NTD Teaser Article: Chagas

Chagas disease also known as American Trypanosomiasis, is a neglected tropical disease affecting 7-8 million people, primarily in Central and South America. It kills approximately 12,000 people annually. It is caused by the parasite Trypanosoma Cruzi. Chagas Disease is a difficult disease to effectively stop for several reasons. The parasite has a vector of transmission, triatomine bugs, also known as kissing bugs. These insects provide both a reservoir and method of transmission for the disease, exponentially increasing the difficulty of treating or eradicating such a scourge. Furthermore, initial symptoms are mild, reminiscent of a flu. Around 60% of those infected may not develop any symptoms at all. As a result, even accurate estimates of how many people around the world might be affected become difficult to ascertain. A huge number of people infected never exhibit even the mild flu-like symptoms of the non-chronic infection. Of those patients who do experience symptoms, around 30% enter into the ‘chronic’ stage of infection. It is there that the infection causes the enlarging of various organs, most dangerously the heart valves. If heart valves suffer too much damage, heart failure may occur, resulting in the highest number of Chagas related deaths. Another 10% of patients may develop a chronic Chagas infection of the bowel.

Chagas is able to be transmitted through the bite of an infected insect, through exposure of the insect’s feces to a mucoidal membrane in the body (eyes, nose, mouth) and through the direct transmission from a mother to her child in vitro. Chagas is interesting because it goes unnoticed in so many patients, creating a reservoir of disease that is very difficult to detect or attack directly since so many patients are asymptomatic.

Chagas Disease infects many important muscle tissues around the body. It infects the heart muscle, putting a great deal of stress on that vital organ. Chronically infected patients may develop heart dysfunctional disease, which can lead to heart failure and death. Another possible complication is an enlarged colon or esophagus, leading to digestive issues or constipation. Possible diagnostic tests for Chagas include an EKG to determine if heart damage has occurred or putting stool under a microscope to search for the protozoans. This new study highlights a treatment that has been shown effective at reversing and or treating the heart damage associated with Chagas disease. Resveratrol could effectively manage the deadliest and most debilitating symptoms of Chagas, however it does not provide a cure, merely a treatment. Recently, scientists have identified a new compound detailed in this study which has shown exceptional promise at defeating a class of common diseases to which Chagas belongs. This class of diseases are known as kinteoplastids, and includes leishmaniasis, sleeping sickness, and Chagas disease. There were no apparent side effects in the mice tested.chagas-disease 1

Sleeping Sickness

Sleeping Sickness, or Trypanosomiasis, is a protozoan borne disease afflicting 36 countries in sub saharan Africa. The disease is transmitted through the bite of the tsetse fly, and has had its transmission rates falling since the turn of the century, with less than 10,000 cases in 2009, and less than 3,000 in 2015. The disease takes two forms, Trypanosoma brucei gambiense, which affects west and central africa while accounting for around 97-98% of all cases reported. This is the more mild of the two, leaving the infected largely asymptomatic until the disease has already reached the nervous system. Trypanosoma brucei rhodesiense affects southern and eastern Africa, attacking the host within a few weeks. The only country to share both forms of the disease is Uganda, however, it afflicts different areas. A similar disease, Chagas, is present in South America, however it is caused by different protozoa. A version that affects both domestic and wild animals exists, however it is also common for the human disease to exist in a reservoir of domestic cattle.

The disease, while ancient, has had few outbreaks since the 20th century. While contained relatively well after an epidemic during 1920, containment lapsed and the disease spread during the 1970’s, leading to an epidemic lasting through the 90’s. Since 2000 however, the disease has dropped by 73%, and the WHO expects it to be eliminated by 2020.

The disease largely affects those in the Congo, it being the only country in recent history to annually have 1,000 new cases. Most of these cases are in rural villages far from a health system. This is a problem in fighting the disease, as infected may have already spread the disease without knowing.  

The disease has been documented to pass from mother to fetus, as well as sexually. This adds further complications as the tsetse fly is not the only vector able to spread the disease. The symptoms of the disease come in two stages, the first, with fever, aches, and itching. After the protozoa pass the blood brain barrier, it becomes neurological, and the disease starts to affect coordination, the sleep cycle, and can become fatal.

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Treatment depends on the stage of symptoms present, if in the first stage, the drugs are relatively harmless, each tooled to the specific strain, Pentamidine and Suramin for Gambiense and Rhodesiense respectively. However, for the second stage of symptoms, treatment is much harder. Nifurtimox and eflornithine are administered through IV’s in a complex process.

To combat the disease on the whole, the WHO has partnered with Aventis and Bayer healthcare to better end the disease. The drugs are provided free of charge to endemic countries in hopes of a quick resolution. As it stands now, the objectives of the WHO are to

  • strengthen and coordinate control measures and ensure field activities are sustained;
  • strengthen surveillance systems;
  • ensure accessibility to the diagnosis and the best treatment available;
  • support the monitoring of treatment and drug resistance;
  • develop an information database for epidemiological analysis, including the atlas of the human African trypanosomiasis, completed in collaboration with the Food and Agriculture Organization (FAO);
  • ensure skilled staff by offering training activities;
  • support operational research to improve diagnostic and treatment tools;
  • promote collaboration with the FAO in charge of animal trypanosomiasis and the International Atomic Energy Agency (IAEA) dealing with vector control through male flies made sterile by radiation. The 3 UN agencies along with the African Union have promoted the Programme Against African Trypanosomiasis (PAAT);
  • synergize vector and disease control activities in collaboration with the Pan African Tsetse and Trypanosomosis Eradication Campaign (PATTEC) of the African Union.

