnesses, such as cholera and shellfish poisoning. Human migration and damage to health infrastructures from the projected increase in climate variability could indirectly contribute to disease transmission. Human susceptibility to infections might be further compounded by malnutrition due to climate stress on agriculture and potential alterations in the human immune system caused by increased flux of ultraviolet radiation. Analyzing the role of climate in the emergence of human infectious diseases will require interdisciplinary cooperation among physicians, climatologists, biologists, and social scientists. Increased disease surveillance, integrated modeling, and use of geographically based data systems will afford more anticipatory measures by the medical community. Understanding the linkages between climatological and ecological change as determinants of disease emergence and redistribution will ultimately help optimize preventive strategies.

Food-borne diseases

Rose, Joan B., Paul R. Epstein, Erin K. Lipp, Benjamin H. Sherman, Susan M. Bernard, and Jonathan A. Patz. 2001. "Climate Variability and Change in the United States: Potential Impacts on Water- and Foodborne Diseases Caused by Microbiologic Agents," Environmental Health Perspectives, Vol. 109, Suppl. 2, May, pp. 211-221. http://ehpnet1.niehs.nih.gov/docs/2001/suppl-2/211-221rose/rose-full.html.
ABSTRACT: Exposure to waterborne and foodborne pathogens can occur via drinking water (associated with fecal contamination), seafood (due to natural microbial hazards, toxins, or wastewater disposal) or fresh produce (irrigated or processed with contaminated water). Weather influences the transport and dissemination of these microbial agents via rainfall and runoff and the survival and/or growth through such factors as temperature. Federal and state laws and regulatory programs protect much of the U.S. population from waterborne disease; however, if climate variability increases, current and future deficiencies in areas such as watershed protection, infrastructure, and storm drainage systems will probably increase the risk of contamination events. Knowledge about transport processes and the fate of microbial pollutants associated with rainfall and snowmelt is key to predicting risks from a change in weather variability. Although recent studies identified links between climate variability and occurrence of microbial agents in water, the relationships need further quantification in the context of other stresses. In the marine environment as well, there are few studies that adequately address the potential health effects of climate variability in combination with other stresses such as overfishing, introduced species, and rise in sea level. Advances in monitoring are necessary to enhance early-warning and prevention capabilities. Application of existing technologies, such as molecular fingerprinting to track contaminant sources or satellite remote sensing to detect coastal algal blooms, could be expanded. This assessment recommends incorporating a range of future scenarios of improvement plans for current deficiencies in the public health infrastructure to achieve more realistic risk assessments.

Food Poisoning

Bentham, G. C., and I. H. Langford. 1995. "Climate change and the incidence of food poisoning in England and Wales," International Journal Biometeorology, Vol. 39, No. 2, pp. 81-86.
ABSTRACT: In recent years there have been several spells of high temperatures providing analogues for the conditions that might become more common as a result of the enhanced greenhouse effect. Statistical models were developed of the relationship between the monthly incidence of food poisoning and temperatures and these were then used to provide estimates of the possible effects of future warmer summers. Routinely collected data on the number of reported cases of food poisoning were analysed for the years 1982-1991. Regression analysis was used to establish the relationship between the monthly of food poisoning and temperatures of the same and the previous month. Published scenarios for future temperatures were applied to these statistical models to provide estimates of the possible impacts of warmer conditions. The monthly incidence of food poisoning was found to be significantly associated with the temperature of the same and of the previous month with the latter having the stronger effect. Using published data on the relationship between reported and actual numbers of cases of food poisoning, it is estimated that annually there might be an additional 179 000 cases of food poisoning by the year 2050 as a result of climate change. The observed relationship with the same month's temperature underlies the need for improvements in storage, preparation and hygiene close to the point of consumption. However, there was a much stronger relationship with the temperature of the previous month, indicating the importance of conditions earlier in the food production process. Improvements in areas such as animal husbandry and slaughtering may also be necessary to avoid the adverse effects of a warmer climate.

