Global & Disaster Medicine

Archive for the ‘H7N9’ Category

China’s H7N9 cases are rising again, partly related to a recent spurt of local infections in Beijing

CHP

China


Hong Kong’s Centre for Health Protection’s weekly update of H7N9 avian flu in mainland China: 14 new cases, 2 of them fatal. 

H7N9 in China

The Centre for Health Protection (CHP) of the Department of Health today (April 14) received notification of 14 additional human cases of avian influenza A(H7N9), including two deaths, from the National Health and Family Planning Commission, and strongly urged the public to maintain strict personal, food and environmental hygiene both locally and during travel, particularly in Easter.

The eleven male and three female patients, aged from 39 to 81, had onset from March 27 to April 11, including three from Sichuan, two each from Henan, Shandong and Xizang, and one each from Anhui, Beijing, Hunan, Tianjin and Zhejiang. Among them, 13 had exposure to poultry, poultry markets or mobile stalls.

Travellers to the Mainland or other affected areas must avoid visiting wet markets, live poultry markets or farms. They should be alert to the presence of backyard poultry when visiting relatives and friends. They should also avoid purchase of live or freshly slaughtered poultry, and avoid touching poultry/birds or their droppings. They should strictly observe personal and hand hygiene when visiting any place with live poultry.

Travellers returning from affected areas should consult a doctor promptly if symptoms develop, and inform the doctor of their travel history for prompt diagnosis and treatment of potential diseases. It is essential to tell the doctor if they have seen any live poultry during travel, which may imply possible exposure to contaminated environments. This will enable the doctor to assess the possibility of avian influenza and arrange necessary investigations and appropriate treatment in a timely manner.

While local surveillance, prevention and control measures are in place, the CHP will remain vigilant and work closely with the World Health Organization and relevant health authorities to monitor the latest developments.

The CHP’s Port Health Office conducts health surveillance measures at all boundary control points. Thermal imaging systems are in place for body temperature checks on inbound travellers. Suspected cases will be immediately referred to public hospitals for follow-up.

The display of posters and broadcasting of health messages in departure and arrival halls as health education for travellers is under way. The travel industry and other stakeholders are regularly updated on the latest information.

The public should maintain strict personal, hand, food and environmental hygiene and take heed of the advice below while handling poultry:

  • Avoid touching poultry, birds, animals or their droppings;
  • When buying live chickens, do not touch them and their droppings. Do not blow at their bottoms. Wash eggs with detergent if soiled with faecal matter and cook and consume them immediately. Always wash hands thoroughly with soap and water after handling chickens and eggs;
  • Eggs should be cooked well until the white and yolk become firm. Do not eat raw eggs or dip cooked food into any sauce with raw eggs. Poultry should be cooked thoroughly. If there is pinkish juice running from the cooked poultry or the middle part of its bone is still red, the poultry should be cooked again until fully done;
  • Wash hands frequently, especially before touching the mouth, nose or eyes, before handling food or eating, and after going to the toilet, touching public installations or equipment such as escalator handrails, elevator control panels or door knobs, or when hands are dirtied by respiratory secretions after coughing or sneezing; and
  • Wear a mask if fever or respiratory symptoms develop, when going to a hospital or clinic, or while taking care of patients with fever or respiratory symptoms.

The public may visit the CHP’s pages for more information: the avian influenza page, the weekly Avian Influenza Reportglobal statistics and affected areas of avian influenza, the Facebook Page and the YouTube Channel.

Ends/Friday, April 14, 2017
Issued at HKT 19:10

China: The reported H7N9 human infections during the 5th epidemic represent a significant increase compared with the first 4 epidemics.

MMWR

Increase in Human Infections with Avian Influenza A(H7N9) Virus During the Fifth Epidemic — China, October 2016–February 2017

On March 3, 2017, this report was posted online as an MMWR Early Release.

