Sorry for the delay…I’ve been both busy and lazy, forgive me 😛 Now. The first two were the ‘good’ and ‘bad’ of parasites. I wanted to end this “Trilogy” with the most interesting bits of information about our little parasitic buddies. Granted, these would still count as the “bad”, but I find these to be more interesting. I hope you will too. Now, allons-y!
Mind-altering Parasitism is mostly what I will focus on today. I find it to be really fascinating how parasites can alter the brain chemistry of its host. Here’s an example of such an occasion…from an article I had read awhile back when I took Parasitology 1 a year ago.
Toxoplasma gondii: the “brain-hijacker”
This single-celled pathogen infects over half the world’s population, including an estimated 50 million Americans. Each of Toxoplasma’s victims carries thousands of the parasites, many of these residing in the brain. Scientists began to study this little fellow to try to find the reason for its impeccable success.
Researchers in Sweden report that the parasite spreads through the body by manipulating mobile cells that are part of the immune system. Toxoplasma hijacks these dendritic cells and makes them race around the body and ignore commands from other immune cells to commit suicide. Thus, a problem. The dendritic cells sneak the parasites into the brain and other organs, acting much like a Trojan horse. Very Ninja like, I’d say. But this can cause SERIOUS issues for the victim, as you can imagine.
Strategies like this one have made Toxoplasma incredibly widespread yet incredibly obscure at the same time. Mention the parasite to most people and chances are you will draw a blank (unless they are enthusiasts like myself!). Pathogens that infect far fewer people, like the Ebola and West Nile Virus, are far more known.
For most people, Toxoplasma causes no serious effects. It manages this by hijacking our cells and immune system, and establishing a careful harmony between parasite and host. Moral of the story: Once you get infected…you’re infected for life. More or less. However, for most people it wouldn’t be much of a problem. Toxoplasma can, however, cause serious brain damage in those with weak immune systems, like fetuses and adults with AIDS (or those taking immunosuppressants).
Cats play a major role in the parasite’s success. Our lovely felines can carry it in their intestines, where they can produce egglike cysts called oocysts. A single infected cat can shed 100 million oocysts in its droppings. The oocysts can survive in the soil for over a year and can contaminate drinking water. Oocysts can infect humans, by the way. Undercooked pork, chicken and other meat is another mode of being infected. So be careful when you cook. Once Toxoplasma enters a host, it spreads quickly. Within hours it can be detected in the heart and other organs. It is even able to infect the brain, which is protected from most pathogens by a tight barrier.
Scientists believe that the parasite is directing cells to move and to disseminate through the body. Antonio Barragan and his colleagues at the Karolinska Institute in Stockholm had put dendritic cells in a dish and injected them with Toxoplasma. They noticed that the parasites triggered a peculiar change: the dendritic cells became hyperactive, crawling for an entire day. Injecting dendritic cells carrying Toxoplasma spread the parasites to the brain and other organs MUCH faster than injecting Toxoplasma alone. The researchers concluded that Toxoplasma was taking charge of the dendritic cells and riding along with them. Their results are published online in the journal Cellular Microbiology if you want to learn more. Or google it, my friends.
Furthermore, As Toxoplasma spreads through the body, it invades cells. Unlike other pathogens, Toxoplasma can enter almost every type of cell in the bodies of thousands of host species. The parasite slips into a cell by latching onto its surface and pulling the membrane over itself. It just sits there, and the host doesn’t recognize it as a foreign body it should destroy. Thus, no autoimmune reaction happens. But have no fear, there is a bit of relief in this. If Toxoplasma simply spread from cell to cell, it could cause serious harm. BUT killing its host is not in the parasite’s best interests: its goal is to get into its final host, cats, the only creature in which Toxoplasma can reproduce by making oocysts that are shed in feces. Toxoplasma has evolved to be extremely contagious, but not very harmful.
However, there are certain individuals who should be careful. Toxoplasma becomes a menace when it does not have a healthy immune system to control. Pregnant women infected for the first time by Toxoplasma may pass it to their unborn children. Without a strong immune system to keep the parasite in check, a fetus can suffer massive brain damage. Up to 4,000 children are estimated to suffer toxoplasmosis in the United States each year. Toxoplasma is also dangerous to adults with weakened immune systems. The cause may be AIDS or immune-suppressing drugs given to people who receive organ transplants. A quiet Toxoplasma infection can suddenly “explode”, if you will.
