A GENERAL PRESENTATION OF CHAGAS’ DISEASE
ARA Journal, Volume 2004, N° 29
Abstract: In our times, terrible diseases are spreading further through our world, affecting society on large scale. Alongside AIDS, tuberculosis, hepatitis and recent diseases such as SARS and the avian flu, Chagas’ disease is affecting more and more people. This work describes the magnitude and effect of this major yet little-known disease, discussing its cause, transmission, symptoms, diagnosis, treatment and prevention.
Keywords: Chagas’ disease, infectious diseases, South American health, exotic diseases
Chagas’ disease is a potentially deadly disease which occurs mainly in South America but has in recent years also spread into North and Central America.
The disease currently affects between 18 and 20 million people and is therefore one of the most widespread diseases on the American continent. Add to this the fact that Chagas’ disease kills 20,000 people annually and puts another 100 million at risk of acquiring it, and we can clearly see that this is not only a growing disease, but a major one that must be dealt with.
Figure 1. Areas affected by Chagas’ disease. It can be seen that nearly all of South America is affected except eastern Brazil and the southern tip of the continent. Central America is also heavily affected.
The disease significantly affects all countries of South and Central America, as far north as Mexico and now penetrating into the USA. Chagas’ disease can affect all mammals, and animals such as foxes, deer and rodents can and have been infected.
The scientific name of the disease is trypanosomiasis, or to distinguish it from others, American trypanosomiasis. However, it is widely known as Chagas’ disease after having been discovered by the Brazilian physician Carlos Chagas in 1910. Even though Chagas’ disease has been known from this time, it only gained international awareness and was seen as a major problem in humans in around the 1960s. Since then, it has spread quite rapidly around South America, even though its spread has been slowed by a number of successful initiatives by governments and health groups. It remains, however, a terrible problem in some countries – in Bolivia, for example, 20% of the population are infected with the disease. Despite its status, the disease is still fairly unknown outside the Americas. Chagas’ disease is known in Spanish as La Enfermedad de Chagas and in Portuguese as A doença de Chagas.
Chagas’ disease is not contagious, even though it is infectious and mainly spread by the vector Triatoma protracta, which is a triatome insect known commonly under many different names, including vinchuca, the assassin bug, chipo and the kissing bug. This insect contains the protozoan Trypanosoma cruzi (named after Oswaldo Cruz, also Brazilian), which actually causes the disease once it enters the human body.
Figure 2. Triatoma protracta, or vinchuca, the vector which spreads Chagas’ disease
The vinchuca vector is around 2.5 cm long and has a proboscis through which it draws blood. It is yellow-orange in colour with a black marking on top of its abdomen.
Though their wings don’t permit them to fly, vinchucas can glide over 100 metres assisted by air currents, and this is what usually happens when they bite humans. Many vinchucas glide down from ceilings or rooves onto sleeping humans.
The vector bites human beings usually at night, earning the disease the nickname of ‘the unexpected killer of the night’. Like mosquitoes, vinchuca bugs feed on human blood, and an increasingly wide number of them carry the disease-causing protozoan in them. The vinchuca can bite anywhere on the body, but usually does so just above the eye, leaving the trademark Chagas’ disease sign known as Romaña’s sign, or the kiss of death. When an infected vinchuca bites a human being, the protozoan Trypanosoma cruzi is transmitted through the blood and that person automatically becomes infected.
There are also a series of other, rarer ways to spread the disease: through unsafe blood transfusions, from infected mothers to their babies via the placenta or maternal milk and contamination of food by the vinchuca’s infected faeces. However, the vast majority of the transmission occurs due to the vinchuca insect’s bite.
Due to this, a significant amount of work has been done to stop the spread by using insecticide, even though this has not always proven successful because the insect is so widespread. Slightly more successful has been the improvement of houses so that they do not harbour as many of these insects. However, in Bolivia, over 70% of homes are infested with the triatome, making its removal very difficult.
The living conditions of the vinchuca strongly affect the geographical distribution of Chagas’ disease. The insects prefer warm, humid conditions, such as those found in the areas of South America near the equator. They also prefer higher altitudes, such as those in the Andes Mountains of Peru and Ecuador. Because of these reasons, it is exactly these areas that are most affected by the disease.