A. Danielle Iuliano, PhD1; Yunho Jang, PhD1; Joyce Jones, MS1; C. Todd Davis, PhD1; David E. Wentworth, PhD1; Timothy M. Uyeki, MD1; Katherine Roguski, MPH1; Mark G. Thompson, PhD1; Larisa Gubareva, PhD1; Alicia M. Fry, MD1; Erin Burns, MA1; Susan Trock, DVM1; Suizan Zhou, MPH2; Jacqueline M. Katz, PhD1; Daniel B. Jernigan, MD1 (View author affiliations)

During March 2013–February 24, 2017, annual epidemics of avian influenza A(H7N9) in China resulted in 1,258 avian influenza A(H7N9) virus infections in humans being reported to the World Health Organization (WHO) by the National Health and Family Planning Commission of China and other regional sources (1). During the first four epidemics, 88% of patients developed pneumonia, 68% were admitted to an intensive care unit, and 41% died (2). Candidate vaccine viruses (CVVs) were developed, and vaccine was manufactured based on representative viruses detected after the emergence of A(H7N9) virus in humans in 2013. During the ongoing fifth epidemic (beginning October 1, 2016),* 460 human infections with A(H7N9) virus have been reported, including 453 in mainland China, six associated with travel to mainland China from Hong Kong (four cases), Macao (one) and Taiwan (one), and one in an asymptomatic poultry worker in Macao (1). Although the clinical characteristics and risk factors for human infections do not appear to have changed (2,3), the reported human infections during the fifth epidemic represent a significant increase compared with the first four epidemics, which resulted in 135 (first epidemic), 320 (second), 226 (third), and 119 (fourth epidemic) human infections (2). Most human infections continue to result in severe respiratory illness and have been associated with poultry exposure. Although some limited human-to-human spread continues to be identified, no sustained human-to-human A(H7N9) transmission has been observed (2,3).

CDC analysis of 74 hemagglutinin (HA) gene sequences from A(H7N9) virus samples collected from infected persons or live bird market environments during the fifth epidemic, which are available in the Global Initiative on Sharing All Influenza Data (GISAID) database (4,5), indicates that A(H7N9) viruses have diverged into two distinct genetic lineages. Available fifth epidemic viruses belong to two distinct lineages, the Pearl River Delta and Yangtze River Delta lineage, and ongoing analyses have found that 69 (93%) of the 74 HA gene sequences to date have been Yangtze River Delta lineage viruses. Preliminary antigenic analysis of recent Yangtze River Delta lineage viruses isolated from infections detected in Hong Kong indicate reduced cross-reactivity with existing CVVs, whereas viruses belonging to the Pearl River Delta lineage are still well inhibited by ferret antisera raised to CVVs. These preliminary data suggest that viruses from the Yangtze River Delta lineage are antigenically distinct from earlier A(H7N9) viruses and from existing CVVs. In addition, ongoing genetic analysis of neuraminidase genes from fifth epidemic viruses indicate that approximately 7%–9% of the viruses analyzed to date have known or suspected markers for reduced susceptibility to one or more neuraminidase inhibitor antiviral medications. The neuraminidase inhibitor class of antiviral drugs is currently recommended for the treatment of human infection with A(H7N9) virus. Antiviral resistance can arise spontaneously or emerge during the course of treatment. Many of the A(H7N9) virus samples collected from human infections in China might have been collected after antiviral treatment had begun.

Although all A(H7N9) viruses characterized from the previous four epidemics have been low pathogenic avian influenza viruses, analysis of human (three) and environmental (seven) samples from the fifth epidemic demonstrate that these viruses contain a four–amino acid insertion in a host protease cleavage site in the HA protein that is characteristic of highly pathogenic avian influenza (HPAI) viruses. Chinese authorities are investigating and monitoring closely for outbreaks of HPAI A(H7N9) among poultry.

