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Human infection with new influenza A (H1N1) virus: clinical observations from a school-associated outbreak in Kobe, Japan, May 2009 (WER, June 12 2009, edited)
Human infection with new influenza A (H1N1) virus: clinical observations from a school-associated outbreak in Kobe, Japan, May 2009 (WER, June 12 2009, edited)
Weekly epidemiological record - 12 june 2009, 84th year
No. 24, 2009, 84, 237?248 - http://www.who.int/wer
Human infection with new influenza A (H1N1) virus: clinical observations from a school-associated outbreak in Kobe, Japan, May 2009
[Original Document: LINK. EDITED.]
As of 11 June 2009, 74 countries had reported to WHO a total of 28 774 laboratory-confirmed cases of new influenza A (H1N1) virus infection, including 144 deaths. The epidemic, which originated in the Region of the Americas, has spread to all WHO regions except the African Region. Japan was among the first countries to detect sporadic imported cases in Asia; New Zealand(1) was the first country in the Western Pacific Region to report cases.
As with initial reports in other urban settings (Australia,(2) New York(3) and the United Kingdom(4)), school-associated outbreaks of new influenza A (H1N1) virus infection in Japan occurred relatively early in its epidemiological timeline and before wider community-level transmissions with broader age distributions had ensued. The response to these outbreaks included aggressive, containment-like public health measures such as hospital isolation of suspected and confirmed cases, treatment of almost all confirmed and partially suspected cases, chemoprophylaxis of close contacts, cancellation of mass gatherings and extensive school closures.
This article summarizes the clinical features of human infection with new influenza A (H1N1) virus in a school associated outbreak in Kobe, Hyogo Prefecture (Japan) during 11?24 May 2009.
Background
As of 2 June 2009, the Ministry of Health of Japan had reported to WHO a total of 379 laboratory-confirmed cases of new influenza A (H1N1) virus infection. The initial cases were reported in travellers who had recently returned from Ontario (Canada) on 8 May 2009; a total of 21 imported cases were subsequently identified.
On 16 May 2009, new influenza (H1N1) virus infection was confirmed in 3 students in Kobe, none of whom were epidemiologically linked to any of the previously reported imported cases. Additional cases were subsequently identified from the northern and western parts of Hyogo Prefecture as well as from neighbouring Osaka Prefecture.
This report includes clinical information as of 25 May 2009 from 49 laboratory-confirmed cases in Kobe City who were hospitalized under the Japanese Infectious Diseases Control Law originally enacted in 1999 and most recently revised in 2008.(5) This law aims to prevent and control emerging and other infectious disease threats and to determine measures for their reporting and control using 5 risk categories. Group 1 infectious disease are those caused by lethal pathogens, such as Ebola and other viral haemorrhagic fevers, plague and smallpox. Group 2 infectious diseases comprise any infection with an influenza virus of pandemic potential, with the requirement that all confirmed cases are hospitalized for isolation and treatment. In accordance with the Japanese Infectious Diseases Control Law, all confirmed cases in Kobe were initially hospitalized.
However, although the number of cases in whom new influenza A (H1N1) was diagnosed during this early phase of the outbreak was limited, all designated hospital beds were filled to capacity by such patients. Given the mild nature of the illness observed in the majority of patients, most of whom did not seem to require hospital care, on 18 May 2009, Kobe City and Osaka Prefecture decided to hospitalize only those cases whose symptoms or underlying conditions warranted clinical admission.
Summary of confirmed cases
Demographic information and underlying conditions
The majority of the 49 laboratory-confirmed cases from the school-associated outbreak in Kobe City are adolescents (median age, 17 years; range, 5?60). The male:female ratio is 1:1 (23 males and 26 females). Underlying conditions include chronic bronchial asthma (6 cases), atopic dermatitis (2 cases) and allergic rhinitis (1 case). None has chronic cardiac disease, immunosuppressive conditions, diabetes or malignant carcinoma. No female cases are pregnant or potentially pregnant. The majority of the cases (33) have been epidemiologically linked through contact tracing to the 2 school-associated outbreaks, including the students and teachers from the schools (n=1874).