In summary, the disease, while dangerous, has had its infection rates fall sharply in most countries, but the DRC still has high infection rates. The disease is able to exist in multiple forms and vectors all across Africa, meaning a comprehensive solution in necessary to fully combat the disease. That being said, the strategy that the U.N. and WHO has been deploying has been effective, meaning that the 2020 goal may be a success.

http://www.who.int/mediacentre/factsheets/fs259/en/

http://www.dovemed.com/diseases-conditions/sleeping-sickness/

http://www.doctorswithoutborders.org/issue/sleeping-sickness

Leprosy

Bacterial infections are a very real and sometimes terrifying thing. Mycobacterium Leprae, commonly known as Leprosy, is one of the oldest, and scariest, bacterial infections known to humankind. Most commonly found in warm, subtropical climates, 80% of all Leprosy cases are found in 5 countries (Myanmar, India, Indonesia, Nigeria, Brazil). While the infection causes nearly 144,000 cases per year, 5.5 million people in the world are estimated to be infected at any given time with the disease, which has 3 notable strains, namely Lepromatous (seen below), Indeterminate, and Tuberculoid Leprosy.

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Leprosy can [and probably will] affect the skin, mucosal membranes (nose), peripheral nervous system (nerve function), eyes, and testes by way of lesions and inflammation. The form, the strain, will affect each subject differently according to the way his or her immune system responds to the initial infection. Regardless of the strain, if Leprosy goes untreated, it can lead to severe deformities.

While the early form of Leprosy may be cured using prescription strength steroids and antibiotics. Steroids such as Prednisone, an anti-inflammatory prescription strength steroid, has been proven to help prohibit inflammation and in some cases will cure patients entirely. Antibiotics like Clarithromycin and Minocycline, strong antibiotics work to prevent infections in affected areas; these drugs are very important for the areas that are strongly affected by Leprosy. Antibiotics, when taken properly, will create helpful immune antibodies that can target Leprosy before it takes hold of an individual patient, as well as helping to treat infections like Leprosy.

Leprosy is an infection that multiplies very slowly, as the incubation period may take up to five years, and may not show symptoms for up to 20 years. Leprosy also is not highly infectious; the bacteria is transferred via droplets from the nose and mouth during very close contact between patients with untreated infections. The ages between 10-14 and 35-44 are the two most common ranges where Leprosy is found. The first symptom is normally numbness in the affected area, which may precede skin lesions by years. Temperature is the first sensation lost, followed by light touch, pain and then deep pressure. Sensory loss usually begins in the extremities (toes and fingertips), however in more severe cases, can begin in the lips or ears (depending on where leprosy has taken hold).

Leprosy has very individually characteristic clinical features, making it easy to diagnose when ob220px-Mycobacterium_leprae.jpegserved in a patient, however the need for confirmation is important because the treatment with antibiotics is a long one. Normal patients will be tested via skin biopsy, which may show characteristic histopathology (the study of the changes skin will undergo as a result of bacterial infectious disease), with granulomas (a reaction to inflammatory infectious diseases in the form of a skin ulcer) and involvement of the nerves. Mycobacterium Leprae exhibits a very tricky evolutionary characteristic called acid-fastness. It is a physical property of certain bacteria, specifically their resistance to decolorization by acids during staining procedures. Special staining of the tissue may show acid fast bacilli, the number visible depending on the type of leprosy. The bacteria may also be found in lepromatous leprosy (mentioned and seen above) on swabs taken from skin slits made in the ears and ear lobes, but they will be negative in the tuberculoid or borderline forms of the disease.

 

According to an NGDO Article, “Leprosy control and prevention has improved significantly due to national and subnational campaigns in most endemic countries. Integration of primary leprosy services into existing general health services has made diagnosis and treatment of the disease easy. The implementation of the global leprosy strategy 2011–2015 national leprosy programmes now focus more on underserved populations and inaccessible areas to improve access and coverage. Since control strategies are limited, national programmes actively improve case holding, contact tracing, monitoring, referrals and record management. According to official reports received from 105 countries and territories, the global registered prevalence of leprosy at the beginning of 2012 stood at 181, 941 cases. The number of cases detected during 2011 was 219, 075 compared with 228, 474 in 2010. In 2016, 144,453 cases were reported.”

When attempting to treat and prevent Leprosy, as with most if not all other Neglected Tropical Diseases, patient education is an absolute necessity. Leprosy can be cured, however it is essential to take the full course of either the steroid or antibiotic, as hard as it may be. Leprosy is rendered absolutely no longer infectious once treatment has begun, so patients need to be instructed how to deal with existing nerve damage for example protecting numb feet from injury once symptoms have appeared. Physical, social and psychological rehabilitation is important also for those who Leprosy has affected.

