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Dynamics of Zoonotic Diseases: Experts Warn of Potential Threats

Experts Warn of Potential Threats from Zoonotic Diseases

United States: The scientists and health experts have mentioned that they are concerned about the risk linked to the humans from zoonotic disease like bird flu. However, they also explained that it is believed that the risk is low.

But, the health experts have mentioned that H5N1 avian flu has been spreading across the United States. Meanwhile, as of now only a few cases have been detected in humans. The concern lies in its potential for wider transmission.

Being a zoonotic disease, it has crossed from animals to humans in what’s known as a spillover event, according to globalnews.ca.

These incidents occasionally pose significant threats to human health. According to the US Centers for Disease Control and Prevention, three out of every four new or emerging infectious diseases in humans originate from animals.

Dr. Isaac Bogoch, an infectious disease specialist, highlighted examples such as SARS-1 from a civet, MERS from a camel, and H1N1 likely from a pig farm, speaking to Global News.

While some infections have sparked pandemics and epidemics upon crossing to humans, Bogoch cautioned that isolated spillover events with minimal human-to-human transmission also occur.

He also warned that environmental shifts, such as climate change, are pushing non-human animals into closer proximity to humans, leading to an uptick in such spillover events. More zoonotic infections may consequently emerge, he noted, according to globalnews.ca.

How do zoonotic infections propagate?

Dr. Bogoch, based in Toronto, explained that various animals harbor vastly different infections. While these may not afflict the animal hosts, they can potentially sicken humans over time.

Visual Representation

“The more a virus spreads and infects new hosts, the more errors in its genetic code accumulate during replication,” explained virologist Dr. Alyson Kelvin to Global News.

One such genetic anomaly could confer an advantage upon the virus, aiding its transmission to other animals of the same species.

“Once it leaps the species barrier, for instance, from birds to mammals like otters or raccoons, as we’ve observed with H5N1, it can accrue mutations that enhance its adaptability to diverse mammalian hosts,” she elaborated, as reported by globalnews.ca.

“This is concerning, as evidenced by the ongoing transmission and infection of dairy cattle by H5N1,” she added.

Dr. Bogoch noted that H5N1 is not highly transmissible among mammals, particularly through respiratory pathways, underscoring the imperative to contain its spread.

How can zoonotic diseases be halted?

Chronic wasting disease (CWD), a fatal brain infection among cervids such as deer and moose, exemplifies one such challenge.

Its prevalence spans vast regions of the US and Canada, with its first detection in British Columbia occurring last February.

The British Columbia Centre for Disease Control (BCCDC) vigilantly monitors this disease, as affirmed by Dr. Aamir Bharmal, the medical director of public health response.

Bharmal emphasized the importance of tracking sick and deceased animals and hospital admissions, which is vital for detecting circulating diseases.

“If a specific virus appears to be circulating more frequently, we seek to identify its potential causes,” he stated from Vancouver.

He stressed the necessity of comprehending the dynamics among fringe-dwelling animals to gain a clearer perspective.

Monitoring remains pivotal, concurred Dr. Bogoch.

Equally critical is acknowledging humanity’s capacity for swift global mobility, which facilitates the rapid dissemination of pathogens.

“What transpires in one’s backyard could swiftly become our concern within a mere 24 hours,” Bogoch cautioned, as reported by globalnews.ca.

MERS initially surfaced in Saudi Arabia in 2012, subsequently spreading to 27 other nations within a few years. In 2015, it claimed 38 lives in South Korea.

“When a South Korean physician encounters a severe respiratory illness in a hospital, would they immediately consider ‘MERS’ as the foremost diagnosis?” Bogoch queried. “Certainly not.”

Bogoch advocated for a unified global health strategy.

The U.S. Centers for Disease Control and Prevention (CDC) defines this strategy as recognizing the interconnections among “people, animals, plants, and their shared environment.”

Visual Representation | Credits: WHO

Bogoch underscored the need for global cooperation, emphasizing measures such as urban planning to reduce human-animal interactions, ensuring farmers employ personal protective gear as necessary, and establishing infrastructure for swift pathogen detection.

“The crux here lies in its global applicability,” he asserted. “A Canadian or European strategy alone would prove inadequate.”

Bharmal acknowledged that while the BCCDC has adopted elements of this approach, a broader embrace is warranted.

What occurs during a spillover event?

According to Bogoch, managing a zoonotic outbreak doesn’t necessitate the culling of animals. Instead, it entails vigilantly tracking the spread of illnesses detected in animals capable of, or known for, inter-species transmission, as per globalnews.ca.

This includes preventing interactions between sick and healthy animals, monitoring wastewater, and screening dairy cow milk, he detailed.

Bogoch noted that spillover events likely occur frequently, citing examples like the Ebola virus and SARS-CoV-2, which are believed to originate from bats and are responsible for COVID-19.

In such instances, vaccines may become imperative.

Determining the necessity for a vaccine involves economic, public health, and scientific considerations, affirmed Dr. Kelvin.

“Not all pathogens induce severe illnesses requiring hospitalization or fatalities. Our focus typically centers on those posing significant threats, such as the common cold,” she explained from Saskatoon.

She stressed the importance of scientific capabilities in developing protective immune responses against pathogens like Borrelia burgdorferi, which causes Lyme disease, a more complex task than with influenza or SARS-CoV-2.

Lyme disease, if untreated, can affect the nervous system, joints, and heart, though presently lacks a vaccine, despite previous existence.

In scenarios requiring a vaccine for a novel spillover event, Kelvin noted the adaptability of previously developed vaccines, such as those for COVID-19 and influenza.

She highlighted the WHO’s global pathogen surveillance system, which is instrumental in tracking virus sequences and crucial for updating vaccines.

Kelvin and Bogoch noted the US’s readiness with a reserve of updated H5N1 vaccine, underscoring proactive measures despite lower prior global concern.

Should a new pathogen necessitate it, preliminary studies akin to those for COVID-19 vaccines commence.

Bharmal emphasized that national bodies, like the US CDC or Canada’s NACI, determine when diseases achieve critical thresholds mandating vaccine distribution.

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