A pseudo-outbreak of influenza A associated with use of laboratory stock strain

Area of Science:

• Virology
• Infectious Diseases
• Laboratory Diagnostics

Background:

• Influenza A(H1N1) viruses were reportedly isolated from hospitalized patients in New Mexico in November 1982.
• These isolates occurred during a period when influenza A(H3N2) viruses were prevalent in the United States.
• Only two of the ten patients exhibited influenza-like illnesses, suggesting atypical presentation.

Purpose of the Study:

• To investigate the source of unexpected influenza A(H1N1) virus isolates.
• To determine if the reported isolates represented a true clinical outbreak or an alternative explanation.
• To emphasize the need for vigilance regarding laboratory procedures in virological diagnostics.

Main Methods:

• Retrospective analysis of reported influenza A(H1N1) isolates.
• Investigation into the laboratory's diagnostic procedures and reagents.
• Examination of the reference stock influenza A/Fort Monmouth (FM)/1/47(H1N1) virus used for fluorescent antibody test slides.

Main Results:

• The influenza A(H1N1) isolates from patients were determined to be a result of laboratory contamination.
• The reference stock virus, influenza A/Fort Monmouth (FM)/1/47(H1N1), was implicated in the contamination.
• The findings underscore a potential for misidentification of viral agents due to laboratory error.

Conclusions:

• Laboratory contamination can lead to spurious identification of viral agents.
• When encountering unexpected clusters of unusual virus isolates, laboratory contamination must be considered as a potential cause.
• Rigorous quality control in diagnostic laboratories is crucial for accurate influenza surveillance.