Goal Compare and contrast some of the important endemic diseases of Central America, and particularly of Costa Rica, many of which are not common or present in the U.S. Identify and consider different...

Goal

• Compare and contrast some of the important endemic diseases of Central America, and particularly of Costa Rica, many of which are not common or present in the U.S.
• Identify and consider different variables (symptoms, living conditions, environment) that are useful in accurate diagnosis of a disease
• Explain the importance of intermediate hosts in disease transmission and alternative mechanisms for disease control and prevention.
• Develop creative problem solving skills

What to Do

The following Case Study is modified from that by Cathy Santanello, Department of Pharmaceutical Sciences, Southern Illinois Univeristy at Edwardsville, and Jennifer Rehg, Department of Anthropology, Southern Illinois University at Edwardsville.Source: The National Center for Case Study Teaching in Science, University at Buffalo, State University of New York.

1. Read the short Backgroundon The Case of a Tropical Disease and Its Treatment: Science, Society, and Economics
2. Read the CaseStudy and Questions listed here for Parts 1 & 2
3. In your Initial Post:
   1. Answer Questions for Parts 1&2and
   2. Answer at least 3 of the following questions in a reflection of this activity
      • What was the most interesting part?
      • What was something new you learned?
      • What are you confused about?
      • Which part would you like to learn more about?
4. In your Deep Responses to peers, please respond mainly to the Reflection piece, although you are free to respond to any portion. Refer to the "Quality" section below for additional information.

Background

This case study highlights the epidemiological and socioeconomic factors associated with a disease which plagues thousands of people in Central and South America. The case follows the story of Adrian, a banana plantation worker in southwestern Costa Rica who develops a mysterious illness. You will learn about infectious diseases, pathogens, and vectors endemic to the region, and are asked to diagnose Adrian’s illness and consider his dilemma with respect to treatment options.

Part I- A Mysterious Ailment

Although he was afraid to take off from work and risk losing his job at the banana plantation, Adrian Mora decided he was much too weak to continue his ten hour shift. He had already spent most of the morning applying pesticides and covering clusters of bananas on the trees with plastic bags in order to protect them from wind, birds, and insects. He informed his boss, Don Jose, he must go home and rest, but he would work extra hours later in the week to make up the lost time. He walked through the farm, set against the edge of remnant fragments of lowland tropical rainforest. T is part of southwestern Costa Rica used to be continuous forests and mangrove swamps, but as the land was developed for fruit plantations, cattle ranches, and other types of agriculture, the forests were cleared. Small wooden houses set on low stilts now lined cleared strips of land between the bananas and the forest edge. Palm trees were left standing to provide some scant shade and so that the workers could make use of the palm fronds for roof thatch. Tangled scrubby, secondary growth vegetation stretched out to the houses from the forest edge, years after the clear-cutting. Many workers lived here to be near the plantation rather than commute from the town of Quepos 65 km away.

Adrian was an illegal immigrant from Nicaragua. He had fled south with his brother, Alejandro, to Costa Rica in search of a better economic future about seven years ago. He and his brother did not want to risk the chance that they might be deported, so they had never applied for official permission to live in Costa Rica. Another Nicaraguan immigrant had helped him and Alejandro get jobs at the banana plantation as temporary workers. The brothers worked whenever the plantation needed some extra help, especially during harvest time. They moved around from one farm or plantation to the next as unskilled laborers. At the plantation Adrian made 100,000 colones (about US$200) per month. This was less than Costa Rican minimum wage, but since he and his brother were not legal workers, they were not listed on official employee records. As an indocumentado, Adrian had to take whatever work was available, and often for less than what a Tico would be paid and without other benefits.* The brothers continued to send money to their mother and younger siblings back in Nicaragua. At least the plantation owner allowed him and his brother to live in one of the plantation houses for free.

Adrian arrived back at the three-room house that he and Alejandro shared. They had trouble keeping the house clean because they rarely took a day off while working at the plantation. Since their jobs were not secure, they worked as much as possible when the plantation needed them. Cracks between the slats of the wooden walls and floor allowed dirt and insects to enter the house. Adrian looked up at a few, small open spaces in the thatched roof, and realized they needed to collect more palm fronds to patch it.

