Zoonotic (animal-to-human) pathogens are responsible for an estimated 70% of the emerging human diseases documented over the past thirty years. Zoonotic transmission and associated pandemic potential are serious global health concerns, exacerbated by the increasing overlap of human and animal ecosystems in developing countries. Recent SARS, MERS and Ebola outbreaks highlight the need to better understand the disease-causing potential of known zoonotic pathogens and focus attention where unknown potential exists.
Twenty years ago researchers estimated the vertebrate viral pool to consist of over one-million different viruses. Consider as an example of viral diversity the Indian flying fox, or fruit bat (Pteropus giganteous). This animal is known to harbor Nipah virus, responsible for a 1999 Malaysian outbreak that caused over 100 human deaths and prompted euthanization of over one-million pigs. In a 2013 study PCR detected 55 different viruses in fruit bats, 50 of which were considered novel. Although infectious particles were not isolated, mathematical modeling estimated that over 300,000 different mammalian viruses may exist, a large potential zoonotic threat considering that only a fraction of this number has been documented to date.
More research and understanding in the area of emerging zoonotic disease is necessary to prevent outbreaks and to focus healthcare efforts.