Zoonotic spillover: Understanding basic aspects for better prevention

Abstract

The transmission of pathogens from wild animals to humans is called "zoonotic spillover" . Most human infectious diseases (60-75%) are derived from pathogens that originally circulated in non-human animal species. This demonstrates that spillover has a fundamental role in the emergence of new human infectious diseases. Understanding the factors that facilitate the transmission of pathogens from wild animals to humans is essential to establish strategies focused on the reduction of the frequency of spillover events. In this context, this article describes the basic aspects of zoonotic spillover and the main factors involved in spillover events, considering the role of the inter-species interactions, phylogenetic distance between host species, environmental drivers, and specific characteristics of the pathogens, animals, and humans. As an example, the factors involved in the emergence of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) pandemic are discussed, indicating what can be learned from this public health emergency, and what can be applied to the Brazilian scenario. Finally, this article discusses actions to prevent or reduce the frequency of zoonotic spillover events.

Global research trends in MERS-CoV: A comprehensive bibliometric analysis from 2012 to 2021

“…The potential routes of MERS-CoV emergence and transmission are presented in Figure 1 . It is necessary to prevent or reduce zoonotic spillover events since 60–75% of human infectious diseases emerged from pathogens originally circulating in non-human animal species ( 12 ).…”

High-throughput sequencing technologies in the detection of livestock pathogens, diagnosis, and zoonotic surveillance

“…Outbreaks of zoonotic infectious disease or reverse zoonotic disease transmission (zooanthroponosis) in humans are caused by the spillover (cross-species spillover) of pathogens from animals, and locations where individuals and animals frequently interact are potential spillover sites [35] . Pathogen potency, host immune defense, and human activities affect spillover events [36] . Several factors determine the success of viral infection, including host support for sufficient virion production, accessibility to enter the host, host receptors, and tropism [37] .…”

Presence and Multi-Species Spatial Distribution of Oropouche Virus in Brazil within the One Health Framework

“…Through spillover events facilitated by the bite of an infected midge or mosquito, OROV has become an increasing concern in human health. Spillover is defined as an event in which the presence of a disease moves from its animal host into a human case [6]. Patients typically present with febrile symptoms of fever, chills, photophobia, skin rashes, and dizziness [1].…”