Clinical Case Practice for Project CURA - Guatemala: USMLE-Style Questions
Gabriel Hanson, M1
Background
This summer, I will be traveling to San Lucas, Guatemala with a group of Creighton medical students and physicians through Project CURA. During our time there, we will partner with Friends of San Lucas, a local organization dedicated to supporting the community in a variety of ways. Our team will help run a pop-up clinic in rural areas surrounding San Lucas, providing care to patients who may have limited access to healthcare. In preparation for this experience, I have written USMLE Step 1-style practice questions focusing on medical conditions commonly seen in rural Guatemala. I am
incredibly grateful for this opportunity and excited for the experience ahead!
Question #1
A 4-year-old child from a rural region of southwestern Guatemala presents to the pop-up clinic with his mother due to fatigue, irritability, and poor appetite. His diet consists of mainly corn tortillas and milk, with little consumption of leafy vegetables or meat. On examination, the child’s skin is pale, a systolic murmur is heard on auscultation, and the mother says she has had to stop her son from trying to eat dirt on multiple occasions. Which of the following is the most appropriate treatment for this child’s condition?
A. Vitamin B12 supplementation
B. Iron supplementation
C. Empiric antiparasitic therapy
D. Blood transfusion
E. Multivitamin
Answer to Question #1
B - Iron Supplementation
Iron deficiency is the most common nutritional deficiency in the world. Dietary factors are the primary cause of iron deficiency in early childhood, and heme dietary sources (fish, poultry, and meat) have a higher bioavailability of iron than do non-heme sources (vegetables). Excessive ingestion of cow’s milk in young children can lead to occult intestinal blood loss, further exacerbating iron loss. The World Health Organization recommends iron supplementation for infants and children (ages 6 months to 12 years) in populations with a high prevalence of iron deficiency.
A - Vitamin B12 supplementation
B12 deficiency causes megaloblastic anemia, and is rare in children unless they have severe malabsorption or a strict vegan diet. Milk and corn provide vitamin B12, but not enough iron
C - Empiric antiparasitic therapy
This child does not exhibit symptoms such as diarrhea, abdominal pain, or failure to thrive, which are more commonly associated with parasitic infections.
D - Blood transfusion
Blood transfusions are reserved for cases of severe anemia. This child’s symptoms are more suggestive of moderate anemia, making iron supplementation the preferred treatment. Additionally, blood transfusions have the potential for serious side effects including iron overload, transfusion reactions, and infection. This may also be a risky choice for the setting of a rural pop-up clinic.
E - Multivitamin
While multivitamins contain some iron, they do not provide enough to effectively treat iron deficiency anemia. Other vitamins (e.g., vitamin C) can help with iron absorption but are not the primary treatment for iron deficiency.
Question #2
A 23-year-old male medical student is volunteering at a local clinic in rural Guatemala when he is bitten by a stray dog during his lunch break. The bite is deep and located on his right calf. The dog appeared to be aggressive and was salivating excessively. The student washes the wound with soap and water, but does not seek medical attention until he is back in the United States two days later. He has no history of prior rabies vaccination. What is the most appropriate next step in management?
A. Prescribe a 14-day course of amoxicillin-clavulanate
B. Administer tetanus vaccine and observe the patient
C. Observe the patient for symptoms before beginning treatment
D. Administer rabies vaccine alone
E. Administer rabies immunoglobulin and rabies vaccine
Answer to Question #2
E - Administer rabies immunoglobulin and rabies vaccine
This would be considered a high-risk exposure, considering the bite was from an aggressive/salivating dog, the bite was deep, and the bite took place in an endemic region (e.g., Guatemala). Because rabies is almost universally fatal once symptoms begin to develop, post-exposure prophylaxis (PEP) is essential for unvaccinated individuals with high-risk exposure. PEP includes wound cleaning plus immunization with killed vaccine and rabies immunoglobulin.
A - Prescribe a 14-day course of amoxicillin-clavulanate
Dog bites have the potential to lead to polymicrobial infections (e.g., Pastuerella multocida) and amoxicillin-clavulanate is first-line in preventing these. However, rabies requires immediate PEP, and is nearly 100% fatal once symptoms develop. While amoxicillin-clavulanate could be given in addition to rabies PEP, it cannot replace it.
