A 23-year-old woman comes to the emergency department due to 4 days of intermittent fever, chills, and diaphoresis accompanied by fatigue, myalgia, and dull headache. She recently returned from a 3-month trip to India, where she worked for a nongovernmental organization. The patient had similar symptoms during her first month abroad that improved after several days of treatment. She has no other medical history and takes no medications. Temperature is 38.3 C (101 F), blood pressure is 110/70 mm Hg, and pulse is 100/min. Physical examination shows mild jaundice and hepatosplenomegaly. Laboratory results reveal anemia and elevated indirect bilirubin levels. A peripheral blood smear using Giemsa stain shows intraerythrocytic ringed inclusions. This patient's current symptoms are most likely due to reactivation of a dormant infection from which of the following sources?

Question

A 23-year-old woman comes to the emergency department due to 4 days of intermittent fever, chills, and diaphoresis accompanied by fatigue, myalgia, and dull headache.  She recently returned from a 3-month trip to India, where she worked for a nongovernmental organization.  The patient had similar symptoms during her first month abroad that improved after several days of treatment.  She has no other medical history and takes no medications.  Temperature is 38.3 C (101 F), blood pressure is 110/70 mm Hg, and pulse is 100/min.  Physical examination shows mild jaundice and hepatosplenomegaly.  Laboratory results reveal anemia and elevated indirect bilirubin levels.  A peripheral blood smear using Giemsa stain shows intraerythrocytic ringed inclusions.  This patient's current symptoms are most likely due to reactivation of a dormant infection from which of the following sources?

Quizplus · Accepted Answer

11ec160b_3873_b11c_9249_b128c0bdf3fa_MD0001_00 Malaria is a mosquito-borne, protozoal infection caused by Plasmodium species. Transmission occurs when an infected female Anopheles mosquito injects Plasmodium sporozoites into subcutaneous capillaries during feeding. Within hours, sporozoites attach to and enter hepatocytes and undergo asexual reproduction. This results in the production of tens of thousands of daughter cells (merozoites) that eventually rupture the hepatocyte and spread to erythrocytes, where another asexual reproduction cycle occurs. Manifestations of malaria arise due to erythrocyte rupture and include fever, flu-like symptoms (eg, myalgia, fatigue, headache, chills), anemia, and indirect bilirubinemia (hepatosplenomegaly is also common). The diagnosis is confirmed when trophozoites (intraerythrocytic, ringed inclusions) are seen on peripheral blood smear using Giemsa stain. Although many different Plasmodium species cause malaria, the 2 dominant organisms are P falciparum (in Africa) and P vivax (in non-African countries). This patient who traveled to India was likely infected with P vivax. Unlike P falciparum, P vivax (and P ovale) sporozoites can undergo a dormant hepatic phase (hypnozoite stage) that may cause recurrent parasitemia and symptoms weeks or months after initial infection. Individuals with these strains of malaria must be treated with a combination of drugs that target both the erythrocyte phase (eg, chloroquine) and the dormant hepatic phase (ie, primaquine) to ensure clearance. Patients who are treated with a medication that only targets the erythrocyte phase (as was likely in this case) may initially improve but are likely to develop recurrent symptoms when the dormant hepatic hypnozoites reactivate. (Choice A) Salmonella typhi can spread from the gastrointestinal tract to the gallbladder, which can lead to long-term gallbladder colonization. Typhoid fever is usually associated with a week of stepwise fever followed by a week of rose spots and abdominal pain and then possible complications such as abdominal bleeding/perforation and hepatosplenomegaly. (Choices C and F) Tuberculosis most commonly reactivates from granulomas in the lung, but reactivation can also arise from latent foci in the liver, spleen, or kidneys (~15% of cases). Tuberculosis reactivation usually causes fever, weight loss, and pulmonary manifestations (eg, cough, dyspnea, cavitary disease). (Choice D) Numerous infections can reactivate from the lymph nodes, including HIV, Epstein-Barr virus, and tuberculosis. These infections are not associated with intraerythrocytic, ringed organisms. (Choice E) Malaria infects and lyses erythrocytes. However, dormant infection occurs in the liver. Educational objective: Plasmodium vivax is the most common cause of malaria in non-African countries. It is transmitted by the female Anopheles mosquito and is associated with a latent liver phase that must be treated (with primaquine) independently of the erythrocytic phase to fully eliminate the organism.

A 23-Year-Old Woman Comes to the Emergency Department Due to 4