Thursday, March 29, 2012

Guinea Worm


This week at Infection Landscapes I will cover dracunculiasis, more commonly known as Guinea worm or the "fiery serpent". Dracunculiasis is an ancient disease, so embedded in human experience that it is stylistically represented as the very symbol of medicine and health across much of the world. Probably. It is also likely to become only the second human infection ever eradicated through public health effort (smallpox was, of course, the first and only human infectious disease eradicated).

The Worm. Dracunculiasis is caused by Dracunculus medinensis, which is a nematode and an obligate helminth:

Dracunculus medinensis larvae 

Let's examine the complex life cycle of this waterborne worm. D. medinensis infects both a definitive host, humans, and an intermediate host, copepods, to complete its life cycle. I'll begin this helminth's developmental story in medias res: a mature adult female occupying an infected human host releases fully motile infective larvae into a community water supply by way of a blister on the host's skin. This blister is formed, and burrowed into, by the female worm. As the larvae are released from the human host, they enter the freshwater source and await their intermediate hosts, the copepods. Copepods are microscopic crustaceans that are ubiquitous in bodies of freshwater throughout the world. There are roughly 2800 species of copepods that occupy freshwater habitats, but those of the genus Cyclops, which alone comprises about 400 species, are probably the most important for maintaining the life cycle of D. medinensis.

Cyclops copepod

These copepods ingest, and are subsequently infected by, the larvae that have been introduced into the body of freshwater by the infected human host. A further 2 to 3 weeks of larval development are then required in the copepod host before the larvae reach their 3rd stage, which is then infectious to new susceptible human hosts. The infectious larvae are transmitted to humans when people consume the same water that is contaminated with the D. medinensis-infected copepods. Thus, transmission is exclusively by way of the common vehicle, water. In fact, this helminth infection is the only worm we will cover in this series that is strictly waterborne. After consumption of the contaminated water, the copepods are digested and the D. medinensis larvae are released in the small intestine. The larvae then migrate out into the abdominal cavity where they begin their migration to and within connective tissue, mature to the adult stage, and mate. Males die after mating, but females continue their subcutaneous migration, usually, but not exclusively, moving distally toward peripheral structures in the lower limb, i.e. bottom parts of the leg or the foot. After approximately one year following the initial infection, the female adult worm, who now harbors the live 1st stage larvae, begins to form an induration on the surface of the host's skin. Underneath, a fluid-filled blister forms into which the tip of the worm protrudes. At this point, the blister causes a very painful, burning sensation that is typically relieved with cooling water. When the blister is submerged in water, it breaks and the larvae are released instantaneously into the body of freshwater from the protruding worm. Thus a new generation is introduced into the water and is capable of infecting new copepods and, thus, recontaminating the water. Here is a nice graphic developed by the Centers for Disease Control and Prevention (CDC) that nicely depicts the life cycle of D. medinensis:


The Disease. Dracunculiasis does not typically cause life-threatening illness, unless the worm is removed incorrectly and dies within the host leading to extensive secondary infection. Nevertheless, because of the pain that is almost always associated with mature infections, particularly in the extremities, the disability that attends dracunculiasis can be severe during the eruptive stage, lasting approximately 3 to 10 weeks.


In addition, chronic musculoskeletal dysfunction is not uncommon due to a hypersensitivity reaction, secondary infections, or if the worm fails to complete its migration and dies and calcifies in musculoskeletal tissue. When the migratory track of the worm intersects the articulation of bones, then joint problems can ensue:



Finally, secondary infection of the ulcer that forms at the site of the blister can be quite serious if this vulnerable tissue is not carefully managed. Such secondary infections can indeed cause fatal disease. 