Most scientists believe that people with healthy immune systems had no effects from Toxoplasma. But some studies in recent years have hinted that the parasite can exert surprising effects on behavior, at least in animals. In 2000, British scientists demonstrated that rats infected with Toxoplasma lost their fear of cats. They proposed that this strategy increased the parasite’s chances of getting into its final host. Clever, isn’t it?
In fact, it went so far as that the mice held a mild ATTRACTION to the cats odor. So, it is not just a loss of an old behavior…but a development of a new (odd) one. The mice were still afraid of other animals such as dogs or rabbits…but not of cats (which they are hard-wired to be frightened of…necessary for survival). It is possible that the parasite alters the production of certain neurotransmitters that are responsible for these instinctive fears and lack of attraction. More studies are being done to get a more accurate sense of what is really going on. So we don’t have all the answers right now.
Last note: Recent studies suggest that Toxoplasma is rare in meat sold in stores in the United States. However, experts still recommend cooking meat thoroughly to kill any parasites…which you should be doing ANYWAY. If you didn’t have any reasons to before, you surely do now. Also, as for the cats…you can keep your darling fluffy…just keep her inside (if you have a weak immune system at least). She will thank you, and you’ll be a bit healthier yourself!
I hope that this didn’t terrify anyone..lol I hope to at least have peaked your interest, even in the slightest bit. Comments are welcome and encouraged. Not sure what will come next week…I’ll be busy with band camp so mentally I’ll be a bit drained…but I’m sure it’ll be something interesting. Perhaps it’s time for me to blog about my FAVORITE disease…Flesh Eating Bacteria! We’ll see. Anyway, see you next time.
~There will be photos of parasites in this post, so you know. Don’t say I didn’t tell you~
For starters, I like parasites. I have stated previous times that I’m a microbiology buff and I like all these creepy and crawly. Parasites are not exempt from this list of things that I enjoy. I have taken a Parasitology class and will be taking another one this coming semester…which, needless to say, I’m pumped about. I can’t explain my fascination with these strange creatures. I guess it’s because I like the unusual and “gross”. So, i decided that I’d blog about parasites for today. Now, parasites always get a bad rep. YES, they can be harmful to both humans and your favorite pet. But, they’re not always that bad. Just a lot of the time. So that’s not too bad right? 😉 That thought has inspired this blog post. You’ll see parasites at their best, their worst and most interesting. Since I have SO much information to cover…I’ll do it in three installments. If you have any questions or comments, feel free to post them in the comments section! Now, Let’s proceed shall we?
~The Good~ aka, some reasons why they’re not THAT bad.
Reason 1: Parasites might cure autoimmune diseases. (Which is of interest to ME because I suffer from one…not that I feel I would ever use them in this way. :P)
In recent years, scientists have discovered that certain parasites have the ability to interfere with autoimmune diseases. For those who aren’t familiar with autoimmune diseases…think Crohns Disease, or a myositis…or inflammatory bowel syndrome. To be very short it’s a disease resulting arise from an inappropriate immune response of the body against substances and tissues normally present in the body. In other words, the immune system mistakes some part of the body as a pathogen and attacks its own cells. In my case, I have polymyositis. It’s an autoimmune disease where my immune system attacked my muscles as if it were a foreign invader…thus causing my muscles to become inflammed and then weakened significantly.The treatment of autoimmune diseases (at the moment…) is typically with immunosuppresion—medication which decreases the immune response.
Of course, that doesn’t mean that just anyone should go out and intentionally infect themselves with stomach worms as opposed to the current medicine available. That’s a terrible idea. But in some select cases where the benefits outweigh the costs, getting a parasite is a legitimate source of medicine.
One of the people involved in this type of parasite therapy research is gastroenterologist Joel Weinstock, who had a revelation of sorts when exploring the question of why diseases, from asthma to multiple sclerosis, are on the rise in developed countries but not in undeveloped parts of the world. Weinstock discovered a possible answer: our favorite friend, the parasite.