 

Cited:

http://www.ntd-ngdonetwork.org/content/leprosy

http://www.dermnetnz.org/topics/leprosy

https://www2.health.vic.gov.au/public-health/infectious-diseases/disease-information-advice/leprosy

 

 

Yaws

The first time hearing the term “yaws,” most people immediately think of the classic 1975 Spielberg film, Jaws. No, yaws has nothing to do with the 25 foot great white shark terrorizing a New England beach town. In fact, yaws might actually be more dangerous. Yaws is one of the many neglected tropical diseases that affect some of the world’s poorest communities. The bacterial infection mainly affects the skin along with bones and cartilage. Possibly having the most interesting name amongst the NTDs, the origin of the title is not entirely known. Some believe it came from the Caribbean Indian language, where “yaya” means “a sore.” Another possibility is from an old African language in which “yaw” might have meant “a berry, ” a potential reference to the lesions that form from the disease. To learn more about the threatening infection, one must examine its epidemiological triangle. An epidemiological triangle includes the three necessary components for a disease to thrive: the agent, the host, and the environment. Eliminate one of these and the disease will most likely be eradicated.

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First, the agent, or the actual disease itself. Yaws is caused by the bacterium treponema pertenue (pictured below). It is closely related to the bacterium that causes syphilis (treponema pallidum). Treponema is a type of spirochete, a double membrane bacteria with long coiled cells.

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The bacteria is transmitted from skin to skin contact. Since it cannot penetrate human skin, it must enter through a scrape or cut. Unlike its close relative treponema pallidum, yaws bacteria cannot be passed on during a sexual encounter. About 2-8 weeks after infection a bump arises at point of entrance. This usually painless bump is called the “mother yaw.” Smaller bumps  form weeks later and are called “daughter yaws.”

Next, the host, or the human carrying the disease. The overwhelming majority of victims of yaws are below the age of 15. Yaws mainly affects the skin, as noticeable and gross bumps protrude from the host’s flesh. Most patients also experience either joint or bone pain along with a fever. Early detection of the disease is absolutely vital. A positive test of yaws comes from a doctor’s examination of an infected skin sample under a microscope. As of now, there is no blood test for yaws.

In terms of treatment, there are actually two good options of antibiotics to combat yaws. The World Health Organization recommends an oral dose of azithromycin.  Azithromycin is an inexpensive antibiotic used to treat various infections, and it is easy to take. The alternative option would be a benzathine penicillin injection. Similar to azithromycin, benzathine is used to treat a range of infections. However, a study funded by the International SOS showed that azithromycin and benzathine are equally effective. One can conclude that azithromycin is the better choice because it is cheaper and can be taken without medical assistance. Both of these treatments can treat yaws if the disease is detected early.

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The final corner of the epidemiological triangle is the environment. Yaws has been a problem in tropical regions all around the globe. This includes areas near the equator in Africa, Asia, South America, Central America, and Pacific Islands. The infection thrives in communities with high poverty rates, where lack of proper treatment allows the disease to spread easily. Areas with overcrowding and poor hygiene also pose as a great environment for yaws to claim victims. The most basic way to prevent yaws is to maintain good hygiene. Wash your hands often, use hand sanitizer, bathe frequently, and tend to open wounds. Sadly, people in impoverished communities do not have good access to these amenities.

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Doctors and biologists around the world are doing their best to minimize yaws outbreaks, and it seems to be working. In fact, the World Health Organization predicted that yaws could be eradicated by as early as 2020 if the necessary steps are taken. A great example of medical success occurred in India in 2016. Medical professionals educated the communities and provided proper screening and treatment to the country until India was declared yaws-free in May of 2016. The India project helped the movement gain momentum. It will hopefully lead to more success in the future.

Leishmaniasis

Agent – What is the causative agent? Scientific name? Image? Type of pathogen? Where is it found?

There are three varieties of leishmaniasis–visceral, cutaneous and mucocutaneous. The species that are the causative agent are L. donovani, L. tropica and L. braziliensis respectively. Leishmaniasis is a general medical term which covers all three forms of the disease. The pathogen is a parasite which is often spread by a sand flee bite. Leishmaniasis can have a whole host of risk factors–poverty, malnutrition, deforestation, and urbanization.  It is found in predominately tropical and subtropical regions, and the climate could range from deep inside of a South American rain forest to the dry sand deserts of Africa and the Middle East. The vast majority of visceral leishmaniasis cases (90%+) are in India, Bangladesh, Nepal, Sudan, and Brazil.

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Image of L. donovani

 

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Image of L. tropica

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Image if L. braziliensis

 

Host – How are humans affected? Which systems are impacted? What treatments are available?

Humans are affected differently based on the variation of the disease. Cutaneous leishmaniasis is the most common form and it causes skin lesions that last for months or even years. These lesions develop weeks to months after the initial expose, making the disease somewhat difficult to trace to a particular event. If a patient develops one lesion, it is likely that he or she will develop more. These open sores often lead to atrophic scarring, and any patient with the disease should seek proper (and complete) treatment. If left completely untreated, then cutaneous leishmaniasis can lead to other forms later on.

