Just When You Thought You Were Safe: Meet the Blood-Feeding Moths

Most people think of moths as  harmless little lepidopterians.  The familiar flutter of these creatures around a porchlight is something almost everyone has seen at some point in their life.  They are often thought of as "night butterflies", embracing the dark side as members of an order more often associated with sunshine and flowers.  Don't kid yourself into thinking that these little guys have yet to discover all the benefits of being blood-feeders.  Meet the genus Calyptera...these aren't your average noctuids!

Before you go jumping to conclusions that I'm making this up, let's consider how something as innocent as moths could have possibly made the leap to blood-sucking.  All lepidopterans (insects including butterflies, moths, and skippers) have a long proboscis used for sucking that unfurls when they are ready to feed.  Most of these animals use these siphoning mouthparts to feed on nectar and other plant fluids.  Some have adapted to feed on sugars and other plant products that require more than simple fluid-sucking.  These lepidopterans have the ability to actually pierce the tissues of the plants they feed on in order to extract the plants' yummy juices.

Over time, many species of lepidopterans have developed a taste for the tears (and other secretions) of a variety of mammals.  Most of the hosts for these lacrophagous lepidopterans are ungulates...often times domestic ungulates.  There are over 100 species of these insects that feed on ungulate secretions, but none of them have the ability to actually severe mammal tissue.  Though not really considered blood-feeders, some of these species have been known to suck blood from open wounds via feeding behaviors that resemble the way similar species feed on nectar.

Which brings us to our genus of choice: Calyptera. Unlike their sister genera, these moth do have the ability to actually pierce through the skin of vertebrates.  After piercing the skin, these moths are able to feast on the iron-rich, warm blood of their hosts.  The mouthparts of this animal are adapted for piercing the tough skins of plant fruits, which is how they were able to make the leap from plant-feeding to blood-feeding from an evolutionary perspective.  There are at least seven known species within the genus Calyptera that feed on the blood of vertebrates. Of those seven, five species have been documented to have fed on humans.

Appropriately, these moths are often called "vampire moths".  They only occur in the Old World as far as I can tell, but they do seem to be expanding their ranges.  They can be found from Malaysia to Sweden.  Unlike mosquitoes and most other blood-sucking arthropods, it is the male moths (as opposed to the females) that take the blood meals.  Wounds from a moth bite are apparently quite painful and remain sore for several days.  Luckily, these little scale-winged vampires aren't known vectors of any blood-borne diseases...yet.

Moral of the Story
The next time you see a sweet little moth fluttering about in the moonlight, remember they they could be more than the quiet, innocent moths you've always known.  Behind that fuzzy facade could lurk a hungry monster just waiting to catch you off guard and sucking your sweet life-blood!  Not so much if you are here in America, but definitely if you hanging out in Asia or Europe. :p Either way, you can't help but marvel at the beauty and audacity of a moth that lands on you gently, then pierces your skin for a tasty late-night snack.  Evolution, like nature herself, is a magnificent jerk...one we can't help but fall in love with despite how terrifying it is that they created hematophagous owlet moths. o.O

The Clock Keeps Tickin’…Maybe I Will Too

SEM image of a tick's capitulum (head)

Dear Faithful Readers,

I'm sorry about my spotty posting this summer...things have been far busier than I'd ever expected!  This week, however, my excuse isn't that I've been busy, but rather that I've been sick.  I had a head cold that had me loopy for a few days.  Luckily I have an awesome friend who insisted that I take some Sudafed.  One pill pretty much fixed me up after a day of utter misery.  The point is, I missed blogging yet again, so here I am making up for lost time.  This is kind of a short one since I've been a bit under the weather, but I hope you enjoy it anyway!

As is my obsession for finding beauty in odd and often disgusting creatures, I’ve started doing a little work with ticks.  I caught several earlier this summer with no intention of actually taking the time to identify them.  Enter the Field Parasitology course.  Along with gear, the professor (the legendary, Dr. Scott Gardner) brought a stack of books.  Among the books was a mite and tick identification guide.  So, naturally, I felt I needed to pull out my preserved ticks and see what we had here.  I readied my station putting fresh sand in my dish and placing the book to my left and my notepad on the right.  After only a little bit of refreshing myself with tick terminology, I was able to get it keyed out to the genus Dermacentor.  As I read the species descriptions, I narrowed my specimen down to either D. andersoni or D. variabilis.  I was having a hard time differentiating the two, so I decided to wait.  A parasitologist who specializes in ectoparasites (Dr. Don Gettinger) would be coming to the station in a few days, so I just needed to have patience.