The Epidemiology and the Landscape. This is an ancient disease. At one time this infection was a scourge that disrupted the lives of many across a vast expanse extending from West Africa, across the Middle East, South Asia, and into Southeast Asia. It also occurred in parts of the Americas. Before the beginning of the global eradication campaign (discussed in the Control and Prevention section below) estimates had the global prevalence of disease anywhere between 3 and 4 million cases. It was likely substantively higher than this at various points in history. Today we may be down to the last couple thousand cases in a few localized parts of a couple of sub-Saharan African countries. Dracunculiasis may become only the second human infection to be eradicated. Time and human experience will tell.

Around the turn of the 21st century the global burden of dracunculiasis was roughly geographically distributed as depicted in the map below published in the Canadian Medical Association Journal (CMAJ February 17, 2004 vol. 170 no. 4 495-500):


By the close of 2007, a much reduced distribution was apparent as depicted in this map published in the American Journal of Tropical Medicine and Hygiene (Am J Trop Med Hyg October 2008 vol. 79 no. 4 474-479):


Official reporting has the number of incident cases identified in 2011 at close to 1100, most of which occurred in small pockets of South Sudan, but a small handful came from Mali, Chad and Ethiopia. These numbers are likely under-reported especially in the areas of conflict in South Sudan, where most of the current cases still occur. Nevertheless, while complete eradication still requires vigilance and is by no means inevitable, it certainly does seem that dracunculiasis is now within reach of genuine eradication. Let's explore the landscape epidemiology more closely to get a better sense of how this worm effectively occupies a shared ecology with humans, and how this can be targeted to block transmission.

As described above in the life cycle of D. medinensis, water is of the essence. Water is the shared ecology between this worm and humans. In fact, it is the way in which water occupies both the physical and social landscapes that is responsible for transmission of infection.

First, by adapting to intermediate copepod hosts, D. medinensis has located within specific bodies of freshwater. In the areas of the world where dracunculiasis is endemic, this fundamental landscape requirement, i.e. bodies of freshwater, frequently overlaps the human social landscape in that high concentrations of infected copepods are found in important water sources for human consumption. For example, stepwells were a critical source of infection in India before dracunculiasis was eliminated in that country at the turn of the 21st century. These sites are typically artesian aquifers, which essentially provide reliable sources of surface water from the groundwater under pressure due to its geologic confinement underground:



These are known as confined aquifers, but unconfined aquifers can also be important constant sources of water, and can sometimes provide larger sources of surface water because they delineate the water table:


The main point is that these water sources are constant over long periods of time, and they stem from those specific points in the landscape where the groundwater breaches the surface and establishes a constant (relative in geologic time) source of freshwater. Because of the geologic structure of these aquifers, they provide extremely reliable sources of water to communities, in contrast to those unpredictable water sources that are more dependent on seasonal precipitation. Furthermore, because these aquifers have typically been reliable across many human generations in the communities where they occur, they are also frequently centers of social gathering and exchange in addition to being fundamental sources of water for consumption. India provides some amazing examples of the extent to which these overlapping geologic/hydrologic systems can intersect with social systems to provide unique landscapes that ultimately provided ecologic niches favorable to D. medinensis. Here is a picture of what is probably the most impressive stepwell in India, the Chand Baori, which was built in Abhaneri in Rajasthan in the 9th century. This stepwell is a full 100 feet deep and its architecture reflects a design that is intended to allow for relaxation and recreation among community members who come to use the well:


In the days before dracunculiasis was eliminated from India, these kinds of water sources, which were already places of social gathering, served as the prefect relief for blistering worms. Once infected individuals would seek relief in the water, the worms released their larvae, which readily infected copepods in the water and were subsequently consumed by the many people gathered at the well. This represents an incredible exploitation by this helminth of this unique landscape that represented the overlapping of geology, hydrology and society to form a very specialized ecologic niche. As mentioned, dracunculiasis is no longer endemic in India, so these stepwells are no longer sources of infection. However, in those parts of the world where dracunculiasis persists, similar hydrogeographic features in the landscape, representing constant water sources derived from aquifers, remain very relevant for continued transmission:


Control and Prevention. The primary approaches to preventing transmission of D. medinensis infection are comprised of 1) stopping the consumption of contaminated water sources, and 2) preventing contamination of water sources by implementing strictly controlled water submersion for infected individuals with blistering worms. In addition, the use of larvicidal agents to kill the larvae as they enter water sources from blistering worms, as well as the use of bore wells as primary water sources, can be important implementations that effectively block transmission. However, the latter two approaches are significantly more costly than the former two approaches.