Seasonal vaccination history and influenza incidence during 2008?2009 influenza season
Among 43 cases for whom vaccination histories were available, 22 (51.2%) had been vaccinated against seasonal influenza in the 2008?2009 influenza season. Such seasonal vaccination has high uptake in students preparing for school examinations in Japan. During the past influenza season, 4 out of 45 cases (8.9%) reported histories of influenza infection (subtype unspecified), of whom 2 (50%) had received 2008?2009 seasonal influenza vaccine. In Japan, ?point-of-care? influenza diagnosis is frequently used in primary health-care settings together with prescription of influenza antiviral medications. These patients had therefore been informed of their influenza infection during medical consultations.
Rapid diagnostic testing (dipstick-type point-of-care rapid diagnostic tests)
The duration between onset of symptoms and testing using rapid diagnostic kits ranged from 0 to 4 days (median, 1 day). Among 43 cases presenting with fever />38 ?C (6 cases had fever <38 ?C), 25 (58%) tested positive and 18 (42%) were negative. The sensitivity of these tests was higher among cases tested on the day following onset of fever than for those tested on the day of onset of fever (Table 1). All cases were subsequently confirmed by real-time reverse transcriptionpolymerase chain reaction (rRT-PCR).(6)
Clinical presentation on hospital admission
The duration between onset of illness and presentation at hospitals ranged from 0 to 7 days (median, 1 day). Among 49 cases, nearly 90% presented with fever />38 ?C. A high proportion (60?80%) presented symptoms such as general fatigue, fever (or feverish), cough and sore throat. Approximately 50% of cases had nasal congestion, nasal discharge, headache and myalgia or arthralgia. Nausea occurred in 24% of cases. Gastrointestinal symptoms including vomiting and diarrhoea were found in 10% of cases, and conjunctivitis in 7%(7)(Table 2). No cases had neurological manifestations.
Laboratory data on presentation at hospitals
Clinical samples were collected from cases for complete blood counts and serum chemistry on presentation at hospitals. No general trends in abnormalities were found. Both lowered and elevated white-blood cell counts were reported (n=26; median, 5100/mm3; range, 3200?11400/mm3). Other findings include slightly increased C-reactive protein (n=28; median, 1.2 mg/dl; range, 0?9.2 mg/dl), normal range or slightly elevated aminotransferases (GOT n=24; median, 17 IU/dl; range, 12?64 IU/dl; GPT, n=24; median, 11.5 IU/dl; range, 7?168 IU/dl); normal serum urea nitrogen and creatinine levels were noted. As there were no suspected cases of clinical pneumonia, chest X-rays were not performed.
Clinical course
Among the 43 cases with fever >38 ?C, upper respiratory tract symptoms, especially sore throat and cough, were commonly reported to have appeared before the onset of fever and persisted after its resolution. Headache, myalgia and arthralgia occurred with the onset of fever in most cases (Table 3, Fig. 1). All of the cases recovered without complications. All but 1 case received antiviral treatment (Table 4). The duration of onset and resolution of fever was 1?8 days (median, 3 days). As of 2 June 2009, no cases had required mechanical ventilation and no deaths had occurred. Most cases were discharged shortly after admission and sent home under isolation conditions and observation.
Antiviral treatment
Of the 49 laboratory-confirmed cases, 48 (98%) were treated with antivirals (22 received oseltamivir and 26 zanamivir). The Ministry of Health of Japan has advised clinicians to limit the administration of oseltamivir in teenagers given its possible neuropsychiatric adverse effects; however, some patients received oseltamivir because of their clinical history of asthma. The median time from the onset of symptoms to administration of antivirals was 1 day (range, 0?4 days). There was no difference in the duration of fever >38 ?C before administration of antivirals between cases treated with oseltamivir (median, 2 days; range, 1?4 days) and zanamivir (median, 2 days; range, 1?5 days). Earlier administration of antiviral medication seems to be associated with reduced duration of fever (Table 5). Both antivirals were well tolerated and no adverse effects were reported.
Editorial note.
This report describes the clinical features of mild upper respiratory tract illness in a school-associated outbreak of new influenza A (H1N1) virus infection in Kobe, Japan during 11?24 May 2009. Upper respiratory tract symptoms such as sore throat and cough preceded the onset of fever, suggesting replication of the virus in the upper respiratory tract and possible virus shedding during the prodromic period. Almost all the 49 laboratory-confirmed cases received antiviral treatment of either oseltamivir or zanamivir.
Early administration of treatment on the day of onset of fever reduced the duration of the symptom but was not statistically significant.
