Sustained fecal-oral human-to-human transmission following a zoonotic event

Abstract

Bacterial, viral and parasitic zoonotic pathogens that transmit via the fecal-oral route have a major impact on global health. However, the mechanisms underlying the emergence of such pathogens from the animal reservoir and their persistence in the human population are poorly understood. Here, we present a framework of human-to-human transmission of zoonotic pathogens that considers the factors relevant for fecal-oral human-to-human transmission route at the levels of host, pathogen, and environment. We discuss current data gaps and propose future research directions.

Figure 1

Fecal-oral transmission between humans. After shedding from the host enteric pathogens can be transmitted between humans by the fecal-oral route via direct contact between humans, or via indirect contact via contaminated fluids, including surface water, food, and carriers such as fomites.

Figure 2

Framework for human-to-human transmission after a zoonotic event showing the key transmission amplifiers from the host (triangle), pathogen (blue) and environmental transmission amplifiers (green), respectively. The transmission amplifiers that are specific to the fecal-oral route are indicated with a red star.