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South Korea recently reported an asymptomatic human case of H5N1. This case represents the 10th confirmed H5N1 human case in South Korea.
See: http://www.flutrackers.com/forum/showthread.php?t=14960
A brief thread early in 2006 at FluTrackers discussed the first few confirmed cases form South Korea.
See: http://www.flutrackers.com/forum/showthread.php?t=1366
Besides the asymptomatic case announced recently, the CDC had retrospectively confirmed nine cases of human H5N1 infection among poultry cullers in South Korea from samples in 2003/2004. (See the details from a ProMed article below.)
WHO does not include South Korea in its list of countries with human cases of H5N1. But with 10 cases, South Korea exceeds the confirmed case counts for Djibouti, Iraq, Azerbaijan, and Cambodia. So what can we interpret from 10 retrospectively CDC-confirmed cases (all survivors) from South Korea?
As noted in the Promed article, only 4 samples of 318 (1.2%) contained the antibodies in the first set of samples and 5 from the next set of 2109 samples (0.2%) evidenced antibodies. Given the large number of samples, there is no reason to believe that the rate of human infection was any higher than about 0.4% in the poultry cullers, unless only samples from cullers who did not die were submitted for testing.
According to WHO data the CFR for current H5N1 cases is about 60%. This would suggest that perhaps up to 25 individuals contracted H5N1 in South Korea and 15 of them died. Of course, the infecting strain in South Korea in 2003/2004 could have had a much lower CFR, maybe even 0%, and only 10 individuals were infected.
The questions for discussion are:
How likely is it that South Korea could have human H5N1 cases and all infected individuals recovered?
Does the fact that South Korea had asymptomatic cases bolster the argument that the CFR for an H5N1 pandemic will be much less than the current rate of 50-60%?
See: http://www.flutrackers.com/forum/showthread.php?t=14960
A brief thread early in 2006 at FluTrackers discussed the first few confirmed cases form South Korea.
See: http://www.flutrackers.com/forum/showthread.php?t=1366
Besides the asymptomatic case announced recently, the CDC had retrospectively confirmed nine cases of human H5N1 infection among poultry cullers in South Korea from samples in 2003/2004. (See the details from a ProMed article below.)
WHO does not include South Korea in its list of countries with human cases of H5N1. But with 10 cases, South Korea exceeds the confirmed case counts for Djibouti, Iraq, Azerbaijan, and Cambodia. So what can we interpret from 10 retrospectively CDC-confirmed cases (all survivors) from South Korea?
As noted in the Promed article, only 4 samples of 318 (1.2%) contained the antibodies in the first set of samples and 5 from the next set of 2109 samples (0.2%) evidenced antibodies. Given the large number of samples, there is no reason to believe that the rate of human infection was any higher than about 0.4% in the poultry cullers, unless only samples from cullers who did not die were submitted for testing.
According to WHO data the CFR for current H5N1 cases is about 60%. This would suggest that perhaps up to 25 individuals contracted H5N1 in South Korea and 15 of them died. Of course, the infecting strain in South Korea in 2003/2004 could have had a much lower CFR, maybe even 0%, and only 10 individuals were infected.
The questions for discussion are:
How likely is it that South Korea could have human H5N1 cases and all infected individuals recovered?
Does the fact that South Korea had asymptomatic cases bolster the argument that the CFR for an H5N1 pandemic will be much less than the current rate of 50-60%?
Archive Number
20060916.2633
AVIAN INFLUENZA, HUMAN (146): SOUTH KOREA, ASYMPTOMATIC
************************************************** *****
A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
[1]
Date: Thu 14 Sep 2006
From: Mike Buman <ayrman@frontiernet.net>
Source: Yonhap News online [edited]
South Korea's disease control agency confirmed on Fri [15 Sep 2006]
that 5 people have developed antibodies to the lethal H5N1 strain of
bird flu after taking part in the slaughtering and disposal of
infected chickens and ducks [in 2003 -- see below. - Mod.JW].
The 5 people tested positive for bird flu antibodies, but none of
them [had] shown symptoms of the disease as defined by the World
Health Organization (WHO), the Korea Center for Disease Control and
Prevention stated.
--
Mike Buman, EMTPS/RN
Western Arizona Regional Medical Center
<ayrman@frontiernet.net>
******
[2]
Date: Sat 16 Sep 2006
From: Nati Elkin <nati@poultrymed.com>
Source: Agence France Presse, Fri 15 Sep 2006 [edited]
Health officials were cited as saying [on Fri 15 Sep 2006] that 5
South Koreans were infected by the H5N1 bird flu virus 2 years ago
while helping slaughter birds that had contracted the disease. The
five were exposed to the virus between late 2003 and early 2004 but
have shown no symptoms, said the Center for Disease Control and
Prevention of the Health Ministry.
