It’s World Zoonoses Day today. The word ‘zoonosis’ is not one that is popular in the common lexicon, and yet it is something that can affect our lives profoundly. Aspiring vet med student, Erin Tan, did some research on the topic and shares what she thinks in this two-part story.
A zoonosis is a disease which can be transferred from animals to humans, and there are many examples of zoonoses which many are familiar with.
One has only to recall the SARS outbreak of 2003 to recognise the destructive potential of zoonoses.
Severe Acute Respiratory Syndrome (SARS), a disease which originated from viruses in bats that jumped to palm civets and then to humans, severely impacted countries like Hong Kong, China, Singapore, and even Canada.
774 lives were claimed globally by this never-before-seen disease.
Stories of doctors, nurses and other health workers who had perished saving the lives of SARS patients filled the papers.
International travel to affected areas dropped sharply by 50-70%, resulting in the closure of many tourism-related businesses.
Clearly, while the containment of SARS – especially in Singapore – is generally hailed as a success story, the outbreak did result in significant social and economic drawbacks.
Another more recent example: the Ebola virus outbreak of West Africa, from 2013-2016.
Bats were implicated as the natural reservoir for the virus, with other non-human primates like gorillas acting as intermediary agents transmitting the disease to humans.
Over 11,000 people reportedly died from the outbreak, five times more than any previous incident.
In contrast to SARS, the response to the Ebola outbreak was seen as a failure.
The World Health Organisation (WHO), which is seen as the global health leader, was criticised as being ‘too slow’ to declare the outbreak a global public health emergency, and did not respond in a sufficient way to contain the outbreak effectively.
Other examples of zoonoses are more familiar: dengue fever, rabies, West Nile Virus, bovine spongiform encephalopathy (better known as ‘mad cow disease’)… the list goes on, and proves that zoonoses are an emerging pandemic threat today, that demands further attention.
One crucial reason named for the quick spread of diseases today is the prevalence of globalisation.
With today’s interconnected world, spreading a disease from one country to the next is just one flight, or one train ride away.
However, that does not fully explain why zoonoses are often so destructive and widespread, especially in comparison to other diseases transmitted between humans alone.
Why, precisely, have zoonoses become so dangerous today?
Firstly, while zoonotic diseases have existed in the past, current changes to the environment effected by humans have caused us to have closer contact with both wild and domesticated animals, both of which can act as reservoirs for zoonotic pathogens.
One example of this change is modern farming practices such as intensification of livestock production, which facilitates disease transmission by increasing population sizes and densities of farm animals, and decreasing genetic diversity and resilience.
Another example of changes effected by humans is anthropogenic habitat destruction to support expanding populations, causing migration of wild animals to urban areas.
The second reason why zoonoses are so dangerous is because zoonotic diseases are usually novel and never-before-seen, and as such there are often few health systems or medicines suited to treat the disease and handle its outbreak.
Doctors may have difficulties in even identifying the disease, since its diagnosis is more commonly found in animals.
* The next part of this 2-part article will cover how technology can help in the fight against zoonosis.