Embedded Files
West Nile Virus and One Health - why human physicians and veterinarians must work together
West Nile Virus and One Health - why human physicians and veterinarians must work together
By Emily Ma (Y12)
‘There is absolutely no relationship between your birds and the people dying in New York City.’ is what the US Centre for Disease Control told Tracey McNamara, the head veterinary pathologist of the Bronx Zoo, in 1999. Exotic birds at her zoo had been dying from massive brain haemorrhages and heart damage, while simultaneously, within New York City, ER doctors had been tracking a mysterious illness in the elderly that caused neurological symptoms such as high fevers, confusion and encephalitis. McNamara believed there had to be a link, and offered to share her research and samples with the CDC. However, the CDC refused to acknowledge the connections and simply told McNamara that they solved human, not animal problems, and thus proceeded to identify the disease as St. Louis encephalitis.
McNamara was unconvinced by the CDC. She recognised that St. Louis encephalitis is transmitted when a mosquito vector bites an infected bird, however it does not cause the birds to exhibit symptoms. It could not explain the flocks of dead crows and zoo birds. Due to the dismissal of McNamara by the CDC, she eventually implored the US Army infectious diseases lab to study tissue samples she had collected. Their results found that this virus was a flavivirus: the same genus as viruses that cause hugely destructive diseases such as Zika, dengue and yellow fever. This virus was West Nile Virus, a positive sense RNA virus (positive sense meaning that its genome can directly be used as mRNA to translate viral proteins using host ribosomes), that is transmitted by mosquitoes and can infect at least 30 mammalian species. In humans, it causes symptoms ranging from a fever and vomiting, to encephalitis and seizures. Before McNamara’s groundbreaking work in 1999, it had never before been detected in the Western Hemisphere.
It took 3 weeks for anyone to listen to McNamara and recognise the new threat to public health: a huge length of time from an epidemiological perspective. In total, the West Nile Virus epidemic of 1999 killed 7 people and caused 62 known encephalitis cases in humans. Since then, cases have increased year on year in the US, and it is unknown how many other mammals such as birds and horses have fallen victim to the disease.
This epidemic and the treatment of Tracey McNamara by public health organisations truly exposed a hypocrisy in public health. The most threatening diseases to the modern world are, and are likely to be zoonotic, so why is human public health so isolated? A permanent two-way dialogue must be opened between human physicians and veterinarians. In 1999, crows had been dying 2 and a half months before any human deaths were recorded - how many lives could have been saved if wild animals were monitored? Urban and wild animals often act as sentinels for emerging zoonoses, as they are the first to start dying before human cases begin, however there is no jurisdiction responsible for the surveillance of wild animals and animals living in cities. The monitoring of human health and the health of agricultural animals of economic importance are prioritised yet also kept separate, leaving gaps in responsibility that could easily contribute to more devastating epidemics. ‘We must stop ignoring the animals in urban settings, or we will serve as the canaries in the coal mine,’ said McNamara during a TEDTalk in 2018.
Now in 2021, all available scientific evidence suggests that the current COVID-19 pandemic had a zoonotic source, adding to the list of notorious modern diseases with a zoonotic origin, such as Ebola, swine flu and HIV. Therefore, it is imperative for us to follow a One Health approach, where multiple sectors work together to achieve the best possible health for humans, animals and the environment. Efforts by just one sector cannot solve nor prevent the massive problems facing the health of the modern world, for example the environment must be protected in order to slow climate change, so vectors such as mosquitoes cannot live in a wider range of regions and therefore transmit zoonotic diseases to more people. Antimicrobial resistance is something that will dramatically affect both human and animal medicine, and solutions may lie in wider scientific fields such as the chemistry of ionic liquids being used to recycle old antibiotics.
When veterinarians and physicians work together, remarkable advances can be achieved. For example, the physician Jedd Wolchok was working on a xenogeneic plasmid DNA vaccination (effectively “tricking” a patient’s immune system into attacking the cancer itself) against melanoma in humans, but testing on humans proved to be a problem due to complex paperwork and legislation. When he collaborated with veterinarian Philip Bergman, they noticed that melanoma was practically one and the same in humans and dogs, so dogs could be used in the clinical trials. Overall, the tumours in the dogs shrank and survival rates soared, culminating in the release of a canine melanoma vaccine in 2009, which then inspired more research into a similar treatment for humans.
Clearly, a brighter future for humans, animals and the Earth can be realised through the collaboration of professionals across all different fields, as well as effective communication with governments and public health organisations. The human population is predicted to continue to grow (to 9 million by 2050), therefore it is crucial for the interconnections between humans, animals, plants and the environment to be realised so adequate food, water and healthcare can be provided to future generations. As the biologist Rudolf Virchow said, “Between animal and human medicine there are no dividing lines—nor should there be.”
MOOCs
MOOCs
During April last year, I decided to utilise the large amount of time I had and so I took a MOOC. Having looked at the options available, I decided to choose one by Harvard University, called Fundamentals of Neuroscience, from the EdX website, a site with many thousands of courses for you to choose from. I really enjoyed this course, I thought it was informative and entertaining, and it really pushes the boundaries of what we learn in AS level biology, especially about cell membranes. For example you learn about different potentials across the membrane, such as resting potential and Nernst potential. I’d definitely recommend this course for anyone who wants to pursue biology or something similar in their further education, or anyone who just wants to expand their own knowledge about this fascinating subject. Sam Antony (Y12)
Sam Antony (Y12)
poster Riana2.pdfReport abuse