Monday, July 29, 2013

Series Post: Ask Dr. Dina - Infection Part III: Fungal

DISCLAIMER: I am not a doctor, nor do I play one on TV. I do not hold a current medical license or certification (I let them lapse because I no longer work in the medical field and don't intend to ever again). What I do have is an extensive medical background in various fields. Everything you read here is the result of either education, training, research and interpretation, or personal experience. The information in this post is not to be taken as a substitute for professional medical advice or examination. Seriously, if you're having an immediate medical problem and you're reading this blog for help, get off the damned computer and call an ambulance! 



We've come now to the infection portion of our "Ask Dr. Dina" series. This piece is going to be broken into a few parts because there are many, many different types of infection and I'm not going to write a book on the subject.

These parts will be –

I – Bacterial 
II – Viral
III – Fungal
IV – Treatment

So far in this portion on infection we've covered bacterial and viral types. There are a lot more of them than I touched on, but the gist was there. I'm going to do the same for this one on fungal infection.

When you hear the word "fungus" or "fungi," what do you think of? Mushrooms, right? Yes, those are types of fungi. ("Fungi" is the plural form of "fungus."  I know. That seems backwards as you've been taught that plurals end with "s." That's true for most things, but in case you haven't figured it out by now, medicine/science likes to do things its own way. Why? Because science is a dick, that's why!)

The kind of fungi I'm going to talk about in this post aren't shiitakes or portabellas or chantrelles (shut up, hippies). I'm going to talk about microscopic fungi. While you can (and very likely do) ingest these microscopic fungi, I wouldn't recommend it.

What I'm going to talk about today is mycosis, which is fancy medical speak for "fungal infection." Why is it called "mycosis" when that doesn't sound a damned thing like "fungus?" Because mycology is the branch of biology dedicated to the study of fungi. So there you go. I told you - science is a dick.

Let's start with something everyone's heard of. Athlete's foot. You've all seen the commercials or heard about different medications for athlete's foot. You know it's gross and painful and so on. What you may not know is that athlete's foot is so named because athletes' feet are constantly moist from sweat and shoved in the warm, dark environment of a dirty sock and sporting shoe for hours on end, then they walk around barefoot in shower/locker rooms subjecting their feet to even more warmth and moisture, creating the perfect environment for that particular fungus to proliferate. That fungus is one we all carry (part of the natural flora of the human body) called Tricophyton. Now there's a shit-ton of subtypes of this fungus, but you'll most likely know them by their common names – jock itch and ringworm to name a few. (Hint: there's no actual worm involved in "ringworm." It's named that because the little assholes responsible for it [called "tinea" by health care professionals] make lesions that look like a ring/worm under the skin.)

Remember what I said about science/medicine being a dick? Yeah. Why should we call it "athlete's foot" when we can call it something fancy like "tinea pedis?" Your head itches? Tinea capitis! (Ringworm of the scalp! Or, you know, just dry scalp or a fucking itch [dermatitis!]. Don't freak out.) Look, we like our Latin and Greek in the medical community, okay? Medical terminology is a language unto itself and if you want to be in the field, you've got to learn to speak it. No, I mean it. They teach it anywhere medical stuff is on the curriculum.

But I digress.

Now, the above are what are known as "cutaneous" fungal infections; that is, they affect things on the surface/outside of the body like your skin, hair, and nails. When fungus gets inside you, things get a little more difficult to handle.

Yeast infections. Ladies, you know what I'm talking about, right? If you've never had one, consider yourself blessed. Dudes…before you smirk and get all smug, you're not exempt from yeast infections, either. Yeast can affect your bits and bobs, too. Remember what I said earlier about fungus liking moist, dark, warm places to grow? I'll wait…THERE you go. Yeah. That. Now, yeast (called Candida in the fancy medical speak) is part of the body's natural flora. It's when things get thrown off-balance by whatever (stress, medications, diet, what have you) and the little bastards run wild that you have an infection on your hands.

And don't go thinking yeast infections are confined to your lower half. Uh-uh. Parents. Ever had to deal with thrush in your kid? Adults? Ever had thrush for one reason or another? Congratulations. You've had a yeast infection of your mouth. (Warm, dark, moist, remember? The human mouth is utterly filthy. You don't even WANT to know what lives in there, so brush your teeth [and tongue!] often, kids!) Yeast can also infect your skin and even your blood (called fungemia). HCPs (health care professionals, remember?) call yeast infections (no matter where they might be) "Candidasis." Most often the culprit is Candida albicans, but sometimes other species like to play, too.

