Thursday, July 25, 2013

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.

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.

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.

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.

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.

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!

Sunday, July 7, 2013

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.

a green bar graph on a white background showing the number of case reports of PAM by year, United States, 1962-2011. N=123; year of exposure unknown for one case.

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.

Purple graph on a white background showing the number of case-reports of Primary amebic meningoencephalitis by age group and gender, from 1962-2011. N=123.

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.

Multi-colored graph showing the number of case-reports of primary amebic meningoencephalitis, by month of illness onset and probable water exposure in the United States, from 1962-2011. Purple indicates lakes, ponds, reservoirs; light purple indicates canals, ditches, and puddles; rust-red indicates a river or stream; yellow indicates geothermally heated water; green indicates tap water, black indicates swimming pools, and gray indicates unknown or multiple locations.
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