Water filtering is a common way to prevent the consumption of contaminated water and can be achieved by using any fine mesh cloth (nylon is best) over the opening of an empty water vessel and pouring the potentially contaminated water through the mesh-cloth covering. This technique is very good at filtering out the larvae-infected copepods and blocks transmission by removing the intermediate host from the water. In some communities, filtering straws have been distributed that allow individuals to drink directly from the water source without ingesting the copepods (this is depicted in the photo above). Boiling is also an effective way to prevent infection as this kills the larvae before consumption.

Management of infected individuals is equally important in the control and prevention of dracunculiasis. These individuals must be prevented from contaminating the water sources used by the community. In order to break the life cycle of the worm and block transmission, infected individuals with blisters submerge their painful limbs in an isolated water container to allow the blister to burst and the adult female to release her larvae. The contaminated water is then sterilized and disposed of to prevent contamination of community water sources. The water can also be disposed of on dry ground as this will kill the copepods and the larvae they carry.

In addition, a combination of community education to prevent individuals from entering water sources, and ongoing rigorous field surveillance to detect any and all new cases of dracunculiasis are two important features of larger elimination programs. Indeed, the extraordinary effectiveness of water filtration and case management to prevent further infections, in concert with good field surveillance, epidemiology and community education are greatly responsible for the widespread successes of regional elimination programs in many parts of the world where dracunculiasis was previously endemic. Only four countries are still reporting cases: Mail, Chad, Ethiopia, and South Sudan, and most of these are coming from South Sudan. While there is still serious work to be done, we are on the verge of the global eradication of dracunculiasis. As mentioned before, global eradication of a human infectious disease is something that has been achieved only once before with smallpox.

The possibility of eradication in the case of dracunculiasis is borne of its epidemiology. First, this worm has no definitive host reservoir other than humans. While an intermediate host exists in copepods, and is required for the completion of the life cycle, without the human reservoir the worm cannot reach adulthood and reproduce. This makes transmission to humans essential for its survival. Pathogens that cause human disease, but which have animal reservoirs outside the human host are probably not eradicable because they don't require humans to replicate. Second, it is much easier to apply effective surveillance (an essential ingredient to any regional elimination program, and thus by extension to any global eradication program). Ongoing surveillance is required in order to monitor geographic and epidemiologic sources of current and new infections. Without this critical knowledge, it is impossible to direct control efforts, and without directed control efforts, you cannot eliminate a disease from a region. Dracunculiasis surveillance is made easier because cases are not easily missed. Infected individuals become clearly identifiable as the worm breaks through the skin, so case detection for this infection has much greater validity and reliability than many other infectious agents. Thus, with good case detection, it is possible to implement good surveillance. Third, there are no asymptomatic infectious individuals because the worm must penetrate the skin in order to release its larvae, without which no new infections can occur. As such, there is no possibility of missing infectious individuals who are capable transmitting infection subclinically. And, fourth, it is relatively simple and cheap to block transmission by 2 routes: 1) once identified, infectious individuals can be managed with relatively little cost to control the release of larvae from their worms and thus prevent further transmission, and 2) contaminated water can be easily decontaminated by filtering or boiling the water.

Treatment. Dracunculiasis requires a treatment that has transited many thousands of years. It is an ancient treatment for an ancient disease. Their is no modern drug that can be used, particularly because of the dangers to the host if the adult worm dies while occupying the musculoskeletal tissues. Some medications can be used to alleviate symptoms, but not to kill the worm. As such, the traditional approach to eliminating this pathogen, which transcends temporal, geographic, and cultural boundaries, is the stick. Yes, you read that correctly. As the worm begins to emerge from the surface of the infected individual's skin, the end of the worm is wound around a small stick. This is done very slowly, gradually winding only a centimeter or two per hour, or even per day, over the course of what can take days to weeks to complete:


The slow process is required because it is critical not to break the worm, which would kill it and present a far greater danger to the host than the mere presence of the worm.

