Population biology of emerging and re-emerging pathogens

摘要

Emerging and re-emerging pathogens present a huge challenge to human and veterinary medicine. Emergence is most commonly associated with ecological change, and specific risk factors are related to the type of pathogen, route of transmission and hostrange. The biological determinants of host range remain poorly understood but most pathogens can infect multiple hosts, and three-quarters of emerging human pathogens are zoonotic. Surveillance is a key defence against emerging pathogens but will oftenneed to be integrated across human, domestic animal and wildlife populations. There are 1415 species of endoparasitic infectious organisms known to be pathogenic in humans, many of which have only recently been recognized (Table 1). These pathogens are responsible for an enormous global burden of disease and cause 14 million human deaths per year. The incidence of many infectious diseases is increasing, and this is true not only of new diseases, such as acquired immunodeficiency virus (AIDS), but also of diseases previously regarded as being in decline, such as tuberculosis (TB). Similarly, pathogens affecting domestic animals are responsible for huge economic losses and welfare problems, and pathogens affecting wildlife can be a threat to conservation. Both novel and resurgent pathogens, such as bovine spongiform encephalopathy (BSE) in cattle and phocine distemper in seals, are having an increasing impact on animal health.