The disease has also been exacerbated by the way houses are constructed in these areas, many of them having thatched rooves and cracks in walls, both of which are places where vinchucas hide during the day, only to come out at night and spread the disease. Therefore, the disease tends to affect poorer people, in rural areas. However, there is a now great deal of migration from rural to urban areas, causing the vinchuca to spread quite dangerously to urban areas. There are cases where vinchucas crawled aboard railway cars to the larger cities, or crawled in the luggage of migrants.
3. TRANSMISSION THROUGHOUT THE BODY
Figure 3. The three forms of Trypanosoma cruzi, from left: tripomastigotic, amastigotic and epimastigotic
Trypanosoma cruzi, the protozoan which infects the body with Chagas’ disease, first enters the bloodstream, due to the fact that the vinchuca extracts blood from the body while infecting it with the protozoan. Once in the bloodstream, the protozoan multiplies, and, because it is a parasite, travels throughout the body to grow, live and reproduce in muscle neurons, the colon, the oesophagus and the heart. In a short time, Trypanosoma cruzi can multiply very rapidly and be found all around the body.
Trypanosoma cruzi is a kinetoplastic flagellate protozoan related to the pathogen that causes African sleeping sickness, which is transmitted by the vector known as the tse tse fly. Trypanosoma cruzi has one nucleus and an organelle, known as the flagellum, which it uses for propulsion. The protozoan reproduces asexually via binary fission and contains a small kinetoplast, which contains its DNA and is located inside the organelle.
Trypanosoma cruzi changes forms in its life cycle as it travels from vectors to mammals. As can be seen in the photos, there are three forms it takes: the tripomastigotic form, the amastigotic form and the epimastigotic form.
There are many symptoms of Chagas’ disease, and it is these which make this disease such an important and horrible one. Trypanosoma cruzi infects the whole body and its organs, and therefore all of these different parts are affected, causing widespread pain. Also, the symptoms are usually very strong.
Figure 4. The colonisation of muscle neurons by Trypanosoma cruzi (magnified at the
The symptoms of being infected with Chagas’ disease are most commonly constipation, fatigue or excessive tiredness, the inability to swallow, fever, general bodily discomfort and abdominal or intestinal pain. Generally, the most immediate and recognisable sign is the bite of the vinchuca, usually above the eyes or on the face.
As the disease progresses, sufferers may find themselves enduring choking or even heart attacks, this being the reason why many people who have Chagas’ disease end up dying.
One of the most common symptoms is fatigue, or malaise. This is due to the fact that, once the disease enters the body, it parasitically colonises muscle neurons, where Trypanosoma cruzi feeds, grows and reproduces, as shown in Figure 4.
This causes an over-reaction in the immune system which actually causes more pain than the parasite itself, potentially causing an auto-immune problem.
Another common symptom is constipation, abdominal pain as well as loss of appetite. These are caused by the fact that Trypanosoma cruzi invades the colon and prevents it from exercising peristalsis, which are involuntary muscular contractions which help food move down the colon. Due to the prevention of peristalsis, blockages occur in the colon, creating swelling, which causes the strong intestinal pain, as well as constipation.
4.3. Dysfunction of the oesophagus
Also related to the prevention of peristalsis is the symptom of dysfunction of the oesophagus and throat. This means that sufferers usually find it very hard to swallow, as again, the peristaltic contractions that normally push food and drink down into the stomach do not occur due to the disease. This is caused by the disruption of the throat’s nervous tissue, and, as the disease progresses, choking may occur, as some liquids may go down the trachea into the respiratory system.
4.4. Heart problems
Perhaps the worst consequence of the disease is the fact that it attacks the heart, possibly resulting in death. Trypanosoma cruzi parasitically infects the heart, progressively causing more and more damage to the heart’s nervous tissue and disrupting the heart’s electrical system. This can lead to irregular heartbeats, beats that are too close together or too far apart, inefficient pumping of blood and an enlarged heart, which can cause heart attack and death. Due to the reaction of the immune system, sufferers can also face swollen lymph glands.
4.5. Problems of the nervous system
Overall, Chagas’ disease tends to affect the nervous system, by denervating nerve and muscle tissue, especially the nervous tissue in the heart, oesophagus and colon. Due to these nerve problems, Chagas' disease causes the aforementioned symptoms, such as an enlarged heart, choking and constipation.
