Published Date: 2009-10-27 21:00:03
Subject: PRO/AH/EDR> Influenza pandemic (H1N1) 2009 (77): Taiwan oseltamivir resistance
Archive Number: 20091027.3725

INFLUENZA PANDEMIC (H1N1) 2009 (77): TAIWAN OSELTAMIVIR RESISTANCE
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Date Tue 27 Oct 2009
From: Jen-Hsiang Chuang, MD, PhD
<jhchuang@cdc.gov.tw>


Second Case of Oseltamivir-resistant Pandemic H1N1
--------------------------------------------------
On Tue 27 Oct 2009, the Pandemic (H1N1) Central Epidemic Command
Center of Taipei announced the detection of another [isolate] of
pandemic (H1N1) 2009 virus which was resistant to oseltamivir. A
summary of epidemiological and laboratory investigation results is
outlined below.

The oseltamivir-resistant pandemic (H1N1) 2009 virus was isolated
from a specimen taken from a 44-year-old man living in northern
Taiwan. On Thu 27 Aug 2009 the patient experienced general malaise
and got fever next day. He visited the local medical clinic for
medications. He was tested with an influenza rapid test and the
result was influenza A virus positive. He began a 5-day course of
oseltamivir. On the night of 2 Sep 2009, he experienced fever and
cough again. Next day, he visited an ER [Emergency Room] and his
chest X-ray revealed pneumonia. He was admitted for further diagnosis
and treatment. On 3 Sep 2009, he tested positive for pandemic (H1N1)
2009 virus by real-time reverse transcription polymerase chain
reaction (rtRT-PCR). Nevertheless, he was discharged upon recovery on
7 Sep 2009.

The National Influenza Center (NIC) in Taipei conducted routine
antiviral resistance tests on specimens taken from confirmed patients
with pandemic (H1N1) 2009. Nucleotide sequencing of the NA
[neuraminidase] gene confirmed the presence of the H275Y mutation in
the virus isolated from the sample collected on 3 Sep 2009,
indicating resistance to oseltamivir, but not to zanammivir.

The virus, isolated from a patient with documented exposure to
oseltamivir treatment, is the 2nd case of oseltamivir-resistant
strain among 339 isolates tested in Taipei since 1 Jun 2009.
Investigations have not found the resistant virus in close contacts
[o patients harbouring oseltamivir-resistant virus]. Therefore, the
patient represents a sporadic case of oseltamivir resistance. The
public and the media were informed of the findings on Tue 27 Oct 2009.

--
Jen-Hsiang Chuang, MD, PhD
IHR Focal Point
Director, Epidemic Intelligence Center
Centers for Disease Control, Taipei, Taiwan
<jhchuang@cdc.gov.tw>

[This report describes the 2nd case of oseltamivir resistance
identified in Taiwan. The 2 Taiwanese patents from whom
oseltamivir-resistant virus has ben isolated appear to be unrelated
and none of their contacts have contracted oseltamivir-resistant
virus infection. In both cases, and all other cases reported
globally, oseltamivir resistance was conferred by the same H275Y
mutation in the neuraminidase protein of the virus.

To date, 39 resistant pandemic H1N1 influenza viruses have been
detected and characterized worldwide. All of these viruses show the
same H275Y mutation that confers resistance to the antiviral
oseltamivir, but not to the other neuraminidase inhibitor zanamivir.
Worldwide, more than 10 000 clinical specimens (samples and isolates)
of the pandemic (H1N1) 2009 virus have been tested and found to be
sensitive to oseltamivir (see: World Health Organization (W1O)
Pandemic (H1N1) 2009 - update 71. Weekly update, Virological
surveillance data. Available at:
<http://www.who.int/csr/disease/swineflu/laboratory23_10_2009/en/index.html>.
The 2 recent cases in Taiwan reported in the above report and in the
preceding ProMED-mail post entitled 'Influenza pandemic (H1N1) 2009
(73): Taiwan oseltamivir resistance 20091021.3626,' will become
presumably the 40th and 41st cases.

Taipei can be located in the HealthMap/ProMED-mail interactive map of
Taiwan at:
<http://healthmap.org/r/00DX>. - Mod.CP]

See Also

Influenza pandemic (H1N1) 2009 (76); El Salvador, dengue co-infection
20091025.3695
Influenza pandemic (H1N1) 2009 (75): southern hemisphere 20091022.3637
Influenza pandemic (H1N1) 2009 (74): Canada (ON) oseltamivir resist
20091022.3634
Influenza pandemic (H1N1) 2009 (73): Taiwan oseltamivir resistance
20091021.3626
Influenza pandemic (H1N1) 2009 (72): pneumonia 20091017.3577
Influenza pandemic (H1N1) 2009 (71): case counts 20091017.3568
Influenza pandemic (H1N1) 2009 (70): Nepal 20091016.3563
Influenza pandemic (H1N1) 2009 (69): case management 20091013.353
Influenza pandemic (H1N1) 2009 (68): Viet Nam, virus clearance 20091011.3519
Influenza pandemic (H1N1) 2009 (67): vaccine delivery 20091011.3515
Influenza pandemic (H1N1) 2009 (66): case counts 20091010.3510
Influenza pandemic (H1N1) 2009 (65): update 20091009.3495
Influenza pandemic (H1N1) 2009 (64): Canada, vaccination update 20091005.3457
Influenza pandemic (H1N1) 2009 (63): USA military vaccine 20091002.3437
Influenza pandemic (H1N1) 2009 (62): Taiwan hosp cases 20091001.3421
Influenza pandemic (H1N1) 2009 (61): FLAARDS 20091001.3419
Influenza pandemic (H1N1) 2009 (60): bacterial coinfection 20090930.3410
Influenza pandemic (H1N1) 2009 (50): oseltamivir-resistance 20090917.3260
Influenza pandemic (H1N1) 2009 (40): global update 20090906.3138
Influenza pandemic (H1N1) 2009 (30): assumptions 20090813.2879
Influenza pandemic (H1N1) 2009 (20): Peru, 33 percent asymptomatic
20090730.2668
Influenza pandemic (H1N1) 2009 (10): vaccine 20090720.2577
Influenza pandemic (H1N1) 2009 - Viet Nam: patient data 20090708.2450
...................................mpp/cp/ejp/lm

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