Global warming causes infectious diseases to spread more easily via vectors like mosquitoes or ticks that are sensitive to temperature changes, according to new research conducted at the University of Haifa. The specific carriers of malaria or West Nile virus, for example, lack the necessary mechanism to maintain a steady body temperature, so they are influenced by climate changes. Global warming will thus cause an increase in the development and multiplication of pathogens that cause these highly infectious diseases. Dr. Shlomit Paz of the university's Department of Geography and Environmental Studies will present her findings at the conference of the Israel Geographic Society, which will hold its annual meetings at Ben-Gurion University of the Negev in Beersheba from today through Tuesday. Paz maintains that climatic changes bring about extreme temperature changes and sometimes an increase in cold waves. These can cause infectious diseases, higher mortality rates, and endanger the elderly. The European heat wave of the summer of 2003, she says, showed that developed countries with large numbers of elderly residents can be harmed as a result of sudden rises in temperature. In addition, sudden and extreme storms and floods directly affect human safety, while also harming their property, eroding the earth and destroying crops. Warmer, more humid weather causes disease carriers to multiply faster, and the influence of these changes can remain for a long time after the change in weather, says Paz. Vibrio vulnificus, a bacterium present in salty-water pond fish, thrives in warm temperatures. Vibrio infections are spread when the fingers of people with weak immune systems are punctured by fish fins and scales, and they can result in pain, amputation and even death. The bacterium was first discovered in fish ponds in the Beit She'an Valley in 1996, and studies at Ha'emek Hospital in Afula showed a clear link between heat waves and the spread of Vibrio bacteria. West Nile virus, which a few years ago caused numerous deaths in Israel, is more virulent during heat waves, as the virus is spread by mosquitoes that bite wild birds and poultry. Paz found a clear connection between high temperatures and West Nile virus outbreaks in the summers of 1998, 1999 and 2000; the disease appeared about two-and-a-half months after the rise in temperatures.