The disease is commonly diagnosed by analysing a combination of these symptoms, even though the usual sign is exterior swelling where the vinchuca bit the victim. On the other hand, the symptoms heavily depend on the immune system and state of health of the sufferer, as well the type of parasite.
Some patients may not live with any strong or visible symptoms for years, even though they may still be infected. For this reason, the easiest way to diagnose the disease is by a blood test, which will be analysed for the parasite or for antibodies.
Another method of diagnosis is known as xenodiagnosis, where uninfected vinchucas are made to bite people suspected of having the disease. After consuming blood for thirty minutes, the faeces of the insects are examined for Trypanosoma cruzi and therefore Chagas’ disease.
4.7. Development of symptoms
It is important to know that the symptoms of the disease are commonly divided into three periods: acute, intermediate and chronic. The acute period lasts for up to 8 weeks after infection, and this is when the symptoms mentioned before, such as fatigue, loss of appetite, intestinal pain and inability to swallow most occur.
The next stage, the intermediate period, occurs between 8 to 10 weeks after infection, and there are usually no symptoms at this time. After this stage, the disease may have been naturally cured by the immune system, and in this case, no chronic symptoms will occur. If, however, sufferers reach the chronic stage, of which around 30% of them do, this is when the heaviest symptoms are felt, such as the disruption of the heart’s rhythm, an enlarged heart and severe constipation and problems with swallowing.
There are some cases where people do not suffer the acute and intermediate phases of the disease, only to find themselves suffering the severe chronic symptoms 10 or 20 years later.
Chagas’ disease is fairly difficult to treat, and this is further made worse by the fact that it affects a high percentage of poor people in rural areas, where health infrastructure is inadequate. Chagas’ disease cannot adequately be cured with medicine, especially in its chronic stages, even though there are some treatments to prolong length of life of sufferers, as well as quality of life and the reducing of strong symptoms.
Treatments work best when given during the acute stage of the disease, and for this reason it is best to diagnose it early. Effective treatment can even prevent the disease from reaching its painful, chronic stage, which is nearly equivalent to a cure.
In more developed countries where Chagas’ disease is apparent, such as in the United States, Chile, Argentina and, in some cases, Brazil, there are prescription drugs that treat the disease. The most common drugs given to sufferers are nifurtimox and benznidazole. Nifurtimox is a powder which is taken dissolved in water, in doses of 10 mg per kilogram of body weight, every day for sixty to ninety days after Chagas’ disease has been contracted. Benznidazole is taken in a similar fashion, although only 5 mg per kilogram of body weight is taken daily. Both of these drugs lead to the inhibition of growth and sometimes death of the disease-causing parasites, consequently causing an easing of symptoms.
There are not many side effects to these drugs, and benznidazole has proven to be particularly effective, preventing people from going into the chronic stage of the disease. Because nifurtimox and benznidazole cause oxidative stress against the parasite, resulting in its death, the drug can be dangerous to people with glucose-6-phosphate dehydrogenase deficiency. Nifurtimox can, in some cases, cause pregnancy problems, and, if alcohol is taken during the treatment period, unexpected effects may occur. Benznidazole, although working against the disease, can actually lower the number of white blood cells and platelets in the body, making it harder to fight against future diseases and making it harder for blood to clot when bleeding occurs. It can also cause vomiting and skin problems such as rashes.
However, despite the availability of treatment drugs, Chagas’ disease mainly strikes poor people in rural areas or poor countries such as Bolivia. In these situations, local clinics are not equipped with such drugs, and sufferers cannot afford going to the larger cities to be treated. However, hope is not lost, as there are a series of traditional, herbal remedies that can ease the symptoms of the disease, even though these are not always effective.
One of the most effective remedies is Sangre do Drago (Blood of the Dragon), which is a resin extracted from the fruit of the Rotan palm tree. Containing benzoic acid, this can treat Chagas’ disease in a similar way to benznidazole. It also has the added benefit of strengthening the immune system, even though there are reports that it reduces the number of red blood cells. Some traditional village herbalists also toast and crush palm seeds and place them in pisco liquor, a traditional drink. This is drunk daily to alleviate the symptoms of fatigue.
