Parasites Eating Us Alive

three and a half billion people worldwide are infected with parasitic worms malaria kills a child every 30 seconds entire african villages are taken down by predatory parasites that leave villagers grossly deformed blind or dead deadly waterborne illness infested fruits and vegetables and debilitating lyme disease threaten communities throughout america every day hookworm sucked the blood of 1.5 million people [Music] parasites voracious animals that live off the very essence of our being thriving since the dawn of man so complex no vaccine will touch them parasites are evolving they appear to be indomitable and they are eating us

alive april 1993 a strange illness creeped across milwaukee personnel called in sick to hospitals and businesses school classrooms stood eerily empty paul nanas was head of wisconsin's health department as the numbers grew from see there were 100 people that presented to the emergency rooms to several hundred people to now a thousand people obviously by then we knew there was something significant going on for five days doctors scientists and administrators desperately looked for answers while hundreds of thousands of the city's residents were writhing wretching and rapidly wasting away if it was a contained neighborhood likely to

be food if it was uniformly dispersed across the city given wind patterns it would be air but what began to emerge was a pattern of illness that kind of mirrored the water distribution in milwaukee the pressure mounted from a terrified public in a frenzied media the city's water system was infested but with what finally one doctor on milwaukee's east side remembered his medical school training in tropical disease he checked his patients for parasites the lab tests came back positive cryptosporidium a tiny one-celled parasite had lodged itself in the intestines of 400 000 of this city's

residents and even when we learned that it was cryptosporidium we still didn't know what the source was and whether our current water was currently infected and until we knew that we only knew part of the equation they had their culprit but the scare was just beginning paul nanus and the city of milwaukee were in the midst of the largest parasitic outbreak ever recorded in the united states nausea cramping some vomiting but particularly diarrhea and the diarrhea in this instance the diarrheal disease was terribly severe there were people that had 20 and 25 episodes of diarrhea

in a day i mean they just couldn't get out of their homes they had to stay home nobody ever believed i mean even when we knew it was waterborne we identified the source we knew what it was there was still this almost incredulous kind of reactions that how could our water be the source of this i mean nobody believed that it could be water the shock deepened at the news of the first death then another by the time the epidemic played itself out 200 people were dead from complications from the cryptosporidium parasite it was difficult

for healthy people to recover from the episode so you can understand what happened to people that didn't have healthy immune systems they just couldn't shed it those who died had compromised immune systems people with hiv people already sick the very old and the very young that first three weeks of it were incredibly intense media wise the public the aids activist community that were marching down through the city of milwaukee wanting to know why people that they knew and cared about were dying and what were we doing about it as i mentioned here we didn't have

answers that's a terrible feeling parasitism is kind of a lifestyle and uh and a parasite is an organism that lives on or in another organism which we refer to as the host and does so either at the detriment of the host or certainly at no benefit of the host so you can have some parasites that really don't cause a lot of harm but they certainly aren't beneficial to the host there are many parasites that actually cause great harm and in fact can kill the host when you look at the human condition and you say what

is a human being you could redefine what a human being is in terms of its ability to harbor parasites almost all of our internal organs all of our blood spaces all of our hollow organs offers opportunities for organisms to live in them and when they do and when they cause us harm we call those parasites parasites are probably the most common agents of human disease on our planet i often like to say that if carl sagan did not go into astrophysics but instead chose to launch a career in medicine or biological sciences he would have

had to become a parasitologist why because this is the only group of organisms where we can really talk about billions and billions of people being infected parasites tenacious behavior toward their human hosts is nothing new they have been at work since the beginning of life itself and no matter what form of life has existed on earth there has always been parasites always that's the nature of things so from the very beginning we assume parasitism parasites are very clever though in the way that they've evolved over time and the mechanisms they've evolved to infect new hosts

or move into new areas where they previously haven't been just the the sheer complexity of some of the life cycles that they've developed or have developed over time in their association with animals it's just amazing as life progresses and becomes more complex and develops defense mechanisms against those parasites and excludes the common ones it now has to put up with the highly evolved parasites which have also evolved along with those highly evolved defense mechanisms for stealth and entry mechanisms and cunning and guile so to speak we would give them human characteristics in fact in their

