A 34-year-old man comes to the emergency department due to headaches, fatigue, and fever. He developed intense chills with shivering, followed a few hours later by high-grade fevers and then profuse sweating. A few days ago, the patient experienced similar symptoms that seemed to resolve. He and his wife returned from a safari in Kenya 2 weeks ago. His wife had diarrhea during the trip but has had no symptoms since their return. The patient has no known medical problems and takes no medications. He lives in Seattle and works as a business consultant. He did not go to a travel clinic prior to this trip. The patient was vaccinated against yellow fever 5 years ago but has received no other vaccinations recently. While in Kenya, he wore long-sleeved clothing, used insect repellent, and did not drink unbottled water or eat uncooked food. His temperature is 38.9 C (102 F), blood pressure is 100/60 mm Hg, pulse is 114/min, and respirations are 18/min. Conjunctival pallor is present. There is no neck stiffness. The rest of his physical examination, including neurologic examination, is unremarkable. Laboratory results are as follows: What is the most likely diagnosis in this patient?

Question

A 34-year-old man comes to the emergency department due to headaches, fatigue, and fever.  He developed intense chills with shivering, followed a few hours later by high-grade fevers and then profuse sweating.  A few days ago, the patient experienced similar symptoms that seemed to resolve.  He and his wife returned from a safari in Kenya 2 weeks ago.  His wife had diarrhea during the trip but has had no symptoms since their return.  The patient has no known medical problems and takes no medications.  He lives in Seattle and works as a business consultant.  He did not go to a travel clinic prior to this trip.  The patient was vaccinated against yellow fever 5 years ago but has received no other vaccinations recently.  While in Kenya, he wore long-sleeved clothing, used insect repellent, and did not drink unbottled water or eat uncooked food.  His temperature is 38.9 C (102 F), blood pressure is 100/60 mm Hg, pulse is 114/min, and respirations are 18/min.  Conjunctival pallor is present.  There is no neck stiffness.  The rest of his physical examination, including neurologic examination, is unremarkable.  Laboratory results are as follows:  What is the most likely diagnosis in this patient?

Quizplus · Accepted Answer

11ec25c8_d460_4b69_bc81_2fc7da723f67_MD0003_00 This returning traveler has classic manifestations of malaria, a protozoal disease caused by Plasmodium (red blood cell [RBC] parasite transmitted by Anopheles mosquitoes). The hallmark is cyclical fever, coinciding with Plasmodium-induced RBC lysis. The typical cycle (uncommon) consists of a cold phase (chills, shivering), then a hot phase (high-grade fevers), then a sweating stage (diaphoresis, fever resolution). Headache, malaise, myalgias, vomiting, and diarrhea are often seen. Anemia and thrombocytopenia are classic. Blood smears are the diagnostic gold standard. Long-sleeved clothing, insect repellent, and insecticide-treated bed nets can be somewhat protective; however, most returning travelers who have malaria did not adhere to chemoprophylaxis. Treatment regimens depend on the species and severity of infection. (Choice A) Babesiosis, also caused by a tick-transmitted RBC parasite, has a similar presentation to malaria but is more commonly seen in the northeastern and midwestern United States. This patient's recent trip to sub-Saharan Africa makes malaria more likely. (Choice B) Mosquito-borne dengue fever can present with fever and headache. However, symptoms typically develop 4-7 days (and almost never >2 weeks) following the mosquito bite and classically include marked muscle and joint pains, retroorbital pain, rash, and leukopenia (diagnostically useful). (Choices C and D) Giardiasis can have acute and chronic gastrointestinal manifestations (eg, diarrhea, bloating, malabsorption, lactose intolerance). However, high-grade fevers, headaches, and anemia are unlikely. Common findings in hepatitis A infection (incubation period ~30 days) include fever, jaundice, hepatomegaly, dark urine, acholic stools, and pruritus. (Choice E) In East Africa, human African trypanosomiasis (sleeping sickness), transmitted by tsetse flies, causes an acute febrile illness with a skin lesion (trypanosomal chancre), myocarditis, and progression to central nervous system involvement. A more chronic form with similar manifestations evolving over years is seen in West Africa due to infection by a different trypanosomal species. (Choices G and H) Meningitis can present with fever and headache, but patients typically have signs of meningeal irritation (eg, neck stiffness, photophobia) with rapid neurologic decline if left untreated. Although headache is common in typhoid fever, gastrointestinal symptoms would likely also be seen, and salmon rose spots and relative bradycardia are classic associations. Educational objective: Malaria is a very common cause of fever in the returning traveler. Classic findings include cyclical fever with nonspecific constitutional and gastrointestinal manifestations, anemia, and thrombocytopenia. References: Treatment of malaria in the United States: a systematic review. (http://www.ncbi.nlm.nih.gov/pubmed/17519416)

A 34-Year-Old Man Comes to the Emergency Department Due to Headaches