A comprehensive review of infectious organisms pathogenic to humans identifies 1415 species, including 217 viruses and prions, 538 bacteria and rickettsia, 307 fungi, 66 protozoa, and 287 helminths. Of these, 868 (61%) are zoonotic, and 175 are associated with emerging diseases. The study tests the hypothesis that zoonotic pathogens are more likely to be linked to emerging diseases than non-zoonotic ones. Out of the 175 emerging pathogens, 132 (75%) are zoonotic, indicating that zoonotic pathogens are twice as likely to be associated with emerging diseases. However, the results vary by taxonomic group, with protozoa and viruses more likely to emerge, and helminths less likely. Transmission route does not show a clear association with emergence. This study is the first quantitative analysis of risk factors for human disease emergence. The findings suggest that zoonotic pathogens are more likely to emerge, but the effect depends on taxonomy and transmission routes. Viruses and protozoa are more likely to emerge, while helminths are less likely. Zoonotic pathogens are more likely to be transmitted by indirect contact or vectors. The study highlights the importance of taxonomy and zoonotic status in disease emergence. It also emphasizes the need for better understanding of pathogen biology and transmission routes. The study concludes that emerging diseases are not a random selection of all human pathogens, and that factors such as genetic diversity, generation time, and reservoirs play a role in emergence. The study also notes that some zoonotic pathogens, like HIV, are no longer zoonotic. The research underscores the importance of collaboration between medical and veterinary researchers in managing emerging diseases.A comprehensive review of infectious organisms pathogenic to humans identifies 1415 species, including 217 viruses and prions, 538 bacteria and rickettsia, 307 fungi, 66 protozoa, and 287 helminths. Of these, 868 (61%) are zoonotic, and 175 are associated with emerging diseases. The study tests the hypothesis that zoonotic pathogens are more likely to be linked to emerging diseases than non-zoonotic ones. Out of the 175 emerging pathogens, 132 (75%) are zoonotic, indicating that zoonotic pathogens are twice as likely to be associated with emerging diseases. However, the results vary by taxonomic group, with protozoa and viruses more likely to emerge, and helminths less likely. Transmission route does not show a clear association with emergence. This study is the first quantitative analysis of risk factors for human disease emergence. The findings suggest that zoonotic pathogens are more likely to emerge, but the effect depends on taxonomy and transmission routes. Viruses and protozoa are more likely to emerge, while helminths are less likely. Zoonotic pathogens are more likely to be transmitted by indirect contact or vectors. The study highlights the importance of taxonomy and zoonotic status in disease emergence. It also emphasizes the need for better understanding of pathogen biology and transmission routes. The study concludes that emerging diseases are not a random selection of all human pathogens, and that factors such as genetic diversity, generation time, and reservoirs play a role in emergence. The study also notes that some zoonotic pathogens, like HIV, are no longer zoonotic. The research underscores the importance of collaboration between medical and veterinary researchers in managing emerging diseases.