own way the physical structure of parasites resembles that of our own they have a complexity of structure and function that is hard to believe most of the parasites i work with have structures that are just like man they have intestinal systems they have their own kidneys they have a complex nervous system organisms such as bacteria and viruses also require nourishment and protection from a host for survival the difference between these microbiological organisms and the classic parasite comes down to size usually when we talk about parasites we talk about either single-celled or larger organisms we don't

talk about smaller organisms such as viruses for sure and usually bacteria bacteria are usually considered kind of as a separate grouping scientists group parasites into three different categories parasitologists will think about the organisms that they study the parasites along three major lines these would include simple single celled organisms classically protozoan organisms such as organisms that cause african sleeping sickness plasmodium which causes malaria cryptosporidium which causes cryptosporidiosis which even despite their tiny size can still be associated with devastating disease then there are larger multicellular organisms generally referred to as worms three different kinds of worms that

we classify as parasites we have round worms uh like asterisk and pinworm uh we have flat worms that are not segmented those are the schistosomes and then finally we have the ones that everybody is familiar with the tapeworms that are segmented flat worms and then there is a series of organisms that are generally referred to as ectoparasites ecto meaning on so they don't live in the host they live on the host mosquitoes take our blood for egg production black flies suck our blood for egg production we would consider fleas the same thing all of those

are ectoparasites but they're temporary parasites for the most part we know of a few that are not so temporary though we can talk about head lice we can talk about pubic lice and we can talk about body lines and in those cases they live on us and they depend on us and we are their home in order for a parasitic infection to take place the parasites must first gain entry into a suitable host since parasites are perceived as being everywhere some of us think we can even catch them by breathing in the air this is

not true there are really only three different ways we can catch the parasites the ones that we're discussing and that is we can eat them we can drink water in which they have stages so that we can catch them this way there's even one we can catch by sexual intercourse but the vast majority of the ones that we're really afraid of the ones that cause the most suffering throughout the world are the ones that are transmitted by arthropod vectors a vector is generally thought of as an organism that transmits a parasite from one place to

another from one stage of its life cycle to another but we don't have to go to the parasites the parasites will come to us they have their own transportation system so to speak mosquito vectors are responsible for transmitting some of the most dangerous diseases on earth one example is lymphatic filariasis lymphatic filariasis which is also known by its common name elephantiasis is a vector-borne parasitic disease caused by a roundworm a nematode it's a very widespread disease throughout the tropics thought to involve somewhere in the order of 120 million people or so around the world for

most people a filariasis infection brings about only mild side effects but when the disease infests the lymphatic system severe pain and intense suffering result the lymphatic channels can be in various parts of the body classically it's in the lower extremities so the adult worms are in the lymphatic channels of the legs and it impedes the return flow of lymph fluid causing buildup of lymph fluid and the subsequent swelling and then the fibrotic reaction that the body has over years and then the infections of the skin that are caused by the compromised lymphatic flow that result

in the fairly grotesque classic elephantiasis of the lower extremities the common underlying result is debility severe inability to to perform one's one's daily routine the disease is very hard to diagnose in its early stages one of the the very frustrating things about this this parasitic infection is that in its early stages it's it's clinically very silent so you can get fairly young children that actually become infected with this parasite and unless you look in their blood to see the embryonic forms of the parasite you wouldn't know that they were infected and then very gradually over

years as they enter puberty in adult life they will begin to manifest slight swellings of one leg or a hydrocele or a swelling of the scrotum that just gradually over time gets bigger and bigger inexorably once they reach that stage there's not much that can be done medically to try and cure them of that parasites have lived both on and in us since the beginning of man they have evolved to develop specialized techniques to invade our bodies and evade our defenses while medical advances have bolstered our ability to detect and treat parasitic infections the parasites

continue their quest for shelter and sustenance within us one method of infection is through our dietary intake imported foods have played a significant part in the increase of parasitic infections in the u.s today after the agricultural revolution and of course with rapid transit and with the ability to ship products from one place to the other in less than 18 hours parasites can come to us now we don't have to go to them any longer so this raises the possibility for the spread of parasites in places that they never existed before another interesting aspect of the

whole phenomenon of foodborne diseases is a parasitic disease called anasakis it's caused by a fish parasite that is transmitted to humans when they eat sushi which of course is uncooked fish and this parasite which is a normal parasite of fish can be acquired by humans and it causes a local invasion of the gastrointestinal tract that in some cases can mimic stomach disease or appendicitis in this country in the united states we've had a burgeoning sushi industry lots of people eat sushi in fact i eat sushi i eat it safely why because we now know how