Vector-borne diseases

Patz, Jonathan A. and William K. Reisen. 2001. "Immunology, climate change and vector-borne diseases," Trends in Immunology, Vol. 22, No. 4, pp. 171-172.
ABSTRACT: Global climate change might expand the distribution of vector-borne pathogens in both time and space, thereby exposing host populations to longer transmission seasons, and immunologically naive populations to newly introduced pathogens. In the African highlands, where cool temperatures limit malaria parasite development, increases in temperature might enhance malaria transmission. St Louis encephalitis viral replication and the length of the transmission season depend upon ambient temperature. Warming temperatures in the American southwest might place at risk migratory, non-immune elderly persons that arrive in early fall to spend the winter. Warm temperatures might intensify or extend the transmission season for dengue fever. Immunologists should examine this interplay between human immunocompetence and vector-borne disease risks in a warmer world.

Kovats, R. S., D. H. Campbell-Lendrum, A. J. McMichael, A. Woodward, J. St H. Cox. 2001. "Early effects of climate change: do they include changes in vector-borne disease?," Philosophical Transactions: Biological Sciences, Vol. 356, No. 1411, July 29, pp. 1057-68.
ABSTRACT: The world's climate appears now to be changing at an unprecedented rate. Shifts in the distribution and behaviour of insect and bird species indicate that biological systems are already responding to this change. It is well established that climate is an important determinant of the spatial and temporal distribution of vectors and pathogens. In theory, a change in climate would be expected to cause changes in the geographical range, seasonality (intra-annual variability), and in the incidence rate (with or without changes in geographical or seasonal patterns). The detection and then attribution of such changes to climate change is an emerging task for scientists. We discuss the evidence required to attribute changes in disease and vectors to the early effects of anthropogenic climate change. The literature to date indicates that there is a lack of strong evidence of the impact of climate change on vector-borne diseases (i.e. malaria, dengue, leishmaniasis, tick-borne diseases). New approaches to monitoring, such as frequent and long-term sampling along transects to monitor the full latitudinal and altitudinal range of specific vector species, are necessary in order to provide convincing direct evidence of climate change effects. There is a need to reassess the appropriate levels of evidence, including dealing with the uncertainties attached to detecting the health impacts of global change.

Gubler, Duane J., Paul Reiter, Kristie L. Ebi, Wendy Yap, Roger Nasci, and Jonathan A. Patz. 2001. "Climate Variability and Change in the United States: Potential Impacts on Vector- and Rodent-Borne Diseases," Environmental Health Perspectives, Vol. 109, Suppl. 2, May, pp. 223-233.
ABSTRACT: Diseases such as plague, typhus, malaria, yellow fever, and dengue fever, transmitted between humans by blood-feeding arthropods, were once common in the United States. Many of these diseases are no longer present, mainly because of changes in land use, agricultural methods, residential patterns, human behavior, and vector control. However, diseases that may be transmitted to humans from wild birds or mammals (zoonoses) continue to circulate in nature in many parts of the country. Most vector-borne diseases exhibit a distinct seasonal pattern, which clearly suggests that they are weather sensitive. Rainfall, temperature, and other weather variables affect in many ways both the vectors and the pathogens they transmit. For example, high temperatures can increase or reduce survival rate, depending on the vector, its behavior, ecology, and many other factors. Thus, the probability of transmission may or may not be increased by higher temperatures. The tremendous growth in international travel increases the risk of importation of vector-borne diseases, some of which can be transmitted locally under suitable circumstances at the right time of the year. But demographic and sociologic factors also play a critical role in determining disease incidence, and it is unlikely that these diseases will cause major epidemics in the United States if the public health infrastructure is maintained and improved.

Reiter, Paul. 2001. "Climate Change and Mosquito-Borne Disease," Environmental Health Perspectives, Vol. 109, Suppl. 1, March, pp. 141-161.
ABSTRACT: Global atmospheric temperatures are presently in a warming phase that began 250-300 years ago. Speculations on the potential impact of continued warming on human health often focus on mosquito-borne diseases. Elementary models suggest that higher global temperatures will enhance their transmission rates and extend their geographic ranges. However, the histories of three such diseases--malaria, yellow fever, and dengue--reveal that climate has rarely been the principal determinant of their prevalence or range; human activities and their impact on local ecology have generally been much more significant. It is therefore inappropriate to use climate-based models to predict future prevalence.

