During this summer’s outbreak of H3N2v swine-origin influenza that infected at least 305 people across 10 states, only Indiana (n=138) reported more cases than did Ohio (n=106).
Today the CDC’s MMWR presents an overview of 11 patients from Ohio that required hospitalization, which represents nearly 70% of all those hospitalized with the virus across the country, and the nation’s only H3N2v related fatality.
It’s a long report, providing extended case histories on two of the patients (including the fatality), and providing (via a chart) basic information on all 11 cases – including likely route of exposure.
Of the 11 cases reported on, only one did not report direct or indirect exposure to swine; a 6 year old that reportedly had:
No contact. No attendance at fairs. Saw grandmother on Aug 23, who works with horses on a farm where pigs are also kept. Grandmother had no recent illness. No known illness in pigs.
Follow the link to read it in its entirety, but I’ve posted a few excerpts.
WeeklySeptember 28, 2012 / 61(38);764-767
Since July 2012, 305 cases of infection with influenza A (H3N2) variant (H3N2v) virus containing the influenza A (H1N1)pdm09 M gene have occurred in multiple U.S. states, primarily associated with swine exposure at agricultural fairs (1). In Ohio, from July 28 to September 25, 2012, a total of 106 confirmed H3N2v cases were identified through enhanced surveillance. Whereas most H3N2v patients experienced mild, self-limited influenza-like illness (ILI), 11 of the Ohio patients were hospitalized, representing 69% of all H3N2v hospitalizations in the United States. Of these hospitalized H3N2v patients, six were at increased risk for influenza complications because of age or underlying medical conditions, including the only H3N2v-associated fatality reported in the United States to date. This report summarizes the epidemiology and clinical features of the 11 hospitalized H3N2v patients in Ohio. These findings reinforce the recommendation for persons at high risk for influenza complications to avoid swine exposure at agricultural fairs this fall (2). In addition, persons not at high risk for influenza complications who wish to reduce their risk for infection with influenza viruses circulating among pigs also should avoid swine and swine barns at agricultural fairs this fall.
Patient A. A woman aged 61 years with type 2 diabetes, congestive cardiomyopathy, hypertension, and a past history of B-cell lymphoma, experienced cough and sneezing on August 10 (Table, patient 11). Beginning 6 days earlier, she spent 4 days at a county fair where she visited a swine barn and had direct swine contact. Over the next 2 weeks, she experienced cough and fever and was treated with antibiotics for a sinus infection. On August 25, she sought care at an emergency department with worsening symptoms. The patient was transferred to a tertiary care center with hemodynamic instability and respiratory distress, and required mechanical ventilation. Her condition deteriorated, and she died on August 26. Blood cultures obtained on August 25 yielded Pseudomonas aeruginosa, and a nasopharyngeal swab was positive for H3N2v virus by rRT-PCR at ODH. Genetic sequencing of H3N2v virus from a clinical specimen from this patient at CDC was nearly identical to sequencing from several nonfatal H3N2v cases in Ohio, and from H3N2pM* viruses identified among pigs at fairs in Ohio.
The MMWR report provides a summary of the findings, which reads:
What is already known on this topic?
Beginning in the summer of 2012, CDC reported increases in numbers of cases of human infections with influenza A (H3N2) variant (H3N2v) viruses associated with swine exposure at agricultural fairs. Nationwide, 305 cases, 16 hospitalizations, and one death across 10 states have been reported since July 2012.
What is added by this report?
Of 16 patients hospitalized with confirmed H3N2v virus infection, 11 were Ohio residents, including the only H3N2v-associated fatality to date. All but one of the Ohio patients were children, and six were considered high-risk for complications of influenza because they were aged <5 years or had underlying medical conditions; four high-risk persons became ill after indirect contact with pigs. These findings support current CDC recommendations that persons at high risk for complications of influenza should avoid exposure to swine at agricultural fairs this fall.
What are the implications for public health practice?
County and state fairs in the United States continue to occur through the month of October, highlighting the potential for continued cases of H3N2v virus infection. Persons at high risk for complications of influenza should avoid exposure to swine at agricultural fairs. Patients with suspected influenza, including H3N2v, who are hospitalized or at increased risk for influenza complications, should receive antiviral treatment with oral oseltamivir or inhaled zanamivir as soon as possible. Antiviral treatment also is encouraged for outpatients with suspected H3N2v who are not at increased risk for influenza complications.