They make up only the 2nd known incident of human infection in South
Korea, which slaughtered 5.3 million poultry during a bird flu
epidemic 2 years ago.
At the time, more than 2100 people who had helped with the
destruction of the birds were tested for the virus [with negative
results. - Mod.JW].
--
Nati Elkin
<nati@poultrymed.com>
******
[3]
Date: Sat 16 Sep 2006
From: A-Lan Banks <A-Lan.Banks@thomson.com>
Source: Reuters Foundation AlertNet, Fri 15 Sep 2006 [edited]
Five more South Koreans were infected with the H5N1 bird flu virus
about 3 years ago but none of them developed any serious illnesses,
officials said on Fri [15 Sep 2006] after recently completed testing
on old samples.
First batch
--------
South Korea, which did not have comprehensive testing at the time,
sent samples of 318 poultry industry workers taken during an outbreak
in late 2003 and early 2004 to the U.S. Centers for Disease Control
and Prevention in 2005 for further examination. Of those workers, 4
South Koreans were infected, the CDC has said. The government said in
February [2006] the 4 did not develop major illnesses.
2nd batch
---------
The results prompted South Korean health officials to send samples to
the CDC from another 2109 people and of these, 5 were also infected,
the health agency said on Friday [15 Sep 2006]. "The 5 did not
develop major illnesses and have no strain to transmit bird flu," the
Korea Centre for Disease Control and Prevention said in a statement.
About 400 000 poultry at South Korean farms were infected by bird flu
between December 2003 and March 2004, but no human cases were
reported at that time. All of the samples sent by South Korea to the
United States were from people involved in the culling of about 5
million poultry. There have been no reported cases of bird flu in
South Korea since the 2003-2004 outbreak.
The World Health Organisation said on Thursday 2 cases in Indonesia
had been recognised retroactively, including one where human-to-human
transmission could not be ruled out. The latest number of cases
globally stands at 246 since 2003, not including the South Korean
cases, with 144 deaths.
--
A-Lan Banks
<A-Lan.Banks@thomson.com>
[Retrospective analysis has established that beginning mid-2003 HPAI
H5N1 virus began to cause outbreaks of poultry disease in Asia which
were unrecognized at that time. In December 2003, 2 tigers and 2
leopards in a Thai zoo died as a result of consuming H5N1-infected
chicken carcasses. Later in the same month South Korea confirmed that
HPAI H5N1 virus infection was the cause of poultry deaths at 3 farms.
In early 2004 H5N1 virus infection was reported from Viet Nam, Japan,
and Thailand. The 1st laboratory-confirmed cases of H5N1 human
infection were reported in Thailand and later sporadically throughout
East Asia (all symptomatic). Just as in Hong Kong in 1997, the
outbreaks in South Korea and Japan were rapidly contained and
eradicated by a combination of early detection, extensive culling,
and continued surveillance. H5N1 virus infection has not recurred in
South Korea. No human cases of infection were reported at that time,
but later a small number of those involved in poultry culling
experienced asymptomatic infection and developed immune responses.
The above reports add another 5 asymptomatic cases bringing the total to 9.
The virus responsible for the outbreaks in South Korea and Japan
belonged to the V genotype of H5N1 avian influenza virus, whereas the
predominant virus in East Asia belongs to the Z genotype. These
genotypes are reassortants which differ in the origin of their NA
genome subunit. It has not been established if this is relevant to
the apparent lack of virulence of the South Korean virus. - Mod.CP]
[see also:
Avian influenza, human - worldwide (15): S.Korea, Malaysia 20060224.0603
2005
----
Avian influenza - Eurasia (41): WHO H5N1 timeline 20051029.3160]
....................................as/cp/pg/jw
20060916.2633
AVIAN INFLUENZA, HUMAN (146): SOUTH KOREA, ASYMPTOMATIC
************************************************** *****
A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
[1]
Date: Thu 14 Sep 2006
From: Mike Buman <ayrman@frontiernet.net>
Source: Yonhap News online [edited]
South Korea's disease control agency confirmed on Fri [15 Sep 2006]
that 5 people have developed antibodies to the lethal H5N1 strain of
bird flu after taking part in the slaughtering and disposal of
infected chickens and ducks [in 2003 -- see below. - Mod.JW].
