Recombinomics: Swine H1N1 In Southern California Children Raise Concerns

Commentary

Recombinomics Commentary 01:27
April 22, 2009

Patient A. On April 13, 2009, CDC was notified of a case of respiratory illness in a boy aged 10 years who lives in San Diego County, California. The patient had onset of fever, cough, and vomiting on March 30, 2009.

The patient's mother had respiratory symptoms without fever in the first few days of April 2009, and a brother aged 8 years had a respiratory illness 2 weeks before illness onset in the patient and had a second illness with cough, fever, and rhinorrhea on April 11, 2009.

patient B, is a girl aged 9 years who resides in Imperial County, California, adjacent to San Diego County. On March 28, 2009, she had onset of cough and fever (104.3°F [40.2°C]).

The patient's brother aged 13 years had influenza-like symptoms on April 1, 2009, and a male cousin aged 13 years living in the home had influenza-like symptoms on March 25, 2009, 3 days before onset of the patient's symptoms.

The above comments from today’s MMWR dispatch describe two children in southern California infected with H1N1 swine flu. The isolates are similar and have an unusual constellation of genes. Although all 8 are reported as being swine, the NA and MP sequences are European, while the other 6 gene segments are North American. The HA, NA, and MP sequences of A/California/04/2009 have been placed on deposit at GISAID.

The lack of contact between the two children, as well as a lack of contact with swine, suggests the virus is spreading human to human. Although both children recovered, the presence of swine H1N1 in humans raises concerns of recombination with H1N1 seasonal flu, including the acquisition of H274Y.

Moreover, the 1918 pandemic strain was a recombinant between human H1N1 and swine H1N1.

The likely ability of this swine H1N1 to transmit efficiently in humans is cause for concern.
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