Researchers publish epidemiologic description of Milwaukee swine flu outbreak
June 17, 2009 College News - Researchers at The Medical College of Wisconsin published the first initial paper describing the Milwaukee prevalence of the largest outbreak of novel swine origin influenza virus (S-OIV) in America in the June 11, 2009, online issue of Viruses. This corresponded to the announcement by World Health Organization of the first influenza pandemic in 41 years.
Beginning April 17, 2009, increased numbers of novel swine origin influenza A (H1N1) virus (S-OIV) cases began appearing in the United States. As part of a rapid clinical and public health response, the Medical College and its two affiliated teaching hospitals – Children’s Hospital of Wisconsin (CHW) and Froedtert Hospital – established full genetic subtyping of all influenza A viruses identified in patient samples sent to the respective clinical laboratories. Froedtert Hospital’s testing is performed by Dynacare Laboratories.
The Medical College’s Midwest Respiratory Virus Program (MRVP) used its newly developed multiplex, rapid diagnostic testing for influenza, to subtype all influenza A samples obtained during the 16-week period prior to April 28 and the first four weeks of the subsequent pandemic.
“Continued rapid local surveillance in Milwaukee should help define important epidemiologic and virologic characteristics during the early phase of this pandemic to help facilitate current and future public health responses,” said Kelly J. Henrickson, MD, Professor of Pediatrics and Microbiology and Molecular Genetics.
During the first four weeks of the epidemic, 679 of 3,726 (18.2 percent) adults and children tested for influenza A were identified with S-OIV infection. S-OIV was confirmed on day two of instituting subtype testing and within four days of reports of national cases of S-OIV. Of the 2,678 children and adolescents from whom respiratory specimens were obtained, 598, or 22.3 percent, were positive for influenza A. Of these 598 children and adolescents, 589 or 98.5 percent, identified as S-OIV. During the same four week period, 94 of 1,048 adults, or 8.9 percent, tested positive for influenza A, with 90, or 95.7 percent, having S-OIV.
Dr. Henrickson, who directs the MRVP and practices at Children’s Hospital, and other researchers at other institutions have developed a number of multiplex, rapid, diagnostic tests for respiratory viruses and pneumonia agents including complete influenza subtyping assays. The genetic tests can identify the majority of human and animal influenza strains and can distinguish between sub types such as H1N1, H3N2, H5N1, H7N2, and H9N2.
In response to the federal government's high priority for accelerated research to combat bird flu and bioterrorism, the Medical College and Dr. Henrickson have been awarded five grants and subcontracts totaling more than $12 million from the National Institutes of Health (NIH) and Centers for Disease Control and Prevention (CDC) to develop rapid diagnostic devices to test for avian flu and the majority of potential bioterrorism agents.
The Medical College and Children's Research Institute participated in carrying out the work of these grants.
The test being offered by the MRVP has been approved by the Clinical Laboratory Improvements Act and awaits FDA approval.