Since April 2013, the Influenza Risk Assessment Tool has been used by CDC to assess the risk posed by certain novel influenza A viruses. Although the current risk to the public’s health from A(H7N9) viruses is low, among the 12 novel influenza A viruses evaluated with this tool, A(H7N9) viruses have the highest risk score and are characterized as posing moderate–high potential pandemic risk (6). Experts from the World Health Organization (WHO) Global Influenza Surveillance and Response System (GISRS) met in Geneva, Switzerland, February 27–March 1, 2017, to review available epidemiologic and virologic data related to influenza A(H7N9) viruses to evaluate the need to produce additional CVVs to maximize influenza pandemic preparedness. Two additional H7N9 CVVs were recommended for development: a new CVV derived from an A/Guangdong/17SF003/2016-like virus (HPAI), which is a highly pathogenic virus from the Yangtze River Delta lineage; and a new CVV derived from A/Hunan/2650/2016-like virus, which is a low pathogenic virus also from the Yangtze River Delta lineage (1). At this time, CDC is preparing a CVV derived from an A/Hunan/2650/2016-like virus using reverse genetics. Further preparedness measures will be informed by ongoing analysis of genetic, antigenic, and epidemiologic data and how these data impact the risk assessment. CDC will continue to work closely with the Chinese Center for Disease Control and Prevention to support the response to this epidemic. Guidance for U.S. clinicians who might be evaluating patients with possible H7N9 virus infection and travelers to China is available online (https://www.cdc.gov/flu/avianflu/h7n9-virus.htm).

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Acknowledgments

Eduardo Azziz-Baumgartner, Stephen A. Burke, Douglas Jordan, CDC; Ying Song, Carolyn Greene, CDC, Beijing, China; National Influenza Center, CDC, Beijing, China; Prevention and Public Health Emergency Center, CDC, Beijing, China; Taiwan CDC, Taipei, Taiwan; Centre for Health Protection, Department of Health, Hong Kong SAR, China.

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Corresponding author: A. Danielle Iuliano, aiuliano@cdc.gov, 404-639-5106.

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1CDC; 2CDC, Beijing, China.

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* Epidemics refer to the seasonal increases in human infections; the fifth epidemic began on October 1, 2016.

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References

  1. World Health Organization. Antigenic and genetic characteristics of zoonotic influenza viruses and development of candidate vaccine viruses for pandemic preparedness, March 2017. Geneva, Switzerland: World Health Organization; 2017. http://www.who.int/influenza/vaccines/virus/201703_zoonotic_vaccinevirusupdate.pdf?ua=1
  2. Xiang N, Li X, Ren R, et al. Assessing change in avian influenza A(H7N9) virus infections during the fourth epidemic—China, September 2015–August 2016. MMWR Morb Mortal Wkly Rep 2016;65:1390–4. CrossRef PubMed
  3. Zhou L, Ren R, Yang L, et al. Sudden increase in human infection with avian influenza A(H7N9) virus in China, September–December 2016. Western Pac Surveill Response J 2017;8. CrossRef
  4. Elbe S, Buckland-Merrett G. Data, disease and diplomacy: GISAID’s innovative contribution to global health. Global Challenges 2017;1:33–46. CrossRef
  5. Federal Republic of Germany. The GISAID initiative. http://platform.gisaid.org/epi3/start
  6. CDC. Influenza risk assessment tool (IRAT). Atlanta, GA: US Department of Health and Human Services, CDC; 2017. https://www.cdc.gov/flu/pandemic-resources/national-strategy/risk-assessment.htm

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Suggested citation for this article: Iuliano AD, Jang Y, Jones J, et al. Increase in Human Infections with Avian Influenza A(H7N9) Virus During the Fifth Epidemic — China, October 2016–February 2017. MMWR Morb Mortal Wkly Rep 2017;66:254–255. DOI: http://dx.doi.org/10.15585/mmwr.mm6609e2.