Point-of-care rapid diagnostic tests for influenza failed to correctly diagnose about 50% of the cases in samples collected on the day of onset of illness.
This finding suggests that the positive predictive value of diagnoses made by clinical and epidemiological information is superior to point-of-care rapid diagnostic tests in outbreak settings and is the preferred option for timely antiviral administration in populations at increased risk of complications. Virological studies are needed to determine the relation between the sensitivity of rapid diagnostic tests and the viral loads in the upper and lower respiratory tracts.
As of 10 June 2009, the majority of cases of school-associated outbreaks of new influenza A (H1N1) virus infection reported to WHO from several countries have been mild and their clinical features similar to those of seasonal influenza. However, the clinical spectrum of disease in such cases is broad, as reported from Mexico and the United States8 and in severe, sometimes fatal, cases, has included pneumonia that rapidly progressed to acute respiratory distress syndrome, and renal and multi-organ failure.
Preliminary clinical and pathological information reported to WHO suggest similarities between severe human cases of new influenza A (H1N1) virus infection and human cases of avian influenza H5N1 virus infection.
As the H1N1 virus becomes more widespread, as was observed in New York City (USA),(9) hospitalization in at-risk groups will likely increase.
Where outbreaks of new influenza A (H1N1) virus infection are occurring in the community, family members of suspected cases and people living with conditions that potentially put them at risk for more severe disease (such as those with chronic heart, lung, renal, liver, metabolic and haematological diseases, immunodeficiencies and pregnancy) should be rapidly informed about self-protection measures that can be taken to reduce the risk of infection.
These individuals are urged to contact a health-care provider early if they think they may have the illness.
Initial guidance on the clinical management of human infection with new influenza A (H1N1) virus is available from the WHO web site.(10)
Updates on the evolving situation will continue be published in the Weekly Epidemiological Record.(11)
Aggressive public health measures undertaken in Japan to contain the school-associated outbreak of the new influenza A (H1N1) virus included closing >1400 schools in both affected prefectures for 7 days and cancelling a major city festival in Kobe, including a planned parade that was expected to attract up to 1 million participants.
After the re-opening of schools, school absenteeism in these prefectures in the following weeks did not increase.
Further epidemiological studies are needed to determine the degree to which human infection with new influenza A (H1N1) virus infection spreads to the community during school-associated outbreaks. Lessons learnt from several countries suggest that close monitoring and preparation are needed to cope with the increased demands on the health-care system after outbreaks occur in schools.
Acknowledgement
WHO thanks the National Institute of Infectious Diseases, Tokyo, Japan and Kobe City Health Centre for collecting and analysing data, and the Medical Centre General Hospital and the West Kobe Medical Centre in Kobe City for their contributions to this report.
Table 1 Results of rapid diagnostic testing in 43 laboratory-confirmed human cases of new influenza A (H1N1) virus infection presenting at hospital with fever >38 ?C in Kobe, Japan, May 2009
(a) Standard error
(b) Fever ≥38 ?C
(c) In one case, the patient received zanamivir for 1 day before administration of the rapid test. This case was diagnosed positive by the rapid test.
Table 2 Clinical presentation on hospital admission of 49 human cases of new influenza A (H1N1) virus infection in Kobe, Japan, May 2009
[Symptom - No. of cases - No. of cases presenting with symptom ? %]
Table 3 Duration of symptoms (days) of human cases of new influenza A (H1N1) virus infection in Kobe, Japan, May 2009
[Symptom ? No. of cases ? Median (days) ? Range (days)]
Table 4 Distribution by age group of antiviral treatment administered to human cases of new influenza A (H1N1) virus infection in Kobe, Japan, May 2009
[Age (years) ? Total cases ? No. of cases receiving oseltamivir ? No. of cases receiving zanamivir ? Antiviral not administered]
Table 5 Initiation of antiviral therapy and duration of fever in human cases of new influenza A (H1N1) virus infection in Kobe, Japan, May 2009
[Initiation of antiviral therapy (days) ? Duration of fever (median) ? Oseltamivir / Zanamivir]
NA = data not available.
(1) See http://www.who.int/csr/don/2009_04_28/en/index.html
(2) Outbreak issue: cases mount through Australia, 5 June 2009. Health Emergency, Australian Government Department of Health and Aging (available at http://www.healthemergency.gov.au/in...m#cases05june; accessed June 2009).