Ventral Anatomy of a Tick

Waiting for this expert’s opinion gave me a chance to think more about ticks.  You know, I’ve always hated them…stupid little blood suckers!  However, after forcing myself to look at them under the dissection microscope I started seeing them as less terrifying and more fascinating.  I recalled that way I had examined the tick for evidence of festoons and punctations, and how I had slowly come to realize just how intricate the anatomy of these simple creatures was.  My initial horror had morphed into silent appreciation as I had noted the bifid coxae and the set of 11 festoons.  Here I was again, privy to yet another stunning work in the glorious underground art gallery that Mother Nature had unfurled before my very eyes. 

As my time comes to an end here at the station and I return home to work on Lithuanian mummies and Mexican coprolites, I can say that I am honestly walking away with a new appreciation for yet another group of animals that most people find disgusting.  I’ve given my ticks to Dr. Gettinger and he should have them identified definitively here in a few weeks. I’m really excited about seeing to which species they belong!

Plans for next summer are far from set in stone, but perhaps if I have some time (and if I am out here with the same job I had this summer) I’ll be able to run a few tick drags and collect more of these creatures.  Maybe we could even see if they are carrying some of the bacteria that they have become famous for carrying!  Or maybe I won’t even get to come back here.  Either way, I’m glad to have had the opportunity to broaden my perspectives on the natural world this summer.  As the next few semesters roll on and my time as a PhD student ticks away, we shall see if I ever get the chance to “go ticking” myself!

Cyclosporiasis: Coming to a City Near You!

Hello fellow parasitophiliacs! Sorry that this is a little late, we had a Field Parasitology class start here at the station so I've been too excited to take the time to write up this post.  A few weeks ago a friend sent me a link about a local parasite outbreak, so today we are going to discuss that parasite.

In 1854, John Snow made quite the name for himself by halting an outbreak of Cholera in London. He famously had the city remove the handle from the Broadstreet pump, thus stopping people from becoming further infected with the water-borne illness.  This summer, we had our own version of John Snow's problem...the difference was that we were dealing with a eukaryotic organism instead of a prokaryotic bacterium. Oh yeah, and people aren't dying of our disease, just getting really, really sick...and we aren't in London...and we have much more advanced ways of studying and halting the spread of infectious diseases...and okay, it's not the best analogy I suppose.  The point is, we have an outbreak on our hands that has grown rapidly in the midwest and we really need to figure out which pump is housing our contaminated water...or to be more accurate, what type of produce is most likely to be the carrier for this parasite.

Cyclospora cayetanensis in various stages of development.

Taxonomy
The scientific name of the parasite is Cyclospora cayetanensis.  It is a type of unicellular organism within the phylum Apicomplexa. It belongs in class Conoidasida because it possesses a structure known as a conoid.  It is further classified in the subclass Coccidiasina and the order Eucoccidiorida.  These organisms are commonly called simply "coccidians". Another well-known coccidian is Toxoplasma gondii, which can cause problems in pregnant women and people with compromised immune systems. (I'll stop right there about T. gondii...otherwise we would be here all day as that is one of my all-time favorite parasites.) C. cayetanensis is placed in the family Eimeriidae with many coccidians of veterinary importance, such as Eimeria tenella, which infects chickens.

Life Cycle
The life cycles for these protists involve direct contact with infected feces.  People most often pick it up by eating foods or drinking water contaminated by infected feces.  When a sick person deposits feces, the protists exist in a life stage called an oocyst.  These oocysts spend a few weeks outside of a host undergoing morphological changes until they develop the necessary parts to become infective. This developmental process is called sporulation.  After sporulation, a host eats whatever the parasites are contaminating and the process repeats itself.

Cyclosporiasis
The disease caused by C. cayetanensis is often called "traveler's diarrhea", but the medical term is cyclosporiasis.   Symptoms typically include fatigue, nausea, flatulence, and anorexia followed by watery stools, abdominal cramping, low-grade fever, gastroenteritis, and weight loss.  If left untreated, these symptoms can persist for about 57 days.

Diagnosis
The diagnosis of cyclosporiasis is fairly difficult because these protists are small and difficult to stain.  There are four commonly accepted methods for diagnosing this disease:



1-Finding it in a fecal smear (a.k.a. checking the poop)
2-Finding that these parasites are undergoing sporulation
3-Finding parasites in bowel biopsy or intestinal fluid.
4-Good old PCR (polymerase chain reaction).

The parasite also auto-fluoresces (glows) under a black light.  So using a UV light while performing microscopy can also be helpful for diagnosis.


Treatment
Despite the nasty symptoms, this infection is fairly readily cured. Current protocol describes using antibiotics (like trimethoprim-sulfamethoxazole for instance).  These drugs are administered over the course of about 7 days. If left unchecked for too long, or if the infection is very severe, some people do have to be hospitalized.  Luckily, very few people ever die from this disease.

