Diseases and Climate change; who will be at risk

I came over this article  talking about how climate change would lead to Malaria becoming more common. Climate change will lead to warmer climate and since mosquito thrives better in those climate the are more likely to increase. This got be thinking about other diseases such as the Avian Influenza and Plague.Avian influenza was especially deadly in 2003 (H5N1) were it spread quickly throughout Asia which reached Europe in 2005. In January 2012 the second death due to H5N1 was recorded in China. Death was also confirmed in Canada.

Wu et al (2011) used econometric models to explore the impact of H5N1 due to future climate change. There result found that outbreak coincided with temperature, precipitation, and regional characteristics. Probability of of outbreak is also found to be higher when there was has been previous events. As in the case of Hong Kong which experience outbreak in 1998 and 2003. Elvander (2006) found that there close occurrence of these two events has might that the H5N1 virus was still circulating within the poultry population. Wu et al (2011) also looking backwards, the changes in rainfall and temperature in the past 20 years is the causes of increase outbreak in ALL countries. An estimation between 8% to 1160%. The form of disorder is not so much as mass infection and the associated economic damage! US is one of the largest producer and exporter of meat. An outbreak would lead to $29 million of economic losses. China also had multiple break since 2003 and this could lead to $106-$146 million because of climate change.

The other threat is the reemergence of Plague, and Ari et al (2011) looked at how the transmitting mechanism is affected by climate change in order to fully understand the future probability of outbreak. Research in Africa have shown that plague were less frequent where the weather was hot (greater 27 degree) and cold (less than 15 degree). The overall transmitting mechanism for a vector-borne diseases is complex to analyse. But climate change  will effect the dynamics of flea vectors and rodent host (fig 2). Rodents are affected by temperature, rainfall, humidity which largely determines flea survival. Moisture which is key for determining the number of fleas. If these changes, the number of diseases spreading vehicle will be affected, hence infection rate as well. Currently, modeling of plague have been done in individual places, but they all confirm that climate changes are associated with the occurrences of plague both in the local and regional scale. For example Stenseth et al (2006) showed that one degree rises in temperature in Kazakhstan would increase plague prevalence among gerbils. The research did not say how this would affect humans. But is important to know that human impact in the environment would Is important to note that component of all the plague cycles (host, vector and pathogen) are affected in different ways and the interaction between hose and vectors also contributes largely to the spread of the disease.

fig 2
Source Ari et al (2011)

A paper by Redshaw et al (2014) looks at the relationship between disease patterns and pharmaceutical uses in response to climate change. This paper looks at the emerging threat of new diseases in the Northern Hemisphere. Climate change is likely to lead to an increase in diseases like mental illness and cardiovascular disease. These are through emotional distresses from natural disasters of severe environmental degradation. They have also shown that climate change will lead to respiratory diseases like asthma and allergies becoming more server and in turn, leading to a increase the use of drugs. Growth in human and animal diarrhea disease will become more common. This will be transmitted through water-faecal contamination which will also lead to the use of antibiotics. Other diseases will become more promoent, like the liver and lung helminths. And to treat these it requires medications for parasitic diseases and will experience an increase in these types of medicine too.

Cordovez et al (2014) explored the impact of climate change and its effect in the risk of Chagas disease transmission in Colombia. They uses basic reproduction numbers in their modeling to explore these changes induced by climate change. They result is interesting and different from the above two for two reasons. Firstly, they found increases in temperature due to climate would decrease the reproduction rate and thus, lowering the chances of mass outbreak. The eastern part of Colombia will see a reduce in R. At the same time, they highlighted the significance of movement of urban settlements. They explored that changes in human settlement is a better method of tracking the geographic location of infection risk. Since these urban centers have the environmental characteristics that sustain higher chance of reproduction. For example, one way of being infected is through insects (who carries the diseases) invade houses to feed on human. This example shows that climate changes doesnt necessarily work in favor of higher infection rates and thus societal disorder through economic and social burden for governments and individuals.

I have shown how increase in certain types of disease will become more common. The emergence of plague and the spreading of Avian influenza (eg H5N1) are looking to affect both humans, but more importantly the economic effect would be large as well. Climate change will also lead to a higher burden in Norther Hemisphere's government since common illnesses will become more server and the emergence of other diseases will also have an affect on society. This is an area where societal disorder will be largely causes by the related economic losses and burden. Unlike the bubonic plague in the 1300s, medical advances are likely to prevent large numbers of death.