(3) Health alert #19: novel H1N1 influenza ? update 21 May 2009. New York City Department of Health and Mental Hygiene (available at http://www.nyc.gov/html/doh/download...09/09md19.pdf; accessed June 2009).
(4) Epidemiology of new influenza A (H1N1) in the United Kingdom, April?May 2009. Eurosurveillance, 14(19):8?9 (available at http://www.eurosurveillance.org/View...ticleId=19213; accessed June 2009).
(5) See http://idsc.nih.go.jp/iasr/29/341/tpc341.html
(6) See http://www.who.int/csr/disease/swine...2009_04_29.pdf
(7) Observations include injected eyes or ocular injection. The diagnoses were not made by ophthalmologists.
(8) See No. 21, 2009, pp. 185?189.
(9) Health alert #21: novel H1N1 influenza ? update 2 June 2009. New York City Department of Health and Mental Hygiene (available at http://www.nyc.gov/html/doh/download...09/09md21.pdf; accessed June 2009).
(10) See http://www.who.int/csr/disease/swine.../en/index.html
(11) See http://www.who.int/wer
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Weekly epidemiological record - 12 june 2009, 84th year
No. 24, 2009, 84, 237?248 - http://www.who.int/wer
Human infection with new influenza A (H1N1) virus: clinical observations from a school-associated outbreak in Kobe, Japan, May 2009
[Original Document: LINK. EDITED.]
As of 11 June 2009, 74 countries had reported to WHO a total of 28 774 laboratory-confirmed cases of new influenza A (H1N1) virus infection, including 144 deaths. The epidemic, which originated in the Region of the Americas, has spread to all WHO regions except the African Region. Japan was among the first countries to detect sporadic imported cases in Asia; New Zealand(1) was the first country in the Western Pacific Region to report cases.
As with initial reports in other urban settings (Australia,(2) New York(3) and the United Kingdom(4)), school-associated outbreaks of new influenza A (H1N1) virus infection in Japan occurred relatively early in its epidemiological timeline and before wider community-level transmissions with broader age distributions had ensued. The response to these outbreaks included aggressive, containment-like public health measures such as hospital isolation of suspected and confirmed cases, treatment of almost all confirmed and partially suspected cases, chemoprophylaxis of close contacts, cancellation of mass gatherings and extensive school closures.
This article summarizes the clinical features of human infection with new influenza A (H1N1) virus in a school associated outbreak in Kobe, Hyogo Prefecture (Japan) during 11?24 May 2009.
Background
As of 2 June 2009, the Ministry of Health of Japan had reported to WHO a total of 379 laboratory-confirmed cases of new influenza A (H1N1) virus infection. The initial cases were reported in travellers who had recently returned from Ontario (Canada) on 8 May 2009; a total of 21 imported cases were subsequently identified.
On 16 May 2009, new influenza (H1N1) virus infection was confirmed in 3 students in Kobe, none of whom were epidemiologically linked to any of the previously reported imported cases. Additional cases were subsequently identified from the northern and western parts of Hyogo Prefecture as well as from neighbouring Osaka Prefecture.
This report includes clinical information as of 25 May 2009 from 49 laboratory-confirmed cases in Kobe City who were hospitalized under the Japanese Infectious Diseases Control Law originally enacted in 1999 and most recently revised in 2008.(5) This law aims to prevent and control emerging and other infectious disease threats and to determine measures for their reporting and control using 5 risk categories. Group 1 infectious disease are those caused by lethal pathogens, such as Ebola and other viral haemorrhagic fevers, plague and smallpox. Group 2 infectious diseases comprise any infection with an influenza virus of pandemic potential, with the requirement that all confirmed cases are hospitalized for isolation and treatment. In accordance with the Japanese Infectious Diseases Control Law, all confirmed cases in Kobe were initially hospitalized.
However, although the number of cases in whom new influenza A (H1N1) was diagnosed during this early phase of the outbreak was limited, all designated hospital beds were filled to capacity by such patients. Given the mild nature of the illness observed in the majority of patients, most of whom did not seem to require hospital care, on 18 May 2009, Kobe City and Osaka Prefecture decided to hospitalize only those cases whose symptoms or underlying conditions warranted clinical admission.