Weinstock’s theory — which is still being tested and has yet to been proven fully — is that there’s a direct correlation between a lack of intestinal worms and a rise in autoimmune diseases. In developed countries like the United States we’ve done an excellent job — some would say too good a job — avoiding parasitic worms, but we may be paying the price in the form of other, even more harmful diseases. We’re “too clean”, so to speak. Especially when you consider how most people, especially in the United States, feel about parasites.
Weinstock, in the early 1990s, noticed how prevalent inflammatory bowel disease had become in North America. At the same time, he realized that parasitic worms, or helminths, have a unique effect on their human hosts. Instead of inducing inflammation (the body’s normal response to invasion), they actually calm the immune system. According to the theory, because people have lived with helminths through much of history, the human immune system has evolved to fight them, and when worms are removed entirely, the body’s immune system turns against itself. Helminthic therapy, or worm therapy, may emerge as a legitimate field of medicine, but it’s still very new and few studies have been done to date. So, there’s no telling what more will come from this type of research. Who knows, maybe that could lead to (or be the) cure to autoimmune diseases. People who suffer from them, like me, can only hope. I can’t say if I’d be the first to jump the gun and TRY out a treatment like that…but if there was enough backing by scientific evidence AND (of course) test trials…I would be willing 😛
For more Information:
Reason 2: Parasites could potentially cure allergies.
Some intestinal worms are also believed to cure allergies, which share some notable characteristics with autoimmune diseases. Some people claim that our old friend the hookworm has the ability to cure everything from allergies to hay fever to asthma — but your allergies would have to be REALLY bad to knowingly infect yourself with blood-sucking worms. Though, I personally think that’s kinda cool…but I’m weird like that. A lovely gentleman named Jasper Lawrence made worm therapy for allergies famous a few years ago. Suffering from debilitating allergies and asthma, Lawrence heard about the theory that hookworms could cure allergies, so he traveled to Africa and walked around with his shoes off in several open-air latrines. After successfully contracting hookworms (and probably a lot of other things), Lawrence reported that his allergies had subsided, and he recently told the public radio program Radiolab that he hasn’t had an asthma attack or allergy symptoms since his visit to Africa. What to make of this? I wouldn’t put everything behind this JUST yet…but it’s something to think about, at least.
Unfortunately, the rest of this story doesn’t end all that well.
Convinced that hookworms are the answer to the world’s allergies and asthma, Lawrence — who isn’t a doctor — returned to North America and began shipping orders of hookworms to allergy sufferers, delivered in the form of a patch, for about $3,000 per treatment. But when the FDA caught wind of Lawrence’s little side project, he fled to Mexico and then flew to England, where he was born. Oops? I guess that wasn’t the brightest idea, bro.
Regardless, the underlying fact is that intestinal worms might provide important clues about how allergies work. Because of new research, as well as personal stories like Jasper’s, the hygiene theory, — which states that cleanliness and the lack of childhood exposure to bacteria and parasites leads to increased incidents of allergies and autoimmune diseases — is gaining wider acceptance. Several different studies are currently underway to look at how parasites like hookworms might be able to cure allergies and asthma, but nobody has definitively proven that hookworms are the answer. So again, we’ll have to see what happens in the future…if anything, that is.
Now. I hope that after reading this, you have a better appreciation for our darling little parasite friends. If not, I did try~ Now, next week, I will talk about the easiest portion of my “parasite chatter”…the bad. For every one good thing, there seems to be 10 ways parasites can screw with you 😛 Either way, I’ll see you then!
Ok, so this week I won’t be focusing so much on any particular microbe. Instead, I wanted to go a bit into a disease that fascinates me a bit more than it probably should lol It’s called Fibrodysplasia ossificans progressiva, also known as Stone Man Syndrome. I first heard about this rare disease a little while back in this month. A girl, Ali Mckean from the UK, suffers from this disease. I read about it in an online news article in the medical section. I was gobsmacked because I had never heard about anything like this before. I started researching online more information about this disease and I was amazed (yet terrified at the same time, a bit.)