Trump & Deadly Disease

NY Times

  • “…..President Trump’s budget would cut funding for the National Institutes of Health by 18 percent.
  • It would cut the State Department and the United States Agency for International Development, a key vehicle for preventing and responding to outbreaks before they reach our shores, by 28 percent.
  • And the repeal of the Affordable Care Act would kill the billion-dollar Prevention and Public Health Fund, which provides funding for the Centers for Disease Control and Prevention to fight outbreaks of infectious disease.
  • (While the budget also calls for the creation of an emergency fund to respond to outbreaks, there is no indication that it would offset the other cuts, or where the money would come from.)
  • We are already witnessing an outbreak of influenza in birds — the H7N9 strain, in China — that could be the source for the next human pandemic. Since October, over 500 people have been infected; more than 34 percent have died. Most victims had contact with infected poultry, yet three recent clusters appear to be from person-to-person transmission. Will H7N9 mutate to become easily transmitted between humans? We don’t know. But without sufficient supplies of a vaccine, we are not prepared to stop it…….”

Hong Kong’s Centre for Health Protection (CHP) announced that China reported 21 more H7N9 avian influenza cases, 4 of them fatal, from Mar 10 to Mar 16.

Hong Kong DOH

 


The WHO weighed in on 84 recently reported H7N9 cases reported by China, including a recent imported case from Hong Kong, noting three possible human-to-human illness clusters.

WHO1

Human infection with avian influenza A(H7N9) virus – China

Disease outbreak news
15 March 2017

Between 24 February and 7 March 2017, a total of 58 additional laboratory-confirmed cases of human infection have been reported to WHO from mainland China and China, Hong Kong Special Administrative Region (SAR).

On 24 February 2017, the National Health and Family Planning Commission of China (NHFPC) notified WHO of 35 additional laboratory-confirmed cases of human infection with avian influenza A(H7N9) virus. On 3 March 2017, the NHFPC notified WHO of 22 additional laboratory-confirmed cases of human infection with avian influenza A(H7N9) virus. On 7 March 2017, the Department of Health, China, Hong Kong SAR confirmed a case of human infection with avian influenza A(H7N9) virus.

Details of the cases

Between 24 February and 3 March 2017, the NHFPC reported a total of 57 human cases of infection with avian influenza A(H7N9) virus. Onset dates of the cases ranged from 26 January to 27 February 2017. Of these 57 cases, 13 were female. Cases range in age from 4 to 81 years and the median age is 56 years. The cases are reported from Anhui (9), Beijing (1), Fujian (1), Guangdong (11), Guangxi (4), Guizhou (2), Henan (3), Hunan (3), Hubei (2), Jiangsu (7), Jiangxi (4), Shandong (2), Shanghai (1), Sichuan (2), and Zhejiang (5).

At the time of notification, there were 11 deaths, and 39 cases diagnosed as either pneumonia (7) or severe pneumonia (32). One case has mild symptoms. The clinical presentations of the other six (6) cases are not available at this time. Forty-three cases are reported to have had exposure to poultry or live poultry market, four (4) cases have possibility of human to human transmission (among them, two cases also had exposure history to poultry or live poultry market), four (4) had no exposure to poultry and for eight (8) the possible exposures are unknown or under investigation.

On 24 February 2017, two clusters of possible human to human transmission were reported.

First cluster:

  • A 40-year-old male from Jiangsu Province, and relative of the 63-year old female described below. He had symptom onset on 26 January 2017 and was admitted to hospital. He bought a live chicken on 24 January 2017.
  • A 63-year-old female from Zhejiang Province. She had symptom onset on 10 February 2017, and was admitted to hospital for pneumonia. She had exposure to domestic poultry (farmer by trade) and contact with her son.

All 21 contacts of these 2 cases were healthy and did not develop any symptoms.

