Human infection with avian influenza A(H7N9) virus – China
On 5 January 2017, the Department of Health, Hong Kong Special Administrative Region (SAR) notified WHO of a case of laboratory-confirmed human infection with avian influenza A(H7N9) virus and on 9 January 2017, the National Health and Family Planning Commission of China (NHFPC) notified WHO of 106 additional laboratory-confirmed cases of human infection with avian influenza A(H7N9) virus.
Details of the cases
On 5 January 2017, a human case of infection with avian influenza A(H7N9) was reported from the Department of Health, Hong Kong Special Administrative Region (SAR). The case is a 62-year-old man with underlying illnesses, who travelled to Zengcheng, Guangzhou on 15 December 2016. He developed influenza-like symptoms on 1 January 2017 while he was in Guangzhou. He was admitted to a hospital in Dongguan on 2 January 2017 and returned to Hong Kong SAR on 3 January 2017, where he was admitted to hospital on 4 January 2017 for further treatment. His condition deteriorated and he was transferred to an intensive care unit for further management. He passed away on 6 January 2017. His samples tested positive for A(H7N9) by RT-PCR on 5 January 2017. The patient reported no recent exposure to poultry or live poultry markets. Contact tracing is underway.
On 9 January 2017, 106 human cases of infection with avian influenza A(H7N9) were reported from the NHFPC. The onset dates ranged from 22 November 2016 to 29 December 2016. Of these 106 cases, 36 are female. The median age is 54 years (age range among the cases is 23 to 91 years old). The cases are reported from Jiangsu (52), Zhejiang (21), Anhui (14), Guangdong (14), Shanghai (2), Fujian (2) and Hunan (1). At the time of notification, there were 35 deaths and 57 severe cases. Eighty of the cases are reported to have had exposure to poultry or a live poultry market.
Two clusters were reported.
- A 66-year-old male from Suzhou city, Jiangsu province. He had symptom onset on 25 November 2016, was admitted to hospital on 28 November 2016 and died on 12 December 2016. He was exposed to a live poultry market.
- A 39-year-old female from Suzhou city, Jiangsu province. She had symptom onset on 8 December 2016 and was admitted to hospital on the same day. She is the daughter of the 66-year old male. At the time of report, she was suffering from severe pneumonia.
Human-to-human transmission between the 66-year-old male and the 39-year-old female cannot be ruled out.
- A 66-year-old male from Hefei city, Anhui province. He had symptom onset on 16 December 2016, and was admitted to hospital on 17 December 2016 and died on 20 December 2016. He was exposed to a live poultry market.
- A 62-year-old male from Hefei city, Anhui province. He had symptom onset on 22 December 2016. He was admitted in the same ward as the 66-year old male. His current condition is severe.
Human-to-human transmission between the 66-year-old male and the 62-year-old male cannot be ruled out.
To date, a total of 916 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 of laboratory-confirmed cases of human infection with avian influenza A(H7N9) in December 2016, the Chinese government has enhanced measures:
- NHFPC strengthened epidemic surveillance, conducted timely risk assessment and studies for any changes in epidemiology.
- NHFPC 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, and reduce occurrence of severe cases and deaths.
- Further enhanced medical treatment.
- Joint investigations 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 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.
- Conducting public risk communication and sharing information with the public.
The Centre for Health Protection of the Department of Health in 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
Similar sudden increases in the number of human cases of avian influenza A(H7N9) infection have been observed in previous years during this period of time (December-January). Nevertheless close monitoring of the epidemiological situation and further characterization of the most recent viruses are critical to assess associated risk and to make timely adjustments to risk management measures.
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, further human cases can be expected. Although small clusters of human cases with avian influenza A(H7N9) virus have been reported including those involving healthcare workers, current epidemiological and virological evidence suggests that this virus has not acquired the ability of sustained transmission among humans. Based on available information we have, further community level spread is considered unlikely.
Human infections with the avian influenza A(H7N9) virus are unusual and because there is the potential for significant public health impact, it needs to be monitored closely.
WHO advises that travellers to countries with known outbreaks of avian influenza should avoid, if possible, poultry farms, contact with animals in live bird 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.