A 6-week-old infant born at 36 weeks gestation is hospitalized with paroxysms of cough followed by gasping and cyanosis due to Bordetella pertussis. His white blood cell count is 94,000/μL with 80% lymphocytes, and his platelet count is 782,000/μL. He develops progressive respiratory failure and cardiogenic shock. Which pathophysiologic process is most strongly associated with this severe clinical course and fatal outcome?
A 6-year-old boy from Arkansas is hospitalized with a 5-day history of high fever, headache, and myalgias. Laboratory tests reveal leukopenia, thrombocytopenia, and elevated liver transaminases. A peripheral blood smear shows morulae within monocytes. In addition to multisystem organ failure, what specific severe syndrome is known to be precipitated by this infection?
A neonate is born to a mother who was diagnosed with rubella at 9 weeks of gestation. The infant presents with cataracts, a heart murmur consistent with patent ductus arteriosus, and is found to have hearing loss. What is the underlying pathogenic mechanism that best explains the severe and widespread defects seen in congenital rubella syndrome?
A family is planning a trip to a forested region of South America where yellow fever is endemic. Their children are 8 months old and 4 years old. Which of the following is a recognized contraindication for the administration of the live-attenuated yellow fever 17D vaccine?
A 4-year-old boy in a daycare center develops high fever, abdominal cramps, and frequent, small-volume bloody stools. A diagnosis of shigellosis is made. Which of the following extraintestinal manifestations is most characteristic of Shigella infection compared to other common bacterial enteritides?
An 8-year-old girl returns from a rural mission trip to Thailand and presents with a 10-day history of high fever, generalized lymphadenopathy, and headache. On her ankle, there is a single, painless eschar with an erythematous rim. Given that some strains in this region may have reduced susceptibility to doxycycline, which of the following has been shown to be an effective alternative therapy?
A 16-year-old male presents with fever and painful, unilateral testicular swelling. He was diagnosed with mumps parotitis 5 days ago. His parents are concerned about the risk of sterility. Which statement accurately reflects the prognosis of mumps orchitis?
A 17-year-old male presents to the emergency department with a 5-day history of fever and myalgia, followed by the rapid onset of cough, dyspnea, and hypoxia. He was recently camping in New Mexico. His chest x-ray shows diffuse bilateral pulmonary edema. Laboratory evaluation reveals a WBC of 26,000 cells/μL with immunoblasts but no toxic granulation, an elevated hematocrit of 62%, and a platelet count of 64,000 cells/μL. Which laboratory finding has the highest sensitivity for differentiating Hantavirus Pulmonary Syndrome from other causes of acute respiratory distress syndrome??
A 7-year-old child in a refugee camp develops profuse, painless, “rice-water” stools and rapidly becomes severely dehydrated. The causative agent is Vibrio cholerae. The massive secretory diarrhea seen in this disease is a direct result of which specific molecular action of the cholera toxin?
A 9-year-old boy living in Connecticut presents with a markedly swollen but only mildly painful right knee for the past month. He was diagnosed with Lyme arthritis and completed a 28-day course of oral doxycycline. Despite this, the knee effusion persists. Physical examination is otherwise unremarkable. What is the next most appropriate step in management?
