Infection: Malaria

I vant to suck your blood!

What better time than Halloween to be thinking about blood suckers. The one you see to the right is Anopheles mosquito, and its bite probably doesn't even hurt, though it might itch later. 41% of the world's population lives in the home territory of these little vampires, but the loss of blood isn't that harmful. What your characters have to be wary of is the VTD - Vampire Transmitted Disease. Anopheles mosquitos are often infected with tiny, microscopic parasites that are the cause of one of the most common parasitic diseases in the world - malaria.

Every year around the world, 350-500 million cases of malaria are diagnosed. This disease is anything but rare.

Malaria is caused by several species of parasites - P. falciparum, P. vivax, P. ovale, and P. malariae. These yummy little microscopic bugs have a powerful hunger for red blood cells. The parasites are injected into the body through the bite of infected mosquitoes. Once injected, they race to the liver and begin to multiply. Victims rarely know they are infested during this stage as the 15-100 parasites build an army 30,000 strong before attacking the choice buffet that is the blood stream.

Once inside the blood cells, the parasites multiply and feed, eventually rupturing the blood cell and causing the symptoms of malaria. Symptoms begin anywhere from 7 to 30 days after the mosquito bite, but can be suppressed up to a year by modern anti-malarial drugs. How fast the symptoms start depends on which species of the parasite are infecting the person, and on the person's own body. Classical malaria attacks are rarely observed these days, but attacks occur every 2-3 days and last 6-10 hours each. The reason for this timing is that the parasites incubate inside infected red blood cells for 2-3 days before the blood cells rupture. In classical episodes, the victim goes through three distinct stages of illness.

• The cold stage - shivering, chills


• The hot stage - headaches, fever, possibly seizures (especially in children), vomiting


• The sweating stage - sweats, normal temperature, extreme tiredness

In general, a victim can experience any of the following symptoms, in any order: chills, fever, weakness, vomiting, sweats, headaches, nausea, muscle aches and generally feeling under the weather. In cases of infection with P. falciparum jaundice (yellowing of the skin and whites of the eyes) can occur along with enlargement of the liver and fast breathing.

Right. Sounds like a nasty case of the flu. What's the big deal?

Malaria infection killed nearly a million people in 1995 alone, and accounts for over 10% of all childhood death in developing nations. The strain of parasite, P. falciparum, are much more aggressive than the others and can lead to "severe malaria" in which one or more organ system fails to function. Systems and their symptoms are listed below:

• Brain infection - abnormal behavior, seizures, decreased ability to remain awake, coma or death


• Severe anemia leading to extreme tiredness and breathing trouble


• Respiratory distress (breathing trouble) - flaring of the nose, head bobbing, panting, fast breathing, blue tinge to the fingertips, lips or mouth, the inability to get enough air, passing out, death


• Longer bleeding times before clotting - this can lead to strokes, bruising, actual bleeding, gut-bleeds (bloody or coffee-ground appearance to the poop), bloody urine, etc..


• Cardiovascular collapse (failure of the blood stream to hold enough fluid in to meet the body's needs or failure of the heart to pump blood) - symptoms can include chest pain or difficulty breathing or may mimic shock - low blood pressure, loss of consciousness, rapid heart rate, shaking, cold extremities, sweating, lightheadedness, confusion


• Low blood sugar (starving the brain) - symptoms include dizziness, hunger, headache, shaking, anxiety, and heart palpitations (feels like your heart's doing flip-flops in your chest. On this I speak from experience)

Today, treatment with antimalarial agents reduces the severity and duration of malaria infection. A list of drugs used appears below, taken from the Centers for Disease Control website.

chloroquine
sulfadoxine-pyrimethamine (Fansidar®)
mefloquine (Lariam®)
atovaquone-proguanil (Malarone®)
quinine (Best bet for pre-modern settings)
doxycycline
artemisin derivatives (not licensed for use in the United
States, but often found overseas)

One more nasty little surprise, malaria caused by the P. ovale or P. vivix strains can lay dormant for months to years in the liver, eventually re-emerging to cause symptoms all over again.

A pound of prevention

Currently, the gold standard for prevention of malaria is using mosquito netting around beds and cribs to prevent mosquito bites. A multitude of non-profit organizations exist whose mission it is to send mosquito netting to poor and under-served populations in areas where malaria is endemic. Other methods include draining wet areas and eliminating standing water where mosquitoes breed, using pesticides to reduce mosquito populations, and using anti-malaria drugs prophylactically (to prevent infection) for pregnant women and individuals traveling to areas where the infection is endemic (native).

An evolutionary twist

One of the most fascinating phenomenon I studied in nursing school was Sickle Cell Anemia. This disorder is a genetic change to the shape of red blood cells that can cause severe problems and even death in those who are symptomatic. However, the trait for Sickle Cell disease actually conveys a protective factor against malaria infection! Considering that this trait developed in the part of the world where malaria have been endemic for the whole of human history, it's interesting that a twist of genetic selection could breed a trait to keep people from getting sick.

Despite this protective factor, those who develop full-blown sickling, where many red blood cells actually change shape to resemble a curved sickle (see picture), can have life-long severe pain and complications.

Addendum - you can find a map of the parts of the world where malaria is currently endemic (native) at the World Health Organization's website, this URL http://www.who.int/malaria/malariaendemiccountries.html.

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 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

Infected Cuts

Q: What do infected cuts look like?

A: First off, there is likely to be an angry red color around the margins that extends anywhere from a few millimeters to several inches (reasonable size for a smallish cut 1-5cm). The area will be swollen, tender to the touch, and warmer than the surrounding skin.

The wound may drain blood, clear fluid, or pus or a combination of these. Pus colors range based on what the infectious organism is, and can include yellow, yellow-green, green, white, or tan/beige, but can also be tinted pink by blood getting into it. Blood from a wound that is infected will often be very dark or have clumps of pus floating in it.

The wound may form a moist-looking yellow scab or a dark, hard scab as it attempts to heal - these are both composed of dead tissue and the wound will heal faster and cleaner if they are removed and the wound bed is kept moist but not sopping wet. That said, constantly picking at a wound is a bad idea, too.

The best treatment for a small cut is to wash with soap and water, and cover with a clean dry bandage (and an ointment like Polysporin if modern era). Try to keep it clean and don't do what my son does and leave the bandage on for two weeks or until it disintegrates in the shower.

Large or deep cuts may require sutures or some sort of adhesive glue meant for surgical application (no, please don't use SuperGlue. It works like a charm, but non-toxic really isn't meant to read: safe to pour into open wounds). Again, washing the wound, keeping it clean, and keeping the wound-bed moist or the sutured cut dry will aid healing.

Infected minor cuts rarely turn into systemic problems, but if the red margin of the wound starts to look streaky or the red starts to follow veins in streaks, this is a sign of serious, potentially fatal infection of the bloodstream and needs emergent treatment. Likewise, a sudden, serious increase in pain, or severe swelling of the area can indicate serious infections.