B - Administer tetanus vaccine and observe the patient
Tetanus can be transmitted through deep wounds, but most U.S. patients are vaccinated, making it less concerning in this scenario. A tetanus booster may be given in addition to rabies PEP, but not as a substitute.
C - Observe the patient for symptoms before beginning treatment
Although rabies has an incubation period of 1-3 months, once symptoms appear, it is almost always fatal. Given the high-risk exposure, waiting for symptoms is not an option; PEP must begin immediately.
D - Administer rabies vaccine alone
The rabies vaccine is a part of rabies PEP, but the vaccine takes time to develop an immune response. Since this patient has no history of rabies vaccination, he also requires rabies immunoglobulin to provide immediate passive immunity.
Question #3
A 27-year old man presents to a rural clinic in Guatemala with foul-smelling diarrhea, bloating, and apparent weight-loss. He denies any blood in his stool or fever. He claims that about two weeks ago he drank untreated river water when he was out for a walk in the hot afternoon sun. Upon physical exam, he appears dehydrated, but there are no significant abdominal findings. He is otherwise healthy, with no conditions suggesting immunosuppression. Which of the following organisms is most likely responsible for this patient’s condition?
A. Cryptosporidium
B. Ascaris lumbricoides
C. Schistosoma mansoni
D. Entamoeba histolytica
E. Giardia lamblia
Answer to Question #3
E - Giardia lamblia
This patient’s foul-smelling diarrhea, bloating, and weight loss are characteristic of giardiasis, an infection caused by the microscopic parasite Giardia lamblia. This organism is found worldwide, particularly in areas with untreated water and poor sanitation. Symptoms typically develop 1-3 weeks after exposure and can last two to six weeks. treatment is generally effective.
A - Cryptosporidium
Cryptosporidium is another waterborne parasite common in developing countries. However, it primarily affects immunocompromised patients (e.g., those with HIV/AIDS), leading to profuse watery diarrhea. Since this patient has no history of immunosuppression, Cryptosporidium is unlikely the cause.
B - Ascaris lumbricoides
Ascaris lumbricoides is a common helminth in rural Guatemala, often acquired from contaminated food and water. However, it typically causes intestinal obstruction and respiratory symptoms rather than diarrhea.
C - Shistosoma mansoni
Shistosoma mansoni is a waterborne trematode found in tropical regions. It causes bloody diarrhea and hepatosplenomegaly rather than the non-bloody, foul-smelling diarrhea seen in this patient. Additionally, it is usually acquired via freshwater exposure, not from drinking contaminated water.
D - Entamoeba histolytica
Entamoeba histolytica is a protozoan that causes diarrhea and is commonly found in developing countries. However, E. histolytica is invasive, leading to bloody diarrhea and potentially liver abscesses. Since this patient lacks blood in his stool and liver tenderness, E. histolytica is an unlikely cause of his condition.
Question #4
A 6-year-old girl from a rural village in Guatemala is brought to the pop-up clinic by her mother due to swelling around her eye that developed two days ago. She states that she just woke up one morning and noticed her eye was swollen. Since then, she has had low-grade fever and malaise. When asked about their living situation, the mother states that their family lives in a mud-brick home just a few miles down the road. Upon examination, the child has unilateral periorbital swelling of her right eye, but no conjunctival infection. What is the most appropriate treatment for this patient’s condition?
A. Atovaquone-proguanil
B. Pentamidine
C. Benznidazole
D. Sodium Stibogluconate
E. Iodoquinol
Answer to Question #4
C - Benznidazole
This patient is presenting with acute Chagas disease caused by a Trypanosoma cruzi infection. The acute phase of Chagas disease occurs shortly after infection, and is characterized by often mild symptoms including fever, malaise, rash, loss of appetite, and nausea. Another symptom of Chagas disease is Romaña sign (swollen eyelid), which occurs when the Trypanosoma cruzi parasite gets into the eyelid. This occurs when feces from the reduviid bug are rubbed into the eye or a nearby bug bite. Benznidazole is FDA-approved for treating Chagas disease in children 2-12 years of age.
A - Atovaquone-proguanil
Atovaquone-proguanil is commonly used for malaria treatment and prophylaxis. Plasmodium infections typically cause cyclic fevers but do not lead to unilateral periorbital swelling.
