Rare Diseases: Yersinia Plague

Yersinia plague is most famously known as The Black Death, a name given to it in the 14th century pandemic that swept away 25 million souls over the course of five horrific years. When plague is mentioned in modern times, folks often scoff - that stuff only happened in the middle ages, right? Nope. Each year, 10-15 cases of Yersinia plague are reported in the United States, and as many as 300,000 deaths world-wide are attributed to the bacteria which causes three distinct forms of plague - bubonic, septicemic, and pneumonic. Asia and Madagascar are currently experiencing "mostly controlled" epidemics, and three major pandemics, the most recent of which began in the 1980's, have brought this deadly menace to nearly every corner of the globe, with the possible exception of Australia.

Yersinia plague is caused by the bacteria Yersinia pestis (see photo). Y. pestis is a rod-shaped bacteria that has developed a solid reservoir among wild rodent populations, including prairie dogs, squirrels, and chipmunks but most famously associated with rats. In fact, it is speculated that the plague originated in Egypt and was introduced to the rest of the world by the black rat stow-aways on trade ships. It is very rare indeed for a human to be infected directly by a rodent, however. Much more commonly, the fleas that pester the infected rats spread the disease among humans. Y. pestis closes off the throat of the fleas, making them unable to swallow food. The poor starving parasites go on a feeding frenzy and with each bite and unsuccessful suck, spread the bacteria into their intended snacks - other rodents, wild animals, and humans.

Bubonic Plague

The most famous form of Yersinia plague, the bubonic plague, is also the least fatal of the three forms. Initial symptoms include the development of large, painful "bubos" (see photo below). The bubos are actually very swollen lymph nodes which served as points of initial infection and most often show up in the groin, under-arm, or neck. They tend to be red with a bruise around them and the tissue may die, turning the characteristic black color. Other symptoms make the common flu look like a kiddy ride - high fever, nausea, vomitting (possibly bloody), severe muscle/joint pain, sore throat, headache, debilitating weakness, chills, and a general sense of feeling so miserable you'd gladly lay down in front of a steam roller for a little relief. With modern antibiotics, if given quickly, the relief is more likely - only 15% of patients treated with antibiotic therapy and supportive therapy die, as opposed to 40-60% of people who go untreated. Bubonic plague can lead to septicemic or pneumonic plague.

Septicemic Plague

Septicemia is a severe, generalized infection - the bacteria circulate through the blood stream and can impact any organ in the body. Septicemic plague can occur after the formation of bubos or without bubos (rare) and the symptoms listed under the bubonic form of the disease. In addition, septicemic plague can cause symptoms throughout the body depending on which areas are affected - diarrhea (often bloody), constipation, severe belly pain, cough (often bloody), muscle pain, stiff neck, bleeding from just about anywhere, gangrene of the fingers, toes, penis, or nose, seizures, confusion, delirium, or coma. Untreated, septicemic plague is 100% fatal and can lead to pneumonic plague.

Pneumonic Plague

Pneumonic plague can be contracted two different ways - from the advancement of bubonic or septicemic plague or from coming into contact with another person or animal who has pneumonic plague. This form of the disease may include bubos and bloody cough, along with general symptoms of the plague and signs of pneumonia. The difference here is unlike bubonic plague and septicemic plague, pneumonic plague is extremely contagious person-to-person. While the other forms of Yersinia plague can pass person-to-person with close contact and exchange of bodily fluid, stepping within a few feet of a person suffering pneumonic plague and taking a few unprotected breaths can be quite literally a death sentence. Survival if treated with modern antibiotics within the first 24 hours of infection with pneumonic plague is often effective at preventing death, but left untreated, this form of the plague is 100% fatal.

The pandemics that swept through the pre-modern world drastically altered the face of the world, not just in terms of the depopulation, but in political, scientific, and religious terms as well. Volumes have been written which point to the Black Death of 14th century Europe as the single most important disease event in shaping the face of the modern world, creating the infancy of modern medicine and ending the dark ages.

Modern sanitation, pest control, and antibiotics have reduced this one-time mega killer to a smaller stature on the scale of world threats, but modern man might yet feel the real bite of this beast. In the age of terrorism, Yersinia plague in aerosol (airborn) form is considered one of the most feared as a potential biological weapon. And unlike small pox and polio, this deadly disease has host colonies the world over and will very likely continue to be a threat looming over us forever.