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Image of a skin lesion from Cutaneous Leishmaniasis

Mucosal leishmaniasis is caused when the parasites are sent from the skin in the cutaneous form to naso-oropharyngeal mucosa. When someone has untreated cutaneous leishmaniasis, it is more likely that they will develop the mucosal form. This version of the disease does not manifest its symptoms until years or decades after the initial cutaneous lesions. The symptoms are usually characterized by unusual nasal stiffness or bleeding, and if left untreated, can lead to the deterioration of the naso-oropharyngeal mucosa.

Visceral leishmaniasis is very broad in its definition, but is definitely the most severe form of leishmaniasis. This version adversely impacts mostly internal organs–more specifically the spleen, liver, and bone marrow. One of the most common symptoms of this disease is an enlarged spleen, which can be palpated in a physical examination. If untreated, visceral leishmaniasis is often fatal. Some people who have visceral leishmaniasis can also develop post kala-azar dermal leishmaniasis (PKDL) which is categorized by skin lesions, mostly on the face, following the treatment of visceral leishmaniasis.

Leishmaniasis can impact the respiratory system (naso-oropharyngeal ), integumentary system (skin lesions), lymphatic system, and the nervous system. Untreated, it can also effect a host of organs as stated earlier.

Treatments for all forms of leishmaniasis involve taking some form of medication. Some commonly prescribed trade-name medicines are Pentostam, AmBisome, and Impavido. The treatment regimen must be followed exactly, and even if followed, can still be unsuccessful in entirely treating the disease. There is no preventative medication someone can take (like anti-malarials)–the only way to prevent the disease while visiting tropical and sub-tropical climates is through a mosquito net. If the net is weaved densely enough, then it will not allow the sand fleas to enter onto skin and subsequently spread the parasites. There are also other ways to deter sand fleas such as higher strength bug repellants like pyrethrins, malathion, or fenchlorvos . These sprays are able to deter many different insects, and oftentimes are effective at repelling them.

Environment – What environmental or behavioral factors result in disease transmission? What environmental or behavioral factors impact treating the disease.

Anyone can contract the disease if they are bitten by sand fleas carrying the required parasite(s), but sand fleas have a certain environment that they prefer to live in. When there is extreme poverty, a large amount of trash, and improperly disposed bodily waste, then the fleas will thrive and be more prevalent. Leishmaniasis can effect people of any socioeconomic class, but it is more likely to occur in areas where people are generally at or below poverty level. This is partially due to the higher amounts of sand fleas in low-income tropical areas, but partially because of the limited access to mosquito nets and insecticides. Once people contract the disease, it is also more dangerous to have with limited to no access to quality healthcare. With a certain perscription regimen, leishmaniasis can often be treated, but many either do not have the disposable income to buy the needed medicines or do not even know what their sickness is. If there are no trained medical professionals, people would have no idea that they needed a certain medicine because they may not even know what the lesions are from. This leads to even more issues because if it is left untreated, then cutaneous  could lead to its more severe forms: either mucocutaneous or visceral. If the person who had the disease moves back to a clean environment out of the tropics, then it is unlikely that they would contract it again after it is treated. People foreign to these tropical areas are also more likely to be prepared for protection from sand fleas through either mosquito netting or some powerful insecticide.

 

SOURCES:

https://www.cdc.gov/parasites/leishmaniasis/health_professionals/

https://upload.wikimedia.org/wikipedia/commons/thumb/7/70/Leishmania_tropica_7.jpg/250px-Leishmania_tropica_7.jpg

http://software.iiar.res.in/tritryp/tritryps_image/leish.jpg

https://upload.wikimedia.org/wikipedia/commons/thumb/b/b4/Leishmania_donovani_01.png/220px-Leishmania_donovani_01.png

http://www.who.int/leishmaniasis/Cutaneous_Leishmaniasis_hr.jpg?ua=1

https://www.cdc.gov/parasites/leishmaniasis/health_professionals/index.html#tx

Schistosomiasis “Teaser”

Agent of Disease:

Schistosoma are a genus of parasitic flatworms responsible for cases of Schistosomiasis in humans. These helminths can be found all over the world, but are primarily found all over Africa, the Middle East, and Southeast Asia. Schistosomiasis is also known as Bilharzia, and Schistosoma are also called Blood-Flukes. These worms have an incredibly complicated life cycle, spread over four forms and two hosts, and have persisted for thousands of years(signs of Schistosomiasis have been found in mummies).

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Mature Schistosome

Here is the life cycle of a successful Schistosoma:

  1. Schistosoma begin their lives as eggs in still water.
  2. They hatch into Miracidia, and swim off in search of their first host, a snail.
  3. Inside snails, they multiply into Cercariae, then leave in search of their final host, a human.
  4. When they find a human in the water, they burrow through their skin over a period of days. Then they can mature into their final worm form, pair up for mating, and release eggs throughout the body until the eggs make their way out through the urinary and/or digestive tract into more water to start the cycle again.

