To the Editor: On March 31, 2013, the National
Health and Family Planning Commission of China notified the World Health
Organization of 3 cases of human infections with avian influenza
A(H7N9) virus. These cases were caused by a novel virus that was
identified by laboratory testing at the China Centers for Disease
Control and Prevention (CDC) on March 29 (
1).
As of April 19, 2013, a total of 91 laboratory-confirmed human cases
(17 deaths) of infection with avian influenza A(H7N9) virus were
reported in 4 provinces in China (
2).
We report clinical features of 2 infected adults who died, 2 critically
ill infected adults who recovered, and 1 infected child who had a mild
case during this outbreak in Shanghai, China.
A 3.5-year-old boy had fever (39.5°C) for 3 days and mild rhinorrhea
starting on March 31. He was admitted to a district pediatric outpatient
clinic on April 1. At admission, the child was given oseltamivir for 5
days, even though signs and symptoms had resolved. Nasopharyngeal swab
samples were positive by real-time PCR for avian influenza A(H7N9)
virus. All symptoms resolved uneventfully by April 3, and CDC was
notified that avian influenza A(H7N9) virus was identified in his
respiratory sample. The patient was discharged on day 11 after illness
onset.
The 4 adult patients were given diagnoses of severe pneumonia with shortness of breath, dyspnea, and marked hypoxia (
Table).
Duration from disease onset to severe illness was 5–7 days. At
admission, the 4 patients with severe cases had decreased peripheral
blood leukocyte counts and increased levels of aspartate
aminotransferase; 3 had increased levels of lactate dehydrogenase (
Table).
Figure
Figure.
. Chest computed tomographic scans for 3 patients infected with avian
influenza A(H7N9) virus, Shanghai, China. A) Patient 1, who died,
showing extensive lung infiltrates at day 7 of illness onset....
All
4 adult patients had radiologically confirmed pneumonia and bilateral
patchy alveolar opacities or diffused lobar consolidation with or
without pleural effusion (
Figure,
Appendix). Findings on chest radiographs for severe cases requiring
mechanical ventilation were consistent with those for acute respiratory
distress syndrome.
Among the 4 severe cases in adults, a 52-year-old woman (patient 1)
and a 49-year-old man (patient 2) died from acute respiratory distress
syndrome and multiple organ failure on days 14 and 10, respectively,
after disease onset and 1–2 days after progression to respiratory
failure. Two other patients showed improvement and were virus negative 6
and 4 days after antiviral treatment. After 23–24 days of treatment in
an intensive care unit, the 2 patients with severe cases recovered and
were discharged (
Table).
The 2 patients who died were given methylprednisolone. Of the 2
patients who recovered, 1 was given a low dose of methylprednisolone for
1 week and the other was not given methylprednisolone. Although it is
difficult to assess the role of glucocorticoids in treatment because of
limited number of cases, caution is advised because of possible serious
adverse events, including death, as reported for human infection with
influenza A(H1N1) virus (
4).
One of the adult patients reported exposure to poultry. The family of
the child patient raised chickens and ducks, but these animals had no
apparent disease, and cloacal swab specimens were negative for avian
influenza A(H7N9) virus. One patient who died (patient 2) had frequent
occupational exposure to poultry. Sixteen contacts of the child and 45
contacts of the 4 adult patients were monitored, and routine virologic
sampling was performed. One contact (husband of patient 1) of a patient
who died (
Table)
became febrile and was positive for avian influenza A(H7N9) virus on
April 12 (day 24 after disease onset for patient 1); as of the date of
this report, he was receiving treatment in an intensive care unit.
However, it is difficult to tell if this is a case of human-to-human
transmission or if both persons were exposed to infectious poultry. All
remaining contacts had no symptoms and were negative for virus by PCR.
Several features of this avian influenza A(H7N9) outbreak are
distinct from those of previous avian influenza outbreaks. Human
infection with this virus showed a case-fatality rate of 18.7% (17/91),
but this rate is not as high as that for avian influenza A(H5N1) virus
(case-fatality rate 59%) (
5).
Avian influenza A(H7N9) virus infection seems to cause more severe
human illness than do other subgroups of H7 influenza A viruses
(subtypes H7N2, H7N3, and H7N7), which are usually associated with
poultry outbreaks but cause mild disease in humans. However, infection
with avian influenza A(H7N7) virus resulted in the death of a
veterinarian during an outbreak in the Netherlands (
6).
In the 5 patients reported here, avian influenza A(H7N9) virus caused
fatal disease in 2 adult patients 52 and 49 years of age, who had other
medical conditions. Older age has been reported to confer higher risk
for developing more severe influenza-associated outcomes (
7).
In conclusion, these cases indicated that avian influenza A(H7N9)
virus might not be as virulent as avian influenza A(H5N1) virus in
humans. Avian influenza A(H7N9) virus does not appear to cause obvious
disease in poultry and causes mild disease in children. More severe
disease in adults occurred among those had concurrent diseases or were
immunodeficient.
Zeng Mei
1, Shuihua Lu
1, Xianzheng Wu
1, Lingyun Shao
1, Yu Hui
1, Jiali Wang, Tao Li, Haixia Zhang, Xiaohong Wang, Feifei Yang, Jialin Jin, Ying Zhang, and Wenhong Zhang
Author affiliations: Children’s Hospital of Fudan University, Shanghai, China (Z. Mei, Y. Hui, X. Wang); Fudan University, Shanghai (S. Lu, T. Li, W. Zhang, Y. Zhang); Tongji Hospital of Tongji University, Shanghai (X. Wu, H. Zhang); Huashan Hospital of Fudan University, Shanghai (L. Shao, J. Wang, F. Yang, J. Jin, W. Zhang); Johns Hopkins University, Baltimore, Maryland, USA (Y. Zhang)
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Figure
Table
Suggested citation for this article:
Mei Z, Lu S, Wu X, Shao L, Hui Y, Wang J, et al. Avian influenza
A(H7N9) virus infections, Shanghai, China [letter]. Emerg Infect Dis
[Internet]. 2013 Jul [
date cited].
http://dx.doi.org/10.3201/eid1907.130523
DOI: 10.3201/eid1907.130523