Climate Change and Re-emerging Diseases
There is a rise in many infectious diseases worldwide today, including some newly circulating ones (HIV/AIDS, hantavirus, hepatitis C, SARS, etc.). The combined results of rapid demographic, environmental, socioeconomic, technological, and other shifts in the way we live, are embodied in this. Climate change also increases the incidence of these infectious diseases.
Since long before the features of infectious agents were established, late in the nineteenth century, humans understood that climate factors influenced viral diseases. In season, Roman aristocrats retired to hill resorts to escape malaria. South Asians found out that highly curried foods were less likely to induce diarrhea in the high summer.
In addition to numerous human, biological, and ecological determinants, climatic factors affect the appearance and re-emergence of infectious diseases. In global temperatures, climatologists have identified upward trends and now estimate an unprecedented increase of 2.0°C by the year 2100.
It is of great concern that these improvements could impact the introduction and spread of many significant infectious diseases. Among those diseases most sensitive to the climate are the incidence of mosquito-borne diseases, including malaria, dengue, and viral encephalitis.
Diseases carried by vectors and by water
Relevant determinants of the transmission of vector-borne diseases include (i) vector survival and reproduction, (ii) biting rate of the vector, and (iii) incubation rate of the pathogen within the vector organism. In a variety of optimum climatic conditions, vectors, pathogens, and hosts each live and reproduce: temperature and precipitation are the most important, while the elevation of sea level, wind, and length of daylight is also important.
Human exposure to waterborne pathogens occurs by contact with polluted drinking water, recreational water, or food. This may occur from human activity, such as excessive handling of wastewater, or weather events. The distribution and propagation of infectious agents can be affected by rainfall, while temperature influences their development and survival.
Climate / infectious disease associations identified and planned
Analysis of the links between climatic conditions and the spread of infectious diseases is available in three categories. The first discusses data from the recent history of interactions between climate variability and the prevalence of infectious diseases.
The second discusses early indications of the already-emerging effects of long-term climate change on infectious diseases. To forecast the potential burden of infectious diseases under the predicted climate change conditions, the third uses the above data to construct statistical models.
The Historical Evidence
There are a lot of correlations between climatic and infectious diseases. Malaria is of considerable public health importance and appears likely to be the most vulnerable vector-borne disease to long-term climate change. In strongly endemic areas, malaria differs seasonally.
By changing the geographical range of the vector and increasing reproductive and biting rates, and shortening the time of pathogen incubation, climate change will directly impact disease transmission. Increases in sea surface temperature and sea level due to the atmosphere can contribute to a higher occurrence of bacterial and toxin-related waterborne diseases, such as cholera and shellfish poisoning.
Human movement and disruption to health infrastructures may indirectly lead to the spread of diseases, as a result of the expected rise in climate variability. Due to climate stress on Agriculture and possible changes in the human immune system caused by an increased flow of ultraviolet radiation, human susceptibility to infections may further be exacerbated by malnutrition. It will thus, take interdisciplinary collaboration among physicians, climatologists, biologists, and social scientists to examine the role of the environment in the emergence of human infectious diseases.
Changes in the dynamics of transmission of infectious diseases are a possible significant effect of climate change, too. We, therefore, need to understand more about the underlying dynamic causal relationships between Climate change and the diseases that come our way. We must apply this knowledge, using complete, better validated, and applied models to the prediction of future impacts.