The 5 people tested positive for bird flu antibodies, but none of
them [had] shown symptoms of the disease as defined by the World
Health Organization (WHO), the Korea Center for Disease Control and
Prevention stated.
--
Mike Buman, EMTPS/RN
Western Arizona Regional Medical Center
<ayrman@frontiernet.net>
******
[2]
Date: Sat 16 Sep 2006
From: Nati Elkin <nati@poultrymed.com>
Source: Agence France Presse, Fri 15 Sep 2006 [edited]
Health officials were cited as saying [on Fri 15 Sep 2006] that 5
South Koreans were infected by the H5N1 bird flu virus 2 years ago
while helping slaughter birds that had contracted the disease. The
five were exposed to the virus between late 2003 and early 2004 but
have shown no symptoms, said the Center for Disease Control and
Prevention of the Health Ministry.
They make up only the 2nd known incident of human infection in South
Korea, which slaughtered 5.3 million poultry during a bird flu
epidemic 2 years ago.
At the time, more than 2100 people who had helped with the
destruction of the birds were tested for the virus [with negative
results. - Mod.JW].
--
Nati Elkin
<nati@poultrymed.com>
******
[3]
Date: Sat 16 Sep 2006
From: A-Lan Banks <A-Lan.Banks@thomson.com>
Source: Reuters Foundation AlertNet, Fri 15 Sep 2006 [edited]
Five more South Koreans were infected with the H5N1 bird flu virus
about 3 years ago but none of them developed any serious illnesses,
officials said on Fri [15 Sep 2006] after recently completed testing
on old samples.
First batch
--------
South Korea, which did not have comprehensive testing at the time,
sent samples of 318 poultry industry workers taken during an outbreak
in late 2003 and early 2004 to the U.S. Centers for Disease Control
and Prevention in 2005 for further examination. Of those workers, 4
South Koreans were infected, the CDC has said. The government said in
February [2006] the 4 did not develop major illnesses.
2nd batch
---------
The results prompted South Korean health officials to send samples to
the CDC from another 2109 people and of these, 5 were also infected,
the health agency said on Friday [15 Sep 2006]. "The 5 did not
develop major illnesses and have no strain to transmit bird flu," the
Korea Centre for Disease Control and Prevention said in a statement.
About 400 000 poultry at South Korean farms were infected by bird flu
between December 2003 and March 2004, but no human cases were
reported at that time. All of the samples sent by South Korea to the
United States were from people involved in the culling of about 5
million poultry. There have been no reported cases of bird flu in
South Korea since the 2003-2004 outbreak.
The World Health Organisation said on Thursday 2 cases in Indonesia
had been recognised retroactively, including one where human-to-human
transmission could not be ruled out. The latest number of cases
globally stands at 246 since 2003, not including the South Korean
cases, with 144 deaths.
--
A-Lan Banks
<A-Lan.Banks@thomson.com>
[Retrospective analysis has established that beginning mid-2003 HPAI
H5N1 virus began to cause outbreaks of poultry disease in Asia which
were unrecognized at that time. In December 2003, 2 tigers and 2
leopards in a Thai zoo died as a result of consuming H5N1-infected
chicken carcasses. Later in the same month South Korea confirmed that
HPAI H5N1 virus infection was the cause of poultry deaths at 3 farms.
In early 2004 H5N1 virus infection was reported from Viet Nam, Japan,
and Thailand. The 1st laboratory-confirmed cases of H5N1 human
infection were reported in Thailand and later sporadically throughout
East Asia (all symptomatic). Just as in Hong Kong in 1997, the
outbreaks in South Korea and Japan were rapidly contained and
eradicated by a combination of early detection, extensive culling,
and continued surveillance. H5N1 virus infection has not recurred in
South Korea. No human cases of infection were reported at that time,
but later a small number of those involved in poultry culling
experienced asymptomatic infection and developed immune responses.
The above reports add another 5 asymptomatic cases bringing the total to 9.
The virus responsible for the outbreaks in South Korea and Japan
belonged to the V genotype of H5N1 avian influenza virus, whereas the
predominant virus in East Asia belongs to the Z genotype. These
genotypes are reassortants which differ in the origin of their NA
genome subunit. It has not been established if this is relevant to
the apparent lack of virulence of the South Korean virus. - Mod.CP]
[see also:
Avian influenza, human - worldwide (15): S.Korea, Malaysia 20060224.0603
2005
----
Avian influenza - Eurasia (41): WHO H5N1 timeline 20051029.3160]
....................................as/cp/pg/jw