Rare Disease Column: Tetanus

Ever gone to the ER for a few stitches in a minor wound and had the nurse ask you when your last tetanus booster was? Oh great. A shot.

Well, don't be too hard on her. Tetanus might seem like no big deal now in the age of the vaccine, but it is still a deadly menace. The number of cases reported in the US has fallen considerably since the invention of tetanus toxoid, which primes the body to immunity against the bacteria that causes this highly infectious (but not contagious) disease - Clostridium tetani (see photo).

Tetanus, known as Lockjaw prior to the 1920's, was described as early as Biblical times, and no wonder. The C. tetani bacteria can live for years in soil or animal carriers and is widespread. While it seems to prefer geographical areas that are warm, moist, and which have high levels of organic matter, it can live just about anywhere and in the inactive spore form can survive most chemical antiseptics as well as autoclaving (heating to sterilize) to 112C or 249.8F for 10-15 minutes. CDC

The real danger of C. tetani is in the toxin it produces - an exotoxin which is one of the most powerful neurotoxins known to man. Less than 200 nanograms of C. tetani's deadly neurotoxin is enough to kill most humans. The generalized form of this disease is among the most dramatic and cruel non-contagious diseases out there. The toxin produces progressive spasming of the muscles, starting with the jaw, which locks tight and prevents opening the mouth or swallowing. Sometimes the illness ends here, with the person having difficulty breathing and a quick death, but most often, the stiffening, uncontrollable muscle spasms progress down the body - the neck stiffens and hyperextends over the back, the arms and shoulders begin to posture and so forth. The spasms themselves can be so powerful as to snap bones, and for those who survive, paralysis from broken spinal cords may be a reality. ~30% of cases will not survive, however, and many will end up looking like this poor soldier (see portrait) who died shortly after this posture was seen.


So how does one get tetanus? A common misconception about the disease is that you have to step on a rusty nail, but in truth, any deep puncture, cut, or chronic wound can become infected, regardless of what caused it. Nails and tools that are left out in soil have an obvious advantage in this regard, as the soil is one of the main places C. tetani is located. However, consider the fiction implications of cultures who thrust their great swords into the dirt prior to battle (please don't try this with your katana or rapier, as your character is more likely to suffer death by virtue of having a broken weapon in battle than to inflict it upon the enemy via tetanus).

In modern times, treatment consists of managing the original wound - keeping it clean and bandaged, plus updating tetanus boosters if appropriate. In individuals who've never had a 3-dose series (which is a standard for children in the US), passive immunity can be confered by giving an injection of antibodies from another human host who is immune. Once symptoms start, the anti-toxin is of limited use, but is often still given to keep symptoms from worsening. Supportive therapy for airway, draining the bladder, providing nutrition, etc are the mainstays of treatment. Each year in the present-day US, approximately 20-100 people still develop tetanus infections, with about 10% dying, most often related to not updating boosters every 10 years or IV drug use (particularly heroin, which is sometimes contaminated with C. tetani).

Another nasty little note about tetanus - surviving it once doesn't protect someone from getting it again. Also, infants can develop tetanus from infection of umbilical cords, particularly if they are cut with non-sterile instruments, but only in mothers who are not vaccinated. The incidence of this worldwide is still relatively high, but in the US, only 2 cases have been reported in the last couple of decades.

For more information on tetanus:

Centers for Disease Control
MedLine Plus, National Institute for Infectious Disease

Rare Disease Column: Guillain-Barre

Guillain-Barre may sound like a pub with a bit of a French flare, but this nasty little syndrome strikes seemingly at random and causes progressive muscle weakness, loss of sensation, paralysis, and in about 5% of cases, even death.

Guillain-Barre belongs to a class of poorly understood syndromes and disorders known as "autoimmune disease" - which basically means that your body's immune system has got its wire's crossed and is attacking you! A bit of friendly fire later and just about anything can go wrong with a body. In the case of Guillain-Barre, the immune system has set its sights on a very important part of the peripheral nervous system - myelin.

