Question
Read the following clinical history and answer the following questions A 45 years old diabetic male was hospitalized in ICU isolation ward for the following complaints. High fever for two days, rapidly progressive sore throat, cough, dyspnoea and headache of one day duration. He gave history of returning from a country which was notified for the presence of a pandemic flu like disease. What is the most probable diagnosis. What specimen do you collect from the patient How do you transport it to laboratory How will you proceed with the specimen in the microbiology lab for the proper lab diagnosis. What is the role of vaccine in preventing this disease (1+1+2+4+2)
Answer
Most probable diagnosis: Pandemic influenza (e.g., pandemic H1N1 influenza A) — high fever, rapidly progressive sore throat, cough, dyspnoea, and headache in a diabetic patient (a high-risk comorbidity for severe disease) with recent travel from a country notified for a pandemic “flu-like” illness is classical.
Specimen to collect: nasopharyngeal and/or oropharyngeal swab (combined swab preferred for optimal yield); in patients with lower respiratory involvement/dyspnoea, a tracheal aspirate or bronchoalveolar lavage may additionally be collected.
Transport to laboratory: the swab is placed immediately into viral transport medium (VTM), which contains antibiotics/antifungals to suppress bacterial/fungal contamination and protein stabilizers to preserve viral viability; the specimen must be transported to the laboratory under a cold chain (2–8°C) as rapidly as possible (ideally within 24–48 hours); if longer delay is anticipated, the sample should be frozen at −70°C, since repeated freeze-thaw cycles degrade the virus. Given the pandemic-potential/high-risk nature of the suspected illness, appropriate biosafety precautions and triple packaging for transport are essential.
Laboratory processing for diagnosis:
- RT-PCR — the primary, most sensitive and specific diagnostic method, detecting viral RNA and allowing subtyping (e.g., confirming a novel/pandemic strain).
- Rapid antigen detection tests — point-of-care, less sensitive, used for rapid initial triage.
- Viral culture — in appropriate cell lines, with detection via cytopathic effect and haemadsorption; slower, mainly used for confirmation/further characterization in reference laboratories, and requires appropriate biosafety-level precautions given the pandemic-potential nature of a novel strain.
- Serology — paired acute/convalescent sera for retrospective confirmation, not useful for acute diagnosis.
Role of vaccine in prevention: influenza vaccination (inactivated or, where appropriate, live attenuated) — provides protection against seasonal and, when a matched pandemic strain vaccine is available/updated, pandemic influenza; particularly recommended for high-risk groups (as in this diabetic patient), healthcare workers, and the elderly; vaccine composition is reviewed and updated periodically (given antigenic drift) and, for a genuinely novel pandemic strain arising via antigenic shift, a specifically matched pandemic vaccine may need to be rapidly developed and deployed, since existing seasonal vaccines would not provide adequate cross-protection against a completely novel HA/NA combination.