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The re-emergence of highly pathogenic avian influenza H7N9 viruses in humans in mainland China, 2019
Abstract
After no reported human cases of highly pathogenic avian influenza (HPAI) H7N9 for over a year, a case with severe disease occurred in late March 2019. Among HPAI H7N9 viral sequences, those recovered from the case and from environmental samples of a poultry slaughtering stall near their home formed a distinct clade from 2017 viral sequences. Several mutations possibly associated to antigenic drift occurred in the haemagglutinin gene, potentially warranting update of H7N9 vaccine strains.
Keywords: Highly pathogenic avian influenza virus, A(H7N9), Phylogenetic analysis, Human case
Since March 2013, influenza A(H7N9) viruses have caused five epidemic waves of zoonotic infections with a large number of reported human cases (1,567 in total up to February 2018). The first wave lasted until September 2013, and the following four occurred annually between October and September of the next year from 2013/14 to 2016/17. During the fifth wave in 2016/17, the emergence of highly pathogenic avian influenza (HPAI) H7N9 viruses raised wide global concern [1]. Compared to low pathogenic avian influenza (LPAI) A(H7N9) viruses, HPAI H7N9 viruses maintained the capacity to bind both human and avian receptors [2] and unreduced transmissibility in mammalian animal models, but exhibited higher virulence and broader tissue tropism [3-5]. Subsequent to 31 human HPAI H7N9 cases being reported in China in the fifth wave, their numbers decreased dramatically from October 2017, with only one additional HPAI H7N9 human case up to February 2018. These 32 latest human cases covered nine provinces of China. During the following 14 months, neither LPAI H7N9 nor HPAI H7N9 was reported in humans in the country. Several HPAI H7N9 outbreaks occurred in poultry, with the latest in March 2019 in peacocks in Liaoning province
In late March 2019, a person in Inner Mongolia, China, presenting with severe pneumonia and respiratory failure was confirmed with HPAI H7N9. The re-emergence of a human HPAI H7N9 virus infection after reports of such cases had ceased for more than a year caused high public health concerns. We hereby describe this case and analyse genome features of the viruses causing the infection and of viruses found near the caseās residence.
THEN, BY ALL ACCOUNTS, 2019/2020 IS THE 6TH WAVE
Case description
The patient, a person in their early 80s with underlying cardiovascular disease, lived in the Inner Mongolia Autonomous region. The first symptoms (day 1 of illness) occurred at the end of March 2019 and included chills, cough, fever (39.0ā°C), headache, muscular soreness and shortness of breath. On day 6 of illness, the patient was admitted to a local hospital. Acute heart failure, hypertension, pneumonia, residuals of cerebral infarction and venous thrombosis were diagnosed. On day 7, the clinical condition deteriorated markedly and the patient was transferred to a hospital in Gansu province, a province near Inner Mongolia. Based on clinical signs and computed tomography (CT) results, bilateral pneumonia and emphysema pulmonum were diagnosed. A patientās throat swab sampled in the beginning of April was positive for influenza A(H7N9) viruses. On day 19, the patient died due to secondary bacterial infections and development of multiple organ failure.
Antigenic Variant of Highly Pathogenic Avian Influenza A(H7N9) Virus, China, 2019
Abstract
In China, influenza A(H7N9) virus appeared in 2013, then mutated into a highly pathogenic virus, causing outbreaks among poultry and cases in humans. Since September 2017, extensive use of the corresponding vaccine, H7-Re1, successfully reduced virus prevalence. However, in 2019, a novel antigenic variant emerged, posing considerable economic and public health threats.
