Disease occurrence due to climate change
The movement of animal diseases across physical and political boundaries threatens food security and creates a global public concern across all countries and all regions. Countries are cautious to limit the spread and control of transboundary diseases and also adapting animal health strategies and coordinating activities at regional and global level for prevention, early warning and control.
It is evident that climate change is altering the distribution, incidence and intensity of animal diseases such as bluetongue and other vector-borne diseases. Animal diseases are not evenly distributed over the globe. The increase in movement has accelerated the redistribution of animal diseases and climate change is able to create a new ecological niches for the establishment and spread of diseases into new geographical areas from one region to another e.g. foot-and-mouth disease, classical swine fever, Rift valley fever etc. New vectors, selection and recombination of disease genotypes may occur due to mixing of animal species and breeds or the introduction of insects and vectors without their natural hosts. Change in climate would result the changes in species composition and interactions which would augment the emergence of unexpected events, including the emergence of new diseases. Climate change has direct impact on vector-borne animal diseases and macro-parasites of animals due to the free stages of these parasites and may also result in new transmission modalities in different host species. Temperate countries will be particularly vulnerable to invasions by exotic vector or arthropod-borne viral diseases.
Diseases caused by arthropod-borne viruses (arboviruses) include a large number of arthropod vector-borne (mosquitoes, midges, ticks, fleas, sand flies, etc.) that are often zoonotic, predominantly RNA viruses, that can cause hemorrhagic fevers or encephalitis. Emerging arbo-virus disease complexes are by far the most important and climate change is only one factor altering disease ecologies. The effects of climate change on internal parasites (gastrointestinal parasites and liver fluke) may include changes in the distribution of the parasites and the intermediate hosts. In wet areas, these will become of greater importance. Apart from the effects on pathogens, hosts, vectors and epidemiology, there may be other indirect effects on the abundance or distribution of the vectors' competitors, predators and parasites.