Hospitalized H3N2v Cases Identify Community Transmission
September 3, 2012
On November 19, a child aged <5 years developed acute onset of fever after 1 week of cough and congestion. The child had been hospitalized for an unrelated condition 2 days before the onset of fever.
Lake County Deputy Health Commissioner Ron Graham said a child was recently hospitalized for a short time, but recovered and is back home.
The above MMWR comment (in red) describes “patient zero” (1F) for the current H3N2v pandemic. As noted, she was hospitalized for an unrelated condition and the initial influenza rapid test was negative. However, a subsequent rRT-PCR test was positive and the sample was forward to the West Virginia Office of Laboratory Services (WV-OLS) confirmed the PCR test with the CDC RT-PCR test which suggested the patient was H3N2v infected. The CDC confirmed H3N2v via sequencing (A/West Virginia/06/2011).
The confirmation led to an epidemiological study which noted that 23 of the 70 contacts had influenza-like illness. One sample was sent to the WV-OLS where the patient (3M) was influenza A positive (see graph), but the H3 and NP tests were negative. However, the sample was forwarded the to CDC where partial sequences (A/West Virginia/07/2011) were obtained for 3 gene segments (HA 230/1701, NA 760/1410, MP 381/982).