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One Health: a multifaceted problem that requires an integrated solution

In a recently concluded infectious disease meeting, the conference kit included a COVID-19 home test kit and a mask. This reflects a new normal, as we resume our daily lives post-pandemic and learn to live with the virus. The pandemic has also brought to fore interconnectedness between humans, animals and their shared environment, and emphasized the importance of One Health. The United States Centers for Disease Control and Prevention defines One Health as a “collaborative, multisectoral, and transdisciplinary approach” at all levels (local, regional, national and global) “with the goal of achieving optimal health outcomes” by “recognizing the interconnection between people, animals, plants, and their shared environment”.

The diseases transmitted due to the human-animal interface are known as zoonotic diseases. Over the past three decades, 75% of novel, emergent zoonotic infectious diseases originated in animals, especially wildlife. According to the World Health Organization, there are over 200 zoonoses which have been listed, including diseases that have been well documented over many years (such as Rabies and Anthrax) and new or emerging diseases that have appeared within the past one to two decades (such as the Nipah, SARS and Ebola). Annually, millions of people and animals around the world are impacted by zoonotic diseases.

Globally, Africa, Asia and South America appear to be growing in importance as places with higher potential for zoonotic disease transmission. For example, the origin of the 2009 swine flu (H1N1 influenza) pandemic was traced to a pig farm in Mexico; the most recent Ebola outbreak (2014-2015) was traced to a small village in Guinea and the COVID-19 pandemic is considered to have originated from a seafood market in China. According to an analysis conducted by the World Health Organization (WHO), there has been a 63% increase in the number of zoonotic outbreaks in the African region in the decade from 2012-2022 compared to 2001-2011.

The common causative factors of the zoonotic ‘spillover’ (transmission of pathogens from wild animals to humans) are a rapidly growing population, increased density of domestic animals, rising urbanization and encroachment on wildlife habitat associated with agriculture and other land use changes, although the combination of factors resulting in a particular spillover event are usually unique. Let us take the example of monkeypox, which is a viral zoonosis endemic to central and west Africa. Monkeypox cases have rarely been reported outside of the endemic countries and they were linked to importation of animals or from travelers who had visited the continent. However, since May 2022, several thousand of monkeypox cases were identified in multiple non-endemic countries, mostly in men who have sex with men, especially those with multiple sexual partners. Additionally, socio-cultural practices such as handling and consumption of bushmeat in Africa and southeast Asia (implicated in the spillover of several virulent zoonotic diseases such as Ebola, HIV, monkeypox and SARS) or date palm sap in India and Bangladesh (implicated as the vehicle for transmission of Nipah virus) and other similar practices pose significant threat to the local communities and beyond.

Closer home, the northeastern region (NER) of India consisting of 8 states, which shares its borders with five countries such as Bangladesh, China, Myanmar, Bhutan and Nepal, is a potential high-risk area for zoonotic diseases. This region is a biodiversity hotspot with dense forests and close human-animal contact due to traditional dependence on livestock and forest produce for livelihood. In Meghalaya, for instance, agroforestry and mixed farming are commonly practiced. The rich biodiversity of the NER is also threatened from infrastructure development projects such as construction of roads and dams in the forested areas. The increasing population result in forests being converted into agricultural land or settlements. Foraging of food such as wild fruits and vegetables, mushrooms and tubers from the nearby forests or consumption of wild animals (invertebrates, amphibians, insects, fish, reptiles, birds and mammals) considered to be an important source of protein in the diet, are common practices. These, along-with poor sanitation facilities, scarce veterinary and medical services, and suboptimal disease surveillance systems, greatly increases the potential for undetected spillover events in the local population.

Outbreak investigation and response mostly focuses on the clinico-epidemiological and environmental factors, but many-a-times overlook the socio-cultural factors facilitating disease transmission. For instance, cultural practices were not factored in during the response to outbreaks occurring at different times and on different continents: Ebola in 2014 and 2019, and Zika in 2016. During the COVID-19 pandemic, a large section of the population in Meghalaya were initially hesitant to vaccinate themselves due to cultural beliefs surrounding vaccination and widespread misinformation through the social media platforms, despite vaccines being provided free of cost. This resulted in avoidable hospitalizations and death during the second wave of the pandemic in India, fueled by the Delta variant and highlights the importance of considering social cultural beliefs and practices in health communication.

The multidimensional character of zoonotic diseases requires integrated solutions. Hence, care should be taken to practice a One Health approach that goes beyond medical and veterinary sciences and includes other relevant disciplines such as ecology and environmental health, demography, anthropology, and social and behavioral sciences to make it transdisciplinary and integrative in true sense of the term.

By Rajiv Sarkar, ISID Emerging Leader, India & Melari Shisha Nongrum
Indian Institute of Public Health Shillong, Meghalaya, India

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