In 2019, during active surveillance for avian influenza infection in China, we identified 7 strains of H7N9 viruses from 4,226 chicken swab samples. We isolated the strains by inoculating them into 10-day-old specific-pathogenāfree chicken embryos and confirmed their identification via reverse-transcription PCR and sequencing. Viruses were from Hebei and Liaoning Provinces
Human infections with the emerging avian influenza A H7N9 virus from wet market poultry: clinical analysis and characterisation of viral genome
Abstract
After no reported human cases of highly pathogenic avian influenza (HPAI) H7N9 for over a year, a case with severe disease occurred in late March 2019. Among HPAI H7N9 viral sequences, those recovered from the case and from environmental samples of a poultry slaughtering stall near their home formed a distinct clade from 2017 viral sequences. Several mutations possibly associated to antigenic drift occurred in the haemagglutinin gene, potentially warranting update of H7N9 vaccine strains.
Keywords: Highly pathogenic avian influenza virus, A(H7N9), Phylogenetic analysis, Human case
Since March 2013, influenza A(H7N9) viruses have caused five epidemic waves of zoonotic infections with a large number of reported human cases (1,567 in total up to February 2018). The first wave lasted until September 2013, and the following four occurred annually between October and September of the next year from 2013/14 to 2016/17. During the fifth wave in 2016/17, the emergence of highly pathogenic avian influenza (HPAI) H7N9 viruses raised wide global concern [1]. Compared to low pathogenic avian influenza (LPAI) A(H7N9) viruses, HPAI H7N9 viruses maintained the capacity to bind both human and avian receptors [2] and unreduced transmissibility in mammalian animal models, but exhibited higher virulence and broader tissue tropism [3-5]. Subsequent to 31 human HPAI H7N9 cases being reported in China in the fifth wave, their numbers decreased dramatically from October 2017, with only one additional HPAI H7N9 human case up to February 2018. These 32 latest human cases covered nine provinces of China. During the following 14 months, neither LPAI H7N9 nor HPAI H7N9 was reported in humans in the country. Several HPAI H7N9 outbreaks occurred in poultry, with the latest in March 2019 in peacocks in Liaoning province
In late March 2019, a person in Inner Mongolia, China, presenting with severe pneumonia and respiratory failure was confirmed with HPAI H7N9. The re-emergence of a human HPAI H7N9 virus infection after reports of such cases had ceased for more than a year caused high public health concerns. We hereby describe this case and analyse genome features of the viruses causing the infection and of viruses found near the caseās residence.
THEN, BY ALL ACCOUNTS, 2019/2020 IS THE 6TH WAVE
Case description
The patient, a person in their early 80s with underlying cardiovascular disease, lived in the Inner Mongolia Autonomous region. The first symptoms (day 1 of illness) occurred at the end of March 2019 and included chills, cough, fever (39.0ā°C), headache, muscular soreness and shortness of breath. On day 6 of illness, the patient was admitted to a local hospital. Acute heart failure, hypertension, pneumonia, residuals of cerebral infarction and venous thrombosis were diagnosed. On day 7, the clinical condition deteriorated markedly and the patient was transferred to a hospital in Gansu province, a province near Inner Mongolia. Based on clinical signs and computed tomography (CT) results, bilateral pneumonia and emphysema pulmonum were diagnosed. A patientās throat swab sampled in the beginning of April was positive for influenza A(H7N9) viruses. On day 19, the patient died due to secondary bacterial infections and development of multiple organ failure.
Antigenic Variant of Highly Pathogenic Avian Influenza A(H7N9) Virus, China, 2019
Abstract
In China, influenza A(H7N9) virus appeared in 2013, then mutated into a highly pathogenic virus, causing outbreaks among poultry and cases in humans. Since September 2017, extensive use of the corresponding vaccine, H7-Re1, successfully reduced virus prevalence. However, in 2019, a novel antigenic variant emerged, posing considerable economic and public health threats.
In 2019, during active surveillance for avian influenza infection in China, we identified 7 strains of H7N9 viruses from 4,226 chicken swab samples. We isolated the strains by inoculating them into 10-day-old specific-pathogenāfree chicken embryos and confirmed their identification via reverse-transcription PCR and sequencing. Viruses were from Hebei and Liaoning Provinces
Human infections with the emerging avian influenza A H7N9 virus from wet market poultry: clinical analysis and characterisation of viral genome