Author: Isabella Hubbard // Editor: Erin Pallott
Scorpion people?
Scorpionism… what a word. For me, it conjures up thoughts of a strange disease where someone unfortunate enough to be stung by a scorpion grows a pair of claws and a long tail ending in that highly recognisable stinger. Turning into some kind of scorpion person. With superpowers.
Not quite.
In reality, scorpionism is a disease that sometimes occurs after being stung, and injected with venom (envenomed), by a few medically significant scorpion species. In its most severe form, scorpion venom can cause left-sided heart failure and an accumulation of fluid in the lungs (amongst other symptoms); this can be fatal. The processes that lead to these symptoms are a little unclear. There is evidence that some neurotoxins in the scorpion venom can cause a massive flood of adrenaline into the system, while also leading to immune system dysfunction. These effects, combined with a possible direct action of the toxins on the organs, may result in the severe symptoms described.
In terms of the scale of the problem, in 2008 scorpionism was thought to cause over 3000 deaths annually. Even in 2008, these numbers were likely to be dramatic underestimates due to the underreporting of scorpion stings, and a more recent appraisal of the problem is unavailable. Despite this, it is clear that severe scorpionism disproportionally impacts the most vulnerable members of society. Children living in the global south, and those impacted by social injustice including conflict, forced displacement, and poor access to healthcare (see this article, and this one) are much more likely to be envenomed, and die, following a scorpion sting.
What about treatments?
At the moment, the only specific treatment for scorpionism is scorpion-specific antivenom. These antivenoms are produced from the serum (the liquid part of the blood) from large animals (usually horses) vaccinated with small amounts of scorpion venom from one or multiple species of scorpion. The active components of these antivenoms are Y-shaped proteins called antibodies. These antibodies have highly specific shapes on the two business ends (antigen binding sites), which specifically interact with targets (antigens) with a complementary shape. This is known as a “lock and key” interaction. In the case of scorpion antivenom, the antigens are the toxins contained within scorpion venom. Importantly, the toxins that cause scorpionism vary in shape, depending on the scorpion species.
Unfortunately, robust evidence concerning the efficacy of scorpion antivenom is severely lacking across the world (other than in North America). Morocco, which is home to at least 12 medically important species of scorpion, has completely stopped using antivenom to treat scorpion stings because it was deemed ineffective. There are lots of reasons why this antivenom might have been ineffective, including that the antibodies within the antivenom may not have been able to recognise the toxins which were causing scorpionism in these patients. Beyond antivenom, supportive care which maintains life for a long enough time to allow the effects of the venom to wear off is the only option.
Why have I never heard of scorpionism?
Good question! In the North African region, the mortality rate from scorpionism is over twenty-seven times higher than that caused by snakebites. However, unlike snakebite, which was designated ‘Neglected Tropical Disease’ (NTD) status in 2018, efforts to highlight scorpionism by designating it NTD status, brought forward by Morocco and Benin, were rejected in 2018 (see the 11th NTD STAG report, 2018). To paraphrase, this appeal was rejected because there is too little research into the scale of the scorpionism problem, and currently available control measures are unlikely to be effective in improving the situation. This is even though scorpionism meets the criteria to be designated as an NTD – i.e. it is absent from the global health agenda, it disproportionately affects populations impacted by economic and social injustice in the global south, and it causes morbidity and/or mortality. This means that scorpionism does not receive anything like the amount of attention and funding received by other neglected tropical diseases (which is still VERY limited). Even more concerningly, due to the unfamiliarity of the international research community with this disease (and, inevitably, a lack of funding), new or innovative control measures are unlikely to be forthcoming anytime soon.
Well, what do you want me to do?
This brings me to the reasons for this post… Last October, I started my PhD at Liverpool School of Tropical Medicine, in the Centre for Snakebite Research and Intervention. In the main, my project will be focused on developing antibodies which recognise toxins that are unique to some medically important Moroccan scorpions, to help determine what species are stinging people and causing severe disease in Morocco. Going forward, this work could guide the development of antivenom and other specific treatments, to ensure these treatments are specific for the toxins of the scorpion species that are stinging people in Morocco. The antibodies could also be used as point-of-care diagnostics to determine if someone has been stung by a medically important scorpion, and therefore requires treatment, following validation. I’m also hoping to use this platform to raise awareness of scorpionism within and outside the scientific community, to encourage more people to investigate this highly neglected problem! This second one I’m going to need your help with, so I leave you with two requests:
Do: Spread the word about scorpionism (and get in touch if you want to know more)!
Don’t: Hate scorpions (they don’t mean to hurt us)!
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