Influenza update: Influenza activity continues to decline in
the
United States, as judged by reductions in the proportion of states
reporting outbreaks of influenza-like illness (Figure 3), the
number
of patients with influenza-like illness reported by family
physicians
(Figure 4), and laboratory reports of influenza virus isolations
(1).
In recent weeks, influenza type B has been more frequently
identified
than type A(H1N1), which had previously predominated.
Antigenic analysis of influenza type B viruses: Influenza type
B,
which has caused outbreaks in some countries in the Northern
Hemisphere this winter, including the United States, has generally
been poorly inhibited by animal sera to the B/Singapore/222/79
reference strain in hemagglutination-inhibition (HI) tests. A
spectrum of different reaction patterns has been observed with
recent
isolates (Table 4). Most isolates from the United States cannot be
distinguished in HI tests from B/USSR/100/83 and B/Norway/1/84,
although a few variants like B/Texas/1/84 are distinct.
Reported by State and Territorial Laboratory Directors and
Epidemiologists; Other Collaborating Laboratories; Physician
Reporters
of the American Academy of Family Physicians; Statistical Svcs Br,
Div
of Surveillance and Epidemiologic Studies, Epidemiology Program
Office, Computer Systems Office, Statistical Svcs Activity,
Influenza
Br, Div of Viral Diseases, Center for Infectious Diseases, ÐÇ¿ÕÓéÀÖ¹ÙÍø.
Reference
ÐÇ¿ÕÓéÀÖ¹ÙÍø. Update: influenza activity--United States. MMWR
1984;33:166-7.
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