When fungal infections get even further into the body, things turn really nasty.

Remember our friend meningitis from the bacterial and viral sections? Guess what? Fungus isn't going to be left out of that party. Fungal meningitis isn't contagious or very common, and generally affects people who have been seriously immuno-compromised, like cancer and AIDS patients. A fungus called Cryptococcus is generally responsible for this kind of meningitis. There are a couple of very nasty subtypes of Cryptococcus (NOT to be confused with Cryptosporidium, which is a whole different type of BAMF I'll talk about in a minute), and both are deadly when they set up housekeeping.

Other fungi get into the lungs (pulmonary system) and wreak havoc. One particular nasty is Aspergillosis. Now, normally aspergillis is fine and dandy when it's outside the body. Breathing the stuff in, however…yeah. Warm, dark, moist…you remember how it works. Most people breathe that crap in every day (as it's just in nature/the air) and are utterly fine. It's the same game – your immune system takes care of it if it's healthy. Your immune system is a BAMF too, and works like a boss when it's on the ball. It's when your immune system is compromised for whatever reason (and there are lots of things that screw with your immune system) that things become a problem.

Those of you allergic to "mold" really mean you have a sensitivity to aspergillis or other airborne fungi. (Hint: the "mold" found on bread you may be sensitive to is a fungi also. You might know it as penicillin.) If your character has an allergy to mold, you can't have them working in a bakery, okay? Because yeast has a lot to do with mold. Baking and brewing yeasts are different from the infectious kind, but they do have a tendency to change/ferment/mold, so keep this in mind if you give your character an allergy to mold.

Mildew is the same. Mildew is a common name for types of mold growth. And mold is what? That's right...fungus - usually Penicillium. (In the plant world, mildew refers to a specific type of fungus called Erysiphales, but that's a whole other thing.)

Now while this post is supposed to be about fungal infections, I'm going to touch briefly on parasitic ones as well, mostly because the two are often confused or combined, mostly because they're related. I just mentioned one above.

Cryptosporidium isn't a fungus. It's a parasite. A protozoa, actually, and it's commonly found in contaminated water. It's ubiquitous and worldwide. I had a nasty bout with it on an archaeological expedition once – it's not pretty. Though generally just unpleasant in people with healthy immune systems, crypto (as it's known) can be lethal to the elderly, infants, and others with suppressed immune systems. If you're going to have your character drink from a water source that could be contaminated, chances are they're going to come down with something. You've heard of "Montezuma's Revenge?" Yeah.

Other parasites responsible for infection are helminths (worms, like tapeworm and roundworm) and ectoparasites (things like mites, ticks, and fleas).

Now I'm only going to touch on these. Parasitism is vast and complex and hugely incestuous when it comes to infection. For example, rats carry a type of flea (as do squirrels and other animals) that carry what's commonly called "plague." This is a vague term for Bubonic plague, AKA "The Black Death," (you know…the thing that wiped out a third of the world's population back in the 1300s) and while the flea (the parasite) is carried by rodentia (what's known in epidemiology as a "vector"), the actual cause of the illness is a bacteria the infected flea carries called Yersinia pestis. Same thing with ticks and Lyme disease. The tick itself is the parasite (or "vector"), but it's the bacteria it carries (Borrelia) that causes the disease.

See what I mean about parasitism being incestuous? It's usually not the parasite itself that causes disease, but the bacteria it carries with it, virus it enables, fungus it promotes, or damage it does while infecting.

Remember what I said about vast and complicated? Yeah. Let's just leave our discussion of parasites as it is, shall we? Just things to keep in mind if you have your character slogging through a field full of chiggers (a type of mite) or a cave full of bats.

This concludes part III of the Infection Sequence of the "Ask Dr. Dina" series. Join us in a couple weeks for the final installment of this sequence, where we'll talk about how the various infections I've talked about are treated.

Questions about medical issues with your writing? Leave them in the comments below and I'll get back to you as soon as I can. (THESE MUST APPLY TO FICTIONAL SITUATIONS ONLY. I AM NOT YOUR DOCTOR, NOR A SUBSTITUTE FOR ONE.)

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