B - Pentamidine
Pentamidine is useful for treating Trypanosoma brucei and pneumocystis pneumonia infections. T. brucei is transmitted by the Tsetse fly, which is found in Africa, not Central America. Unlike Trypanosoma cruzi, it often involves the central nervous system, leading to symptoms such as confusion and coma. Pentamidine specifically is first-line treatment for the West African (T. gambiense) type of T. brucei infection.
D - Sodium stibogluconate
Sodium stibogluconate is used for treatment of Leishmaniasis, specifically Leishmania braziliensis infection. L. braziliensis is endemic to Central America, transmitted by sandflies, and initially presents as a painless papule at the bite site. However, no unilateral periorbital swelling should be observed.
E - Iodoquinol
Iodoquinol is used for treatment of Entamoeba histolytica. E. histolytica causes bloody diarrhea, liver abscesses, and inflammation of the colon. Given the absence of GI symptoms, this is an unlikely diagnosis.
References
Q1
1. López-Ruzafa, E., Vázquez-López, M. A., Galera-Martínez, R., Lendínez-Molinos, F., Gómez-Bueno, S., & Martín-González, M. (2021). Prevalence and associated factors of iron deficiency in Spanish children aged 1 to 11 years. European journal of pediatrics, 180(9), 2773–2780. https://doi.org/10.1007/s00431-021-04037-8
2. Mayo Clinic Staff. (2022, January 4). Iron deficiency anemia. Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/iron-deficiency-anemia/symptoms-causes/syc-20355034
3. Powers, J. M. (2024, June 11). Iron deficiency in infants and children <12 years: Screening, prevention, clinical manifestations, and diagnosis. UpToDate. https://www.uptodate.com/contents/iron-deficiency-in-infants-and-children-less-than12-years-screening-prevention-clinical-manifestations-and-diagnosissearch=iron+deficiency+anemia+in+children&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1
Q2
1. Brown, C. M., & Demaria, A. (2024, June 14). Clinical manifestations and diagnosis of rabies.
&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1
2. Centers for Disease Control and Prevention. (n.d.). Clinical overview of Rabies. Centers for Disease Control and Prevention. https://www.cdc.gov/rabies/hcp/clinical-overview/index.html
3. Nigg, A. J., & Walker, P. L. (2009). Overview, prevention, and treatment of rabies. Pharmacotherapy,29(10), 1182–1195. https://doi.org/10.1592/phco.29.10.1182
4. USMLE. (n.d.). Rabies virus. Scholar Rx. https://usmle-rx.scholarrx.com/first-aid?id=350&firstAidYear=2024
Q3
1. Bartlet, L. A. (2024, December 12). UpToDate. https://www.uptodate.com/contents/giardiasis-treatment-and-prevention?search=giardia+treatment&source=search_result&selectedTitle=1~100&usage_type=default&display_rank=1
2. Benedict, K. M., & Roellig, D. M. (2023, May 1). Giardiasis. Centers for Disease Control and
Prevention. https://wwwnc.cdc.gov/travel/yellowbook/2024/infections-diseases/giardiasis
3. Mayo Clinic Staff. (2022, November 8). Giardia infection (giardiasis). Mayo Clinic.
https://www.mayoclinic.org/diseases-conditions/giardia-infection/symptoms-causes/syc-20372786
Q4
1. Bern, C. (2023, May 16). Chagas disease: Acute and congenital Trypanosoma cruzi infection Topic.
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2. Montgomery, S., Roy, S. L., & Dubray, C. (2025, January 31). Trypanosomiasis, American / Chagas
disease. Centers for Disease Control and Prevention. https://wwwnc.cdc.gov/travel/yellowbook/2024/infections-diseases/trypanosomiasis-american-chagas-disease
3. Sales Junior, P. A., Molina, I., Fonseca Murta, S. M., Sánchez-Montalvá, A., Salvador, F., Corrêa-Oliveira, R., & Carneiro, C. M. (2017). Experimental and Clinical Treatment of Chagas Disease: A Review. The American journal of tropical medicine and hygiene, 97(5), 1289–1303. https://doi.org/10.4269/ajtmh.16-0761