The threat of zoonotic diseases

Crossing the species barrier Zoonotic infectious diseases have been important concerns to humans since the beginning of the domestication of animals 10,000 years ago. Approximately 75% of emerging infectious diseases are zoonoses. The phenomenon of emerging and reemerging infectious diseases is driven by various anthropogenic factors, including: genetic and biological factors, such as microbial adaptation to macro- and microenvironmental changes along with changes in host susceptibility to infection; environmental factors, including climate change, changes in ecosystems, and changes in human and animal population densities; and socioeconomic and political factors, such as increasing international travel and commerce, social inequality, poverty, conflict, famine, lack of political will, and changes in economic development and land use.

Over the last 15 years, our planet has faced more than 15 deadly zoonotic or vector-borne global outbreaks, both viral (e.g., Ebola, Hanta, highly pathogenic avian influenza [H5N1 and H7N9], West Nile, Rift Valley fever, norovirus, severe acute respiratory syndrome [SARS], Marburg, influenza A [H1N1]) and bacterial (e.g. Escherichia coli O157:H7, Yersinia pestis, and Bacillus anthracis). Since 1980, more than 87 new zoonotic and/or vector-borne EIDs have been discovered.

The global economic burden due to zoonotic diseases is very high. According to a recent World Bank estimate, the economic burden due to six of the zoonotic diseases that have occurred in specific countries between 1997 and 2009 is estimated to be US$80,000,000,000. In a worst-case scenario, potential losses from a pandemic influenza outbreak could be US$3 trillion, which is equivalent to 5% of the global GDP. A recent report from the International Livestock Research Institute highlighted zoonoses as major obstacles to poverty alleviation, affecting 1,000,000,000 livestock keepers. The report estimated that there are over 2,500,000,000 cases of human illness and 2.7 million deaths annually due to the top 56 zoonoses.

While zoonotic EIDs are a major concern globally, their impact in less developed countries is disproportionately high because of the occurrence of risk factors such as a high rate of population growth, lack of infrastructure and skilled-manpower capacity to tackle disease outbreaks, a high proportion of people with compromised immunity due to comorbidities such as HIV/AIDS or parasitic diseases, and lifestyles in which daily life depends on animals.

The Global One Health Paradigm: Challenges and Opportunities for Tackling Infectious Diseases at the Human, Animal, and Environment Interface in Low-Resource Settings. (2014) PLoS Negl Trop Dis 8(11): e3257. doi:10.1371/journal.pntd.0003257
Zoonotic infectious diseases have been an important concern to humankind for more than 10,000 years. Today, approximately 75% of newly emerging infectious diseases (EIDs) are zoonoses that result from various anthropogenic, genetic, ecologic, socioeconomic, and climatic factors. These interrelated driving forces make it difficult to predict and to prevent zoonotic EIDs. Although significant improvements in environmental and medical surveillance, clinical diagnostic methods, and medical practices have been achieved in the recent years, zoonotic EIDs remain a major global concern, and such threats are expanding, especially in less developed regions. The current Ebola epidemic in West Africa is an extreme stark reminder of the role animal reservoirs play in public health and reinforces the urgent need for globally operationalizing a One Health approach. The complex nature of zoonotic diseases and the limited resources in developing countries are a reminder that the need for implementation of Global One Health in low-resource settings is crucial. The Veterinary Public Health and Biotechnology (VPH-Biotec) Global Consortium launched the International Congress on Pathogens at the Human-Animal Interface (ICOPHAI) in order to address important challenges and needs for capacity building. The inaugural ICOPHAI (Addis Ababa, Ethiopia, 2011) and the second congress (Porto de Galinhas, Brazil, 2013) were unique opportunities to share and discuss issues related to zoonotic infectious diseases worldwide. In addition to strong scientific reports in eight thematic areas that necessitate One Health implementation, the congress identified four key capacity-building needs: (1) development of adequate science-based risk management policies, (2) skilled-personnel capacity building, (3) accredited veterinary and public health diagnostic laboratories with a shared database, and (4) improved use of existing natural resources and implementation. The aim of this review is to highlight advances in key zoonotic disease areas and the One Health capacity needs.

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