Influenza B and influenza A(H3N2) viruses continue to circulate
throughout the United States. For the week ending February 1, 13
states* and the District of Columbia reported widespread outbreaks
of
influenza-like illness, and 18 states** reported regional
outbreaks.
The preceding week, five states reported widespread outbreaks, and
13
states reported regional outbreaks.
Although influenza B viruses are more prevalent, there is
evidence
of at least one mixed outbreak. Beginning January 14, an outbreak
of
influenza-like illness was observed among students seen at the
student
health center at North Carolina State University in Raleigh.
Influenza viruses were isolated from nine students tested from
January
19 to January 21; seven type B viruses and two type A(H3N2) were
identified. This is the first outbreak this season where both
virus
types B and A(H3N2) were isolated and raises the possibility of
co-circulation of these viruses in other outbreaks.
Influenza virus type A(H3N2) has been isolated from a
nursing-home
outbreak near Minneapolis-St. Paul, Minnesota, where approximately
33
(25%) of the 132 residents were ill between January 16 and January
28. Influenza type B viruses were isolated during the same week
from
two students in an outbreak of influenza-like illness at the high
school in the same community as the nursing home.
Several more states have recently reported their first
influenza
isolates of the season. West Virginia has reported influenza type
A(H3N2) virus; Maryland, Nebraska, and Rhode Island have reported
influenza type B virus; and Delaware, Kentucky, North Carolina, and
Ohio have reported both influenza type B and influenza type A(H3N2)
viruses. Forty-two states and the District of Columbia have now
reported influenza virus isolates this season. Thirty-eight states
and the District of Columbia have reported type B isolates; 21 have
reported type A(H3N2); and one, Hawaii, has reported type A(H1N1).
Tallies of patients with influenza-like illnesses seen by
sentinel
physicians nationwide continued to increase from an average of 7.6
for the reporting week ending January 15, to an average of 9.2 for
the
week ending January 22.
Pneumonia and influenza (P&I) deaths reported from the 121 U.S.
cities for the week ending February 1 represent 5.8% of total
deaths,
compared with 6.1% reported for the preceding week.
Reported by State and Territorial Epidemiologists; State Laboratory
Directors; R Meriwether, MD, Div of Health Svcs, North Carolina
Dept
of Human Resources; E Balkovic, PhD, G Hsiung, PhD, Virology
Laboratory, Veterans Administration Medical Center, West Haven,
Connecticut; J Braun, MPH, Minnesota Dept of Health; Statistical
Svcs
Br, Div of Surveillance and Epidemiologic Studies, Div of Field
Svcs,
Epidemiology Program Office, WHO Collaborating Center for
Influenza,
Influenza Br, Div of Viral Diseases, Center for Infectious
Diseases,
CDC.
*Colorado, Georgia, Idaho, Michigan, Minnesota, Nebraska, New
Hampshire, New Jersey, North Carolina, Oklahoma, Pennsylvania,
Washington, and West Virginia.
**California, Connecticut, Delaware, Illinois, Iowa, Kansas,
Kentucky,
Maryland, Mississippi, Missouri, Montana, Oregon, South Carolina,
South Dakota, Texas, Vermont, Virginia, and Wisconsin.
SCases reported by those members of the American Academy of Family
Physicians Research Panel who serve as sentinel physicians for
influenza.
Disclaimer
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