Second cluster:

  • A 29-year-old male from Anhui Province. He had symptom onset on 3 February 2017, and was admitted to hospital for severe pneumonia. He had exposure to live poultry before onset of disease.
  • A 62-year-old female from Anhui Province. She was admitted to the same hospital as the 29-year old male case mentioned above for chronic cough. She had been on the same ward for one day. After initial improvement her condition worsened and she passed away on 16 February 2017.
  • A 58-year-old male from Anhui Province, the father of the 29-year-old male case mentioned above. He had symptom onset on 17 February 2017 and was admitted to hospital. He had exposure to live poultry on 31 January 2017 but took also care for his sick son.

All 32 contacts of these 3 cases were healthy and did not develop any symptoms.

On 3 March 2017, one cluster of possible human to human transmission was reported.

  • A 60-year-old male from Anhui Province, and grandfather of the 10-year-old male described below. He had symptoms onset on 24 February 2017 and was admitted to a hospital on 25 February 2017. He passed away on 1 March. He had exposure to live poultry.
  • A 10-year-old male from Anhui Province. He had symptoms onset on 27 February 2017, and was admitted to hospital on 1 March 2017 for pneumonia. He also had a history of exposure to live poultry.

On 7 March 2017, the Department of Health, China, Hong Kong SAR confirmed a case of human infection with avian influenza A(H7N9) virus in a 76-year-old man with underlying illnesses. The patient travelled to Fuzhou, Fujian between 11 February and 1 March 2017 and he visited a wet market there.

He developed symptoms on 3 March 2017. His nasopharyngeal aspirate specimen tested positive for avian influenza A(H7N9) on 7 March 2017. His clinical diagnosis is pneumonia and he is now in a critical condition. The patient’s close contact has remained asymptomatic so far and has been put under medical surveillance. Tracing of his other contacts in China, Hong Kong SAR is underway.

To date, a total of 1281 laboratory-confirmed human infections with avian influenza A(H7N9) virus have been reported through IHR notification since early 2013.

Public health response

Considering the increase in the number of human infections with avian influenza A(H7N9) since December 2016, the Chinese government has enhanced measures such as:

  • The NHFPC strengthened epidemic surveillance, conducted timely risk assessment and analysed the information for any changes in epidemiology.
  • The NHPFC requested local NHFPCs to implement effective control measures on the source of outbreaks and to minimize the number of affected people.
  • Strengthened early diagnosis and early treatment, treatment of severe cases to reduce occurrence of severe cases and deaths.
  • Further enhanced medical treatment.
  • Joint investigation teams between NHFPC and Ministries of Agriculture, Industry and Commerce visited Jiangsu, Zhejiang, Anhui and Guangdong provinces where more cases occurred for joint supervision, inspection and guidance on local surveillance, medical treatment, prevention and control and to promote control measures with a focus on live poultry market management and cross-regional transportation.
  • Relevant prefectures in Jiangsu province have closed live poultry markets in late December 2016 and Zhejiang, Guangdong and Anhui provinces have strengthened live poultry market regulations.
  • Conducted public risk communication and shared information with the public.

The Centre for Health Protection of the Department of Health in China, Hong Kong SAR has taken the following measures:

  • Urged the public to maintain strict personal, food and environmental hygiene both locally and during travel.
  • Issued an alert to doctors, hospitals, schools and institutions of the latest situation.

WHO risk assessment

The number of human cases with onset from 1 October 2016 is greater than the total numbers of human cases in earlier waves.

Human infections with the avian influenza A(H7N9) virus remain unusual. Close observation of the epidemiological situation and further characterization of the most recent human viruses are critical to assess associated risk and to adjust risk management measures timely.

Most human cases are exposed to avian influenza A(H7N9) virus through contact with infected poultry or contaminated environments, including live poultry markets. Since the virus continues to be detected in animals and environments, and live poultry vending continues, further human cases can be expected. Although small clusters of human cases with avian influenza A(H7N9) virus have been reported including those involving patients in the same ward, current epidemiological and virological evidence suggests that this virus has not acquired the ability of sustained transmission among humans. Therefore the likelihood of further community level spread is considered low.

