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Influenza encephalopathy by pandemic (H1N1) 2009 virus
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(1) Encephalopathy cases: week 28 to 45: 128 cases from 30 prefectures
Virus type: Pandemic (H1N1) 116 cases (88 percent), A type 15 cases,
B type 1 case
Ages: Under 15 years - 95.5 percent, median 8 years, range 1-67
(For comparison in weeks 1 to 27, there were 48 cases of encephalopathy)
(2) Total of acute influenza encephalopathy cases as a result of
pandemic (H1N1) influenza virus infection in Japan
60 reported cases as of 13 Nov 2009
Median: 8 years
Sex: male 35, female 25
25 cases had diseases before influenza infection
All 60 cases had disturbance of consciousness:
Days of beginning of onset of fever to disturbance of consciousness:
Median - 1 day
0 day - 12 cases
1 day - 36 cases
2 days - 8 cases
a single case - 3,4,7 & 8 days
Level by Japan Coma Scale (JCS):
Over 20 - 34 cases(GCS A-3)
10-19 - 9 cases(GCS A-4)
1-9 - 16 cases
unidentified -1 case
Period of disturbance of consciousness:
Unidentified - 2 cases
Over 48 hours - 19 cases
24-48 hours - 15 cases
Under 24 hours - 15 cases
Miscellaneous:
Cramps - 31 cases of 60 (52 percent)
Abnormal behaviors - 45 cases of 60 (75 percent)
Abnormal electroencephalogram - 35/47 (74 percent)
Brain CT - 23/56 (41 percent)
Brain MRI - 14/47 (30 percent)
No signals from electroencephalogram, CT and MRI - 8 cases
Treatment:
Tamiflu - 38/60 (63 percent)
Relenza - 13/60 (22 percent)
Both - 9/60 (15 percent)
Period of drug dose to disturbance of consciousness:
Median - 1 day
Before disturbance of consciousness - 12/60 (20 percent)
Same day - 38/60 (63 percent)
1 day - 10/60 (17 percent)
Brain low temp 6/60 (10 percent)
Blood plasma change 1/60 (2 percent)
Respirator 12/60 (20 percent)
None 13/60
Outcome:
Death - 3/59 (5 percent) (4.5.7 years)
After effects - 7/59 (12 percent)
Healing - 49/59 (83 percent)
Bed days in 50 cases - 2-39 days (median 9 days)
--
Communicated by:
Kunihiko Iizuka
[There was a report of cases of encephalitis and encephalopathy
following infection with the pandemic H1N1 influenza virus in the USA
earlier this year [2009]. The MMWR editorial note mentioned the
following: "Neurologic complications in children associated with
seasonal influenza have included acute cognitive and behavioral
problems, focal neurologic deficits, and death from neurologic
complications (4). Influenza-associated neurologic complications are
estimated to account for up to 5 percent of cases of acute childhood
encephalitis or encephalopathy (4) and were reported in 6 percent of
influenza-associated deaths among children during one influenza
season (2003-04) in the United States (5). The epidemiology of
influenza-associated encephalopathy has been described extensively in
Japan, where incidence has appeared to be higher than in other
countries (1). In Japan, approximately 80 percent of
influenza-associated encephalopathy cases occur in children aged less
than 5 years (1,6), and neurologic signs typically develop within 1-2
days of influenza symptom onset (1,6). Manifestations have included
seizures, altered consciousness, incoherence, irritability, and
psychotic behaviors (1,6). Outcomes reported in one case-series from
Japan ranged from complete resolution (in nearly 50 percent of
cases), to mild (20 percent) or severe neurologic sequelae (10
percent), to death (20 percent) (6). (See: Neurologic Complications
Associated with Novel Influenza A (H1N1) Virus Infection in Children
--- Dallas, Texas, May 2009. 24 Jul 2009. 58(28));773-778.
<http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5828a2.htm>).
References from the MMWR article:
1.Morishima T, Togashi T, Yokota S, et al. Encephalitis and
encephalopathy associated with an influenza epidemic in Japan. Clin
Infect Dis 2002;35:512--7.
2.Maricich SM, Neul JL, Lotze TE, et al. Neurologic complications
associated with influenza A in children during the 2003--2004
influenza season in Houston, Texas. Pediatrics 2004;114:e626--33.
3.Dawood FS, Jain S, Finelli L, et al. Emergence of a novel
swine-origin influenza A (H1N1) virus in humans. N Engl J Med
2009;360:2605--15.
4.Amin R, Ford-Jones E, Richardson SE, et al. Acute childhood
encephalitis and encephalopathy associated with influenza: a
prospective 11-year review. Pediatr Infect Dis J 2008;27:390--5.
5.Bhat N, Wright JG, Broder KR, et al. Influenza-associated deaths
among children in the United States, 2003--2004. N Engl J Med
2005;353:2559--67.
6.Wada T, Morishima T, Okumura A, et al. Differences in clinical
manifestations of influenza-associated encephalopathy by age.
Microbiol Immunol 2009;53:83--8.
