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#12,785
The swine variant flu outbreak connected to three county fairs in Maryland (see here, here, and here) continues to expand with both the Maryland Department of Health and the CDC reporting this morning a total of 32 presumptive and confirmed cases.
According to today's FluView Report, 14 cases have been fully identified as H3N2v, while an additional 18 cases have tentatively been identified as H3v (variant) influenza.With 34 fully identified cases thus far in 2017, and 18 more in the pipeline, 52 cases this year will easily make this the second biggest reporting year for swine variant flu in the United States.
Given the aggressive ongoing epidemiological investigation, it would not be unexpected to see additional cases to turn up over the next week or so.This report from today's FluView.
Novel Influenza A Virus:
Thirty-two human infections with novel influenza A viruses were reported by two states (Delaware [1] and Maryland [31]). Fourteen of these viruses have been fully characterized and are influenza A (H3N2) variant (H3N2v) viruses; the remaining 18 viruses have tested presumptive positive for H3v at the Maryland public health laboratory and further confirmatory testing is being performed by CDC to characterize these viruses.
All 32 patients reported exposure to swine at one of three agricultural fairs during the week preceding illness onset. Swine influenza A(H3N2) viruses were identified from respiratory samples collected from pigs at two of the three fairs. The exposure to swine at the agricultural fair reported by the Delaware resident occurred at one of the agricultural fairs in Maryland.
Thirty of the 32 patients were children younger than 18 years and two patients were adults aged > 50 years. One of 32 patients was hospitalized but is improving. All other patients are recovering or have fully recovered from their illness. No human-to-human transmission of these viruses has been identified.
To date, CDC has confirmed a total of 34 variant virus infections in the United States during 2017. Thirty-two of these were H3N2v viruses (Delaware [1], Maryland [13], North Dakota [1], Ohio [15], Pennsylvania [1], and Texas [1]) and two were influenza A (H1N2) variant (H1N2v) viruses (Ohio [2]). An additional 18 viruses have tested presumptive positive for H3v and further analysis is being conducted at CDC (Maryland [18]).
Early identification and investigation of human infections with novel influenza A viruses are critical to ensure timely risk assessment and so that appropriate public health measures can be taken. Additional information on influenza in swine, variant influenza infection in humans, and strategies to interact safely with swine can be found at http://www.cdc.gov/flu/swineflu/index.htm.
H3N2v is the most common swine variant virus reported in the United States, but is far from the only swine flu virus of concern. Co-circulating in North America are also H1N1 and H1N2 swine viruses, along with occasional reassortants like H3N1 (see J. Virol: Novel Reassortant Human-like H3N2 & H3N1 Influenza A Viruses In Pigs).
Globally the picture becomes even more complicated, with reports of other swine flu variants coming from Europe, South America, and Asia. As surveillance and testing is spotty at best, the constellation of of swine flu viruses in circulation is likely much larger and more complex than we know.Earlier today, in WHO: Candidate Vaccines For Pandemic Preparedness - Sept 2017, we looked at recommendations from the World Health Organization for the creation of 3 new candidate vaccine viruses (CVVs); 2 for H1N2v and 1 for H3N2v.
It may be a few weeks before we learn exactly how well these Maryland H3N2v viruses match the existing and proposed H3N2v vaccine candidates.
