Respiratory viruses (influenza, RSV, parainfluenza) — MCQs

A 6-month-old infant is brought to the physician’s office by his parents due to a fever, cough, and shortness of breath. The cough is dry and has been progressively worsening for the past 48 hours along with the shortness of breath. His fever never exceeded 37.8°C (100.0°F) at home. The parents say that he has also had abundant nasal drainage and loss of appetite. He is irritable and vomited twice during this period. He has no relevant medical or family history. His vitals are the following: Pulse rate 165/min Respiratory rate 77/min Temperature 38.0°C (100.4°F) On physical examination, there is nasal congestion with thick secretions, accompanied by nasal flaring. On chest examination, intercostal retractions are seen and diffuse wheezing on both sides are heard on auscultation. What is the most likely cause?

A 2-year-old boy is brought to the physician by his parents for the evaluation of an unusual cough, a raspy voice, and noisy breathing for the last 2 days. During this time, the symptoms have always occurred in the late evening. The parents also report that prior to the onset of these symptoms, their son had a low-grade fever and a runny nose for 2 days. He attends daycare. His immunizations are up-to-date. His temperature is 37.8°C (100°F) and respirations are 33/min. Physical examination shows supraclavicular retractions. There is a high-pitched breath sound on inspiration. Which of the following is the most likely location of the abnormality?

A 72-year-old man comes to the physician with chills, nausea, and diffuse muscle aches for 3 days. His niece had similar symptoms 2 weeks ago and H1N1 influenza strain was isolated from her respiratory secretions. He received his influenza vaccination 2 months ago. His temperature is 38°C (100.4°F). A rapid influenza test is positive. Which of the following mechanisms best explains this patient's infection despite vaccination?

A 61-year-old man presents to the family medicine clinic with a worsening cough for the last week. He denies hemoptysis, sputum production, shortness of breath, or upper respiratory tract symptoms. He does endorse nausea and heartburn after he eats large meals, as well as an occasional metallic taste in his mouth throughout the day. He has been diagnosed with hypertension and osteoarthritis, for which he takes lisinopril and aspirin. He has smoked half a pack of cigarettes per day since he was 20 years old. Three years ago, he had his second colonoscopy performed with normal results. His heart rate is 76/min, respiratory rate is 16/min, temperature is 37.3°C (99.2°F), and blood pressure is 148/92 mm Hg. He exhibits signs of truncal obesity. Heart auscultation reveals wide splitting of S2. Auscultation of the lungs is clear, but wheezing is noted on forced expiration. Which of the following is recommended for the patient at this time?

An investigator studying viral replication isolates the genetic material of an unidentified virus strain. After exposing a cell culture to the isolated, purified viral genetic material, the cells begin to produce viral polymerase and subsequently replicate the viral genome. Infection with the investigated strain is most likely to cause which of the following conditions?

A 3-year-old boy presents to an urgent care clinic with his mother. She states that his behavior has been lethargic for the past 3 days. She also notes that he has had a runny nose, mild cough, and sore throat during this time. She does not believe that he has been febrile. His temperature is 99.1°F (37.2°C), blood pressure is 105/67 mmHg, pulse is 100/min, respirations are 18/min, and SpO2 97% on room air. Which nucleic acid structure most accurately describes the most likely virus responsible for this boy’s clinical condition?

A 7-month-old infant with Tetralogy of Fallot is brought to the emergency department by her parents because of a 1-day history of fever, cough, and difficulty breathing. She was born at 29 weeks of gestation. Her routine immunizations are up-to-date. She is currently in the 4th percentile for length and 2nd percentile for weight. She appears ill. Her temperature is 39.1°C (102.3°F). Physical examination shows diffuse wheezing, subcostal retractions, and bluish discoloration of the fingertips. Administration of which of the following would most likely have prevented this patient's current condition?

A scientist is studying the influenza A virus. He focuses on two strains – one from humans (H7N1) and one from horses (H3N8). He takes cells from chickens and coinfects these cells with both influenza strains. From these chicken cells, the scientist isolates a new strain and finds that this new strain can infect human cells. He further characterizes the new strain’s hemagglutinin and neuraminidase description as H7N8. What term best describes the process that underlies these experimental results?

A scientist performed an experiment to produce hybrid viruses by mixing two different serotypes of influenza virus, H1N1 and H2N2, in a respiratory epithelium cell line. Several days later, the scientist collected the media and analyzed the viral progeny. She found the following serotypes of virus: H1N1, H2N2, H1N2, and H2N1. Which of the following terms best explains the appearance of new serotypes?

An investigator studying influenza virus variability isolates several distinct influenza virus strains from the respiratory secretions of a study subject. Mass spectrometry analysis of one strain shows that it expresses neuraminidase on its surface. Subsequent sequencing of this strain shows that its genome lacks the neuraminidase gene. Which of the following is the most likely explanation for this finding?