Wednesday, April 20, 2016

More On Hong Kong's Imported H7N9 Case

Credit HK CHP


Hong Kong holds the dubious dual distinction of having dealt with the first human outbreak of H5N1 in 1997, one that resulted in 18 infections and 6 deaths, followed six years later with the SARS epidemic, where they saw 1750 local cases, and 286 deaths.

Since then - Hong Kong’s Centre for Health Protection (which was created in the wake of the SARS epidemic) - has a well earned reputation for taking an open and proactive stance against all communicable disease threats.

Whenever an avian flu case is detected in Hong Kong, the Centre for Health Protection (CHP) activates their pandemic preparedness plan, albeit for imported cases like the one reported yesterday, at the lowest (ALERT) level of response.

20 April 2016
Avian Influenza 

The Alert Response Level under the Government's Preparedness Plan for Influenza Pandemic is activated

Avian influenza is caused by those influenza viruses that mainly affect birds and poultry, such as chickens or ducks. Clinical presentation of avian influenza in humans includes eye infection (conjunctivitis), flu-like symptoms (e.g. fever, cough, sore throat, muscle aches) or severe respiratory illness (e.g. chest infection). The incubation period ranges from 7 to 10 days. The more virulent forms can result in respiratory failure, multi-organ failure and even death. People mainly become infected with avian influenza through close contact with infected birds and poultry (live or dead) or their droppings. Human-to-human transmission is inefficient. People in close contact with poultry are more susceptible to contracting avian flu. The elderly, children and people with chronic illness have a higher risk of developing complications such as bronchitis and chest infection. For details, please refer to the factsheet of  Avian Influenza.

We've two updates this morning on yesterday's imported case.  First a brief statement from the CHP on contact tracing, then excerpts from a more detailed letter sent to local doctors.

After that I'll have a postscript on the odds of Hong Kong seeing two imported cases over the past four weeks from a province that hasn't reported any local cases in more than a month.

Update on imported human case of avian influenza A(H7N9) infection

The Centre for Health Protection (CHP) of the Department of Health today (April 20) reported an update on the third imported human case of avian influenza A(H7N9) infection in Hong Kong this year affecting a male patient aged 80.

Epidemiological investigations have so far identified nine close contacts and 82 other contacts. All have remained asymptomatic and will be put under medical surveillance for 10 days since last exposure to the patient.

Close contacts include the patient's home contacts as well as relevant patients and visitors of United Christian Hospital (UCH). They will be given antiviral prophylaxis with oseltamivir (Tamiflu) for five days.

Other contacts include healthcare workers of UCH, ambulance officers in patient transfer and clinic contacts.

Investigations and contact tracing are ongoing.

Ends/Wednesday, April 20, 2016

A more detailed statement has been sent to all doctors and hospitals in Hong Kong from Dr. SK Chuang for Controller, Centre for Health Protection, excerpts of which you'll find below:

A Confirmed Imported Case of Human Infection with Avian Influenza A(H7N9) Virus

I would like to draw your attention to the third confirmed imported case of human infection with avian influenza A(H7N9) virus in Hong Kong this year affecting an 80-year-old man.

The patient had history of hypertension, gout and renal stone. He travelled to Dongguan, Guangdong from April 1 to 5. He presented with cough with sputum, headache and gouty attack on April 6 and consulted a private doctor on April 7. He did not have fever at that time. He had persistent cough with sputum, headache and decreased appetite. He sought medical consultation from another private doctor on April 14 and was found to have fever. He subsequently developed confusion and refused eating on April 17, and was sent to the Accident and Emergency Department of United Christian Hospital by ambulance on the same day. He was admitted to an isolation ward.Chest X-ray showed right middle lobe consolidation.

The patient's nasopharyngeal aspirate collected on April 17 was tested negative for influenza A and B by polymerase chain reaction (PCR) on April 18 while a sputum specimen collected on April 18 was tested positive for avian influenza A(H7N9) virus by PCR by the Public Health Laboratory Services Branch of the Centre for Health Protection (CHP) on April 19. He has been treated with Tamiflu and is currently in stable condition.

Initial investigations by the CHP revealed that the patient visited a wet market near his residence in Dongguan on April 2. He bought a live chicken from the wet market and slaughtered it on April 3. His travel collaterals and close contacts have remained asymptomatic so far. Tracing of the patient's contacts in Hong Kong is ongoing.The CHP's investigation is continuing.- 2 -

Prior to this case, fifteen imported cases of human infection with avian influenza A(H7N9) virus were recorded in Hong Kong since December 2013. Cumulatively, a total of 761 confirmed human H7N9 cases have been reported globally since March 2013, including at least 308 deaths (as of April 19, 2016). These included 738 cases in Mainland China and 23 cases exported from Mainland China to Hong Kong (16), Taiwan (4), Canada (2) and Malaysia (1).


We would like to urge you to pay special attention to patients who presented with fever or influenza-like illness. Travel history and relevant exposure history during travel should be obtained from them. Any patients with acute respiratory illness or pneumonia,and with at-risk exposure (such as history of visiting market with live poultry, contact with poultry, etc.) in affected areas within the incubation period (i.e. 10 days before onset of symptoms) should be managed as suspected cases and immediately reported to the Central Notification Office (CENO) of the CHP via fax (2477 2770), phone (2477 2772) or CENO On-line
The reporting criteria have been updated to specify visiting markets with live poultry as one of the epidemiological criteria (Annex). Please refer to the following website for the reporting criteria: Also, the list of affected areas is regularly updated and is available from the following webpage of the CHP website:

In addition, private doctors should contact the Medical Control Officer of the Department of Health at pager: 7116 3300 (call 9179) when reporting any suspected case outside office hours. The CHP will make arrangement to send the patient to a public hospital for isolation, testing and treatment. Besides, it is important to isolate the patient to minimise contact with or exposure to staff and other patients and advise the patient to wear a surgical mask while waiting for transfer.

According to the most recent WHO: Influenza at the Human-Animal Interface - April 2016 report, China is reporting the lowest level of H7N9 activity since the virus first emerged in 2013 (see chart below).  

Credit WHO

Guangdong Province has only reported 13 cases since the winter 2015-16 season began, compared with a total of 72 during the previous winter, and 108 the year before that.

This sharp drop in case counts has come - perhaps coincidentally - at the same time China has limited their reporting on avian flu activity. 

It is more than a little curious that Guangdong Province - with a population in excess of 100 million -  has not reported any H7N9 cases in more than a month, yet two travelers from that province have turned up in Hong Kong carrying the virus during that time.

Avian influenza can produce a wide spectrum of symptoms, ranging from mild or even asymptomatic presentation, to severe and/or life threatening. And we've seen estimates (see  Lancet: Clinical Severity Of Human H7N9 Infection) that the actual number of H7N9 cases in China may be 10 to more than 100 times greater than reported. 

During the first three winter outbreaks of H7N9, China detected and reported a number of `mild' H7N9 cases due to proactive screening of all hospitalized flu and pneumonia cases in affected provinces.  

One has to wonder whether the sharp drop in H7N9 cases this year can be attributed to changes in the behavior or distribution of the virus, or whether there has been a change in the way China is now screening for, and reporting on, the virus.

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