 

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Life Cycle of a Successful Schistosome

How it Hurts Us:

Schistosomiasis is a tricky problem for humans. Although they do siphon off our blood, Schistosoma do little to actively hurt us. Our main problems with them comes from their rapid reproduction. As they lay eggs by the thousands each day, the circulatory system brings them all over the body, and they work their way into all of our organs, especially our digestive tract and bladder. Although death isn’t a concern for a long time(Schistosoma live in humans for years), Schistosomiasis is by no means pleasant. It means pain, bloody stool and urine, swelling of the body, impaired growth in children, and organ damage. Fortunately, we have an effective treatment for the infection. Praziquantel is cheap and easy to use, only requiring one dose annually to clear the body of blood-flukes.

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A Child with the Characteristic Swelling of Schistosomiasis

Environmental Challenges:

Due to it’s complicated life cycle, one would think Schistosoma have a hard time reproducing, but that couldn’t be further from the truth – 200 million people are infected with Schistosomiasis right now. The problem comes from people using contaminated water. When children play games in the water(especially in the hot parts of the world this disease affects), or women do laundry in the water, or someone falls out of a fishing boat, they are at risk. Because thousands upon thousands of Cercariae are swimming around in infested water at any time, no exposure is safe. Mass transmission of the disease comes when sewage systems are underdeveloped, and either someone uses the local lake to relieve themselves, or a latrine overflows and spreads the eggs around again.

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Children Playing in Infested Water

Thankfully, there are multiple ways to deal with Schistosomiasis:

  1. Using drugs like Praziquantel to treat existing cases
  2. Encouraging people to stay away from the water, and to boil the water they use
  3. Killing off the snails that help the Schistosoma reproduce

None of these are too difficult on their own, and consequently the biggest problems with treating and fighting Schistosomiasis is access to medical infrastructure. While convincing people to take strange pills and change how they work and play is difficult, Schistosomiasis is a big enough scourge for most people to make the effort, and consequently, the WHO hopes to have eradicated Schistosomiasis by 2020.

Taeniasis

            Taeniasis is a neglected tropical disease caused by the ingestion of a parasitic tapeworm found in undercooked meat. There are two species of the worm that are capable of infecting humans: Taenia saginata, which is found in beef, and Taenia solium, found in pork. This type of disease falls under the category of helminth, or worm. This disease uses cattle and pigs as initial, intermediate hosts, but it is believed that this worm was brought about in humans via hyenas 2 million years ago and then given to the animals humans typically consume. While Taeniasis is worldwide and can be found anywhere raw meat is consumed, it has strongholds in underdeveloped areas of Eastern Europe, eastern Africa, and Latin America. It emerges occasionally in the United States as Latin American immigrants enter the country.

taenia_solium           It is difficult for a person to tell when they are infected with the disease, as it does not directly cause significant symptoms. However, if these worms grow large enough in size, their presence will be evident. T. saginata can grow to be 10m in length, causing abdominal pain, upset stomach, and loss of appetite, with the main system targeted by this parasite being the digestive system. The most prevalent consequence of Taeniasis, however, is its implications in the development of cysticercosis. When a person swallows this worm’s eggs in their own feces or the feces of another person who was infected with the worm, they are then infected with this disease. This sort of infection leads to the buildup of cysts in the muscles, spinal cord, or brain. When in the central nervous system, symptoms include seizures, headaches, confusion, brain swelling, stroke, or death. When simply in the muscles, they protrude under the skin yet typically do not cause symptoms.

There are two drugs effective in treating taeniasis: Praziquantel and Niclosamide. Both of these diseases are anthelmintics: drugs that kill helminthes on contact. These are dangerous drugs and have many stipulations for taking them (pregnancy, allergies, heart problems, etc.) as well as side effects such as nausea, vomiting, and headache.

Since the taeniasis’s environment is worldwide, more developed countries have set laws in place to prevent the consumption of contaminated or undercooked meat. All meat is required by law in the United States to be inspected for cystsercercosis, and areas of grazing must be inspected for this kind of contamination. These foods then must be cooked sufficiently to prevent the spread of any sort of tapeworm. Once infected with the disease, people should practice good hygiene in order to prevent their tapeworm from eventually causing problems with the nervous system. Today, the area most affected by taeniasis is West Papua, a province of Indonesia. As this disease is neglected in its relevaendemicity_taenia_solium_2015ncy in tropical areas, there is little data showing just how prevalent taeniasis is in places like this. However, a study in the 70s showed that in a local hospital in Irian Jaya, Indonesia, about 9% of all stool samples taken at any given time contained eggs from this worm. Numbers have only risen since, as there has still been little awareness raised in the effort
to rid the planet of this worm.

