A 24-year-old man comes to the emergency department after 1 week of fever, chills, and headache. He also complains of nausea and an episode of vomiting. He has no abdominal pain or diarrhea. Three weeks ago, he returned from travelling in southern Africa, where he volunteered at a medical clinic in rural Malawi for 3 months. He took doxycycline for the entire trip until returning to the United States. He drank mostly bottled water but did eat local cooked food. He had no sexual activity, injected drug use, or freshwater exposure during his travels.
His temperature is 39.4 C (103 F), blood pressure is 120/76 mm Hg, pulse is 106/min, and respirations are 18/min. He is uncomfortable but nontoxic-appearing. There is no skin rash. Pupils are equal, round, and reactive and there is mild scleral icterus but no conjunctival lesions or suffusion. There is no neck stiffness or meningeal signs. Abdominal examination reveals tenderness in the left upper quadrant and mild splenomegaly.
Laboratory results are as follows:

Which test is most likely to establish the diagnosis in this patient?

Question

A 24-year-old man comes to the emergency department after 1 week of fever, chills, and headache.  He also complains of nausea and an episode of vomiting.  He has no abdominal pain or diarrhea.  Three weeks ago, he returned from travelling in southern Africa, where he volunteered at a medical clinic in rural Malawi for 3 months.  He took doxycycline for the entire trip until returning to the United States.  He drank mostly bottled water but did eat local cooked food.  He had no sexual activity, injected drug use, or freshwater exposure during his travels.
His temperature is 39.4 C (103 F), blood pressure is 120/76 mm Hg, pulse is 106/min, and respirations are 18/min.  He is uncomfortable but nontoxic-appearing.  There is no skin rash.  Pupils are equal, round, and reactive and there is mild scleral icterus but no conjunctival lesions or suffusion.  There is no neck stiffness or meningeal signs.  Abdominal examination reveals tenderness in the left upper quadrant and mild splenomegaly.
Laboratory results are as follows:

Which test is most likely to establish the diagnosis in this patient?

Quizplus · Accepted Answer

11ec193a_9644_2ab3_853d_1388a9a667f6_MD0002_00 This patient with recent travel to Sub-Saharan Africa has an acute-onset febrile illness, scleral icterus, mild splenomegaly, anemia, and thrombocytopenia. This presentation is most consistent with malaria. Plasmodium falciparum accounts for the majority of deaths from malaria, followed by Plasmodium vivax. Many of the clinical symptoms seen in malaria are due to the infected parasite-containing red blood cells adhering to nearby vessels, causing small infarcts, leakage of capillaries, and, ultimately, organ dysfunction. Diagnosis is confirmed with examination of a peripheral blood smear looking for trophozoites. peripheral blood smear Commonly used malaria prophylaxis drugs (eg, chloroquine, mefloquine, and doxycycline) target the blood stage of the parasite (blood schizonticides) when released from the liver. Tissue schizonticides (eg, atovaquone/proguanil) are designed to target the liver stage, where the parasites grow and can stay dormant in the liver (or other tissues). The blood schizonticides must be continued for at least 4 weeks after leaving an endemic area to ensure eradication of parasites released from the liver. This patient did take doxycycline for malaria prophylaxis but discontinued his medication on return to the United States, causing it to be ineffective. (Choice A) Blood culture is of limited utility in the diagnosis of malaria as the organism cannot be cultured in traditional media. For bacterial infections such as salmonellosis (typhoid fever), fungal infection, and meningococcemia, blood cultures would be an appropriate diagnostic test. (Choice B) In the absence of meningeal signs (eg, neck stiffness and rash) lumbar puncture is less helpful. (Choice D) Acute viral hepatitis can cause jaundice and right upper-quadrant pain but would not result in anemia and splenomegaly. (Choice E) Stool sample for ova and parasites would be helpful for infections such as schistosomiasis, but this patient did not drink fresh water or swim during his travels. The lack of eosinophilia argues against this testing. Educational objective: Malaria should be considered in a traveler returning from an endemic area who has acute febrile illness, anemia, splenomegaly, and jaundice. Persons who have received inadequate prophylaxis are at risk. Identification of the parasite on peripheral blood smear can establish the diagnosis. __________ References: Spectrum of disease and relation to place of exposure among ill returned travelers. (http://www.ncbi.nlm.nih.gov/pubmed/16407507) Imported malaria. clinical presentation and examination of symptomatic travelers. (http://www.ncbi.nlm.nih.gov/pubmed/7717795) Fever after a stay in the tropics. diagnostic predictors of the leading tropical conditions. (http://www.ncbi.nlm.nih.gov/pubmed/17220752)

A 24-Year-Old Man Comes to the Emergency Department After 1