This ancient treatment method for what was once an extraordinarily common disease across much of the world is likely the source of the symbolism in the Staff of Asclepius, who was the god of healing and medicine in Greek mythology:

The Staff of Asclepius

And which today likely serves as the basis for the symbol of healing for many health and health care organizations around the world:

The Star of Life: International and United States symbol for the emergency medical services

Flag of the World Health Organization

32 comments:

  1. I found three things to be very surprising about this article.
    1. I was surprised to find that such an ancient disease that features so heavily in medical symbolism was one that I had never heard anything about. As well, I have heard about the success of eradicating smallpox so many times, but never of how close we are to eradicating Guinea worm.
    2. Since smallpox is the only disease which has been eradicated, I expected other such successes to occur by similar means. Perhaps it is the bias of a biomedical perspective, but I expected eradication to occur via vaccine or a pharmaceutical intervention. I did not expect it to occur in a disease in which the pathogen must actually be kept alive until removal from the host. Most surprising of all, for me, was that we were so close to eradication of an exclusively water-borne disease. Unlike vaccines, which can be a one-time intervention, clean water requires extensive and ongoing vigilance. I did not expect a water-borne disease to be close to eradication, simply because of the effort involved in maintaining clean water.
    3. Given that, in this case, eradication requires a great deal of ongoing effort (clean water and avoidance of water by infected individuals), and also that the remaining incident cases occur in relatively poor countries, I wondered if eradication would truly be possible. I wondered if instead, as with Measles, once there were very few cases, people would be less vigilant, and cases would rise once more. I think that this depends on how long Guinea worm can survive in water or in copepods without a human host. The shorter this time frame,the more attainable I think that eradication is.

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    1. I can see why you'd be doubtful about eradication but the disease has actually been successfully eradicated from about 16-17 countries around Africa in 22 years. That is some accomplishment! I'm actually rather surprised it took this long considering our knowledge about the epidemiology of the disease and the simple strategies to block it's transmission.

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    2. In response to Yousra's comment: Even the simplest of the ideas would take the longest and the most amount of work when it has to be implemented by masses-in this case it is several countries. Achieving a goal (i.e. a disease free country) is actually an enormous feat. A similar example would be diet and lifestyle change to combat non-communicable diseases like diabetes and hypertension.

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    3. For sure, anything done in large scale needs time to generate results, Abhishek. What I was referring to in my previous comment was why did it take health care organizations this long- until the 1980s after work led by The Carter Center- to notice this disease. What surprises me is that such an ancient disease, as Dr. Walsh refers to it, with our knowledge of its epidemiology and its simple known prevention strategies is still classified as a neglected tropical disease.
      Of course, the answer is pretty obvious, Dracunculiasis mostly affects people of low-income, developing countries where resources are scarce. To me this just seems to be a matter of justice and how we, the public health world, allocate or rather, share our resources and labor to help these endemic countries eliminate this and other such diseases.

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    4. hi yousra

      having read many, many articles for a paper the answer to why so long is not as simple as nobody cares about 3rd world countries.

      one article wrote about the need to larvicide all of the ponds in a village but the people would not let them treat the sacred ponds so the disease continued. also there is a new threat that the dogs are eating the fish guts which have the worm in it and becoming infected. they then roam and contaminate a pond.

      as of 2015, 335 million has been spent on this effort. education is key to the final push of elimination.