Prevention
The best way to prevent contracting this parasite is to always thoroughly wash any produce that you have (especially raspberries, as you will see in a moment) and to make sure that you are getting clean water when traveling to countries with sanitation problems.  These parasites are often contracted by people traveling in  Peru, Brazil, and Haiti, but if you know your water is coming from a reliable source and your produce is properly washed, you should be fine. Outbreaks have occurred in the U.S. and in Canada from fruits imported out of Central and South America.

Recent Outbreaks
The most recent outbreak began in Iowa during June of this year.  When I first read about the outbreak, there had been 22 cases reported. As of today, there have been 138 confirmed cases in Iowa.  Many other states have seen an increase in cases as well. Nebraska jumped from 16 cases a few weeks ago (11 cases coming out of Douglas Co.) to 70 cases as of this morning. My home state of Texas has seen 66 cases. Georgia has reported 2 while Wisconsin has reported 3, and single infected individuals have popped up in Kansas, Ohio, Illinois, Minnisota, New Jersey, and Connecticut.  That brings us up to 285 cases spanning 11 states in the last month. Ten of these people wound up in the hospital and who knows how many cases have gone unreported.  This is certainly well above the average number of annual cases which has been around 150 for the last eight years according to the CDC. So far, no one has been able to determine what is causing the outbreak, but the best guess is some type of imported fruit was tainted.

Risk Areas for Traveler's Diarrhea: Green=Low, Off-White=Intermediate, Red=High

Less Recent Outbreaks

Someone had fun with Photoshop.
I thought this was pretty clever.

In 1996 there were over 1,000 cases reported in the U.S. and Canada that were linked to raspberries imported from Guatemala.  In 1997 an additional 90 cases from five U.S. states were reported.  These cases were also linked to berries that came from Guatemala and Chile.  More recently (2000), there was an outbreak where 54 people got sick after eating infected raspberries baked into an unlucky couple's wedding cake. Having recently planned a wedding myself, the thought of such a possibility is absolutely terrifying.

Moral of the Story
The biggest lesson learned from doing research for this post is that you should ALWAYS thoroughly wash your produce. These little guys can't burrow their way into the foods they are contaminating, so giving your fruits and veggies a good wash is really all it takes to save you from 57 days of things coming out of both ends. Also, if you are traveling, take extra care in paying attention to where your food and water are coming from. Finally, if you live in any of the areas in or around outbreak zones, be sure to see a doctor if you start to experience any of the symptoms of this disease.  Get yourself a strong dose of antibiotics and be glad you only had to suffer 7 miserable days of illness instead of 57!  Where is John Snow when you need him?  I bet he'd know nothing about cyclosporiasis anyway...(that may or may not have been a Game of Thrones reference...).

Is his name Guatemala? No? Alright, we'll blame Lone Star!

The Not-So-Rare, Yet Still Uncommon Brain-Eating Amoeba

Greeting All! First and foremost I must apologize for my lack of blogging in the past month. As some of you may know, I've been working at a biological field station and time has sort of flown by here with all of the projects I'm currently working on. This is the first chance I've really had to sit down and type something up for all of my fellow parasitophiliacs.

My lame excuses aside, I ran across a clip this morning from a show called "Monsters Inside Me". I have seen this show before and liked what I had seen even though they make some things a little excessively dramatic.  However, this clip was appropriately dramatic.  This episode was about a family that lost their beautiful son and brother to an infection of Naegleria fowleri.

Some of you gasped when you read that scientific name (as you should) and others of you are sitting there with a confused look on your face.  Naegleria fowleri is a species of amoeba that becomes opportunistically pathogenic when its natural freshwater habitats are exposed to prolonged periods of high temperatures.  My first post was written about this parasite and can be read here for further information.

After watching the Monsters Inside Me clip, I Googled the name of the victim from the show.  His name was Kyle Lewis.  He was taken by the disease at only seven years old.  His family lives in Arlington, Texas (which is pretty close to home for me) and has started an amoeba awareness organization called Kyle Cares.  You can access the site from here.

After browsing the site for a bit and reading about other people who had been taken by these parasites, I began to notice that there were more confirmed cases than I had realized in the last few years.  For those who may not know, this disease is extremely rare despite the ubiquitous nature of the non-infective forms of the amoebae in the southern United States.  The disease caused by an infection of these amoebae is termed "Primary Amoebic Meningoencephalitis" or "PAM".  I've always learned, as I stated above, that this is an extremely rare disease.  However, this site claims that the disease is not as rare as many people think.  Upon further reading, I learned that have been nearly 45 cases reported since the year 2000.  Granted, this is pretty low, but it isn't nearly as low as I had imagined.  Last summer alone there were at least three confirmed cases of PAM in the U.S. between the months of July and August.  Below is a graph taken from the CDC's website showing how many cases of N. fowleri have been reported from 1962-2011.