this parasite is transmitted uh it requires the fish to sit around for a while in a non-fresh state now you can define that any way you want but in fact if you catch a fish and place it on ice immediately this parasite stays in the gut track to those fish if on the other hand you catch the fish and it sits on the deck of the boat for a while and warms up the parasites will then crawl out of the gut tissue into the meat of the fish now when you put it on ice and

bring it in and make sushi out of that you have the option at least of catching that worm we've become aware of that the fish that are served in the sushi parlors of america at least and i'm sure in japan as well is as fresh as the day it was caught but not all food-borne parasitic infections have been conquered because of their insatiable appetite for suitable hosts parasites will always search out new ways of infecting us tapeworms are parasitic flatworms that live in the intestine of humans most commonly they're acquired through the ingestion of uncooked

flesh that has the larval stages of the parasite and there appears to be a tapeworm that corresponds to each type of major meat that's ingested for instance there's a beef tapeworm tina saginata there's a fish tapeworm known as diphylobathrium latum there is a pork tapeworm named tinia soleum teeniacolium the pork tapeworm has emerged as an important infection not only in many developing countries but also in the united states as well the parasite is particularly prevalent in central america and in mexico and now the organism has been imported over the border to the point where it

has become a major infection in u.s cities that are near these countries so we find high rates of tesolium infection in los angeles and san diego and san antonio and tucson arizona reason this is of importance to note is because the larval stages of the pork tapeworm have been linked to an illness in the brain there is a syndrome associated with solium known as neurocystic psychosis that has now become one of the leading causes of epilepsy among children living in these cities in the southwestern united states the pork tapeworm the egg when it's ingested into

the human the larva that emerges from that egg and thinks it's in a pig the larva will go and insist in various parts of the human anatomy unfortunately including and apparently the parasite seems to have a tropism for human neural tissue so you can get cysts in the brain you can get cysts in the eyes you can get cysts in the musculature as well this disease is called cysticercosis imported and undercooked food is not the only way we can ingest a parasite fresh clean water can never be taken for granted and the water we drink

in our homes can be tainted one of the most common parasites in the united states besides cryptosporidium is giardia lamblia majority of lamblius is one of our more photogenic parasites uh parasitologists love to talk about giardia because it looks like a little monkey face or it has a personality it has a smile it has a little flagella people like to talk about it they don't like to catch it so where do you catch giardia well you catch it from drinking contaminated water by the breakdown of public health practices which ensures the safety of our drinking

water it's a constant struggle to maintain filtered water supply for communities that are dependent upon those filtered water supplies in reservoirs for instance or natural bodies of water they have a real problem ensuring the fact that the giardia lamblia doesn't enter their drinking water supply and any time the filtration system fails you can get outbreaks of giardia it's well known that giardia cysts can survive chlorination especially if the chlorination is not being done to adequate levels so there have been large water-borne outbreaks of giardiasis in the united states associated with either malfunctioning or poorly designed

municipal water supplies the diarrheal disease caused by giardia is somewhat different than the usual diarrheal illness because of where the parasite lives in the human host and the fact that in especially in heavy infections the parasite actually adheres to the walls of the small intestine but generally speaking it can be treated with antibiotics while gr diocese may cause us temporary discomfort waterborne disease in the tropics can bring crushing illness the guinea worm known formally as dracunculus medinensis is found throughout the tropical world is transmitted through ingestion of contaminant and water there's a certain organism a

crustacean in that grows in fresh water that serves as the intermediate host for the disease and when humans ingest water that has an infected cyclops which is the name of the intermediate host they will acquire this disease it's a worm that's about twice the length of a yardstick in some cases it lives in your subcutaneous tissues and it seeks out the lowest part of your body and there the head of the worm elicits a blister it's a visible blister you can actually see the head of this worm under the blister when you step in the

water the blister bursts open releasing larvae that the worm has produced into the water column and then you get to see this ugly disfiguring blister on the end of your foot which you now have to do something about and in most countries what you do is you grab a small stick and the head of the worm wrap the head of the worm around this stick and slowly every day turn the stick slowly pulling the worm out from your skin if it should break you will experience the worst anaphylactic reaction you can possibly imagine you'll get