Summary of confirmed cases
Demographic information and underlying conditions
The majority of the 49 laboratory-confirmed cases from the school-associated outbreak in Kobe City are adolescents (median age, 17 years; range, 5?60). The male:female ratio is 1:1 (23 males and 26 females). Underlying conditions include chronic bronchial asthma (6 cases), atopic dermatitis (2 cases) and allergic rhinitis (1 case). None has chronic cardiac disease, immunosuppressive conditions, diabetes or malignant carcinoma. No female cases are pregnant or potentially pregnant. The majority of the cases (33) have been epidemiologically linked through contact tracing to the 2 school-associated outbreaks, including the students and teachers from the schools (n=1874).
Seasonal vaccination history and influenza incidence during 2008?2009 influenza season
Among 43 cases for whom vaccination histories were available, 22 (51.2%) had been vaccinated against seasonal influenza in the 2008?2009 influenza season. Such seasonal vaccination has high uptake in students preparing for school examinations in Japan. During the past influenza season, 4 out of 45 cases (8.9%) reported histories of influenza infection (subtype unspecified), of whom 2 (50%) had received 2008?2009 seasonal influenza vaccine. In Japan, ?point-of-care? influenza diagnosis is frequently used in primary health-care settings together with prescription of influenza antiviral medications. These patients had therefore been informed of their influenza infection during medical consultations.
Rapid diagnostic testing (dipstick-type point-of-care rapid diagnostic tests)
The duration between onset of symptoms and testing using rapid diagnostic kits ranged from 0 to 4 days (median, 1 day). Among 43 cases presenting with fever />38 ?C (6 cases had fever <38 ?C), 25 (58%) tested positive and 18 (42%) were negative. The sensitivity of these tests was higher among cases tested on the day following onset of fever than for those tested on the day of onset of fever (Table 1). All cases were subsequently confirmed by real-time reverse transcriptionpolymerase chain reaction (rRT-PCR).(6)
Clinical presentation on hospital admission
The duration between onset of illness and presentation at hospitals ranged from 0 to 7 days (median, 1 day). Among 49 cases, nearly 90% presented with fever />38 ?C. A high proportion (60?80%) presented symptoms such as general fatigue, fever (or feverish), cough and sore throat. Approximately 50% of cases had nasal congestion, nasal discharge, headache and myalgia or arthralgia. Nausea occurred in 24% of cases. Gastrointestinal symptoms including vomiting and diarrhoea were found in 10% of cases, and conjunctivitis in 7%(7)(Table 2). No cases had neurological manifestations.
Laboratory data on presentation at hospitals
Clinical samples were collected from cases for complete blood counts and serum chemistry on presentation at hospitals. No general trends in abnormalities were found. Both lowered and elevated white-blood cell counts were reported (n=26; median, 5100/mm3; range, 3200?11400/mm3). Other findings include slightly increased C-reactive protein (n=28; median, 1.2 mg/dl; range, 0?9.2 mg/dl), normal range or slightly elevated aminotransferases (GOT n=24; median, 17 IU/dl; range, 12?64 IU/dl; GPT, n=24; median, 11.5 IU/dl; range, 7?168 IU/dl); normal serum urea nitrogen and creatinine levels were noted. As there were no suspected cases of clinical pneumonia, chest X-rays were not performed.
Clinical course
Among the 43 cases with fever >38 ?C, upper respiratory tract symptoms, especially sore throat and cough, were commonly reported to have appeared before the onset of fever and persisted after its resolution. Headache, myalgia and arthralgia occurred with the onset of fever in most cases (Table 3, Fig. 1). All of the cases recovered without complications. All but 1 case received antiviral treatment (Table 4). The duration of onset and resolution of fever was 1?8 days (median, 3 days). As of 2 June 2009, no cases had required mechanical ventilation and no deaths had occurred. Most cases were discharged shortly after admission and sent home under isolation conditions and observation.
Antiviral treatment
Of the 49 laboratory-confirmed cases, 48 (98%) were treated with antivirals (22 received oseltamivir and 26 zanamivir). The Ministry of Health of Japan has advised clinicians to limit the administration of oseltamivir in teenagers given its possible neuropsychiatric adverse effects; however, some patients received oseltamivir because of their clinical history of asthma. The median time from the onset of symptoms to administration of antivirals was 1 day (range, 0?4 days). There was no difference in the duration of fever >38 ?C before administration of antivirals between cases treated with oseltamivir (median, 2 days; range, 1?4 days) and zanamivir (median, 2 days; range, 1?5 days). Earlier administration of antiviral medication seems to be associated with reduced duration of fever (Table 5). Both antivirals were well tolerated and no adverse effects were reported.