This graph pretty much blew me away.  I had no idea that we had THAT many confirmed cases.  Upon further reading, I found this chart showing gender and age distribution of cases within the same dataset as the above graph.



The final graphic I wanted to include in this post shows a time distribution in addition to a means of infection for the same cases used in the dataset above.


As you can see, the parasites are most often pathogenic during the hottest months of the year and tend to be contracted from lakes, ponds, and reservoirs.  It seems to occur more often in males than in females and is found most frequently in children and teenagers...though it is certainly not limited to these genders or ages. 

This disease has a rapid onset and is between 97% and 99% fatal depending on your source.  The few who have survived this disease were given Amphotericin B...which has harsh side-effects from what I understand.  The Kyle Cares website mentions that a group of researchers out of California have found a possible cure for PAM that works in vitro, but I have not yet been able to locate this particular paper. (If anyone has a copy, please e-mail me!)  However, I was able to find a paper about a possible vaccine that a group of researchers in Korea have been working on.  The vaccine has a 90% survival rate in experimentally infected mice.  The big question here (other than the obvious, will it work for humans?) is whether or not a vaccine is practical.  If it would save lives, it would be practical for people who live or vacation near freshwater bodies that exceed 80 degrees F during the summer months to get vaccinated.  However, because the disease is relatively rare, does it really make sense to vaccinate everyone that we can?  These are issues for people with far more public health experience than myself, but I do find it to be a fascinating new development for the worlds of parasites and immunology.

Moral of the Story
I suppose the best thing to take away from this is to remember that our definitions of "rare" diseases may be a bit more fluid than what we realize.  Though this disease is by no means common, we do seem to have spikes in cases during the hot, dry summer months such as those we are experiencing right now.  The best idea is to avoid recreational water sports in lakes, ponds, etc. when the water is warmer than 80 degrees F.  Also, if you haven't already done so, consider popping over to the Kyle Cares website and donate to their cause for continuing research and providing support for families affected by N. fowleri.  Here's that site again, in case you missed it: Kyle Cares

Mother Nature's Underground Art Gallery

I finally finished reading Parasite Rex a few days ago.  It was an amazing book, and if you haven't read it already, you should!  As I started thinking about what to write about for today's post, I started reflecting on the last chapter of the book.  I also started thinking about why I am so intrigued by parasites and why so many other people find them disgusting.  So, I decided that rather than talk about a specific parasite today, I would blog about how I came to be a lover of things that many people consider "repulsive".

To further preface this post, I've been living at a biological field station for a little over a week.  I'll be working here all summer doing various odd jobs and being a teaching assistant for summer sessions.  In addition to being a parasitophile, I'm also an araneophile (lover of spiders).  I started collecting a few spiders after arriving here just for funzies, but now I've fallen into working on building a permanent spider collection for the station since we don't already have one here.  Over the course of four or five days, I've already collected 30 specimens representing at least 6 different families as far as I can tell.  I will be ordering a spider identification manual soon so that we can officially identify what I've collected so far.  Like parasites, spiders are creatures of great beauty, complexity, and diversity that are vastly under-appreciated by the general public. 

What is it with me and liking creatures most people are disgusted by or avidly afraid of?  I pondered this question for a very long time last night as the thought of getting a spider tattoo crossed my mind.  Why a spider tattoo?  Because it would be more than simply a thing I found interesting, it would be highly symbolic of my growth as a scientist.  You see, I haven't always loved spiders...in fact, most of my life I was very much an arachnophobe.  I would squeal and stomp just like any girl would do despite being surrounded by them the majority of my childhood growing up on a farm.  I was also afraid of snakes and some of the more threatening flying insects like wasps and muddobbers.  I wasn't so keen on ants either.  But things change as we grow older, and more importantly wiser.

As a young biologist, I took a class in vertebrate zoology that made me decide I wanted to become a herpetologist (one who studies reptiles and amphibians).  I loved frogs and lizards and was even developing a fondness for turtles.  Then there were snakes.  Most people who long to be herpetologists love snakes...I was the opposite.  Snakes were the last creatures I wanted to study, but I knew that they sort of came with the territory if I wanted to be a herpetologist.  So I set out to change my fear of snakes into at the very least a mild tolerance.  I tried to handle them every chance that I got and I read up on how they worked and how to handle them safely.  In my quest for better understanding, I soon realized that many snakes were completely harmless to us humans.  I even started seeing some of these as "cute"...a word I never would have used to describe a snake in the years prior to college.  It wasn't long before snakes no longer frightened me, though I have a healthy respect for venomous ones like diamond backs (Crotalus atrox).

