There’s nothing quite like a mail-order disease to propel a pathogen into notoriety. In 2001, several envelopes containing spores of the bacteria Bacillus anthracis were shipped across the United States, infecting those exposed with anthrax. This was hardly the first time B. anthracis cropped up as a prominent pathogen or agent of biological warfare; the bacterium has a sordid history as a major player in biological warfare in the past century, along with a biblical history of outbreaks.
Amyotrophic lateral sclerosis
I was recently challenged to participate in the latest viral social behavior: the ice bucket challenge. The activity raises awareness for Amyotrophic lateral sclerosis, now more commonly known as ALS. I have decided to respond to the challenge with this blog post rather than pouring water over my head, since I’ve come to realize that watching over twenty ice challenge videos has taught me next to nothing about the disease!
ALS is both the most common and most aggressive type of adult motor neuron degeneration. The death of upper motor neurons in the motor cortex and lower motor neurons in the brainstem and ventral horn of the spinal cord result in a progressive loss of muscle control. This progression is characterized by stiffness, overactive reflexes, muscle twitching, muscle atrophy, and finally full paralysis. Approximately 15% of patients also suffer from cognitive and behavioral problems known as frontotemporal dementia due to the death of neurons in the prefrontal and temporal cortex in the brain[1,5].
Finally, it is a heterogeneous disease: the age, site of onset, rate of progression, and the presence and degree of cognitive dysfunction can vary widely between patients. The disease is fatal within 3-5 years of onset.
No other disease has captured the modern imagination with such sensational horror as Ebola. The possibility of infection being transported into dense cities and the western world along with the possibility of bioterrorism captures our attention. However, much of the disease’s infamous reputation is due to sensationalized stories of the outbreaks along with the popular perception of the disease causing a disconcerting amount of bleeding from every orifice. In actuality, the disease’s outbreaks are relatively rare (although increasing) and the presentation itself only includes external bleeding in less than half of the cases. Still, with a mortality rate ranging between 40-90% and no current treatments, Ebola is not a disease to be taken lightly.
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.
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.