Jpn. J. Infect. Dis., 54, 2001

Laboratory and Epidemiology Communications

Necesslty Of Two‑Stool Sample Test for Sensitive Detection of Poliovirus
Tetsuo Yoneyama*, Hiromu Yoshida, Kumiko Yoshii, Junko Wada,
Hiroyuki Shimizu and Tatsuo Miyamura
Department of Viy10logy II, National Institute of Infectious Diseases,

Gakuen 4‑ 7‑1, Musashimurayama‑shi, Tobo 208‑0011
Communicated by Tatsuo Miyamura(Accepted February 4, 2002)

By the initiative of a WHO polio‑eradication program, theWestem Pacific Region is now declaredfree of wild poliovirus

virus detection. NPEVs were isolated by uslng HEp‑2 andRD cell lines, and polioviruses were detected byuslng theabove two cell lines plus L20B cell lines.

Pirculation (l )･ However, Wild poliovimses are still circulaト

lng in other restricted areas in the world (2). Consequently,

Among 772 cases ofAFP patients, NPEVs were isolated

prompt and accurate laboratory diagnosis as well as mainte‑from 278 cases; 200 cases were detected in both of the twonance of high immunity levels are of critical importance untilsamples, 42 cases in only the first stool sample, and 36 cases

eradication of poliomyelitis is truly achieved at global level.

in only the second stool sample. The isolation rate (36%) of

As a basic strategy, the examination of two stool specimens

NPEVs uslng three different cell lines, HEp‑2, RD, and L20B

from one acute flaccid paralysis (AFP) case within 2 Weeks

cells far exceeded the WHO requirement (10%) (5). If thehas been practiced in the global laboratory network f♭r thenumber of samples collected had been reduced from two toprogram (3). Irit were possible to reduce the number ofstool collections from two specimens to one without loslng

one, the detection rate ofNPEVs would have been reduced

diagnostic accuracy, the workload required for laboratory

polioviru.S.isolation･ only 65% of the AFP cases (17 cases)

testlng and suⅣeillance would be reduced.

were posltlVe in both samples, and 3 1% of the A戸P cases (8Since 1996, stool specimens from AFP patients in Lao
People's Democratic Republic (Lao) and Cambodia (Cam)were directly sent to the National Institute of Infectious

only (Table I )･ The latter.poliovirus could have gone‑undetec‑from 278 cases to 242 or 236 cases, 1.e., by 14%.As forcases) were polioviruS‑positive in the second stool specimen
ted in the one‑stool speclmen protocol.

Diseases in Tbkyo and were examined f♭r the presence ofThe above data suggest that a substantial number ofpolio‑

polioviruse.s and non‑polio enteroviruses (NPEVs)･ The lastwild poliovlruS (type 1) isolate was obtained from a specimen
sent from Cambodia in 1997 (4).
We retrospectively analyzed the virus isolation data in ourvirus isolations might have been missed irthe second stoolspecimens had not been examined. The polio ouぬreak associ‑ated with type I circulating vaccine derived polioviruS (CVDPV)

inthe Caribbean island of Hispaniola (6) was a quiteunexpected,

laboratory from I 998 to 2000 and investlgated whether theas that polio outbreak was first thought to be due to a re‑two‑stool specimen test actually increased the e爪ciency ofintroduction of wild polioviruses from other reglOnS. Thatoutbreak reaffirmed the importance of maintainlng Sensitive*Corresponding author: Fax: +8 I ‑47‑256‑4729, E‑mail:tyoneyamlaboratory poliovirus surveillance for the possible occurrence@nih.go.jp

of CVDPV as well as wild poliovims ouぬreaks. The two‑stool250

Jpn. J. Infect. Dis., 54, 2001
Tablc 1. Virus Isolation from first (Stl), second (St2), or both stools collected from AFPcases in Lao and Cambodia, 1998‑2000
Country‑Year No. ofAFP Results ofNPEV isolation Results ofpoliovjrus isolation No. of mix isolation No. of negative cases
case Stl十, St2+La0‑ 1 998

7 0 7 ′LU 7 0ノ 7 4 1 5 0 71･2 1 5 つJ 4Stl+, St2‑

Stl‑,St2十Stl+, St2+

4 tJ 4 つJ つJ Oノ1 2 3 ′LU tJ 2Stl+, St2‑0 0 nXU 4 4 05 2 ′h〉 I tJ 50 0 0 0 0 1‑

Stト,St2十1 21 211(NPEVandpoliovims)

inbothstools

0 2 ‑ つん 0 0

La0‑ I 999
La0‑2000

Cam‑1 998
Cam‑ 1 999

Cam‑2000
Tbta1

772

200(72%)42(15%)

36(13%)

specimen.protocol, which significantly increases the sensitivity

strategleS, disappearlng disease. Lancet, 343, 1 33ト1 337.

ofpoliovlruS detection, should be maintained until the global

4. Hagiwara, A., Yoneyama, T., Yoshii, K., Yoshida, H.,

eradication of poliomyelitis has been achieved.

Shimizu, H., Wada, ∫., Thanh, N. H., Tu, P. V andMiyamura, T･ (1999): Genptic analysis of wild polio‑
The authors thank the laboratory staff in Lao People'sviruses towards the eradicatlOn Of poliomyelitis from thewestem pacific region. Jpn. J. Infect. Dis., 52, 1461149.

Democratic Republic, Cambodia, and WPRO fわr arranglng

5. World Health Organization (1998): Global eradication

the sending of stool samples.

of poliomyelitis: Report of the second meetlng Of theglobal technical consultative gro叩(TCG), 28 April 1 997.

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