Later in my career I became a graduate student.  In working towards a general biology degree, I wanted to take all of the "-ology" classes I didn't get to take as an undergrad.  I filled my time with mammalogy (study of mammals), araneology (study of spiders), mycology (study of fungi), and entomology (study of insects).  I was delighted to take entomology because I wanted to learn more about butterflies and beetles...and I did.  I also learned about the dreaded wasps, bees, and ants that I had admittedly trembled in fear of before.  (I recall even locking myself in a bathroom until my now-husband came home to rescue me once because a wasp found its way into our home.)  But I wasn't about to let these little devils stand between me and getting an "A" on my insect collection.  I learned more about these terrifying creatures and I forced myself to capture some of them (though I also conned some of my friends into doing my dirty work).  As I became more knowledgeable about the complexity, diversity, and downright coolness of these creatures, my fears slowly evaporated into non-existence.  By the end of it, I was no longer afraid to approach nests of these little beasts.

Feeling confident about my ability to work with virtually any type of insect and feeling unburdened by the shackles of my former fear was intoxicating.  I didn't want to be afraid of anything that nature could throw at me anymore.  I had truly learned that knowledge is power.  Understanding something made it less scary...and the next natural step after conquering one's fear is starting to see the beauty in the biology of such magnificent creatures.  So I decided to step it up...I registered to take a class about spiders.  For an entire semester, I focused on learning about these creepy crawlers.  Just as with the metamorphosis I underwent with insects, I slowly began to shift my perspectives about spiders.  They weren't the things of nightmares...they were animals with fascinating behaviors, intricate physiology, and astounding beauty once you could appreciate them.  I came to call some of these "adorable" like the jumping spiders with iridescent chelicerae or the happy face of a crab spider.  Talk about a giant leap towards conquering my fears!

This was my most miraculous change and the experiences of that semester really started to shape how I saw both the natural world and how I viewed society in general.  These lessons made me realize that some of the most beautiful things are things you have to want to understand and you have to take the time to really get to know before you can appreciate the amazing insights they have to offer.  This applies to people as well.  I won't go too deep into my sociopolitical views as you aren't here to read about those viewpoints...but I will say that understanding diversity in nature really shifts the way we see diversity amongst human populations.  We start to see that people who are different from us have a place and a purpose in our society.  We start to understand that if everyone was the same, our societal ecosystem would be dull and also...more importantly...would not be healthy.  We need diversity in society just as any ecosystem needs more than one type of flower or more than one species of insect.  Diversity keeps things interesting, beautiful, vibrant, and healthy.  Diversity = Progress from a human societal perspective as well as from a biological perspective.

By this time in my career I had discovered the sweet love that dare not speak its name...no, I'm not a lesbian...I'm talking about becoming a parasitophiliac.  The world doesn't always see parasites in the best of light...in fact, the opposite is more often true.  However, I had begun to see the beauty in another group of creatures most people found disturbing and even disgusting.  I had fallen for stories of bizarre life cycles and unimaginable diversity.  Things that once seemed like creatures that rarely inundated hosts and caused problems for people and other animals started to seem much more ubiquitous and subsequently much more vital to a healthy ecosystem.  I started to learn that parasitism was an extremely common and successful way of life for a plethora of invertebrate creatures.  They lived in things, on things, and around things.  They seemed to be interwoven into every aspect of biology...genetics, immunology, ecology, you name it!  Being a parasitologist was more than understanding a single phylum or class of animals...it was about understanding biological principles in a broad sense as well as understanding specifics of whatever creature you specialized in working with. 

These creatures really do have a hand in every biological jar. One of the most fascinating aspects of parasitology is the insane intricacy of parasite evolution.  Parasites have been the driving force of adaptation in more species than I can count.  They have been the culprits behind many of the evolutionary arms races amongst a wide variety of host species.  As they become better at evading the immune systems of their hosts, hosts develop better means for detecting the presence of parasites and back and forth the battle rages.  They affect more than animal immune systems.  In many instances they affect animal morphologies, physiological processes, and even host behaviors.  Many parasites are master of host manipulation and behavioral modification.  They have developed an arsenal of clever ways to transfer themselves from one host to another. I think Carl Zimmer put it best in Parasite Rex when he said, "When it comes to the tapestry of life, parasites are the hand on the loom." How elegantly beautiful is that?

With such fascinating life styles, I don't understand how any knowledgeable person could not be fascinated or at the very least intrigued by natures most "terrifying" creatures.  From snakes, to wasps, to spiders and parasites...nature has shown me that choosing to stay fearful and ignorant keep you from ever seeing some of the really interesting and amazing things she has to offer.  Things that most people fear in nature or know very little about are often some of her best works of art. Her underground gallery is rife with stories and images that would evoke the most profound emotions and senses of wonder if only more people would take the time to find the exhibitions.  This is why I'm so passionate about the "disgusting"...this is why I love spiders and parasites.  Call me a biological hipster (the only form of "hipster" that I wouldn't punch someone in the face for calling me) but having access to mother nature's underground gallery makes me feel privy to the exclusive works of art that we all, in reality, possess the potential to see for ourselves in we just take the time to look.