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    5. hi yousra

      having read many, many articles for a paper the answer to why so long is not as simple as nobody cares about 3rd world countries.

      one article wrote about the need to larvicide all of the ponds in a village but the people would not let them treat the sacred ponds so the disease continued. also there is a new threat that the dogs are eating the fish guts which have the worm in it and becoming infected. they then roam and contaminate a pond.

      as of 2015, 335 million has been spent on this effort. education is key to the final push of elimination.

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  2. So it turns out that there is no chemotherapeutic agent for the treatment of dracunculiasis, and the old treatment holds good-let the worm leave the host's body on its own. And an equally interesting part is that once treated (i.e. when the worm leaves the body) there is no carrier state. And in this case, as all worms lead to the globe (in the direction of gravity), treatment and control are fairly simple options, albeit requires patience on the individual's part.

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  3. You mentioned India had a Dracunculiasis endemic. I was wondering if the same methods of eradication such as preventing consumption of contaminated water and controlling patient exposure to water was used there too or were larvicidal agents used for control?
    Also you named South Sudan as one of the countries contributing to the current number of cases. Given the consistently volatile political situation there and the large number of refugees and refugee camps with stretched health resources, it seems global eradication might just take that much longer no matter what has been achieved in other countries.

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  4. Dr. Walsh has extensively outlined the reasons why the steps taken to eradicate guinea worm are more amenable than for many of the other infectious diseases described here on this site. Given that the closeness to eradication of this disease is due to those characteristics, it would be interesting to see if the interventions and programs taken to move to eradicate guinea worm can be translated to other diseases as well. Many of the diseases that are talked about on this site take place in poor, developing areas, which are frequently hard to reach (and which consequently makes interventions hard to implement). However, given the success in some of these interventions to surveil, educate, and provide alternatives to safe water, I wonder if how effective these steps would be in reducing the disease burden for some of the other waterborne (although this is the only one that discussed that is purely waterborne). Regardless, education is critical, particularly in dealing with clean water practices, and it would be interesting to build off the success of eradicating guinea worm.

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  5. Thank you very much for sharing this study, I'm hope that they can solve this problem with drinking water.

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  6. Russel Sharif (MPH)October 26, 2012 at 11:39 PM

    As we all know that infected people often try to relieve the pain by immersing the infected part in water. If it is immersed in open water sources such as ponds and shallow step wells the worm emerges and releases thousands of larvae. The larva is ingested by a water flea, where it develops and becomes infective in two weeks. When a person drinks the water, the water flea is killed by the acidity of the stomach and the larva is freed and penetrates the gut wall.So it is a very dangerous disease. Right now South Sudan has the highest number of Guinea Worm cases which is approximately 98% of total cases in the world.

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  7. Wow,that is a lot of cases of Guinea Worm in one country. I hope that one day South Sudan will be able to eradicate this infectious disease from its people.

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    1. They are making progress seeing as there were only 521 cases in South Sudan in 2012 in comparison to 1,028 in 2011. The final cases are generally the hardest to wipe out because of the population/community affected, the location and other reasons. Hopefully the Carter Center can keep pulling through to bring us closer to eradicating the Guinea Worm.

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  8. Guinea worm seems to be a great example of the almost perfect storm of conditions for eradication of an infectious disease, as outlined above. The lack of animal reservoir, externally visible nature of the worm, and simple and inexpensive treatment are all required in order for this goal to be attainable. While we spoke about these requirements in class, it's nice to have this very clear example.

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  9. I must say that this is, by far, the most...disturbing infectious disease that I've come across. It's incredible how this organism, fit itself so flawlessly into human society (at least into societies, for example the agrarian, that revolve around water), although it also lends itself so perfectly to infection control and eradication. The fact that human infection is a prerequisite for replication, there are no sub-clinical cases, cases are very easily identifiable, and transmission can be controlled cheaply all make this a textbook example for potential eradication. On the other hand, the year-long incubation period might raise concerns, especially as we, hopefully, near eradication.
    I am wondering, though, how many larvae are released when the blister is immersed in water, is this something in the order of hundreds? Thousands? This would have an impact on the infection rate in the copepods and subsequent infection among humans exposed to the contaminated water.