Martens, Willem J.M., Theo H. Jetten, J. Rotmans and L. W. Niessen. 1995. "Climate change and vector-borne diseases: A global modeling perspective," Global Environmental Change, Vol. 5, No. 3, June, pp. 195-209.
ABSTRACT: GCM-based scenarios of anthropogenic global climate change are used for the assessment of potential changes in areas vulnerable to malaria and schistosomiasis transmission. The study shows that the transmission potential of both vector-borne diseases is very sensitive to climate changes on the periphery of the present endemic areas and at higher altitudes within these areas. The health impact will be most pronounced in populations living in the less economically developed temperate areas in which endemicity is low or absent.

Malaria

Patz, J.A., M. Hulme, C. Rosenzweig, T.D. Mitchell, R.A. Goldberg, A.K. Githeko, S. Lele, A.J. McMichael, and D. Le Sueur. 2002. "Regional warming and malaria resurgence," Nature, Vol. 420, pp. 627-628. http://www.giss.nasa.gov/gpol/docs/2002/2002_PatzHulme.pdf.
ABSTRACT: Disease outbreaks are known to be often influenced by local weather, but how changes in disease trends might be affected by long-term global warming is more difficult to establish. In a study of malaria in the African highlands, Hay et al. found no significant change in long-term climate at four locations where malaria incidence has been increasing since 1976. We contend, however, that their conclusions are likely to be flawed by their inappropriate use of a global climate data set. Moreover, the absence of a historical climate signal allows no inference to be drawn about the impact of future climate change on malaria in the region. the existence of critical climate thresholds, the association between change in malaria incidence and change in climate can be biologically meaningful, even without "significant" climate change.

Rogers, D. J., and S. E. Randolph. 2000. "The global spread of malaria in a future, warmer world," Science, Vol. 289, No. 5485, September 8, pp. 1763-6.
ABSTRACT: The frequent warnings that global climate change will allow falciparum malaria to spread into northern latitudes, including Europe and large parts of the United States, are based on biological transmission models driven principally by temperature. These models were assessed for their value in predicting present, and therefore future, malaria distribution. In an alternative statistical approach, the recorded present-day global distribution of falciparum malaria was used to establish the current multivariate climatic constraints. These results were applied to future climate scenarios to predict future distributions, which showed remarkably few changes, even under the most extreme scenarios.

Martens, P., R. Sari Kovats, S. Nijhof, P. de Vries, M. T. J. Livermore, D. J. Bradley, J. Cox and Anthony J. McMichael. 1999. "Climate change and future populations at risk of malaria," Global Environmental Change, Vol. 9, Suppl. 1, October, pp. S89-S107. http://147.46.94.112/e_journals/pdf_full/journal_g/g02_199905_099907.pdf.
ABSTRACT: Global estimates of the potential impact of climate change on malaria transmission were calculated based on future climate scenarios produced by the HadCM2 and the more recent HadCM3 global climate models developed by the UK Hadley Centre. This assessment uses an improved version of the MIASMA malaria model, which incorporates knowledge about the current distributions and characteristics of the main mosquito species of malaria.
The greatest proportional changes in potential transmission are forecast to occur in temperate zones, in areas where vectors are present but it is currently too cold for transmission. Within the current vector distribution limits, only a limited expansion of areas suitable for malaria transmission is forecast, such areas include: central Asia, North America and northern Europe. On a global level, the numbers of additional people at risk of malaria in 2080 due to climate change is estimated to be 300 and 150 million for P. falciparum and P. vivax types of malaria, respectively, under the HadCM3 climate change scenario. Under the HadCM2 ensemble projections, estimates of additional people at risk in 2080 range from 260 to 320 million for P. falciparum and from 100 to 200 million for P. vivax. Climate change will have an important impact on the length of the transmission season in many areas, and this has implications for the burden of disease. Possible decreases in rainfall indicate some areas that currently experience year-round transmission may experience only seasonal transmission in the future. Estimates of future populations at risk of malaria differ significantly between regions and between climate scenarios.