This worm has a rather complex life cycle, being transported in and out of two different hosts. To start off, an oncosphere, a tapeworm embryo develops in the muscle of either a cow or a pig. A human then consumes that muscle and now a worm, Taenia saginata for300px-taenia_saginata_lifecycle a cow or Taenia solium for a pig, begins to mature in the small intestine. Male worms only live long enough to reproduce, while the female worms grow to full size, become gravid, or pregnant, and allow eggs to exit through the feces. The animals may then consume these eggs due to open-air defecation and develop cysts of oncospheres, thus starting the cycle anew. This neglected disease is extremely easy to prevent using ethical ways of meat preparation, however, there is little awareness of this going on in underdeveloped countries. If similar amounts of attention were paid to Taeniasis as they are to nearly eradicated diseases like Guinea worm, this disease drop off the map very quickly.

 

 

Sources:

https://www.cdc.gov/parasites/taeniasis/

http://web.stanford.edu/class/humbio103/ParaSites2004/Taeniasis/

https://www.cdc.gov/parasites/taeniasis/gen_info/faqs.html

https://www.cdc.gov/parasites/cysticercosis/disease.html

https://www.drugs.com/cdi/praziquantel.html

https://www.drugs.com/cons/niclosamide.html

http://www.who.int/taeniasis/Endemicity_Taenia_Solium_2015.jpg?ua=1

http://www.tabletsmanual.com/wiki/read/taeniasis

 

Elephantiasis (LF)

Lymphatic Filariasis, abbreviated as LF, also known as elephantiasis, is a disease caused by the burrowing of parasitic worms inside of the human lymphatic system. The parasitic nematode worms are called filariae, and the species of worms that tend to burrow in the lymph system are the Wuchereria bancrofti, Brugia malayi and Brugia timori. Like many other parasitic worms, male worms are of smaller stature, ranging from three to four centimeters in length, and females around eight to ten centimeters.

The lymphatic helminthes survive only in the lymphatic system, colonize and build “nests” in lymph vessels and nodes, disrupting the bodies natural response to foreign pathogens. As phagocytes move throughout the body to destroy pathogens, their microscopic journeys are blocked by the nesting worms. As lymph, or lymphatic fluids attempt to get past the helminth, the fluid stretches the vessels and begins to build up, resulting in an enlargement of the area. The area is filled with lymph, and tissue fluid from swelling, which can grow in some cases to over one hundred pounds. The disfigurement causes excessive pain in many cases, and are usually associated with “infection-like symptoms” such as fever and swelling because of the bodies’ response to the foreign parasite.

Many victims of the disfiguring infection do not realize they are infected until years after the contraction of the filariae. Host often notice lymphedema (swelling of the extremities) or hydrocele (swelling of scrotum) in their adult years; leading scientists to believe that the disease is often contracted at a younger age, and the parasites gradually cause enough damage to result in such large build ups of fluid.

Image showing the disfiguring effects of Lymphatic Filariasis on lower extremities

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Not only do the parasites cause swelling of the breast, extremities, and scrotum, but they also cause proteinuria and hematuria due to damage of the kidneys. The devastating parasites are found in mosquitoes all over the world. More specifically the Brugia malayi are most often located areas of east and south Asia, India, Indonesia, Malaysia and Thailand. The Wuchereria bancrofti are commonly found in rural Africa and Pacific Islands. The reason that these areas are hotbeds for Lymphatic Filariasis infection is due to poverty rates and access to preventative and post-infection treatments.

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Map showing “hotbeds” for LF and areas with an LF epidemic

In areas of low poverty, it is rare that people will have a steady, filtered water supply, a sewage or waste system, and closed bathrooms. With areas covered in defecation, bugs, rabid animals and infectious pathogens are common. In areas of low poverty, people are often not educated on how to safely prepare a meal by boiling water and food to eliminate pathogens before consumption. For LF, mosquitoes are the carrier, and starter of the “Lymphatic Filariasis cycle.” When mosquitoes bite an infected human, they consume the microfilaria or parasitic larvae, which will then develop and migrate to the mosquito’s’ mouth. When that mosquito goes and bites another person, it drops off those larvae into another human, thus creating another LF cycle.

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The transmission cycle of LF

Especially in destitute areas, where mosquitoes can feast, people are at high risk of infection. It is hard for people to contract LF after just one bite because of the small amount of parasitic larvae in each bite. Often, people require multiple bites over a short period of time to contract the disease from mosquitoes. Once the larvae develop in the bloodstream and settle in the lymphatic system, they lay eggs which will continue in their parent’s trails; burrowing, and nesting in their human hosts’ only real internal defense system.

 

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Parasitic Worm which causes LF

Treatment for the disease is fairly basic when taking preventative measures. Sadly this is not the case for those already infected with the disease. Once infected, there are antiparasitic medicines which can be administered every few months to hopefully eliminate adult, full sized worms. In areas of extreme poverty often people are unable to get these medicines. To lessen the negative effects of LF, sufferers should wash their infected body part with soap and clean water to eliminate bacteria and infected tissue. In addition, the swollen body part should be massaged and elevated to dissipate swelling and improve lymph flow.