As he lay in his hammock into the evening hours, he wondered why he was not feeling well. “Maybe I’ve just been in the sun too long. Or maybe I am sick from the chemicals sprayed on the fruit trees,” he thought. “I have heard of Ticos who have gotten cancers from their prolonged exposure to the pesticides. Could the pesticide that we use on the bananas cause me to feel so poorly?” Adrian rubbed absent-mindedly at his eyelid, which was becoming swollen. “I am so tired, and should eat something to keep my strength. But I am not hungry at all.”

Adrian was worried enough he considered visiting a doctor at a local clinic. “Despite my low wages, I could probably still afford to visit a doctor.” Costa Rica had a national health care system with affordable services and treatments, and healthcare was extended to illegal immigrants as well as citizens and legal refugees. “But I do not want to take the chance that if I go to a doctor, someone might find out that I am here illegally and report me.”

His heart seemed to beat oddly and he felt flushed. Adrian hoped that this was simply a result of his anxiety. He blankly stared at the insects swarming around the electric lamp on the porch, lit each night to keep away nocturnal animals. Adrian swatted at a bug alighting on his forehead as he drifted off to a restless sleep.

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In order to become familiar with diseases endemic to Costa Rica, read the following webpages on health concerns in Mexico and Central America from the U.S. Centers for Disease Control and Prevention:

Costa Rica Traveler View(Links to an external site.)

(note, you can change the location to nearby countries such as Panama on this same site)

Make sure to investigate the links to additional information on diseases listed for this region, or other internet sites which include information on these diseases and their symptoms.

Q1: What are some important infectious human diseases that are endemic to Costa Rica and Central America, based on information from the Centers for Disease Control (list 3-4)?

Q2: What types of symptoms characterize these diseases that you listed?

Q3: What are some similarities in the symptoms of these diseases that might complicate diagnosis of a specific condition?

Q4: What are some peculiar or specific symptoms to each disease that might aid in diagnosis?

Q5: How might a patient’s environment (e.g., living conditions, socioeconomic situation) relate to accurate diagnosis?

Part II - The Diagnostic Dilemma

Adrian’s condition had deteriorated by the next day. His left eyelid was extremely swollen and he had developed a high fever. There was no way that Adrian could work. Alejandro was worried and decided that his brother needed to see a doctor. If Adrian could not work, their boss at the plantation might simply fire him. Alejandro helped Adrian walk to the highway where he could flag down a bus to Quepos, while Alejandro returned to the plantation.

After waiting for a few hours at a small clinic on the outskirts of Quepos, Adrian was seen by Dr. Rodriguez. Te doctor was immediately suspicious that Adrian might have Chagas disease due to his swollen eyelid, a characteristic symptom known as Romaña’s sign (see Figure 1), and given that he lived in an area in which the disease vector was prevalent. Dr. Rodriguez took a blood sample from Adrian. Visual inspection of the blood with a thin blood film under a microscope confirmed the doctor’s initial guess. There were characteristic forms of the unicellular protozoanTrypanosoma cruziin his bloodstream. These forms of the protozoan, known as trypomastigotes (see Figure 2), are present in the bloodstream of individuals in an acute stage of Chagas disease.

Dr. Rodriguez explained to Adrian that he had Chagas disease, caused by a type of trypanosome, which is a microscopic protozoan. While the disease can be transmitted through blood transfusion from an infected individual or from mother to child during pregnancy the most common form of transmission is through the bite of an insect vector, a type of triatomine insect, which is also known as thevinchucaor “kissing bug” (see Figure 3). Given that Adrian lived near the forest, the triatomine that infected him was likely Triatoma dimidiate. Te doctor further explained that the bug serves as a host for the protozoan. When these bloodsucking bugs bite a human, the protozoan enters the human’s blood from the infected bug feces deposited at or near the bite. The vinchuca likes to bite people around the mouth or eyes because the skin is thinner there. If the bug is infected withT. cruziand the bug feces get into the bite, another open cut, or into the eye, there is a good chance the person will become infected.