7.Ito Y, Ichiyama T, Kimura H, et al. Detection of influenza virus
RNA by reverse transcription-PCR and proinflammatory cytokines in
influenza-virus-associated encephalopathy. J Med Virol
1999;58:420--5. - Mod.MPP]
(For description of a genetic component in the
condition, see: Im Dev Med Child Neurol. 2009 Oct 7, Gika AD, Rich P,
Gupta S, Neilson DE, Clarke A. (Department of Paediatric Neurology,
St George's Hospital NHS Trust, London, UK.) - Mod.CP]
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(1) Encephalopathy cases: week 28 to 45: 128 cases from 30 prefectures
Virus type: Pandemic (H1N1) 116 cases (88 percent), A type 15 cases,
B type 1 case
Ages: Under 15 years - 95.5 percent, median 8 years, range 1-67
(For comparison in weeks 1 to 27, there were 48 cases of encephalopathy)
(2) Total of acute influenza encephalopathy cases as a result of
pandemic (H1N1) influenza virus infection in Japan
60 reported cases as of 13 Nov 2009
Median: 8 years
Sex: male 35, female 25
25 cases had diseases before influenza infection
All 60 cases had disturbance of consciousness:
Days of beginning of onset of fever to disturbance of consciousness:
Median - 1 day
0 day - 12 cases
1 day - 36 cases
2 days - 8 cases
a single case - 3,4,7 & 8 days
Level by Japan Coma Scale (JCS):
Over 20 - 34 cases(GCS A-3)
10-19 - 9 cases(GCS A-4)
1-9 - 16 cases
unidentified -1 case
Period of disturbance of consciousness:
Unidentified - 2 cases
Over 48 hours - 19 cases
24-48 hours - 15 cases
Under 24 hours - 15 cases
Miscellaneous:
Cramps - 31 cases of 60 (52 percent)
Abnormal behaviors - 45 cases of 60 (75 percent)
Abnormal electroencephalogram - 35/47 (74 percent)
Brain CT - 23/56 (41 percent)
Brain MRI - 14/47 (30 percent)
No signals from electroencephalogram, CT and MRI - 8 cases
Treatment:
Tamiflu - 38/60 (63 percent)
Relenza - 13/60 (22 percent)
Both - 9/60 (15 percent)
Period of drug dose to disturbance of consciousness:
Median - 1 day
Before disturbance of consciousness - 12/60 (20 percent)
Same day - 38/60 (63 percent)
1 day - 10/60 (17 percent)
Brain low temp 6/60 (10 percent)
Blood plasma change 1/60 (2 percent)
Respirator 12/60 (20 percent)
None 13/60
Outcome:
Death - 3/59 (5 percent) (4.5.7 years)
After effects - 7/59 (12 percent)
Healing - 49/59 (83 percent)
Bed days in 50 cases - 2-39 days (median 9 days)
--
Communicated by:
Kunihiko Iizuka
[There was a report of cases of encephalitis and encephalopathy
following infection with the pandemic H1N1 influenza virus in the USA
earlier this year [2009]. The MMWR editorial note mentioned the
following: "Neurologic complications in children associated with
seasonal influenza have included acute cognitive and behavioral
problems, focal neurologic deficits, and death from neurologic
complications (4). Influenza-associated neurologic complications are
estimated to account for up to 5 percent of cases of acute childhood
encephalitis or encephalopathy (4) and were reported in 6 percent of
influenza-associated deaths among children during one influenza
season (2003-04) in the United States (5). The epidemiology of
influenza-associated encephalopathy has been described extensively in
Japan, where incidence has appeared to be higher than in other
countries (1). In Japan, approximately 80 percent of
influenza-associated encephalopathy cases occur in children aged less
than 5 years (1,6), and neurologic signs typically develop within 1-2
days of influenza symptom onset (1,6). Manifestations have included
seizures, altered consciousness, incoherence, irritability, and
psychotic behaviors (1,6). Outcomes reported in one case-series from
Japan ranged from complete resolution (in nearly 50 percent of
cases), to mild (20 percent) or severe neurologic sequelae (10
percent), to death (20 percent) (6). (See: Neurologic Complications
Associated with Novel Influenza A (H1N1) Virus Infection in Children
--- Dallas, Texas, May 2009. 24 Jul 2009. 58(28));773-778.
<http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5828a2.htm>).
References from the MMWR article:
1.Morishima T, Togashi T, Yokota S, et al. Encephalitis and
encephalopathy associated with an influenza epidemic in Japan. Clin
Infect Dis 2002;35:512--7.
2.Maricich SM, Neul JL, Lotze TE, et al. Neurologic complications
associated with influenza A in children during the 2003--2004
influenza season in Houston, Texas. Pediatrics 2004;114:e626--33.
3.Dawood FS, Jain S, Finelli L, et al. Emergence of a novel
swine-origin influenza A (H1N1) virus in humans. N Engl J Med
2009;360:2605--15.
4.Amin R, Ford-Jones E, Richardson SE, et al. Acute childhood
encephalitis and encephalopathy associated with influenza: a
prospective 11-year review. Pediatr Infect Dis J 2008;27:390--5.
5.Bhat N, Wright JG, Broder KR, et al. Influenza-associated deaths
among children in the United States, 2003--2004. N Engl J Med
2005;353:2559--67.
6.Wada T, Morishima T, Okumura A, et al. Differences in clinical
manifestations of influenza-associated encephalopathy by age.
Microbiol Immunol 2009;53:83--8.
7.Ito Y, Ichiyama T, Kimura H, et al. Detection of influenza virus
RNA by reverse transcription-PCR and proinflammatory cytokines in
influenza-virus-associated encephalopathy. J Med Virol
1999;58:420--5. - Mod.MPP]
(For description of a genetic component in the
condition, see: Im Dev Med Child Neurol. 2009 Oct 7, Gika AD, Rich P,
Gupta S, Neilson DE, Clarke A. (Department of Paediatric Neurology,
St George's Hospital NHS Trust, London, UK.) - Mod.CP]
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