For those who do not have the disease, and are looking for preventative measures, MDA, or mass drug administration is the most feasible and cost efficient option. A cocktail of albendazole and medicines like ivermectin (commonly used to treat worms in dogs) or diethylcarbamazine citrate can be administered twice a year and effectively lessen the density of microfilariae in the bloodstream, and stop the transmission of larvae to mosquitoes, essentially stopping the LF cycle. With over one billion people at risk for contracting this disease and 120 million people already infected, it is estimated that over 600 million albendazole tablets are donated each year for MDA. Because the disease is so disfiguring and debilitating it actually gives people an incentive to take the donated tablets even if they do not know much about the medicine, if it lessens the chance of them getting infections. Simple tactics people can use to lessen their chance of infection is sleeping under a mosquito net, cleaning any open sores, and wearing mosquito repellent frequently.

Echinococcosis Overview

As a neglected tropical disease, Echinococcosis is a lesser-known infectious disease that largely affects the poorer subpopulations of the world. Impacting over one million people, Echinococcosis is widespread and deserving of more attention than it currently receives. The disease can be found in two main forms: Cystic Echinococcosis (CE) and Alveolar Echinococcosis (AE). The disease can be best understood by understanding its three main components: agent, host and environment.

Agent:

Both forms of Echinococcosis are helminthic; the disease itself is caused by worms entering the human body. The helminths are both part of the genus Echinocococcus, a subdivision of the phylum Cestoda. As cestoda (commonly known as tapeworms), the helminths appear flat and both genera are fairly singular biologically. However, key differences are found in the epidemiology and pathology of the two different forms of Echinococcosis.

Cystic Echinococcosis

       Caused by larvae of the Echinococcus granulosus tapeworm and also known as hydatid disease, Cystic Echinococcosis is often asymptomatic. These Echinococcus granulosus eggs are able to survive harsh conditions such as snow and freezing temperatures, and often mature in dogs. The worm, which grows to two to seven millimeters at full length, can also be found in other livestock breeds — namely sheep, cattle, goats, and pigs — but is only uses these animals as intermediate hosts (whereas dogs are definitive hosts for the Echinococcus granulosus).

 

 

       Echinococcus granulosus worms can be found throughout the world, in Africa, Europe, Asia, the Middle East, and Central and South America. However, the abundance of the helminth is very much dependent on the amount of sheep being raised by the local population, and the population of dogs in the area.

Alveolar Echinococcosis

Caused by the larval stage of the Echinococcus multilocularis tapeworm, Alveolar Echinococcosis differs significantly from its counterpart CE. The Echinococcus multilocularis worms are shorter in length, ranging between one and four millimeters, and are primarily found in northern areas of the world. However, the worm is still fairly widespread, calling northern  Europe, Russia, China, Central Asia, Japan, and North America home.

The hosts of Echinococcus multilocularis also vary significantly from those of Echinococcus granulosus. While both are found in dogs, definitive hosts for the multilocularis species also have definitive hosts in foxes, coyotes, and domesticated dogs and cats. The list of intermediate hosts for the tapeworm includes many species of small rodents.

Host:

While intermediate hosts play important roles in the transmission and understanding of both CE and AE, the human form of the disease is crucial in understanding Echinococcus’s status as a neglected tropical disease.

 

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Mature worm attaching itself to the liver

The two main forms of the disease impact humans differently.

  • Cystic Echinococcus is largely asymptomatic and creates cysts in the human body, primarily in the liver and lungs. These cysts grow and become painful over time, and are often unnoticed (and therefore neglected and untreated) for years. Any observed symptoms are usually caused by cysts restricting and interacting with other parts of the body; these include: pain or discomfort in the upper abdominal region or chest, nausea, vomiting, or coughing may occur as a result of the growing cysts, are usually caused by cysts restricting and interacting with other parts of the body. Cysts also lyse and leak, which could create bacterial infections, abscesses or immune reactions within the body. The main treatment for Cystic Echinococcus is surgery to remove the cyst. Alternate treatments, namely medication and an aspiration surgical procedure, are being developed but their effectiveness is still being questioned.

  • Alveolar Echinococcus has a much harsher impact than CE, and — although less common — is much more fatal. The larvae form many cysts which become mestocodes, continuously growing tumorlike masses that are not clearly separated from host tissues. Alveolar Echinococcus is able to stay in a presymptomatic phase for years before the host develops symptoms, but the symptoms come quick and fast. Often infecting the liver, lungs, brain, and bones, the larvae grow from tumorlike buds into multiple lesions (warning: graphic image). The mestocodes formed also result in severe fibrosis throughout the infection period, compressing and obstructing major vessels and bile ducts throughout the human body. Similarly to CE, surgery is the only viable treatment for Alveolar Echinococcus, needing to remove the whole parasitic mass and then medicate the host in order to prevent the cyst from growing back.
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Diagram outlining the progression of Echinococcus in the human body

Environment:

Because all forms of Echinococcosis are zoonotic (transmitted to humans from animals), humans can only be called accidental intermediate hosts, meaning we become infected in the same way as all other intermediate hosts, but are not able to transmit the disease. Humans do not excrete the eggs of the disease, and only become infected by ingesting food or water contaminated with faeces of animals which have been infected with the tapeworm. The location and abundance of these animals, the various definitive hosts mentioned above, largely dictate the spread of Echinococcosis and the number of people that fall ill with the disease.