Despite all of the methods of treatment, Chagas’ disease remains a serious one due to the fact that it can be spread so easily, especially due to the environment in South America. Also, there is currently no vaccine or preventative medicine that can be taken to shield people from the disease.
Therefore, there are four main ways to prevent the spread of the disease: education and development campaigns to help people maintain hygiene and therefore prevent the transmission of the vinchuca insect, the sterilisation of blood used in transfusions, which can be infected with the disease, the use of insecticide and environmental protection. All these are ways of community-based prevention to reduce infestation, rather than active personal prevention.
Due to unsanitary practices and lack of funds, many South American blood supplies are contaminated with the protozoan Trypanosoma cruzi, which causes Chagas’ disease. These unsafe supplies have been injected into humans during a blood transfusion and passed on the disease. In recent years, however, countries such as Uruguay, Argentina and Chile have limited the spread of the disease by screening and treating the blood with Gentian violet, which kills off the disease, making the blood safe for transfusions.
However, by far the main way via which the disease is spread remains the vinchuca triatome insect, and consequently, the best way to prevent the disease from spreading is to remove the factors and conditions for its survival. This has been popularised both by public education campaigns, which have informed rural people on how to maintain hygiene in their homes and keep them free of the vinchuca, as well as through the upgrading of housing.
As discussed before, the disease basically spreads by using the vinchuca as a vector. If a vinchuca carries the disease, it will infect the human which it bites. Moreover, if an uninfected vinchuca bites a human after they have contracted the disease, that insect will also become infected and will potentially spread the disease to other members of the family or other people.
Therefore, the easiest way to break this parasitic cycle is to prevent vinchucas from nesting in homes. Vinchucas usually nest in the cracks of walls, in thatched rooves and under mattresses. Community education campaigns have resulted in public awareness, and many people in vinchuca-infested areas now maintain a level of hygiene so that vinchuca nests are no longer apparent.
Funds have also been given by national governments to village communities so that they can upgrade their housing by removing thatched rooves and cracks in their walls, which are a favourite place of nesting for vinchucas. Many villages now have successful community projects, in which houses are being upgraded, as shown in Figure 5, from simple ones to more advanced and hygienic ones, so that the risk of vinchuca infestation is considerably reduced. This also leads to a higher standard of living overall.
Figure 5. The upgrading of housing from simple, thatched homes to more advanced brick ones prevents the nesting of vinchucas.
Insecticide has also been an easy-to-access way to rid houses, or entire villages, of vinchucas. In many countries, especially poorer ones such as Bolivia and Ecuador, the World Health Organisation and non-government organisations have started campaigns to provide insecticide to local people.
Figure 6. Percentage of total population infected with Chagas’ disease in South American countries.
Moreover, community projects in certain South American villages now use strong insecticides that are sprayed inside and outside a house to kill all insects. If this is done regularly, along with measures of hygiene, almost all risk of Chagas’ disease can be eliminated.
A method of long-term prevention is reforestation or protection of forests. Because many forests in countries such as Brazil have been cleared for the use of their resources, vinchucas have increasingly migrated from these habitats to urban or populated areas, where they are potentially spreading Chagas’ disease. If reforestation occurs, the above trend can be broken and this can prevent further problems with vinchuca migration infestations in villages and can actually cause the insects to re-adapt to their former natural environment, where they are much less prone to infect humans with Chagas’ disease.
In the wealthier countries of South America, which have more funds for health initiatives, preventative measures that reduce contact with vinchucas have been very effective. This has meant that the rate of infection with Chagas’ disease has been reduced significantly due to prevention, and the chance of dying from the disease has also been reduced due to better treatment.
As shown in Figure 6, the percentage of people affected with Chagas’ disease has dropped between 1985 and 1995. This decrease has been especially pronounced in those countries which have invested in national preventative measures such as housing improvement.
On the other hand, some countries have not seen an improvement in rates of Chagas’ disease and poor, isolated communities continue to suffer from the disease, since many do not have the money or awareness to maintain hygiene and adequate housing, and their governments do not have the funds to invest in insecticide, public campaigns and housing improvement. Also, deforestation continues to be a major problem on the continent, and Chagas’ disease continues to be a growing crisis.