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  10. During my undergraduate years I did a research paper on guinea worm and something I found quite interesting that this article doesn’t touch on is the belief that Dracunculiasis is a result of witch craft. Some villagers believe the disease is not caused by larva in water sources but rather a curse by a god or witch. I feel this belief has hindered efforts to eradicate the disease. Health education is definitely the best tool that can be utilized to change this stigma and aid in the eradication process. As this article states, it is simple and cheap to block transmission and treatment seems very inexpensive, so why hasn’t eradication been reached? I believe one of the biggest obstacles may be these ancient and traditional social beliefs by villagers.

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    1. You are right, traditional beliefs can hinder eradication efforts, not only with dracunculiasis but with other diseases as well. Even diabetes was considered to be a result of witchcraft in African culture and a series of rituals (which can lead to other infectious diseases) are performed to cure the disease. I do hope that this belief is changing, but I agree education is important in this regard. Whether they are receptive to education may depend on if they trust the source of the education.

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  11. Eradication and reduction of cases of Dracunculiasis in some countries are likely due to the global effort to provide access to clean water in developing countries and is a testament to progress. This is certainly one disease for which surveillance and control are less complicated.

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  12. Reading this article points out the importance of having clean water in the countries afflicted by the Guinea Worm. Water being the vehicle makes it easy for thousands of people to be affected especially when water is scarce in this part of the world.

    Interestingly, reading about the history of disease shows that eradication has been a successful endeavor with transmission stopping in Benin, Burkina Faso, Chad, Côte d'Ivoire, Kenya, Mauritania, Togo, and Uganda by 2007 and Cameroon, Central African Republic, India, Pakistan, Senegal, Yemen were WHO certified meaning they successfully eradicated the infectious disease.

    The Carter Center (Former US President Jimmy Carter) funds and provides logistical support for disease eradication in the countries mentioned above. This has proven to be vital as Guinea Worm doesn't have a vaccine.

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  13. I think it's so interesting how the life cycle of the guinea worm requires this behavioral reaction in the host i.e. sticking their feet in cold water to relieve the pain of the blister caused by the worm. It's also cool to see the history behind the symbol of medicine connected with this disease.

    It gives hope that such a widespread disease that affected millions was brought down to 3 confirmed cases from Jan 2015-Apr 30 2015 according to the Carter Center, by seemingly simple strategies.

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  14. So glad to see people mentioning the Carter Center in the discussion of guinea worm. There's some really fascinating work that they're doing, and it seems that we are well on our way to eradication. There are a few articles since 2011 that have some interesting insights into final steps for eradication, including stopping the worm's ability to infect by providing cleaner drinking water (check out the filters that are being provided, which stop the larvae from being ingested) and improving surveillance in the areas no longer reporting cases.

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  15. Prior to watching a somewhat horrifying video on YouTube that showed guinea worms being removed from a foot, I had no idea how this disease was treated. Turns out it can't be! The CDC reports that once part of the worm begins to come out of the ulcer, the rest of the worm can only be pulled out a few centimeters each day, which seems like such a primitive treatment. Complete removal of the parasite can take days to weeks. What I think was even more horrifying was reading that when infected person try to relieve the burning sensation by immersing the infected part of their body in water, the female worm contracts at the base of the ulcer and hundreds of thousands of first stage larvae are released....seriously out of a horror movie.

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    1. Although I don't think I can stomach watching such a video, I also did not know the process to remove these types of worms takes such a long time and is a tedious process. I can't imagine not having access to proper medical care to receive proper treatment for this. This would be hard especially if soothing the pain requires immersing the infected part in water, not having access to clean water can prompt for the site to become even more infected.