a sloughing of skin in the region where the worm is it will become secondarily infected with bacteria and when it heals you'll have a nasty scar for the rest of your life another bloodthirsty parasite that burrows through our skin is the schistosome the schistosome is endemic in parts of asia and africa and utilizes a snail as an intermediate host before infecting humans juvenile schistosomes called circaria emerge from their snail host into fresh water where they swim frantically looking for the only host where they can complete their development a human once the swimming circaria find human

skin they eject their tail and utilize skin dissolving enzymes to burrow through the skin of the foot and eventually into the bloodstream one of its remarkable abilities is its capacity to live in what should be the most inhospitable place on earth an individual's bloodstream these worms actually live in blood vessels now think of it if you were an infectious agent where is the last place you would want to set up shop where you're being bombarded daily by antibodies being bombarded daily by white blood cells and yet here the schistosome not only survives but it thrives

once the juveniles have matured the male and females pair up for life where they mate continuously producing and releasing eggs let's take the example of the bladder schistosome known as schistosoma hematobium with this type of schistosomiasis the egg has the ability to traverse through the bladder wall as the egg does this it elicits in a host inflammatory response that's also associated with bleeding as a result people who harbor bladder schistosomes develop blood in their urine a condition known as hematuria a curious instance where the presence of hematuria caused by bladder schistosomes affected history was when

napoleon entered egypt napoleon's troops it was prophesied would be stricken by pharaoh's curse should they choose to enter into egypt and what was pharaoh's curse it was male menstruation and sure enough when many of his troops came into egypt they acquired bladder schistosomiasis and many of the troops believed that this was the prophecy of pharaoh's curse fulfilled another fascinating parasitic disease is one called oncocerciasis the common name of which is river blindness this is a parasitic disease caused by a roundworm parasite of man that in its clinical end stages causes a very devastating and irreversible

blinding disease it's a parasite that is transmitted from human to human by the bite of a black fly which is the vector the black fly breeds in fast flowing streams and therefore the disease is most endemic in the valleys of these streams and thus the name river blindness after the vector bites the human it deposits the larval worms which invade the skin and eventually end up forming a nodule under the skin where the adult worms develop while they're in this fibrous nodule under the skin the adult worms shed on the order of three to five

thousand microfilarii or larval worms per day per adult these larval worms instead of entering the bloodstream remain in the subcutaneous tissue and migrate through the subcutaneous tissue causing changes to the skin that can manifest in such ways as very hypoelastic skin baggy skin as the disease progresses and the number of larval worms in the subcutaneous tissue increase they eventually gain access to the tissues of the eye and cause microcalcifications which over time build up and cause the blindness [Music] this is where they slit my truth and had some sort of plastic tube the iv site

went bad here and they cut it out and left me with this car and i also have the scarf for my feeding tube my body is scarred now thirty-four-year-old haslam bostwick is a native of south america who lives in fort lauderdale florida hasland knows a lot about one particular parasite plasmodium falciparum it is the most deadly of all parasites and more commonly known as malaria [Music] i go into the interior of ghana very often i used to spend up to 10 days in there at the time and in order to make sure that i don't

come in to cut it doesn't anything nothing bites me was i would make sure that my tent was sprayed before i go to bed at night while i'm outdoor i make sure that my body is totally covered so nothing could bite me in the spring of 1999 haslam had her blood checked for malaria when she returned from a trip to oversee a gold mine she owns in guyana she wasn't feeling well but her tests proved negative so hasland took her son on a school trip to washington dc she became weaker more nauseous three days into

the trip haslam took to her bed so i lied down and then i got up later on went to the bathroom and went back to bed and when i went back to bed i never got back up again haslam bostwick slipped into a coma she was taken over by the malaria parasites hasland joined the ranks of 250 million victims around the globe who contract malaria each year three million of those people die and it's the young who suffer the most every 30 seconds of every hour of every day the malaria parasite kills a child the

research done over even the last 50 years have not been able to reduce the mortality the in-hospital fatality rate of severe malaria in children in the tropics in primary care hospitals in the tropics one percent nothing that we've done has been able to reduce the mortality of severe malaria malaria had been a mystery for centuries no one knew exactly where it came from nor how it was passed from victim to victim the evil illness seemed simply to emerge from the stale air around swamps in fact the literal translation of malaria is bad air in 1880