Fibrodysplasia ossificans progressiva, Stone Man Syndrome, is pretty much what it sounds like. It is an extremely rare disease of the connective tissues. Somehow a mutation of the body’s repair mechanism causes fibrous tissues (including muscle, tendon and ligaments) to be ossified when damaged. Ossified meaning, turning into bone. Injuries can often cause the joints to become permanently frozen into place. Even surgical removal of the extra bone has shown to cause the body to “repair” the area with even more bone. So surgery doesn’t appear to help the problem.
People born with this disease are usually born with deformed big toes and sometimes missing a joint. The first flare-up that leads to the Stone man Syndrome occurs (usually) before the age of 10. FOP (shortened version of the technical name) is a genetic disease. The bone growth progresses from the top downward. This is just how bones grow in a fetus. A child afflicted with FOP will develop bones starting in the neck and then on to the shoulders, arm, chest area and onward on to the feet. The gene that causes ossification in the body is normally deactivated after a fetus’s bones are formed in the womb. However, in people with FOP, the gene continues to work long after. Because the disease is so rare, the symptoms are often misdiagnosed as cancer or fibrosis.
The best known FOP case is that of Harry Eastlack . His condition began to develop at the age of ten and, by the time of his death from pneumonia in November 1973, six days before his 40th birthday, his body had completely ossified, leaving him able to move only his lips. Hence the “Stone Man” aspect, it was as if he had been “turned to stone”, almost literally. Before his death, he had made it clear that he wanted to donate his body to science in the hopes that his death would be able to help find a cure for this disease. You can find his body kept at the Mutter Museum in Philadelphia. There have approximately been 700 confirmed cases across the globe from an estimated 2500. Unfortunately, there is no current cure for this disease. Attempting to remove any bone only results in more bone growth (and sometimes more rigorous growth). This puts quite a damper on the life of the person affected since there appears to be nothing that can really be done. Even their current living situations change. Activities that increase the risk of falling need to be avoided, as injuries from falling can provoke the growth of more bone. This is a considerable problem for young children since they run around, play and fall often…which is normal for a young child. I can’t imagine what it must be like to be young and have this rare disease.
Many years ago there was a trial going on where scientists had discovered that a component in sharks can prevent the growth of blood vessels in tissues, which would prevent the creation of bones…in sharks. The trial started in 2002 but was ended in 2007. Since then, there has been no clinical trials for FOP.
I can kind of relate to this, on just the basis that I suffer from an autoimmune disease that currently has no cure. Granted, It is not life threatening and does not do the same things to my body as FOP would. But, I do understand what one feels like when you suffer from something that can’t be cured. I consider myself lucky that (even though i can’t be “cured”), my illness can be treated and I can get back to a mostly normal physical life, with hard work. I hope that there will be a day when the people who do suffer from FOP, can count themselves lucky too because their illness will no longer affect them.
That is my ‘Little Friend of the Week’ for this week, sort of. Next week, I will either delve into Yersinia Pestis (involved in the Black Death) OR…go into another biology related topic I enjoy…Parasitism! I was thinking of eventually doing a post on Parasites…the good (their not all bad) and the bad (to be fair) and the interesting. See you next week 🙂
~Well hey there~ This weeks ‘Little friend of the Week’, as I had mentioned last week, will not be a bacteria…but a fungus. I’m talking about Yeast…and don’t make that face. Yes, Yeast is a fungus. It is a eukaryotic microorganism classified under the fungi kingdom. But don’t worry so much about the fungus part (for all the non-biology loving people), you will enjoy the many ways this fungus has positively influenced our lives. That, however, will come a bit later.
*Pro-Tip: A lesson on pronunciation. It is not pronounced fun-GUY <— H A T E…it is pronounced fun-jy (the ‘g’ sounds like a ‘j’ and you sound out the ‘y’ like you would in guy, like you’re saying “I”). It’s a pet peeve of mine 😛 (Don’t piss of biologists).
First, a bit of info about this lovely specimen. I’ll start with a side note: Yeasts do not form a single taxonomic (or phylogenetic)grouping. The term yeast is often referred to as a synonym for the species Saccharomyces cerevisiae, but the phylogenetic diversity of yeasts is shown by their placement in two separate phyla: the Ascomycota and the Basidiomycota. The budding yeasts (“true yeasts”) are classified in the order Saccharomycetales. Just to clarify, lol
The term “Yeast” comes from Old english word “gist” or “gyst” and from Indo-European root ‘yes’, meaning boil, foam or bubble. Yeast microbes are probably one of the earliest domesticated of all organisms. Yeast has been used for fermentation and baking throughout history. Archaeologists have found early grinding stones and baking chambers for yeasted bread, as well as drawings of ancient bakeries or breweries. So, using Yeast in many products has been going on for a lot longer than you’d think…the techniques have just been improved and perfected over time. But this is not a new concept.