Dermatobia hominis: The Human Skin Bot

D. hominis larva

For those of you who haven't already heard, I made a journey across the state yesterday to my home for the summer.  I'll be spending the next three months working at a biological field station owned by the university I am attending.  Yesterday while sitting in the dining hall, I saw an adorable little rabbit hopping around the cedar trees.  The first thing I thought about was how I scared my roommate last week with a video of a bot fly emerging from a recently killed rabbit.  (You can view this video yourself here.)  When I awoke this morning and began thinking about what to write for today's post, I realized I had never really talked about bot flies.  So here we are! There were lots and lots to chose from, but I decided we would take a human perspective and look exclusively at the human skin bot (Dermatobia hominis) for this post.

Taxonomy
As you probably already know, flies are animals belonging in phylum Arthropoda under the class Insecta. All flies belong to the order Diptera, meaning "two-wing"; this is in reference to the fact that these insects have only one pair of wings as opposed to two pairs like most other insects.  The second pair of wings in most flies have been reduced to vestigial structures called "halteres".  These structures now function mostly as balancing organs and have a knob-like appearance.  This order houses about 120,000 species representing 140 families.  The family that contains bot flies is the family Oestridae.  This family is split into four subfamilies: Cuterebrinae (skin bot flies), Oestrinae (head maggots), Hypodermatinae (cattle grubs, ox warbles, and heel flies), and Gasterophilinae (stomach bots flies infecting horses and their relatives, elephants, and rhinos).  Our D. hominis is found in subfamily Cuterebrinae and is common from Southeast Mexico down through the South American continent, extending to Argentina and Chile. Though we call it the "human skin bot", it will actually develop beneath the skin of just about any warm-blooded animal...mammals or even birds.

Adult human skin bot fly

Life Cycle,
The life cycle of this fly is similar to other flies in that it involves the laying of an egg what will hatch into a larva, which will go on to form a pupa from which an adult fly will eventually emerge.  Unlike most flies that infect their hosts (a condition known as "myiasis" which we will discuss in a moment), this fly does not lay eggs directly onto their hosts' bodies.  Nope, these guys are much more devious. An adult female fly will catch another parasitic insect, like maybe a mosquito, and glue her eggs onto the insect's body with the opercula (little flaps that open to release the eggs' contents) of the eggs facing downward.  It is unknown how many different types of insect carries are used by D. hominis, but there are at least 48 different types of flies and on tick species that have been known to be carriers.  Once one of these carriers lands on warm skin, the opercula open releasing the larvae onto their new hosts.  The larvae then burrow into unbroken skin and make a home in the dermal layers of the skin, where they stay for about 6 weeks before burrowing out of the skin and falling into the soil where they form a pupa and undergo metamorphosis, emerging as adult flies ready to mate and restart the cycle.

Myiasis

Bot fly larva being removed from a leg

This is the clinical term for an infection of fly maggots.  This can occur either opportunistically, as is the case in facultative myiasis...a condition in which  a non-parasitic maggot accidentally winds up in a host, or it can occur as part of a parasitic fly's life cycle, which is the case with obligatory myiasis.  If one becomes infected with D. hominis, that is obligatory myiasis.  Myiasis can occur just about anywhere there is exposed skin for a carrier to land on.  In fact, I even ran across a case of penile myiasis...that's right, some poor schmuck got infected with a bot fly on his penis.  No matter the site, these types of infections cause painful lesions, but almost never results in secondary infections.  In fact, there have been reports that fly maggots actually secrete antibacterial substances that are alkaline in nature, making wounds unfavorable environments for bacterial growth!  How cool is that??!!!

Human skin bot fly larva

Treatment
No matter how awesome it is that these guys make antibacterials from their spit, they are not fun to have burrowing into your dermis.  The best way to remove a bot fly larva from yourself is to suffocate the little guy and then pull him out by squeezing or using tweezers.  There are several ways to suffocate the larva.  One way is to put tape over the wound, but this is not recommended as it can actually rip the larva causing problems with total removal.  Another, less damaging way is to apply several coats of nail polish to the wound, but this can be problematic when removing the nail polish and is easily applied incorrectly due to the nature of skin.  The best, most effective way with the easiest cleanup is to apply a generous coating of petroleum jelly to the wound.  Which ever method you use, leave the applied substance on the wound for about a day or more, then you can remove the substance and subsequently remove the fly.  Some sources say that a venom extractor (found in snake-bite first aid kits) can be very effective at removing these larvae.

Moral of the Story

I think if you get a bot fly,
someone should buy you this shirt.