a protozoan parasite was found living in the blood of malaria patients the female anopheles mosquito was soon identified as the vector for the malaria parasite sixty years later malaria was still the leading cause of sickness and death in humans on earth the medicine quinine made from the bark of the cincona tree had been used to ease symptoms for 400 years but it took until the 1950s to find hope in a weapon that would wipe out malaria's carrier chlorinated hydrocarbon insecticide ddt there was nothing quite like it before and there has been nothing like it since

here was a chemical that could be sprayed on the walls of a house and for up to six months any insect that rested on that surface would die it was then thought to be non-toxic to humans and it was inexpensive to manufacture the female anopheles mosquito was public enemy number one and world health officials had a brand new weapon eradication efforts were effective in north america and europe but after a decade of trying to annihilate the mosquito in africa india and asia the success of ddt slowed war corruption inaction famine and a host of other

problems detracted from the battle against malaria by the late 1970s the world health organization bitterly admitted that malaria was back and worse than ever today only the hiv virus comes close to the destruction malaria brings upon this earth it's estimated by some economists that malaria alone reduces the gross domestic product of the countries in sub-saharan africa by about one percent perhaps even more that translates into billions of dollars of loss in those countries every year so it has an enormous impact in every military campaign in which u.s forces have been involved in the last hundred

years where malaria was transmitted we've always had more casualties to malaria than we've had from hostile fire that means from a military perspective that malaria has tremendous mission aborting potential the swamps around haslam bostwick's south american gold mine were a perfect breeding ground for the anopheles mosquito as the mosquito fed on hasland's blood in its nightly ritual it released thousands of thread-like malaria parasites that were stored in its salivary glands for 12 days haslan would go without symptoms while parasites invaded her liver and transformed into organisms that moved on to her red blood cells the

tiny creatures divided and multiplied by the millions they became so numerous that her red blood cells exploded by the time haslin fell into a coma parasites were shutting down most of her vital organs including her brain the only organ that was functioning was my heart everything else had already shut down by the time i got to the hospital and they had to pretty much they had to put catheters and whatever else they had to put in me dr stephen hoffman was rushed in to work with haslan so what was going on was these parasites were

binding to these small blood vessels in her brain and blocking up blood flow if there's no blood flow then no oxygen gets to your brain and you slip into a coma after centuries of suffering and death decades after the discovery that malaria is a parasite and research into a cure there is still no effective modern drug to combat malaria in its late stages and there is no practical vaccine against malaria we are in a situation where the two major drugs in this world used for treating severe malaria cerebral malaria severe malarial anemia hyper paracetamia high

levels of parasites in the bloodstream are quinine and artemisinin derivatives both of those have been available for hundreds if not thousands of years it's not that we haven't developed new drugs for treating the parasite but that the parasite has either developed resistance to those drugs or they're actually not as good as these age-old remedies through the developed world's best medical efforts hasland did stabilize and miraculously she survived after five weeks of devastating illness haslam responded to treatment and has been malaria free ever since this this particular parasite kills and not too many people can survive

to tell a story because especially getting to the point where i was because i should have been dead i should not be here sitting with talking to you today i should really be dead efforts to eradicate and treat the terrifying destruction of parasites all over the world meet with varied and intermittent success in the case of vector-borne parasites african governments have attempted to eliminate the vectors the flies and mosquitoes and other insects that carry parasites for river blindness elephantiasis and malaria these efforts have slowed the spread of some infections but many scientists argue that eradication

of parasites may not be possible we've actually never been able to control to the point of extinction any parasitic infection the only disease producing agent we've ever been able to get rid of is smallpox and that's because smallpox only infected the human and no other host some of these parasites can infect multiple hosts you can have reservoirs out there so even if you could affect cures in people you still couldn't get rid of it in the animal populations it might also harbor the same stages so even if you could control everything in the human population

you could still reintroduce it every now and then because of these animal reservoirs if eradication isn't an option then controlling the spread of infection is the answer to limiting parasitic outbreaks one control success story is the onco-circiasis control program when oncochiasis was at its height in the late 60s and early 70s it became evident that this disease was a major impediment to successful development particularly of these countries in west africa where it was so highly endemic because of that the world bank the who and other international organizations banded together to form the encore crisis control