Ecologically speaking…Yeasts are very common in the environment. Examples include naturally occurring yeasts on the skins of fruits and berries (such as grapes, apples or peaches) and parts from plants (such as plant saps or cacti). Some yeasts are found in association with soil and insects. Some yeasts like Candida albicans or Trischosporon cutaneum have been found living in between people’s toes as part of their skin flora. Yum :P. Yeasts are also present in the guts of mammals and some insects.
Enough about all the technical stuff and onto something more relevant. How is yeast really used?
I like to drink beer…so I thank Yeast every friday and saturday night for bringing me beer. You should too. Yeast is the most important ingredient in beer brewing. When added, the yeast reacts and feed off the sugar, in what is called the fermentation. The yeast continues to grow and metabolize in the sugar solution, creating an alcohol by-product. The yeast will continue this process until the alcohol content reaches a high enough level that kills the yeast cells. Basically, without the yeast there would be no beer. Yeast is also the final component that determines the flavor of the beer.
The two main varieties of yeast used for beer brewing are top-fermenting yeast (Saccharomyces cerevisiae) and bottom-fermenting yeast (Saccharomyces uvarum). The names of both are descriptive of where fermentation takes place in the wort when the yeast is used. The top-fermenting yeast is similar to the yeast for baking bread. It is applied for making ales and stouts. The bottom-fermenting yeast is utilized for production of lagers and steam beer.
Wine (for you Wine-O’s out there…)
In wine making, Yeast is used where it converts the sugars present in grape juice into ethanol. Yeast is normally already present on grape skins. Fermentation can be done with this wild yeast but this procedure gives unpredictable results, which depend upon the exact types of yeast species present. For this reason, a pure yeast culture is usually added ; this yeast quickly dominates the fermentation. The wild yeasts are repressed, which ensures a reliable and predictable fermentation.
Most added wine yeasts are strains of S. cerevisiae. However, not all strains of the species are suitable. Different S. cerevisiae yeast strains have differing physiological and fermentative properties, therefore the actual strain of yeast selected can have a direct impact on the finished wine…which may or may not be a positive thing.
Many breads are leavened by yeast. The yeast used for leavening bread is (once again) Saccharomyces cerevisiae. This yeast ferments carbohydrates in the flour, including any sugar producing carbon dioxide. Many bakers leaven their dough with commercially produced bakers yeast. Baker’s yeast has the advantage of producing uniform, quick, and reliable results, because it is obtained from a pure culture. Many artisan bakers produce their own yeast by preparing a growth culture that they then use in the making of bread.I don’t believe I need to post another photo of Saccharomyces since I have twice already.
As you can see, these few fungi serve multiple purposes industrially…which I think is pretty awesome. I hope that this was at least a bit informative. I didn’t know about the particulars of yeast, bread/beer/wine production and all that until I took a formal Mycology class (a class about fungi…). So, I’m hoping this isn’t all common knowledge. If you walked away learning SOMETHING, I’m happy with that. I hope you all enjoyed this weeks ‘Little friend of the week’. I actually partook in said friend today when I had a few beers myself. I hope you go forth and do the same. Or drink wine…or eat a piece of toast, or something.
Next week! I am not totally sure about what next weeks edition will bring…BUT, I have been itching to do something ‘gross’. To an extent, have no fear people with weak stomachs! I think I will present my first ‘disease’ that I find interesting and the microbe behind it. I kind of wanted to stray away from the microbiology aspect and post a blog about ‘Stone man’ syndrome…which is a fascinating (albeit sad) connective tissue disease. I also wanted to start my first disease post with one of the more deadly: the bubonic plague (believed to be one of the causes of the famous Black Death). So I will start with that and then the following week (or maybe do two posts that day) progress to Stone Man Syndrome. Can’t wait to see you all there.
~Biology: Cause it works~