AVIAN INFLUENZA H5N2, HUMAN - JAPAN (IBARAKI)(04)
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Date: Thu 12 Jan 2006
From: Akira Goto <dolphin@mail.ne.jp>


Avian Influenza (H5N2), Human, Interim Report of Serological Survey
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[Akira Goto writes: "Regarding the serological survey for antibodies
to avian influenza virus A(H5N2) in Ibaraki, Japan, the Ministry of
Health, Labour and Welfare of Japan has published an official press
release quoting an interim report from the National Institute of
Infectious Diseases, available in Japanese only at its web site.

The following is not a complete translation; merely, a synopsis
translated by the sender, which may contain translation errors."]

Date: Tue 10 Jan 2006
Source: Web site of the Ministry of Health, Labour and Welfare of Japan
<http://www.mhlw.go.jp/houdou/2006/01/h0110-4.html>


National Institute of Infectious Diseases. Interim Report on a
Serological Survey for [Human] Antibodies to the Highly [sic]
Pathogenic Avian Influenza Virus in Ibaraki and Saitama Prefectures,
10 Jan 2006.
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Object:
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[group 1a] - Chicken farm workers who had close contact with sick birds

[group 1b] - Local government staff who engaged in outbreak control operation

[group 2 ] (control) - Local government staff who did not engage in
outbreak control operation

Blood sampling:
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1st sampling - Just after the outbreak among farm chicken had
observed [group 1a], or just before taking part in outbreak control
operation [group 1b]

2nd sampling - One month after 1st sample had been drawn

Antibody tested:
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Neutralizing antibody to the avian influenza virus strain
A/Ck/Ibaraki/1/2005 (H5N2)

Results:
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1. Antibody titer increased four times or more: 15 people all of them
are farm workers [group 1a]

2. Determination of a tentative threshold for "positive" antibody titer

(a) titers of the control group:
97 percent of them: 10x or less
none of them: 40x or more
thus, a titer value 40x or more is tentatively considered as
"positive" in this report

(b) "positive" samples:
1st sampling: 49 [out of 338?(=353-15)] samples were "positive"
2nd sampling: 24 [out of 249?(=264-15)] samples were "positive"
among them, 11 people had "positive" titer value in both samplings

3. In total:
15 + (49 + 24 - 11) = 77 people were considered as "positive" [i.e.
suspected to have been infected with the virus at some time before or
during the outbreak]

Summary Table:
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Group:  1a / 1b / Total
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Titer increased 4 times or more:
15 / 0 / 15

--
"Positive" Samples
1st only: 34 / 4 / 38
2nd only: 13 / 0  / 13
Both:  10 / 1 / 11

--
Total: 72 / 5 / 77

Number of Samples
--
1st: 319 / 34 / 353
2nd: 231 / 33 / 264

--
Akira  Goto
<dolphin@mail.ne.jp>