If you travel south for research or for funzies, be sure to take both insect repellent and petroleum jelly.  A snake-bite kit wouldn't be a bad idea either! Also keep in mind that though these things seem scary, they have tremendous potential in the field of medicine.  Perhaps if we could isolate some of these secretions, we could get new forms of antibacterial medicines or even substances that can be used to treat necrosis (dying tissue).  Heck, maybe someone already has figured out how to do either or both of those things! The point is if you do get a bot fly, remember that it is easily treated and that you aren't likely to get any weird secondary infections. Easy enough to deal with...it's all mind over being freaked out by a parasite! :p

Meet the Crimson Rambler

When I was a child, my mother...like many other mothers...used to say, "Good night.  Sleep tight. Don't let the bed bugs bite!".  Good advice for a child not sure what bed bugs really were...otherwise I'd probably have had nightmares!  I spent most of my young life thinking bed bugs were mythical because of that phrase.  As I got older, I discovered that they were very real creatures that actually do bite people as they sleep.  As you can imagine, I was filled with fear and panic when I first learned about how pesky these little buggers can be.  As I've grown into the young parasitologist that I am, these pests have moved from something I fear to something I find fascinating.  Like most other parasites, these guys have very interesting lives and guess what...they aren't terribly dangerous to tell the truth.  The worst they can do is be an annoyance and an extremely difficult one to rid yourself of at that.  So, today we look at the strange lives of these odd insects that have had aliases such as the "wall louse", "heavy dragon", "chinche bug", "redcoat", and my personal favorite, "crimson rambler".  

Taxonomy
These animals belong to the largest of all the animal phyla: Phylum Arthropoda.  Within this phylum they exist as members of class Insecta.  Something tells me you can guess what other types of creatures make up this class.  They belong to order Hemiptera, meaning "half-wing", which refers to the partially membranous wings of most member of this order.  Interestingly enough, not all members of this order have wings (as we see with bed bugs).  However, members of this order do all possess piercing-sucking mouthparts often called the proboscis. This is used for penetrating tissues..both animal and plant in nature. They further belong to family Cimicidae.  Members of this family are all wingless blood-feeders that seek out birds, bats, and humans. There are 22 genera within this family; twelve feed on bats, two on humans, and the rest on birds...typically birds that live in caves or along cliffs.  The three species that feed on humans are colloquially called "bed bugs" due to their nocturnal feeding habits.  These three are Cimex lectularius, Cimex hemipterus, and Leptocimex boueti. The first is the most commonly found species globally, but prefers temperate climates, while the second prefers more tropical areas.  The last is found only in West Africa.

Bed Bug Bodies

SEM of a bed bug.  The piercing mouthparts have
been artificially colored with purple and red.

As mentioned previously, these little bugs are wingless...actually, if you want to be technical, they have vestigial (reduced to the point of being useless) wings. As adults, they are small reddish-brown ovals reaching as big as 5mm x 3mm in size.  Newly hatched nymphs are transparent, but become progressively darker as they go through successive molts.  These insects use chemical signals to communicate with one another about nesting, feeding, and reproducing.

Coming Out of the Woodwork...Err...Cave-work?!
These insects can proliferate quickly and be extremely difficult to eradicate once they have an established home.  But where did they originally come from?  Though no one can say for sure when or where bed bugs originated, we do know that the three species that feed on humans are also known to feed on bats.  It is likely that humans picked up these parasites from living in caves alongside infested bat colonies.  C. lectularius has also been known to feed on rodents, which may have helped to spread these insects into human dwellings outside of caves.

There is a long and fascinating history associated with these little bugs, but I'll save that for a future post. Today, we are experiencing a time of resurgence in bed bug populations.  As more people take over the planet, we build more places to house more people in fewer areas.  This space-saving comes with a price. Not only are apartments, dorms, and condos more prone to infestations with cockroaches and ants, now we are seeing more and more cases of bed bug infestations as well.  As you probably would have guessed, they are a bigger problem in places with larger populations.

The Feeding: Adventures of the Crimson Rambler
After closing your eyes and drifting off to dreamland, these little creatures make their way out of mattresses, dressers, pillows, and cracks or crevices in the walls near your bed. They find their way to you by detecting the carbon dioxide you exhale with every breath, by feeling the warmth of your body heat as they get closer, and by using a variety of navigation chemicals.

After discovering your exposed skin, the creatures pierce you with their tiny little beaks.  This blood derrick finally strikes paydirt when it enters into a blood vessel.  From here, the pressure within the vessel itself forces this iron-rich liquid into the body of this miniscule beast. Their bites are not painful and often go unnoticed in the beginning. The wounds left behind eventually become small itchy welts around your neck, arms, and jaw. The bug draws on the fresh blood for the next 5-10 minutes before dropping off and crawling back into the home from which they emerged. This is a ritual that occurs every 5-10 days.

