Hello! You may have noticed a lack of updates in the past two weeks. Unfortunately, in the midst of finals my laptop decided to join the technology revolution and promptly crashed. Through much begging, cursing, resisted physical violence, and the occasional keystroke, I managed to get it working once more—albeit losing my notes and Photoshop in the process. Sorry about that.
I would like to thank everyone who has read, liked, or followed my blog in the past five months (whether through your own interest or coercion due to our friendship). This started off as an independent course for the final semester of my senior year at college, and while my graduation is looming on the horizon, I have no intention of abandoning this blog. There are far too many fascinating diseases, microbes, and strange biological phenomena to explore! However, to celebrate my survival and miraculous completion of college, I will be traveling for the month of June. I will not have any computer access while traipsing across the globe, so my blog will be on a brief hiatus until July.
Thank you once again for being such awesome readers, and I’ll see you in a month!
Leprosy is known as the Death before Death; a disease of unparalleled historical stigma and fear that has earned the appellation kushtha, ‘eating away.’ Today, whilst its effects are none the less awful, it is known under the more innocuous title of Hansen’s Disease. In 1948, Dr. Earnest Muir wrote that leprosy was the most dreaded disease—ironically, not because it kills, but rather, because it leaves its victims alive. Leprosy and humans have a long, bitter relationship. Though it has plagued us since at least 2000 BC, we barely understand it four thousand years later and we are still wrestling with its legacy of stigmatization.
If you have a weak stomach, you may want to turn away now. Parasitism is unpleasant at the best of times, but occasionally it can get downright creepy. Some organisms have perfected the art of infection to the point of controlling the minds and behavior of their hosts. I’ve previously discussed Toxoplasma gondii, a behavior-altering parasite that has spread to infect over a third of the human population, but there are many other parasites that infect non-human hosts in more extreme ways. While the examples I have included in this post are not exhaustive by any means, they are some of the most bizarre and spine-chilling examples of parasites taking control.
When someone mentions the plague, the Black Death often leaps to mind: an infamous, decimating disease that we tend to associate with the medieval period. However, since the beginning of recorded history the plague has sinisterly spread across the globe and wiped out up to 30-40% of the world’s population three times, as well as hundreds of smaller outbreaks. The most recent pandemic (a worldwide outbreak of disease) was less than two hundred years ago, and is arguably still going on. Several thousand cases of plague occur worldwide each year, and the plague has now been classified as a reemerging disease. While we may view the plague as an ancient disease, when we consider the facts that we lack a vaccination, there are antibiotic resistant strains, and the pathogen has been utilized for biological warfare, it is very much a modern issue.
Source: nocturnalmoth (click for gallery)
Tardigrades: Animal Survivors
We’ve covered the nigh invulnerable bacteria Deinococcus radiodurans and near-indestructible prions, but what about animals? Generally, animals do not come to mind when we think of surviving in extreme environments; we’re a little too squishy to survive in vacuums, sub-Antarctic temperatures, or sans water. However, there are a few astonishing animals that have mastered survival skills that put the rest of us to shame, and even offer up a challenge to D. radiodurans. The animal phylum Tardigrada contains species of Tardigrades that can survive 10 years without water, subsist in temperatures from -196°C (-320°F) to 151°C (304°F), live in a vacuum or under six times the pressure of the deepest point in the ocean, shrug off 5,000 Gy of gamma radiation and 8,000 Gy of heavy ion radiation, and dodge the toxic effects of most environmental toxins. These astounding animals have been given very dignified and fearsome nicknames to live up to their reputation; they are known as Water Bears and Moss Piglets.
Photo sources: astrographics & bbc.co.uk
Remember my past post on botulinum toxin, the deadliest substance known to mankind? Well, it’s time to visit the second runner up. Tetanospasmin is a neurotoxin created by another member of the Clostridium genus: Clostridium tetani. That is one genus you don’t want to mess with! This particular member of Clostridium is the cause behind all those lovely tetanus shots and boosters you have been subjected to through the years. When you consider the fact that you’re being vaccinated against the second deadliest toxin in the world, maybe you won’t mind the needle jab quite as much. In a rather bizarre twist, the neurotoxin has no apparent use or benefit to C. tetani in its natural environment. The intoxication of other organisms, such as us, appears to be mainly incidental.
Photographs adapted from cedarcrest.edu
If you had to name the most epic, mindboggling bacteria in the world, Deinococcus radiodurans would be a top contestant. D. radiodurans has managed to make it into the Guinness Book of World Records, quite the feat for microbiology, and is pretty darned close to invulnerable. It is the most DNA damage-tolerant organism we have ever discovered. One of its natural habitats is the frigid dry valleys of Antarctica and it can also survive in a vacuum (think outer space!). There is no phage or virus capable of infecting it, and it can survive over six years with no water [2,3]. D. radiodurans shrugs off having its genome shattered into thousands of pieces, while other organisms die with only a handful of breaks. Last but not least, it can survive 2,000 to 6,666 times the gamma radiation that would kill a human and 250 to 5,000 times the UV radiation used to kill microbes in our water supply [2,4]. Luckily for us, it is so focused on being the coolest microbe around that it has no pathogenic qualities. In fact, there’s no sign of it ecologically interacting with any other organism out there.