Sutherst, R. W. 1998. "Implications of global change and climate variability for vector-borne diseases: generic approaches to impact assessments," International Journal for Parasitology, Vol. 28, No. 6, 1 June, pp. 935-945.
ABSTRACT: Global change is pervasive and occurring at a dramatic rate. It involves changes in land use, vegetation cover, species translocations and even the climate of the planet. The consequences for the biosphere are uncertain. Past research emphasis has been on the science of climate change as the major driver of policy. The present priority in the global-change community is to define the likely nature and extent of those impacts on biodiversity and the functioning of ecosystems. In addition, increasing consideration is now being given to adaptation measures. The way in which that is being initiated is to develop adaptation measures to respond to medium-term climate variability in the form of altered El Nino and similar cycles, and changes in the frequency of extreme events. Given the large number of stakeholders in agriculture, human health and the environment, there is a need for great efficiencies if the scientific community is going to be able to respond in a meaningful way with foreseeable resources. The plethora of problems means that generic approaches are needed. The present situation, with parasitologists each doing their own thing in terms of developing and using software tools, is like the tower of Babel. Parasitologists need common tools and languages to facilitate communication and collaboration. Advances in computing, with object-oriented programming languages and seamless exchange of information between different packages and platforms, are providing some exciting opportunities to overcome these problems.

Walker, John. 1998. "Malaria in a changing world: an Australian perspective," International Journal for Parasitology, Vol. 28, No. 6, 1 June, pp. 947-953.
ABSTRACT: Three elements must be present for endemic malaria: infected humans, susceptible mosquitoes and a suitable climate. All three occur in parts of Australia and yet this country has always been a region of marginal malaria endemicity. With the exception of a large epidemic in Cairns during the Second World War, most outbreaks have occurred in small, isolated populations of the Northern Territory. The last epidemic was at the Roper River Mission in the Northern Territory in 1962. Since Australia was declared to be free of endemic malaria in 1983, only sporadic cases of local transmission have occurred. There have been suggestions that future climate change may increase the range of the major vector in Australia, Anopheles farauti, and consequently lead to the re-establishment of endemic malaria. This possibility is discussed in relation to experiences in this and other regions. It is stressed that climate change is only one component in a complex epidemiological setting, and that other aspects such as human activity are probably more important.

Russell, Richard C. 1998. "Mosquito-borne arboviruses in Australia: the current scene and implications of climate change for human health," International Journal for Parasitology, Vol. 28, No. 6, 1 June, pp. 955-969.
ABSTRACT: Of the mosquito-borne arboviruses, the encephalitic Murray Valley encephalitis and Kunjin viruses are a major public health concern, but the arthritides Ross River and Barmah Forest viruses are more important in a public health sense, being responsible for a far greater number of infections. Reported cases of Ross River totalled approximately 30 000 during 1991-1996; there have been several widely separated outbreaks of Barmah Forest in recent years and case reports are increasing annually. Surveillance programmes have increased our understanding of the geographic regions, climatic conditions and vector factors associated with viruses. Virus activity is widespread but is often localised, is driven primarily by mosquito abundance and various species are involved; host factors are involved also, but are not well understood. Typically, mosquito populations are governed by availability of habitat and environmental conditions. Models of climate change predict increases in rainfall, tides and temperature for parts of Australia, and such changes have the potential to increase the risk of arbovirus transmission by increasing the distribution and abundance of vectors, and duration of mosquito and arbovirus seasons. However, the amplitude of climate change is uncertain and the ecology of arbovirus transmission is complex. It is likely that some areas will have increases in arbovirus activity and human infection with predicted climate change, but risk of increased transmission will vary with locality, vector, host and human factors.

Martens, Willem J.M., Theo H. Jetten and D. A. Focks. 1997. "Sensitivity of malaria, schistosomiasis and dengue to global warming," Climatic Change, Vol. 35, pp. 145-56.
ABSTRACT: Global assessment of the potential impacts of anthropogenically-induced climate change on vector-borne diseases suggests an increase in extent of the geographical areas susceptible to transmission of malarial Plasmodium parasites, dengue Flavivirus and Schistosoma worms. The transmission potential of the three associated vector-borne diseases studied is highly sensitive to climate changes on the periphery of the currently endemic areas and at higher altitudes within such areas. Our findings vis-à-vis the present endemic areas indicate that the increase in the epidemic potential of malaria and dengue transmission may be estimated at 12-27% and 31-47%, respectively, while in contrast, schistosomiasis transmission potential may be expected to exhibit a 11-17% decrease.