Editorial note.
This report describes the clinical features of mild upper respiratory tract illness in a school-associated outbreak of new influenza A (H1N1) virus infection in Kobe, Japan during 11?24 May 2009. Upper respiratory tract symptoms such as sore throat and cough preceded the onset of fever, suggesting replication of the virus in the upper respiratory tract and possible virus shedding during the prodromic period. Almost all the 49 laboratory-confirmed cases received antiviral treatment of either oseltamivir or zanamivir.
Early administration of treatment on the day of onset of fever reduced the duration of the symptom but was not statistically significant.
Point-of-care rapid diagnostic tests for influenza failed to correctly diagnose about 50% of the cases in samples collected on the day of onset of illness.
This finding suggests that the positive predictive value of diagnoses made by clinical and epidemiological information is superior to point-of-care rapid diagnostic tests in outbreak settings and is the preferred option for timely antiviral administration in populations at increased risk of complications. Virological studies are needed to determine the relation between the sensitivity of rapid diagnostic tests and the viral loads in the upper and lower respiratory tracts.
As of 10 June 2009, the majority of cases of school-associated outbreaks of new influenza A (H1N1) virus infection reported to WHO from several countries have been mild and their clinical features similar to those of seasonal influenza. However, the clinical spectrum of disease in such cases is broad, as reported from Mexico and the United States8 and in severe, sometimes fatal, cases, has included pneumonia that rapidly progressed to acute respiratory distress syndrome, and renal and multi-organ failure.
Preliminary clinical and pathological information reported to WHO suggest similarities between severe human cases of new influenza A (H1N1) virus infection and human cases of avian influenza H5N1 virus infection.
As the H1N1 virus becomes more widespread, as was observed in New York City (USA),(9) hospitalization in at-risk groups will likely increase.
Where outbreaks of new influenza A (H1N1) virus infection are occurring in the community, family members of suspected cases and people living with conditions that potentially put them at risk for more severe disease (such as those with chronic heart, lung, renal, liver, metabolic and haematological diseases, immunodeficiencies and pregnancy) should be rapidly informed about self-protection measures that can be taken to reduce the risk of infection.
These individuals are urged to contact a health-care provider early if they think they may have the illness.
Initial guidance on the clinical management of human infection with new influenza A (H1N1) virus is available from the WHO web site.(10)
Updates on the evolving situation will continue be published in the Weekly Epidemiological Record.(11)
Aggressive public health measures undertaken in Japan to contain the school-associated outbreak of the new influenza A (H1N1) virus included closing >1400 schools in both affected prefectures for 7 days and cancelling a major city festival in Kobe, including a planned parade that was expected to attract up to 1 million participants.
After the re-opening of schools, school absenteeism in these prefectures in the following weeks did not increase.
Further epidemiological studies are needed to determine the degree to which human infection with new influenza A (H1N1) virus infection spreads to the community during school-associated outbreaks. Lessons learnt from several countries suggest that close monitoring and preparation are needed to cope with the increased demands on the health-care system after outbreaks occur in schools.
Acknowledgement
WHO thanks the National Institute of Infectious Diseases, Tokyo, Japan and Kobe City Health Centre for collecting and analysing data, and the Medical Centre General Hospital and the West Kobe Medical Centre in Kobe City for their contributions to this report.
Table 1 Results of rapid diagnostic testing in 43 laboratory-confirmed human cases of new influenza A (H1N1) virus infection presenting at hospital with fever >38 ?C in Kobe, Japan, May 2009
- Rapid diagnostic test results for influenza A / Positive / Negative / Sensitivity (+/- S.E.(a))
- Day of onset of fever(b) - 12 - 12 - 50(?10)%
- +1 day - 12(c) - 6 - 67(?11)%
- +2 days - 1 - 0 - 100(? 0)%
- Total - 25 - 18 - 58(? 8)%
(a) Standard error
(b) Fever ≥38 ?C
(c) In one case, the patient received zanamivir for 1 day before administration of the rapid test. This case was diagnosed positive by the rapid test.