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  16. I reviewed the lifecycle of the guinea worm several times over. I have a clear understanding of what happens to the adult male as well as how the larvae are released from the mother and the path they take to get into the human host. I am curious about what happens to the adult female. I don't know if I overlooked any part of the reading. The adverse effect of it dying in the human host was stated, and one can conclude that is not the typical fate of the adult female, therefore, am I to assume that it too emerges from the host's skin? I read several other sources, but they never seem to explain that part. What happens to the adult female guinea worm after the larvae are released?

    I find this to be a great example of how more than one component of public health worked in concert and achieved what I believe to be great success towards eradication of an infectious agent. It is remarkable how such a complex lifecycle could have been mapped and such inexpensive measures can be used to interrupt said lifecycle. I would imagine that more community health education is needed, but I do not want to assume that everyone has access to the resources used for safe consumption of contaminated water sources. Surely, ending the lifecycle of the guinea worm by using a more contained source of water, as explained in the reading, might be more attainable.

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  17. The guinea worm eradication is very interesting. First, it is amazing that living in the modern times of medicine that we do not have or have yet successfully created a treatment involving medication of some type, but instead still rely on the ancient practice of using a stick. I also found it to be a fun fact that that method could be the widely known image of health and healing. Another interesting section of the eradication is that it is mostly through prevention and public health with the use of special filtering straws or even boiling water and prevention of infected humans entering public water sources. If this does become eradicated, I think it will definitely change the way a lot of the world sees public health and prevention in that it will open it new possibilities for eradicating a number of illnesses and diseases especially waterborne illness.

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    1. The impact that public health has had on the incidence and subsequently, prevalence of guinea worm infection can get lost in the idea that we have not yet achieved eradication of the infection. The impact is nonetheless quite powerful and should not be ignored. We have to consider limitations, such as poverty, that explain how the landscape may limit the public health impact. I still maintain that irrespective of the fact that eradication has no been achieved, this is a remarkable example of the impact of public health.

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    2. Nicole, aside from Dr. Walsh's explanation of how no modern drug can be used because of the dangers to the host, I don't think a drug is the best option in this case. The traditional stick method has been working effectively to the point that this disease is close to eradication due to a simple traditional approach. It's amazing. A vaccine or drug would cost money to distribute; it also would take away funds from issues that developing countries like South Sudan are already facing. However, you make a great point that the global eradication of dracunculiasis will be a great feat in public health.

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    3. Yes, Nicole, I agree with you that by this time I would have hoped that research has found a way to treat this disease when it occurs. But Kesha brought up a great point about money. Meds cost way more than the straws. That and it's also probably because the mortality rate is low. I wonder if they could distribute a preventative type of medicine to the remaining locations since it's only found in small pockets of the world, kind of like heart worm medicine (it reminded me of heartworm preventative medicine for pets).

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  18. As disgusting as I find this topic, I can't help feel some measure or respect for the Guinea worm. First, it can withstand one of the most caustic environments possible, the human stomach. It then travels it's way to the extremities manifesting symptoms that would require the host to hand deliver (or foot deliver in this case) the parasite to the water where it exits the body to let its offspring find its intermediate host. It then "hitches a ride" into another human host to begin the cycle all over again. It's almost elegant in design. What is not elegant in sitting around for a few weeks while you wrap a worm around a stick as it exits your body.

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  20. Considering dracunculiasis is an ancient disease, why hasn't the human immune system evolved to attack or have an immune response to the parasite? A possible crucial opportunity would have to be before the larvae becomes large enough to cause musculoskeletal damage or before mating occurs. Also, it was interesting that the males die after copulation; is there an evolutionary reason for sexual suicide?

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  21. This was very very interesting! I originally picked this disease because I am currently reading a book by David Sedaris and he mentions how his husband and mother-in-law had guinea worm and how common it was. I guess it wasn't too accurate since they seem to be living in France, so I'm glad to know that this is almost eradicated. However, he was pretty accurate in his description. I found it so cool how they take out the worm and also how intricate the the Indian's stepwells are. I also never knew why the medical symbol was a staff, with what I believed to be a snake was. If the worm dies in the body, how does it became calcified instead of broken down by our immune system?

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