Lindsay, S. W., and M. H. Birley. 1996. "Climate change and malaria transmission," Annals of Tropical Medicine and Parasitology, Vol. 90, No. 6, Dec., pp. 573-88.
ABSTRACT: There is a consensus among climatologists that our planet is experiencing a progressive rise in surface temperature due to the increased production of "greenhouse" gases. Some of the possible consequences of elevated temperature on malaria transmission are examined in the present review. A simple mathematical model is first used to examine the effect of temperature on the ability of Anopheles maculipennis to transmit vivax malaria. This indicates that small increases in temperature at low temperatures may increase the risk of transmission substantially. This is important, since vulnerable communities, poorly protected by health services, in areas of unstable or no malaria are likely to be at increased risk of future outbreaks. In contrast, areas of stable transmission may be little affected by rising temperature. It is thought that global warming will lead to coastal flooding, changes in precipitation and, indirectly, changes in land use. Just how these changes will effect transmission at a regional level requires an understanding of the ecology of local vectors, since environmental changes which favour malaria transmission in one vector species may reduce it in another. Methods for predicting future changes in malaria in different regions are discussed, highlighting the need for further research in this area. Most importantly, there is a need for researchers to validate the accuracy of the models used for predicting malaria and to confirm the assumptions on which the models are based.

Martens, Willem J.M., Louis W. Niessen, Jan Rotmans, Theo H. Jetten, and Anthony J. McMichael. 1995. "Potential Impact of Global Climate Change on Malaria Risk," Environmental Health Perspectives, Vol. 103, No. 5, May, pp. 458-64.
ABSTRACT: The biological activity and geographic distribution of the malarial parasite and its vector are sensitive to climatic influences, especially temperature and precipitation. We have incorporated General Circulation Model-based scenarios of anthropogenic global climate change in an integrated linked-system model for predicting changes in malaria epidemic potential in the next century. The concept of the disability-adjusted life years is included to arrive at a single measure of the effect of anthropogenic climate change on the health impact of malaria. Assessment of the potential impact of global climate change on the incidence of malaria suggests a widespread increase of risk due to expansion of the areas suitable for malaria transmission. This predicted increase is most pronounced at the borders of endemic malaria areas and at higher altitudes within malarial areas. The incidence of infection is sensitive to climate changes in areas of Southeast Asia, South America, and parts of Africa where the disease is less endemic; in these regions the numbers of years of healthy life lost may increase significantly. However, the simulated changes in malaria risk must be interpreted on the basis of local environmental conditions, the effects of socioeconomic developments, and malaria control programs or capabilities.

Matsuoka, Yuzuru, and Keiko Kai. 1994. "An estimation of climatic change effects on malaria," Journal of Global Environment Engineering, Vol. 1, p. 1-15.
ABSTRACT: In this study, we focus on one of the socio-economic impacts of global warming, that of human health, and quantitatively estimate the increased risk of malaria infection. The climate change expected in the next century will cause a surface temperature rise, an increase in precipitation, and a sea level rise. These changes are expected to affect human lives in various ways such as land loss, impacts on agricultural productivity, natural ecosystem, and human health. In this study, we will first describe the estimated magnitude of these impacts and then focus on the health risk by malaria. For malaria, in particular, although the impacts on propagation of Anopheles (the disease vector) and so on are considered to greatly increase the likelihood of the disease, these factors have never been evaluated quantitatively. In this study, we estimate the increase in risks to health caused by malaria. First, we estimated the current and post-global warming distribution of Anopheles by calculating its eco-climatic matching using annual and daily temperature and soil moisture as basic parameters. These parameters were deduced from a water balance model based on General Circulation Models, results. Then, we quantitatively analyzed the change in malaria endemicity taking into account the relationship between temperature and the duration of sporogony of malaria parasites in the Anopheles. We concluded that climate change caused by a doubling of CO2 will allow the malarial area to increase by 10%~30% (population percentage).