Monitoring the disease is also becoming increasingly problematic as, in most countries, doctor’s rarely report cases of the disease, and many patients do not see doctors but rather village herbalists or no-one at all.
7. HISTORY AND BACKGROUND INFORMATION
Carlos Chagas, a Brazilian researcher, was the first person to actively research the disease and discover the pathogen that causes it. He also found out about the transmission from the triatome insect (vinchuca) to humans.
Figure 7. Carlos Chagas
One interesting point about the disease is the fact that it is thought that Charles Darwin suffered from the it in the late 19th century, after a voyage to the Argentinean Pampas, where he was bitten by what was then known as the Great Black Bug of the Pampas. Many believe that Chagas’ disease ultimately led to his death in 1882.
In conclusion, Chagas’ disease, despite being fairly unknown outside its affected area, is one of the world’s major vector-spread diseases. It continues to kill thousands per year and cause pain to millions of others. Luckily, however, the spread of the disease is being slowed by prevention and treatment techniques and funding to stop the dangers of epidemic proportions posed by this unknown killer of the night.
 BASTIEN, Joseph, The Kiss of Death: Chagas' Disease in the Americas, 1998 http://www.uta.edu/chagas
 WIKIPEDIA, Chagas' disease, 2004 http://en.wikipedia.org/wiki/Chagas_disease
 U.S. CENTER FOR DISEASE CONTROL AND PREVENTION, Chagas' Disease Fact Sheet, 2003
 ALLREFER.com HEALTH, Chagas' Disease, 2003 http://health.allrefer.com/health/chagas-disease-info.html
Many thanks to Dr Joseph Bastien, a specialist in Andean anthropology from the University of Texas at Arlington, USA, for his in-depth research about this topic and for all the help and understanding that has made this work possible.
Also, special thanks to Chris Gates, a very talented medical designer and illustrator from Portland, Oregon, USA, for the illustrations and for the permission to use them in this work.
ABOUT THE AUTHOR
Raymond Roca is a school student in Year 9 (2004) at Sydney Boys High School, a selective school where he is the dux of his year. Also, he excels in English, French, German, Commerce, Geography, History and Visual Arts, where he is the first among the 180 students in his form.
Raymond is also a keen debater, being part of the team of three that won the Debating Championships for the state of New South Wales, Australia.
He has already self-published more than thirty books, created as part of his school assignments. One of his books, Euro: The Largest Monetary Changeover in the World, received the appreciation of the European Commission and is currently housed in the Euro Museum in Brussels, Belgium.
Raymond also has a passion for writing short stories for children. Some of them were translated in several languages and published on the Internet and in magazines.
One of his other hobbies is design and visual arts. He has created several websites and presented some of his sculptural artworks in exhibitions. Raymond also paints, but his great enjoyment is to design large billboards and posters, as well other print design media and digital photography.
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Multumiri domnului ROCA JUNIOR din Sidney si webmasterului acestui site, domnul Hetco pentru acest articol (primul ca l-a scris, al doilea ca l-a postat). Recunosc ca in materie de limba engleza sunt un afon, mai mult intuiesc decit inteleg suta la suta. Totusi, in mare, m-am lamurit ce-i cu aceasta boala Chagas de-al carui nume auzisem, dar nu stiam nimic despre ea.
Uitindu-ma si pe harta anexata am sesizat ca aria unde opereaza aceasta boala se opreste exact la granita intre Mexico si United States of America, adica intre America Latina si America Anglo-saxona. Sau altfel spus: la granita intre saracie pe de o parte si bogatie (+ opulenta) pe de alta. Cite nu s-ar fi putut realiza pentru atenuarea saraciei in lume daca superputerea mondiala S.U.A. - unica ramasa in lume, in loc sa cheltuiasca an de an peste 400 miliarde $ pentru inarmare ar scapa macar 100 miliarde $ printre degete pentru eradicarea saraciei.
Razboiul din Irak a costat Statele Unite pina acum peste 350 miliarde $, nemaivorbind de nenumaratele vieti omenesti pierdute si de la americani dar mai ales de la irakieni. Rezultatul? Il vedem in fiecare zi la TV. Mai bine tac!
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Colectivul de redactie: Lucian Hetco (Germania) , George Roca (Australia), Melania Cuc (Romania, Canada)