program which has in its 25 years of existence had a major impact on blocking the transmission of the disease protecting the vision of over 600 000 africans in west africa and allowing somewhere in the order of 15 million children in this area to be able to grow up without the threat of blinding onco psychiatrists the guinea worms story is one of our shining lights in terms of parasite controls it's found throughout the tropics throughout africa throughout the middle east throughout india and even in south america as well it's intermediate host that is it lives in

other things besides humans it lives in this little water flea and by filtering out the water flea you can get rid of the guinea one and we taught people how to do that they went and did it and we've controlled this infection now in all but 13 countries throughout the world used to be in hundreds of countries in the developed world new water treatment practices have been developed to keep out cryptosporidium parasites milwaukee spent 80 million dollars building a new water plant but the tragedy in milwaukee brought attention to the daily efforts being made on

the part of water treatment officials to ensure that our drinking water remains safe the lessons that we learned in milwaukee is you need to be prepared you need to know the capabilities and the vulnerabilities of your water treatment system one can never say this will happen again but one can never say it won't and so until there's assurance between the health department the water officials and others that you're as prepared as you can be you're at risk david leiby of the american red cross believes the milwaukee outbreak was a wake-up call the sheer size of

the incident suggests that there's a potential for this type of thing to occur in the future i mean even though our water supply like our blood supply is very safe as well and great measures are taken to prevent these kind of instances or these kind of occurrences from happening however it just points out the fact that parasites can in fact be very opportunistic and then if there is a possibility of them getting into a system in this case a water system which they are allowed an opportunity to grow and develop and to replicate then they

certainly can take advantage of it some see a future in biological controls putting parasites at war with each other introduce a benign echinostome flute to the host of a parasite like the schistosome fluke in hopes that the benign flute will attack and kill its harmful cousin the snail is infected with this evil schistosome and along comes this nice a kind of stone that has a mouth and a gut and it seeks out the schistosome in the snail and wammo it it sucks it up it swallows it and the schistosome uh larval stage is gone uh

and this is a marvelous biological adaptation whereby this tug of war is going on in the snail and the schistosome this evil schistosome is destroyed by this nice kind of stone the idea of biological control in some respects is very attractive as opposed to something like ddt which is very harmful to the environment if you could have a biological control for instance another animal eating the intermediate host or one of the the vectors of a parasite you know that's a great idea because that doesn't involve something that generally harms the environment or disrupts the ecology

at least in most cases another avenue of protection is the development of a vaccine against parasitic infections dr stephen hoffman and his team at the navy medical research center in bethesda maryland are developing groundbreaking vaccines for malaria the team begins with thousands of anopheles mosquitoes from the research centers in sectary volunteers are bitten by malaria-infected mosquitoes that have been exposed to radiation the radiation weakens the malaria parasites harbored within the infected mosquitoes the weakened parasites evoke responses from the volunteers autoimmune system after thousands of these responses the volunteers develop immunity to malaria while progress towards

a workable vaccine is made every day the complex nature of parasites creates a moving target for medical science they have multiple antigens or proteins that are expressed on their surface at different courses in their life cycle that makes the design of a vaccine almost impossible the more we learn about these parasites the more respect we gain for their side of the life cycle and the more respect we gain for the immense amount of selection those parasites have caused our biology to undergo the ability of these organisms to infect new hosts and infect virtually every animal

that we know there's just so many different varieties of parasites and so many complex things that you you can learn as well simple things there's nothing easy about studying parasitic organisms they tend to be very difficult to maintain in the laboratory it tends to be very difficult to get large numbers of organisms to study as a result doing biochemistry on these organisms is difficult doing genetics on these organisms are difficult parasitologists scientists who study parasites tend to be of a very special breed there's something else that motivates parasitologists to study these organisms that would not

ordinarily motivate a person studying another class of organisms the wonder of it all and the the complexity of what we see in these organisms going from single cell organisms to very complex organisms from parasites that you have to look at under a microscope to tapeworms found in whales that are 100 feet long the ultimate goal of studying parasites and to learn about their biologies is to ultimately exercise some control over the way they spread my cousin rabbi felizowski told me about a hebrew concept which he calls tikkun olam and it means to better the world

it kind of refers to the fact that an individual's obligation in life is to try to want to better the world and i think that's the one unifying feature i've always seen among my colleagues in parasitology is no matter what particular parasite they're studying there is some humanitarian motivation in wanting to study these classic organisms [Music] you