Dengue

Patz, Jonathan A., Willem J.M. Martens, Dana A. Focks, and Theo H. Jetten. 1998. "Dengue Fever Epidemic Potential as Projected by General Circulation Models of Global Climate Change," Environmental Health Perspectives, Vol. 106, No. 3, March, pp. 147-153.
ABSTRACT: Climate factors influence the transmission of dengue fever, the world's most widespread vector-borne virus. We examined the potential added risk posed by global climate change on dengue transmission using computer-based simulation analysis to link temperature output from three climate general circulation models (GCMs) to a dengue vectorial capacity equation. Our outcome measure, epidemic potential, is the reciprocal of the critical mosquito density threshold of the vectorial capacity equation. An increase in epidemic potential indicates that a smaller number of mosquitoes can maintain a state of endemicity of disease where dengue virus is introduced. Baseline climate data for comparison are from 1931 to 1980. Among the three GCMs, the average projected temperature elevation was 1.16°C, expected by the year 2050. All three GCMs projected a temperature-related increase in potential seasonal transmission in five selected cities, as well as an increase in global epidemic potential, with the largest area change occurring in temperate regions. For regions already at risk, the aggregate epidemic potential across the three scenarios rose on average between 31 and 47% (range, 24-74%). If climate change occurs, as many climatologists believe, this will increase the epidemic potential of dengue-carrying mosquitoes, given viral introduction and susceptible human populations. Our risk assessment suggests that increased incidence may first occur in regions bordering endemic zones in latitude or altitude. Endemic locations may be at higher risk from hemorrhagic dengue if transmission intensity increases.

Tick-borne diseases

Estrada-Peña, Agustín. 2002. "Increasing Habitat Suitability in the United States for the Tick that Transmits Lyme Disease: A Remote Sensing Approach," Environmental Health Perspectives. Vol. 110, No. 7, July, pp. 635-640.
ABSTRACT: The warnings about the spread of Ixodes scapularis, one of the vectors of Lyme disease, into the United States are based on reports about regional distribution and increasing local abundance. In a modeling approach, I used the recorded, current distribution of this tick and remotely sensed bioclimatic factors over the United States to establish the changes of habitat for this tick since 1982 and to detect the areas with factors adequate to support tick colonization. Results indicate the geographic expansion of areas with adequate habitat suitability in the period 1982-2000. A discriminant analysis of counties with different degrees of habitat suitability shows that the increase in winter temperatures and in vegetation vitality (as a direct consequence of higher rainfall) is key to habitat switch from unsuitable to suitable.

Lindgren, Elisabet, Lars Tälleklint, and Thomas Polfeldt. 2000. "Impact of Climatic Change on the Northern Latitude Limit and Population Density of the Disease-Transmitting European Tick Ixodes ricinus," Environmental Health Perspectives, Vol. 108, No. 2, February, pp. 119-123.
ABSTRACT: We examined whether a reported northward expansion of the geographic distribution limit of the disease-transmitting tick Ixodes ricinus and an increased tick density between the early 1980s and mid-1990s in Sweden was related to climatic changes. The annual number of days with minimum temperatures above vital bioclimatic thresholds for the tick's life-cycle dynamics were related to tick density in both the early 1980s and the mid-1990s in 20 districts in central and northern Sweden. The winters were markedly milder in all of the study areas in the 1990s as compared to the 1980s. Our results indicate that the reported northern shift in the distribution limit of ticks is related to fewer days during the winter seasons with low minimum temperatures, i.e., below -12°C. At high latitudes, low winter temperatures had the clearest impact on tick distribution. Further south, a combination of mild winters (fewer days with minimum temperatures below -7°C) and extended spring and autumn seasons (more days with minimum temperatures from 5 to 8°C) was related to increases in tick density. We conclude that the relatively mild climate of the 1990s in Sweden is probably one of the primary reasons for the observed increase of density and geographic range of I. ricinus ticks.

Chagas Disease

Schistosomiasis

Leishmaniasis

Cross, Eleanor R. and Kenneth C. Hyams. 1996. "The Potential Effect of Global Warming on the Geographic and Seasonal Distribution of Phlebotomus papatasi in Southwest Asia," Environmental Health Perspectives, Vol. 104, No. 7, July, pp. 724-727.
ABSTRACT: The distribution of Phlebotomus papatasi in Southwest Asia is thought to be highly dependent on temperature and relative humidity. A discriminant analysis model based on weather data and reported vector surveys was developed to predict the seasonal and geographic distribution of P. papatasi in this region. To simulate global warming, temperature values for 115 weather stations were increased by 1°C, 3°C, and 5°C, and the outcome variable coded as unknown in the model. Probability of occurrence values were then predicted for each location with a weather station. Stations with positive probability of occurrence values for May, June, July, and August were considered locations where two or more life cycles of P. papatasi could occur and which could support endemic transmission of leishmaniasis and sandfly fever. Among 115 weather stations, 71 (62%) would be considered endemic with current temperature conditions; 14 (12%) additional stations could become endemic with an increase of 1°C; 17 (15%) more with a 3°C increase; and 12 (10%) more (all but one station) with a 5°C increase. In addition to increased geographic distribution, seasonality of disease transmission could be extended throughout 12 months of the year in 7 (6%) locations with at least a 3°C rise in temperature and in 29 (25%) locations with a 5°C rise.