WHO2

Human infection with avian influenza A(H7N9) virus – China

Disease outbreak news
16 March 2017

On 10 March 2017, the National Health and Family Planning Commission of China (NHFPC) notified WHO of 26 additional laboratory-confirmed cases of human infection with avian influenza A(H7N9) virus in mainland China.

Details of the cases

Onset dates ranged from 19 February to 4 March 2017. Of these 26 cases, 8 were female. The median age is 56.5 years (age range among the cases is 15 to 79 years old). The cases were reported from Chongqing (1), Fujian (2), Guangxi (5), Guizhou (2), Henan (4), Hunan (2), Hubei (1), Jiangsu (2), Jiangxi (4) and Sichuan (3).

This is the first case of human infection with avian influenza A(H7N9) reported in Chongqing municipality since H7N9 cases were first reported in 2013.

At the time of notification, there were 3 deaths, and 21 cases were diagnosed as either pneumonia (3) or severe pneumonia (18). The clinical presentations of two (2) cases were not available at time of notification. Twenty-two (22) cases were reported to have had exposure to poultry or live poultry market. Two (2) cases had no exposure to poultry and two (2) cases are still under investigation. No clusters were reported.

To date, a total of 1307 laboratory-confirmed human infections with avian influenza A(H7N9) virus have been reported through IHR notification since early 2013.

Public health response

Considering the increase in the number of human cases since December 2016, the Chinese government at national and local levels is taking further measures including:

  • Provincial governments convened meetings; some key provinces have closed live poultry markets.
  • The provinces have further strengthened multi-sectoral supervision, inspection and guidance on local surveillance, prevention and control, and are promoting source control measures focused on live poultry market management and cross-regional transportation.
  • Training is continued in health care facilities in all places to guide medical treatment of cases.
  • Strengthening the technical guidance for prevention and control for some central and western provinces, as cases reported in those provinces increased recently.
  • Risk communication and information is provided to the public with guidance on self-protection.

WHO risk assessment

The number of human infections with avian influenza A(H7N9) in the fifth epidemic wave (i.e. onset since 1 October 2016) is greater than the numbers of human cases reported in earlier waves.

.Human infections with the avian influenza A(H7N9) virus remain unusual. Close observation of the epidemiological situation and further characterization of the most recent human viruses are critical to assess associated risk and to adjust risk management measures in a timely manner.

Most human cases are exposed to avian influenza A(H7N9) virus through contact with infected poultry or contaminated environments, including live poultry markets. Since the virus continues to be detected in animals and environments, and live poultry vending continues, further human cases can be expected. Although small clusters of cases of human infection with avian influenza A(H7N9) virus have been reported including those involving patients in the same ward, current epidemiological and virological evidence suggests that this virus has not acquired the ability of sustained transmission among humans. Therefore the likelihood of further community level spread is considered low.

WHO advice

WHO advises that travellers to countries with known outbreaks of avian influenza should avoid, if possible, poultry farms, contact with animals in live poultry markets, entering areas where poultry may be slaughtered, or contact with any surfaces that appear to be contaminated with faeces from poultry or other animals. Travellers should also wash their hands often with soap and water, and follow good food safety and good food hygiene practices.

WHO does not advise special screening at points of entry with regard to this event, nor does it currently recommend any travel or trade restrictions. As always, a diagnosis of infection with an avian influenza virus should be considered in individuals who develop severe acute respiratory symptoms while travelling in or soon after returning from an area where avian influenza is a concern.

WHO encourages countries to continue strengthening influenza surveillance, including surveillance for severe acute respiratory infections (SARI) and influenza-like illness (ILI) and to carefully review any unusual patterns, ensure reporting of human infections under the IHR 2005, and continue national health preparedness actions.

 


China: 22 additional human cases of H7N9, including three deaths, were recorded from March 3 to 9.

Hong Kong DOH

A CDC Scientist harvests H7N9 virus that has been grown for sharing with partner laboratories for research purposes

 


The Centre for Health Protection (CHP) of the Department of Health is today (March 6) closely monitoring two additional human cases of avian influenza A(H7N9) in Guangxi.

