How West Nile Virus has been affected by Climate Change (Global Warming)

Introduction

Climate change is not only currently on everyone's lips, but is also regarded as fact. Thus, the dry summer, the extreme winter temperatures and high precipitation and other phenomena are explained by a change of climate. Even in the animal disease control you begin to prepare for "new" or not yet in our latitudes existing diseases. While in the past a disease depending on contagiousness (probability of disease transmission) has spread slowly, more or less, and natural boundaries often constitute a major obstacle to the disease, and erratic spread of animal disease is more frequently observed. Temperature is a critical factor that depends on both vector density and vectorial capacity: increases or decreases the survival of the vector that determines the growth rate of the vector population, changed vector susceptibility to pathogens, alters the length of extrinsic incubation of the pathogen in the vector and changes the activity and the pattern of seasonal transmission.

By increasing the water temperature, mosquito larvae take less time to mature and, consequently, increase the number of pups during transmission station. It shortens the period of egg-adult metamorphosis, reducing the size of the larvae and adults being generated in a shorter time, but these are smaller, so that females have to take more frequent blood to get to lay eggs, which resulting in an increased rate of inoculation. The extrinsic incubation period (time taken from that infects arthropod until it is infectious) is directly related to the temperature: the higher the temperature the time is less. This change in geographical distribution must also take into account factors such as changes in land use, increased host species such as deer and rodents, changes in work and recreational activities that could explain the heterogeneity of epidemiological changes in a more homogeneous heating context.

Most likely, the effect of climate change on arthropod-borne diseases is observed to vary the temperature limits of transferability: 14-18 ° C as the lower limit and is higher 35-40 ° C. A minimum increase in the lower limit may lead to transmission of disease, while the upper one could suppress increase (above 34 ° C substantially shortens the life of the mosquito). However, around 30-32 ° C vectorial capacity can be changed substantially since small increases in temperature shortens the extrinsic incubation period, increasing transmissibility. The climate has a decisive influence on the phenology of arthropods that even enter in the unfavorable season, this behavior widespread species in the Palearctic region. The seasonal activity period may be extended for many species to persist the more favorable weather conditions.

The increased temperature accelerates the maturation of mosquito larvae and adult stage of development. Besides these adult mosquitoes need to be smaller more frequent feedings increasing biting rate and inoculations. Another effect of temperature increase is that it reduces the time required for the vector to be infective since the pathogen acquires, thereby, within certain margins, global warming increase the transmissibility of infectious diseases transmitted by ...