Myelin (see photo) is a layer of cells that cover the long branching fibers of nerve tissue, acting as both insulation and more importantly, speed enhancer for nerve signals. Nerves with myelin coverings transmit signals many times faster than nerves without myelin. That's why Guillain-Barre causes such devastating weakness and even paralysis - with the myelin damaged and out of commission, the signals from the brain to the body and back get crossed and move slower than your average arthritic turtle.

A neuron with its branching nerve fibers and myelin sheath.

All this leads to a rapid progression of weakness, generally starting in the feet and progressing up the body. The weakness can progress all the way to full paralysis. Weakness generally peaks by 2-3 weeks after onset of symptoms and can take a very long time to resolve completely. 30% of patients still experience weakness three years after their initial onset, and a small percentage of patients may have recurrence or relapse of symptoms many years after recovery.

So what causes Guillain-Barre? We'd like to know, too. The truth is, while we know it isn't contagious and it is caused by an auto-immune process, how it occurs is poorly understood. In most cases, symptoms begin within a few weeks of a respiratory or GI infection (cold, flu, stomach bug, vomitting, diarrhea). It makes sense, because after the immune system fights off an infection, it is vulnerable to other problems. Symptoms can also be triggered by surgery or immunizations - two more things that mess with your immune function.

The effects of this syndrome are temporary for most sufferers, but during the worst part of the weakness or paralysis, the person is totally dependant on others for daily needs. Even chewing food or breathing may be too demanding for sufferers of Guillain-Barre and it is not uncommon for artificial feedings, IV nutrition, and even respirators/ventillators to be employed. Guillain-Barre can be mild enough to require a great deal of assistance for a home recovery, but in most cases an admission to a hospital and often an intensive-care unit (ICU) is required.

Side effects of the syndrome - poor nutrition, loss of muscle tone, risk of falls, risk of pressure sores (bed sores), and the risk of failing respiratory effort - can lead to further complications. Recovery requires a great deal of physical therapy, and during the high point of the symptoms and thereafter, sufferers have a significant risk for being unable to emotionally cope with their sudden loss of function and dependence on others for basic needs. Emotional support and counseling are highly recommended.

Rare Diseases: Necrotizing Fasciitis

Necrotizing Fasciitis, or flesh-eating disease as the media likes to call it, is a rapidly spreading infection along the fascia or the layer of tissue that binds skin to muscle. This deadly disease is caused by a virulent strain of the same bacteria also responsible for strep throat, rheumatoid fever, scarlet fever, impetigo, childbed fever, and toxic shock syndrome - Group A Streptococcus pyogenes.

This particular form of strep infection usually starts at an area of trivial skin injury - a bruise, scrape, or small cut. The area becomes reddened and hot to the touch as the infection begins, but over 2-3 days the infected tissue begins to die (necrotize). The skin will gradually darken to purplish or black, and large, blood-filled blisters called bullae will begin to form. The below photo from UCSD med school illustrates both the appearance of skin infected with necrotizing fasciitis and the blood-filled bullae.



Left untreated, this infection can quickly march over enormous areas of the body and lead to death in a matter of a couple of days. Treatment involves surgically removing all dead and infected tissue in a process called debridement (de-breed-ment), which usually leaves the muscle layer intact and simply removes all the superficial tissue and skin in the affected region and for a clear margin around the lesion. If the infection continues to spread over limbs after attempts to debride, amputation may be life saving.

Both the infection itself and the treatment are horrendously painful. The lady in the photo above would likely have all the skin stripped off her leg from below the knee to the crotch if she wants to live, after which she'll look like she's been partially dissected until after skin grafts are applied. Meanwhile, not having skin is a huge risk for other types of infections. Recovery is likely to be a long process, involving physical therapy and plastic surgery and lots and lots of medications.

While very rare, the Centers for Disease Control reports that there are fewer than 1000 cases a year in the US. Even with quick treatment, death occurs in many cases. Some names you may recognize of individuals who have been infected or died from Group A Strep necrotizing fasciitis include Jim Henson of muppet fame, and Melvin Franklin of The Tempations.

For more information, see these articles from:
-- The Centers for Disease Control though this article discusses all invasive forms of Group A Strep together, not just Necrotizing Fasciitis.
-- WebMD