“Adrian, it is estimated that 17 million people throughout Central and South America are infected with this disease and that 50,000 will die annually. You have symptoms characterizing the acute stage of Chagas disease, and there is a small chance you could eventually die if your symptoms become severe enough. If instead you seem to get better, even without treatment, after years or even decades of being infected with the parasite you could develop serious problems in your heart or other internal organs from long-term infection. The protozoa will settle into your muscles, heart tissue, or intestines and you could eventually die from complications and damage to the organs. Once the parasites become established in your body, which is considered the chronic stage of the disease, it is nearly impossible to treat. We need to attempt to destroy all of the parasites in your body now.”

Dr. Rodriguez wanted Adrian admitted to a hospital for treatment, but Adrian was adamant that he would not go. “I do not want to be stuck in a hospital in Quepos, away from my brother.” Adrian did not speak out loud his other fears—that he would be fired from his job at the plantation and someone at the hospital might suspect he was in Costa Rica illegally. Dr. Rodriguez gave up trying to convince Adrian to admit himself to a hospital, and instead told Adrian that he must start medical treatment to destroy the protozoa. The doctor provided Adrian with a prescription for benznidazole, which is one of the only two drugs presently available to treat Chagas disease. The doctor warned Adrian about the need to take the medication on the prescribed schedule, as well as potential medication side effects, including sleeplessness, nausea, diarrhea, and skin rashes. The doctor also warned him that it was important to complete the full course of medication, or he was less likely to be cured.

“You will have to visit me for an additional serological blood test after you finish taking the medications to determine if there are any remaining protozoa in your body. Approximately 30 to 40% of individuals treated in the acute stage of Chagas disease may not be completely rid of the parasite following the initial course of medication.” Dr. Rodriguez continued, “If side effects of the drugs become very strong, you need to see me as soon as possible. Te drugs are very potent, and could make you ill.”

The doctor knew about the condition of the houses around the fruit farms, and told Adrian, “Your house may be harboring more vinchucas, or new bugs may enter your house from the nearby forest and reinfect you. You will need to take measures to prevent additional bites from these insects.”

Adrian asked whether he could treat the disease with some pills he had remaining from a previous prescription for a skin infection. He also wondered if there was some kind of injection that could make him immune to the disease in the future. Dr. Rodriguez responded that the pills were probably a general bacterial antibiotic, which were not any use in treating the parasite. An injection wouldn’t have helped either. “Currently, there is no vaccine to prevent Chagas disease, and it is unlikely a vaccine will soon be developed. Your best option to prevent future infections is to not be bitten by any more vinchucas.” Dr. Rodriguez was himself frustrated at the lack of prevention and treatment options available for this disease, but could do nothing more than send Adrian on his way.

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Read the following references, which provide background information on Chagas disease, and triatomes (kissing bugs) to help you answer the questions below.

WHO- Chagas Disease(Links to an external site.)

Control of Chagas Disease vectors

Q6: How does the kissing bug (e.g., Rhodnius sp., Triatoma dimidiate ) locate its human prey?

Q7. What type of environment does the kissing bug inhabit?

Q8. Given the behavior and ecology of this insect, what are some factors that could cause the incidence of Chagas disease to increase in Central and South America in areas like the banana plantation, and why?

Q9. What are some of the steps that can be taken to reduce the likelihood of infection by Chagas disease through insect vectors like kissing bugs?

Q10. Which of these approaches might be easiest, or most useful, for Adrian, given his circumstances?

** There is more to the story that considers more socioeconomic concerns related to this as well as treatment, but for our purposes, we will stop here as far as the questions go! I will include Part III (see Additional information) for your interest, but it will not be a part of the assignment.

3. Do Initial Post

Answer Q1-Q10 & Answer at least 3 of the following questions in a reflection of this activity

• What was the most interesting part?
• What was something new you learned?
• What are you confused about?
• Which part would you like to learn more about?

4. Reply to Peers

In your Deep Responses to peers, please respond mainly to the Reflection piece, although you are free to respond to any portion. Refer to the "Quality" section below for additional information.

Discussion Directions

After you type your initial post byWednesdayevening at 11:59pm, read through the other entries and reply directly to at leasttwo classmatesbySaturdayevening, 11:59pm.When you reply, please type the name of the classmate you are responding to, provide a welcome message to that person, and type your name at the bottom of the message. Make sure to use propergrammar, capitalization, (I instead of i) and punctuationin this college-level course in all correspondence. Please avoid “text” or “twitter speak” when corresponding.