Table 2 Clinical presentation on hospital admission of 49 human cases of new influenza A (H1N1) virus infection in Kobe, Japan, May 2009
[Symptom - No. of cases - No. of cases presenting with symptom ? %]
- Fever ≥38 ?C ? 49 - 43 - 87.7
- Cough ? 48 - 38 - 79.1
- General fatigue ? 43 - 34 - 79.0
- Feverish ? 43 - 32 - 74.4
- Sore throat ? 49 - 35 - 71.4
- Myalgia/arthralgia ? 49 - 27 - 55.1
- Nasal congestion/nasal discharge ? 47 - 25 - 53.1
- Headache ? 48 - 25 - 52.0
- Nausea ? 49 - 12 - 24.4
- Vomiting ? 49 - 6 - 12.2
- Diarrhoea ? 49 - 7 - 14.2
- Conjunctivitis ? 43 - 3 - 6.9
Table 3 Duration of symptoms (days) of human cases of new influenza A (H1N1) virus infection in Kobe, Japan, May 2009
[Symptom ? No. of cases ? Median (days) ? Range (days)]
- Fever ≥38 ?C ? 41 - 2 - (1?5)
- Headache ? 15 - 2 - (1?4)
- Nasal discharge/nasal congestion ? 13 - 2 - (1?3)
- Sore throat ? 18 - 4 - (1?8)
- Cough ? 25 - 4 - (1?7)
- Nausea ? 7 - 1 - (1?2)
- Vomiting ? 4 - 1 - 1
- Diarrhoea ? 4 - 1 - (1?2)
- Myalgia/arthralgia ? 12 - 1 - (1?4)
Table 4 Distribution by age group of antiviral treatment administered to human cases of new influenza A (H1N1) virus infection in Kobe, Japan, May 2009
[Age (years) ? Total cases ? No. of cases receiving oseltamivir ? No. of cases receiving zanamivir ? Antiviral not administered]
- <9 - 1 - 1 (100%) - 0 (0.0%) - 0 (0.0%)
- 10?19 - 40 - 14 (35.0%) - 25 (62.5%) - 1 (2.5%)
- />20 - 8 - 7 (87.5%) - 1 (12.5%) - 0 (0%)
- Total - 49 - 22 - 26 - 1
Table 5 Initiation of antiviral therapy and duration of fever in human cases of new influenza A (H1N1) virus infection in Kobe, Japan, May 2009
[Initiation of antiviral therapy (days) ? Duration of fever (median) ? Oseltamivir / Zanamivir]
- Onset of fever (day) ? 1.5 days (range, 1?4 days; n=6) ? 1 day (range, 1?5 days; n=11)
- +1 day ? 3 days (range, 2?5 days; n=13) ? 3 days (range 2?5 days; n=10)
- +2 days ? NA ? NA
- +3 days ? NA ? 4 days (n=1)
- Total - 2 days (range, 1?5 days; n=19) ? 2 days (range, 1?5 days; n=22)
NA = data not available.
(1) See http://www.who.int/csr/don/2009_04_28/en/index.html
(2) Outbreak issue: cases mount through Australia, 5 June 2009. Health Emergency, Australian Government Department of Health and Aging (available at http://www.healthemergency.gov.au/in...m#cases05june; accessed June 2009).
(3) Health alert #19: novel H1N1 influenza ? update 21 May 2009. New York City Department of Health and Mental Hygiene (available at http://www.nyc.gov/html/doh/download...09/09md19.pdf; accessed June 2009).
(4) Epidemiology of new influenza A (H1N1) in the United Kingdom, April?May 2009. Eurosurveillance, 14(19):8?9 (available at http://www.eurosurveillance.org/View...ticleId=19213; accessed June 2009).
(5) See http://idsc.nih.go.jp/iasr/29/341/tpc341.html
(6) See http://www.who.int/csr/disease/swine...2009_04_29.pdf
(7) Observations include injected eyes or ocular injection. The diagnoses were not made by ophthalmologists.
(8) See No. 21, 2009, pp. 185?189.
(9) Health alert #21: novel H1N1 influenza ? update 2 June 2009. New York City Department of Health and Mental Hygiene (available at http://www.nyc.gov/html/doh/download...09/09md21.pdf; accessed June 2009).
(10) See http://www.who.int/csr/disease/swine.../en/index.html
(11) See http://www.who.int/wer
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