Hong Kong DOH

 


During March 2013–February 24, 2017, annual epidemics of avian influenza A(H7N9) in China resulted in 1,258 avian influenza A(H7N9) virus infections in humans being reported to the World Health Organization

 

MMWR

Increase in Human Infections with Avian Influenza A(H7N9) Virus During the Fifth Epidemic — China, October 2016–February 2017
Early Release / March 3, 2017 / 66
A. Danielle Iuliano, PhD1; Yunho Jang, PhD1; Joyce Jones, MS1; C. Todd Davis, PhD1; David E. Wentworth, PhD1; Timothy M. Uyeki, MD1; Katherine Roguski, MPH1; Mark G. Thompson, PhD1; Larisa Gubareva, PhD1; Alicia M. Fry, MD1; Erin Burns, MA1; Susan Trock, DVM1; Suizan Zhou, MPH2; Jacqueline M. Katz, PhD1; Daniel B. Jernigan, MD1 (View author affiliations)
During March 2013–February 24, 2017, annual epidemics of avian influenza A(H7N9) in China resulted in 1,258 avian influenza A(H7N9) virus infections in humans being reported to the World Health Organization (WHO) by the National Health and Family Planning Commission of China and other regional sources (1). During the first four epidemics, 88% of patients developed pneumonia, 68% were admitted to an intensive care unit, and 41% died (2). Candidate vaccine viruses (CVVs) were developed, and vaccine was manufactured based on representative viruses detected after the emergence of A(H7N9) virus in humans in 2013. During the ongoing fifth epidemic (beginning October 1, 2016),* 460 human infections with A(H7N9) virus have been reported, including 453 in mainland China, six associated with travel to mainland China from Hong Kong (four cases), Macao (one) and Taiwan (one), and one in an asymptomatic poultry worker in Macao (1). Although the clinical characteristics and risk factors for human infections do not appear to have changed (2,3), the reported human infections during the fifth epidemic represent a significant increase compared with the first four epidemics, which resulted in 135 (first epidemic), 320 (second), 226 (third), and 119 (fourth epidemic) human infections (2). Most human infections continue to result in severe respiratory illness and have been associated with poultry exposure. Although some limited human-to-human spread continues to be identified, no sustained human-to-human A(H7N9) transmission has been observed (2,3).

CDC analysis of 74 hemagglutinin (HA) gene sequences from A(H7N9) virus samples collected from infected persons or live bird market environments during the fifth epidemic, which are available in the Global Initiative on Sharing All Influenza Data (GISAID) database (4,5), indicates that A(H7N9) viruses have diverged into two distinct genetic lineages. Available fifth epidemic viruses belong to two distinct lineages, the Pearl River Delta and Yangtze River Delta lineage, and ongoing analyses have found that 69 (93%) of the 74 HA gene sequences to date have been Yangtze River Delta lineage viruses. Preliminary antigenic analysis of recent Yangtze River Delta lineage viruses isolated from infections detected in Hong Kong indicate reduced cross-reactivity with existing CVVs, whereas viruses belonging to the Pearl River Delta lineage are still well inhibited by ferret antisera raised to CVVs. These preliminary data suggest that viruses from the Yangtze River Delta lineage are antigenically distinct from earlier A(H7N9) viruses and from existing CVVs. In addition, ongoing genetic analysis of neuraminidase genes from fifth epidemic viruses indicate that approximately 7%–9% of the viruses analyzed to date have known or suspected markers for reduced susceptibility to one or more neuraminidase inhibitor antiviral medications. The neuraminidase inhibitor class of antiviral drugs is currently recommended for the treatment of human infection with A(H7N9) virus. Antiviral resistance can arise spontaneously or emerge during the course of treatment. Many of the A(H7N9) virus samples collected from human infections in China might have been collected after antiviral treatment had begun.