Water-borne diseases

Casman, Elizabeth, Baruch Fischhoff, Mitchell Small, et al. 2001. "Climate Change and Cryptosporidiosis: A Qualitative Analysis," Climatic Change, Vol. 50, No. 1-2, July, pp. 219-249.
ABSTRACT: The effects of climate change on drinking-waterborne cryptosporidiosis transmission in the United States are analyzed using an influence diagram representation of epidemic development. Results from a systematic qualitative analysis indicate that climate change will have little effect on cryptosporidiosis incidence if the United States continues to be wealthy and maintains its commitment to public health. The major impact will, instead, be the additional costs of adapting to new climate regimes in order to avoid drinking-waterborne disease risk. These costs, for the most part, will be from improved monitoring and treatment of drinking water. The consequences of disaster scenarios are also considered. These, too, suggest that climate change per se will be a poor predictor of waterborne cryptosporidiosis in countries with high standards of living. Rather, the risk of epidemics will depend on the interplay between population, public health investment, infrastructure maintenance, emergency planning/response capabilities, water-treatment technologies, drinking-water regulations, and climate.

Cholera

Lipp, Erin K., Anwar Huq, and Rita R. Colwell. 2002. "Effects of Global Climate on Infectious Disease: the Cholera Model," Clinical Microbiology Reviews, Vol. 15, No. 4, October, pp. 757-770. http://www.mbio.ncsu.edu/SL/MB590790/cholerae/cholera.pdf.
ABSTRACT: Recently, the role of the environment and climate in disease dynamics has become a subject of increasing interest to microbiologists, clinicians, epidemiologists, and ecologists. Much of the interest has been stimulated by the growing problems of antibiotic resistance among pathogens, emergence and/or reemergence of infectious diseases worldwide, the potential of bioterrorism, and the debate concerning climate change. Cholera, caused by Vibrio cholerae, lends itself to analyses of the role of climate in infectious disease, coupled to population dynamics of pathogenic microorganisms, for several reasons. First, the disease has a historical context linking it to specific seasons and biogeographical zones. In addition, the population dynamics of V. cholerae in the environment are strongly controlled by environmental factors, such as water temperature, salinity, and the presence of copepods, which are, in turn, controlled by larger-scale climate variability. In this review, the association between plankton and V. cholerae that has been documented over the last 20 years is discussed in support of the hypothesis that cholera shares properties of a vector-borne disease. In addition, a model for environmental transmission of cholera to humans in the context of climate variability is presented. The cholera model provides a template for future research on climate-sensitive diseases, allowing definition of critical parameters and offering a means of developing more sophisticated methods for prediction of disease outbreaks.

Colwell, R.R. 1996. "Global climate and infectious disease: the cholera paradigm," Science, Vol. 274, No. 5295, Dec 20, pp. 2025-31.
ABSTRACT: The origin of cholera has been elusive, even though scientific evidence clearly shows it is a waterborne disease. However, standard bacteriological procedures for isolation of the cholera vibrio from environmental samples, including water, between epidemics generally were unsuccessful. Vibrio cholerae, a marine vibrio, requiring salt for growth, enters into a dormant, viable but nonculturable stage when conditions are unfavorable for growth and reproduction. The association of Vibrio cholerae with plankton, notably copepods, provides further evidence for the environmental origin of cholera, as well as an explanation for the sporadic and erratic occurrence of cholera epidemics. On a global scale, cholera epidemics can now be related to climate and climatic events, such as El Nino, as well as the global distribution of the plankton host. Remote sensing, with the use of satellite imagery, offers the potential for predicting conditions conducive to cholera outbreaks or epidemics.

General Studies Spread of Disease Thermal Stress CLIMATE CHANGE AND SPREAD OF DISEASE