EN
There is a wide range of differing opinions relating to assessing the risk of zoonotic pathogens which cause avian influenza (AI) and bovine spongiform encephalopathy (BSE), and, in the case of humans, variants of Creutzfeldt-Jakob disease (vCJD) and influenza. The aim of the study was to analyze the most essential publications in this field. It compared the number of cases of disease and death in animals and humans and presented the variety of mechanisms within influenza viruses as well as the consequences of their adaptations in relation to both birds and humans. The study concluded that subtype H5N1 of the influenza virus was the cause of the pandemic influenza in domestic and wild birds which started in 2003, is still continuing, and has so far caused the death of over 200 million domestic birds and an undefined number of wild birds, but that it is not a danger to humans to such a degree as subtypes H1N1, H2N2 and H3N2. These subtypes caused the death of about 50 million, 1 million, and over 700 000 humans during respective outbreaks in the 20th century. The present situation, related to the H5N1 strain has, on the other hand, only caused 129 deaths so far with the most recent cases of mortality occurring in Asia, Turkey and Egypt. As far as BSE is concerned, cases of transmitting the prion which causes vCJD from cattle to man have been much fewer, with the highest numbers in the past 20 years occurring in the United Kingdom - about 160 human fatalities, France - 15 cases and a few other countries with smaller numbers of fatalities. No cases of vCJD have been encountered to date in some countries where BSE has been diagnosed such as Switzerland, Germany and Poland. Even in the U.K. however, where in 2000 the number of fatalities of vCJD were 28, this number decreased in 2005 to 5 cases, indicating the disappearance of this zoonosis.