Flu turns severe in U.S., Chattanooga area; young, middle-age adults at greater risk


The CDC recommends vaccination for anyone 6 months or older. Several versions of the vaccine are available including a new vaccine that protects against four flu strains. Traditional vaccines guard against three strains.For the uninsured, the Chattanooga-Hamilton County Health Department is offering influenza shots free of charge to people ages 19-64.No appointment is necessary. Learn more at health.hamiltontn.org/.

photo CDC Clinic chief nurse Lee Ann Jean-Louis extracts influenza virus vaccine from a 5 ml. vial.

Youth appears to be no match for the flu this year.

The influenza strain known as H1N1 has resurged as the predominant strain of influenza circulating in the Chattanooga area and across the nation this season -- meaning young and middle-age adults are far more vulnerable to the illness than they typically are.

Local health officials say their concern is not so much the number of cases they are seeing, but the severity of the strains they are treating.

"What our providers are seeing are reports of severe illness, particularly in young and middle-age adults," said Nettie Gerstle, communicable disease program manager for the Chattanooga-Hamilton County Health Department.

"These are often the people who don't get vaccinated, who say, 'I never get the flu.' They are young, they don't have a chronic illness. But that is not necessarily a safe mindset -- especially this year."

At least one of the influenza-related cases has proven fatal, although other factors may have been at play.

"We are aware of one adult patient who came to Erlanger with respiratory distress, who tested positive for influenza, and who later died," said Erlanger spokeswoman Pat Charles.

The Chattanooga-Hamilton County Health Department only tracks the number of flu-related deaths of children, so county officials could not report whether there had been any more flu-related deaths at area hospitals. No children have died of the flu here this year.

H1N1, also known as swine flu, made headlines during a 2009 global pandemic. The virus is less discriminating than other strains of the flu that typically afflict children and the elderly. Along with younger people, pregnant women are also particularly susceptible to the H1N1 virus.

The strain is included in both flu vaccines being offered this year, so those who are contracting the illness are typically those who were not vaccinated, Gerstle said.

The U.S. Centers for Disease Control and Prevention already has reported that the Southeast has been hit especially hard by the virus this year.

The number of states reporting "widespread" seasonal flu activity rose from four to 10 last week, and Alabama was included in that list. Tennessee and Georgia have both reported "moderate" flu activity this year, the CDC reported.

photo This picture provides a 3D graphical representation of a generic influenza virion's ultrastructure, and is not specific to a seasonal, avian or 2009 H1N1 virus. There are three types of influenza viruses: A, B and C. Human influenza A and B viruses cause seasonal epidemics of disease almost every winter in the United States. The emergence of a new and very different influenza virus to infect people can cause an influenza pandemic. Influenza type C infections cause a mild respiratory illness and are not thought to cause epidemics. Influenza A viruses are divided into subtypes based on two proteins on the surface of the virus: the hemagglutinin (H), and the neuraminidase (N). There are 16 different hemagglutinin subtypes and 9 different neuraminidase subtypes. Influenza A viruses can be further broken down into different strains. Current subtypes of influenza A viruses found in people are influenza A (H1N1) and influenza A (H3N2) viruses. In the spring of 2009, a new influenza A (H1N1) virus emerged to cause illness in people. This virus was very different from regular human influenza A (H1N1) viruses and the new virus has caused an influenza pandemic. Influenza B viruses are not divided into subtypes. Influenza B viruses also can be further broken down into different strains.

The graphs tracking influenza-like illnesses in Hamilton County continued to climb higher into the hundreds the last week of the year, with more than 600 cases of flulike symptoms now counted by local providers.

Since Nov. 1, Parkridge Medical Center alone has reported a total of 136 flu diagnoses. During the same period in 2012, the hospital only had 59 diagnoses of flu, Parkridge spokeswoman Alison Counts said.

At Erlanger Health System, 123 flu diagnoses have been reported since the week of Nov. 30, with cases escalating each week, a trend Charles said was "fairly standard" for the hospital this time of year.

Health department officials stressed that flu season is far from over. While it peaks at different times each year, the span of the season can run from September to May.

"We're urging people to get vaccinated, because the risk is still there," Gerstle said.

Contact staff writer Kate Harrison at kharrison @timesfreepress.com or 423-757-6673.