After many generations have emerged, scientists must continuously form new vaccinations to combat the components of the disease that evolve every time a generation appears. Two sets of experiments were performed which tested the correlation of pathogens and declining organism populations as well as zoonotic pathogens being associated with emerging infectious diseases. The first experiment focused solely on a pathogen’s ability to decrease or completely wipe out a whole population of organisms. In this experiment, researchers used Daphnia magna as the host and six microparasites were vertically transmitted to the host. Researchers Ebert, Lipsitch, and Mangin found that while pathogens and parasites do cause a change in a population, they do not have the ability to destroy an entire population. The pathogens did however have an impact on the host’s fertility. Some females involved in the experiment were unable to reproduce after being infected with the microparasites. The second experiment focused more on zoonotic pathogens being correlated with emerging infectious diseases in humans. The researchers comprised a database with separate infectious species, infectious pathogens that cause disease in patients with abnormal immune systems, and pathogens that have only been found in one case of human disease. The researchers broke this database down into five portions which were viruses, bacteria, fungi, protozoa, and helminths. Direct contact, indirect contact, and vector borne were the routes of transmission used. They found that 1415 zoonotic pathogen diseases have been found in humans.