The CDC informs that it has received twelve reports of humans infected with swine flu – A(H3N2) virus. Reported cases have come in from West Virginia, Pennsylvania, Maine, Iowa, and Indiana. Eleven of them were children. Half of all the cases had not been exposed to swine, the CDC (Centers for Disease Control and Prevention) adds. All patients have made a full recovery; three had to be admitted to hospital.

One of the patients, an adult male, had been exposed to swine through his job.

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Indiana, West Virginia, and other states have had reported swine flu cases.

An adult male was reported on October 28th this year by the Indiana Dept of Health as having likely A(H2N2) virus infection. His symptoms included body aches, vomiting, nausea, shortness of breath, cough, and fever – which started appearing on October 20th. He was admitted to hospital and stayed there for four days. He was not treated with flu antiviral drugs and made a full recovery.

A sample of mucus taken from the patient came back positive for influenza, according to a hospital pathologist. The virus was identified by rRT-PCR (real-time, reverse transcription-polymerase chain reaction) as an inconclusive influenza A virus by the Indiana Public Health Laboratory. This is consistent with other A(H3N2)v infection lab results. The genome sequencing was confirmed by the CDC on October 30th as being of an “A(H3N2)v virus with the M gene from the A(H1N1)pdm09 virus” – this is similar to the ones detected in other human infections in the USA in 2011 (August).

The male said he had been in direct contact with pigs during the week before his symptoms appeared. He reported not having worn any PPE (personal protective equipment) because the swine appeared healthy. None of his family members or close friends and working colleagues became infected.

A small child (under 5) developed flu-like symptoms, including an elevated body temperature on November 19th – this was preceded by a week of congestion and coughing. Initial tests did not detect influenza or respiratory syncytial virus, however, an alternative rRT-PCR test carried out at the hospital identified influenza A.

The sputum sample was sent on to the West Virginia Office Laboratory Services, which identified the influenza A(H3N2)v virus. Genome sequencing done at the CDC confirmed that it was an “A(H3N2)v virus with the M gene from the A(H1N1)pdm09 virus”. The child had neither been exposed to pigs nor travelled recently. On 21st November, the patient was discharged from hospital and made a full recovery.

Health authorities investigated whether anybody who had come into contact with the child between 9th and 19th December had been ill with respiratory illness. Several children had respiratory infections during this time. A second child (under 5) became ill on November 29th – this child went to the same day care center as the other infected one; this child had not travelled recently, and had had no contact with swine. The second kid developed symptoms of rhinorrhea, diarrhea, cough and fever. The parents did not seek medical help, and he/she made a full recovery at home. A specimen of mucus was collected on 7th December and came back inconclusive by the West Virginia Office of Laboratory Service (by rRT-PCR). A(H2N1)v with the M gene from the A(H1N1)pdm09 virus via genome sequencing at CDC was subsequently confirmed.

Nobody else who came into contact with the two patients recently have developed A(H3N2) infections, authorities inform.

The CDC, in a communiqué, wrote:

“Enhanced surveillance for influenza-like illness and increased diagnostic testing of respiratory specimens is being conducted in West Virginia and adjacent counties in Maryland as part of the ongoing investigation of these cases. Currently, no evidence of additional human-to-human transmission in the community has been identified.”

Swine influenza virus (SIV) surveillance is supervised by the USDA, mainly in pigs that show flu-type illness.

The CDC wrote:

“In July 2009, USDA’s Animal and Plant Health Inspection Service and the swine industry implemented a SIV surveillance program* to characterize the distribution of SIV in U.S. swine herds. To date, approximately 150 SIV isolates have undergone sequencing of three genes (hemagglutinin, matrix, and neuraminidase gene segments) and sequences have been submitted to GenBank.

Thirty isolates have been identified as A(H3N2) viruses and eight of those 30 have the M gene from the influenza A (H1N1)pdm09 virus as determined by an informal analysis of GenBank submission data by the USDA Agricultural Research Service. Further characterization and analysis are ongoing, and new submissions are added as diagnostic work is completed.”

Written by Christian Nordqvist