Despite the fact that these creatures tend to feed once or twice a week, they can actually go for about 5 months without feeding under typical conditions.  Under ideal conditions (for them) they can live for up to a year.  Speaking of time, here's a fun fact: These insects digest their blood meals slowly and human DNA can be recovered from bed bugs up to 90 days post feeding!  This gives them a unique place in forensic entomology for determining whether or not a person was in a place where the bed bugs were found!

Male (behind) traumatically inseminating a female.

And the Most Traumatizing Mating Ritual Goes To...
One of the things that I've always found most fascinating about bed bugs is their means of reproduction.  These animals mate when a male finds a female, grabs her from behind, and literally stabs her in the abdomen with his hypodermic genitalia.  That's right hypodermic genitals.  After the stabbing, he ejaculates into her body and the sperm swim around in her hemolymph until they reach sperm storage structures.  Eventually, the sperm are released and move to the ovaries where fertilization occurs.  This process is appropriately called traumatic insemination.

Human Health Issues

Bed bug welts.

Despite being exclusive blood feeders, and being known to become infected with over 28 human pathogens, these animals have never been documented to have transmitted any diseases to humans.  The worst that these bugs can do is cause skin irritation that may be mild or could cause blisters in sensitive individuals. The biggest problem humans experience when living with bed bugs is the psychological effect associated with living in an infested home.  Much fear and disgust surrounds these organisms, and it is easy to have such feelings when faced with an infestation. 

These bugs are often associated with sub-par living spaces in our minds, but the truth is that a home can be a very nice home and still get an infestation.  They can be brought into a home through clothing, luggage, furniture, etc. from an infested home.  They can also come from wild animals or pets that have been exposed to nesting sites.

Detection and Management
Bed bugs are not always easy to detect because they are nocturnal feeders, usually feeding in the wee hours of the morning.  If you haven't had any reactions to the bites, you can still detect bed bugs by finding their fecal spots, blood smears on your bedding, or empty exoskeletons left behind as the insects molt.

A bed bug harborage.

Sometimes you can find a single bed bug, but they are more often found congregated at nesting sites.  These clusters of bed bugs, young and old, are often known as "harborages" and are the end of the chemical trail after feeding for most of these insects.  Harborages can exist in bedding, luggage, furniture...even electrical sockets and laptops.

Some people employ the help of specially trained bed bug detection dogs to help them find harborages.  Apparently, these dogs are very good at their jobs.  Under controlled lab conditions, these dogs are 97.5% accurate.  Of course, we expect that rate to be lower under real-world conditions, but that's still pretty impressive! Bed bugs are said to have a smell that some describe as rotting raspberries.  Trained dogs can typically pick up on the origins of these smells within minutes, which pest control specialists usually need about an hour.

A New York bed bug detection dog.

Bed bugs die if exposed to 115°F heat for 7 minutes or more.  Heat along with pesticides like malathion are the best course of action for managing bed bug infestations.  These animals can also be killed by freezing temperatures, but this takes several days rather than a matter of minutes. It is also recommended to vacuum areas, heat treat bedding and mattresses, and above all else to call in professionals to help with eradication efforts.  In extreme cases, you may have to dispose of a heavily infested mattress or couch.


There was an interesting paper that came out recently talking about a traditional method of bed bug control that involved the use of plant leaves scattered around the bed as traps.  Apparently this method actually works to some degree and scientists are working to develop artificial traps that have the same design as the hairs on these bed bug-snaring leaves.  More about that paper in a future post.

Bed bugs and their eggs
inside an infested dresser drawer.

To prevent bites, try to minimize the amount of skin you leave exposed while you sleep and think about infesting in a pesticide-impregnated mosquito net until you know you have gotten rid of these insects.  To prevent bringing these guys home be careful of secondhand items and sketchy hotels. Keep your luggage off the floor when possible in hotels, even non-sketchy ones may be infested. Bed bugs don't need a dirty place to live...they just need a place with hosts and lots of hiding places. Also, be sure to thoroughly look at your personal items after a trip...especially if you were in close proximity with birds or bats...and be sure to wash your trip clothing with hot water and dry them in a dryer for at least 20 minutes at a medium-high heat.

If you do develop skin problems from bites, you can treat them using a hydrocortisone cream or an oral antihistamine like Benedryl.  The bites usually heal within a few weeks.

Moral of the Story
If you get bed bugs, be sad that you have something hard to get rid of, but happy that you have something that can't transmit any sort of deadly disease! (Always a silver lining!) These creatures are fascinating even though they cause a lot of human annoyance and can be costly to eradicate from your home. Be in awe of the crimson ramblers...just hope you never have to deal with them up-close and personal! :p