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Map showing the endemic regions of Echinococcosis: it is an incredibly widespread disease.

While treatment often requires surgery, preventing Echinococcosis is a much more straightforward and simple process. According to the CDC, the best ways to prevent CE are:

  • Limiting the areas where dogs are allowed and preventing animals from consuming meat infected with cysts. You should:
    • Prevent dogs from feeding on the carcasses of infected sheep.
    • Control stray dog populations.
    • Restrict home slaughter of sheep and other livestock.
    • Not consume any food or water that may have been contaminated by fecal matter from dogs.
  • Washing your hands with soap and warm water after handling dogs, and before handling food.
  • Teaching children the importance of washing hands to prevent infection.

And AE is best prevented by:

  • Avoiding contact with wild animals such as foxes, coyotes, and dogs and their fecal matter and by limiting the interactions between dogs and rodent populations. You should:
    • Do not allow dogs to feed on rodents and other wild animals.
    • Avoid contact with wild animals such as foxes, coyotes and stray dogs.
    • Not encourage wild animals to come close to your home or keep them as pets.
  • Washing your hands with soap and warm water after handling dogs or cats, and before handling food.
  • Teaching children the importance of washing hands to prevent infection.

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Dengue “Teaser” Article

Chris Morrison

 

 

 

Imagine you are in a tropical or subtropical region.  To show you where these regions are located, look at the map below. The red indicates the subtropical regions throughout the world while in between the tropic of Cancer and tropic capricorn represent the tropical regions in the world.

You can see that you the reader may live or have at least vacationed in one of these regions of the world. While sitting in a home or roaming throughout town, a mosquito bites you. The bite feels the same as if you were bitten by a normal mosquito. This bite is different. You are now infected with the Dengue fever. Now you ask yourself, what is dengue fever and how did I get it? The person to blame in this scenario is the human race. Believe it or not humans carry the virus inside of them and uninfected female mosquitos are then infected with this virus. The next time this mosquito, who has now acquired this virus, bites a human, it will infect that human and thus continue the process of this disease spreading. Can all mosquitoes pick up and transmit this disease? Well no. Only Aedes ageypti is the primary carrier of this disease. These mosquitos can most commonly be found in urban areas or man made containers.

The Dengue virus is an RNA virus. It belongs to the group of yellow fever, West Nile, etc. The Dengue virus genetic material contains about 11,000 nucleotide bases which code for three different protein molecules. The Dengue virus enters through skin by the mosquitos saliva. It binds to white blood cells and reproduces inside of cells. White blood cells create signaling proteins which then cause symptoms like high fever. Fluid from bloodstream leaks through the wall of small blood vessels, resulting in less blood circulation. Also results in blood pressure that is so low that it cannot supply blood to vital organs.

You swat at the mosquito who just bit you while you were shopping for food at the market. You think nothing of it. You will not feel the affects of the disease until 4-10 days later but once the symptoms occur, you will know that you should seek professional medical attention. Dengue fever treatments can vary on what doctor you see because there is no specific treatment. Some medical professionals will recommend you to use pain relievers like acetaminophen but discourage you from using medicines like aspirin because this could worsen bleeding. Also, make sure to rest and drink an ample amount of fluids but if none of these treatments work and you feel the symptoms are worsening, then immediately go to the emergency room. Some people can develop severe dengue fever which can result in worsen symptoms and lead to death.

Now you may be wondering how you can prevent and control this illness. The most obvious way to avoid this disease is to live in a cold environment because you will never encounter any mosquitos in these regions. No one likes the cold all year round so there are other ways to prevent and control this disease. First, we need to manage the environment in in order to interrupt the mosquitos egg laying habit. We can also need to make sure to properly dispose and provide protection for waste. Those are just a few ways to control the mosquito problem but some ways you can prevent dengue fever mosquito bites is by using pesticide spray (OFF) or wear long sleeves.

The Dengue fever problem has now gained attention and the first vaccination has been developed. The first vaccination is called Dengvaxia which was in production in 2015 for people of the ages 9-45 living in these endemic areas. This vaccination is only approved in Mexico as of right now show it seems to not be reliable. Because of an economic issue for many countries and the short supply of this vaccination, WHO.int recommends that only people where the disease is very prevalent should be given most of the vaccination attention. Other vaccinations are being developed and are currently in Phase III clinical trials.

Why pay attention to the Dengue fever? The Dengue fever is on the rise in the world. Before 1970, only 9 countries reported severe Dengue cases but now over 100 countries have reported Dengue fever cases. A recent estimate, reported on WHO.int, indicates 390 million dengue infections per year with 95% of these reports being credible. Another recent estimate shows that 3.0 million people in 128 countries are in risk of contracting the Dengue fever. This is around half of the world’s population which is a significant issue. Now the Dengue fever is spreading to other non tropical environments. It is spreading into Europe. The first local transmission of the dengue fever was reported in 2010 in France. The Dengue fever statistics show that it is only growing in all the countries that it is in and that it is spreading into as of right now.