Although all A(H7N9) viruses characterized from the previous four epidemics have been low pathogenic avian influenza viruses, analysis of human (three) and environmental (seven) samples from the fifth epidemic demonstrate that these viruses contain a four–amino acid insertion in a host protease cleavage site in the HA protein that is characteristic of highly pathogenic avian influenza (HPAI) viruses. Chinese authorities are investigating and monitoring closely for outbreaks of HPAI A(H7N9) among poultry.

Since April 2013, the Influenza Risk Assessment Tool has been used by CDC to assess the risk posed by certain novel influenza A viruses. Although the current risk to the public’s health from A(H7N9) viruses is low, among the 12 novel influenza A viruses evaluated with this tool, A(H7N9) viruses have the highest risk score and are characterized as posing moderate–high potential pandemic risk (6). Experts from the World Health Organization (WHO) Global Influenza Surveillance and Response System (GISRS) met in Geneva, Switzerland, February 27–March 1, 2017, to review available epidemiologic and virologic data related to influenza A(H7N9) viruses to evaluate the need to produce additional CVVs to maximize influenza pandemic preparedness. Two additional H7N9 CVVs were recommended for development: a new CVV derived from an A/Guangdong/17SF003/2016-like virus (HPAI), which is a highly pathogenic virus from the Yangtze River Delta lineage; and a new CVV derived from A/Hunan/2650/2016-like virus, which is a low pathogenic virus also from the Yangtze River Delta lineage (1). At this time, CDC is preparing a CVV derived from an A/Hunan/2650/2016-like virus using reverse genetics. Further preparedness measures will be informed by ongoing analysis of genetic, antigenic, and epidemiologic data and how these data impact the risk assessment. CDC will continue to work closely with the Chinese Center for Disease Control and Prevention to support the response to this epidemic.

Guidance for U.S. clinicians who might be evaluating patients with possible H7N9 virus infection and travelers to China is available online (https://www.cdc.gov/flu/avianflu/h7n9-virus.htm).

References
World Health Organization. Antigenic and genetic characteristics of zoonotic influenza viruses and development of candidate vaccine viruses for pandemic preparedness, March 2017. Geneva, Switzerland: World Health Organization; 2017. http://www.who.int/influenza/vaccines/virus/201703_zoonotic_vaccinevirusupdate.pdf?ua=1
Xiang N, Li X, Ren R, et al. Assessing change in avian influenza A(H7N9) virus infections during the fourth epidemic—China, September 2015–August 2016. MMWR Morb Mortal Wkly Rep 2016;65:1390–4. CrossRef PubMed
Zhou L, Ren R, Yang L, et al. Sudden increase in human infection with avian influenza A(H7N9) virus in China, September–December 2016. Western Pac Surveill Response J 2017;8. CrossRef
Elbe S, Buckland-Merrett G. Data, disease and diplomacy: GISAID’s innovative contribution to global health. Global Challenges 2017;1:33–46. CrossRef
Federal Republic of Germany. The GISAID initiative. http://platform.gisaid.org/epi3/start
CDC. Influenza risk assessment tool (IRAT). Atlanta, GA: US Department of Health and Human Services, CDC; 2017. https://www.cdc.gov/flu/pandemic-resources/national-strategy/risk-assessment.htm
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Suggested citation for this article: Iuliano AD, Jang Y, Jones J, et al. Increase in Human Infections with Avian Influenza A(H7N9) Virus During the Fifth Epidemic — China, October 2016–February 2017. MMWR Morb Mortal Wkly Rep. ePub: 3 March 2017. DOI: http://dx.doi.org/10.15585/mmwr.mm6609e2.


U.S. officials say of all emerging influenza viruses, H7N9 currently poses the greatest risk of a pandemic threat if it evolves to spread readily from human to human.

Portland Press

“….Centers for Disease Control and Prevention officials are developing a vaccine that would target a newly evolving version of the virus….”


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