Quality

For each discussion, you'll be required to make three or more contributions. Your first contribution should add substantially to the conversation. This involves a couple of steps:

1. Summarize the resources you are responding to. Whether you are responding to an issue raised in a chapter, a film, or another reading from the module, your first step is writing a clear summary of the point(s) you are responding to.
2. Clearly identify the source(s) you are responding to. Your summarycaninclude quotes, summary, or paraphrase, butmustinclude the author, the title, and the page number (when available).
3. Use the key terms of the unit. The discussions are designed to give you the opportunity to practice the key terms of the unit, so be sure you are taking advantage of this.
4. Provide your response to this source.

The post should be sufficiently developed to illustrate you are engaged in the reading, keeping up with the reading and module resources, and actively engaged in trying to understand the topics.

In addition, you'll be responding to your peers. There are deep responses, and then there are the not so deep responses...
A deep response builds on the conversation by offering more information to support the claims made in the original posting. You can do this by offering an alternative interpretation, or competing evidence, or by creating a link to another resource. Deep responses are thoughtful, are based on the information from the unit, and cite sources. Not so deep responses are valuable, too, but don't earn as much 'credit' as deep responses. They offer support or a thumbs up but don't necessarily add more to the conversation. They are very important!!! They allow us to let others know we like their work or ideas, they help us form online relationships, and they let others know we read their post even though we didn't offer a deep reply. For all you Facebook users, deep responses are like posting something cool on someone's wall, while not so deep responses are simply "liking" a post. In this class, you should be including at least three major contributions--new topics and post replies that are substantially developed--in order to get full credit. But you should also be engaging in not-so-deep responses, too.

FOR ADDITIONAL INTEREST - This Case Study continues...

Part III— The Search for an Alternative Treatment

Adrian considered purchasing the medication prescribed by Dr. Rodriguez. He wondered how much the medication would cost and how long he would have to wait for the prescription to be filled. He considered the possible side effects of the medication, how long he would have to take the pills, and how often he would need to take them each day. How was he to work outside at the plantation if sunlight reacted with the medication to cause skin rashes? Where could he store the medication to keep it cool and retain its effectiveness? And he still might not be cured after weeks of treatment! As he stood outside the clinic in Quepos, he looked down the road in the direction of the nearest pharmacy, with no idea what to do.

Then Adrian recalled that his brother knew someone who had lived in this area before it was converted to plantations. His brother’s friend, Carlos, had spent time with several groups of indigenous Costa Rican peoples in the south of the country, including the Bribri and the Guaymi. Carlos had learned how the curanderos (healers) among the Bribri and Guaymi used different plants to treat many ailments, including arthritis, infertility, and other diseases. Adrian had hope that there was a more natural and less expensive way to treat the “kissing bug” disease. Adrian decided that he would have his brother arrange a meeting with Carlos to get advice on alternative treatments for Chagas disease.

The following day Carlos met with Adrian at his house at the plantation and Adrian explained the diagnosis of Chagas disease. Adrian’s left eyelid was almost swollen shut and he still had a high fever. Carlos nodded his head, “Chagas disease is very uncommon among indigenous Central Americans—but people do become infected occasionally. What you should do is brew a tea from a plant called gavilana. Drink a cup of this tea every day until the eye is no longer swollen and there is no more fever. It may take a few weeks for the symptoms to go away, but if you keep drinking the tea you will eventually feel better.” Carlos told Adrian the story of a young girl with Chagas disease who seemed on the verge of death. “She was given gavilana tea for four weeks every day without fail, and her eye got better and all of her other symptoms disappeared. She is now a grown young woman, with her own family— and she has had no problems with her eye since then.”

Carlos continued, “I will show you how to find the gavilana. It is a relatively common plant in grasslands, bordering forests, and cleared areas near forests” (see Figure 4). Adrian was very hopeful that this remedy would work. Then he would not have to use an expensive, unnatural medication, and if he was feeling better in a few weeks, he wouldn’t even visit Dr. Rodriguez again. If one cup of tea each day might cure him in a few weeks, maybe drinking more tea more often would cure him even sooner ….

Think about: What would be some potential consequences for Adrian if he opted for this type of self-treatment?