Global movements of horses and men, climate change, global worming etc. are responsible for the increasing immigration of foreign organisms and an international exchange of infectious diseases. In this context the vector-borne diseases of equines and human beings are of special significance. Environmental factors, climate - driven changes are the reasons for changes in the size and activity of specific vector populations. They have significant influence to the biological behaviour of many different arthropods - acting as biovectors - and enable their transmission in previously non endemic areas, countries or continents. Factors that determine populations of reservoirs and amplifying hosts are in part due to the weather, winter mortality of adults and success of hatching. This is linked to management of land, agriculture, watering practising and the presence of wildlife hosts. Different populations of mosquitoes are sensitve to natural and man-induced factors. Climate change in the sense of global warming supports overwintering, which depends on temperature and snow cover. Summer populations are largely determined by the right quantity and frequency of rainfall, high humidity and warm temperatures. Low temperatures and low humidity can reduce it and low temperatures can also slow down the growth of virus in the vector mosquitoes. In this context the north-word migration of competent biovectors (arthropods) have established diseases in formerly non-endemic areas. Examples are the West Nile Virus (WNV) and the Virus of African Horse Sickness (AHS) expanding into the northern hemisphere. WNV belongs to the Japanese - B- Encephalitis complex, and AHS is an orbivirus. American Encephalomyelititides of Equidae (EEE, WEE, VEE) - belonging to the Flaviviruses - are also dependent on suitable weather conditions, but many other variable factors in their epidemic occurrence and spread are involved. WEE and EEE - like WNV - are maintained in nature between mosquitoes and birds, VEE between mosquitoes, birds and different, portly unidentified rodents. Cases of EEE or WEE have been reported from different Asiatic countries. In contrast to the mentioned viruses, which affects men and horses, the Equine Infectious Anaemia (EIA) is caused by a lentivirus and affects only equides. The virus can be transmitted by blood suckling biovectors, but also by different ex- and secretions, foetal infection, colostrum, tissue, blood transfusion, plasmaproducts etc. We have to consider that the invasion of EIA from endemic countries like Italy or regions in different countries like Romania and others into non-endemic countries is easy, supported by missing diagnostic tests and experience, uncontrolled horse travellings and imports, missing documentation etc. Tick borne diseases infecting men and horses are also common, examples are the Early Summer Meningoencephalitis (Flavivirus) and infections caused by bacteriums belonging to the familiy Boerrelia and Anaplasma. The chance of diseases from the mentioned viruses and bacteriums and their invasion into new countries can be reduced and controlled only by a coordinated strategy plan combining environmental management procedures, vector surveillance and control, surveillance of reservoirs in domestic animals, wild fauna - esp. birds - and humans and specific preventive measurements. The primary goal is to reduce vector populations by identifying and eliminating breeding and resting sites, use of larvacides and insecticides. International coordination in data and reporting systems, im- and export controls of animals, sandardization and validation of diagnostic tests have to go hand in hand.
