H5N1 strain from Alberta nurse resembles Chinese strain
Complete genome sequence of H5N1 virus a research priority for national lab
Canadian scientists studying H5N1 bird flu virus samples taken from an Alberta woman who died with the infection say that so far it seems to resemble a Chinese strain.
Researchers at Canada's National Microbiology Laboratory and Alberta’s provincial laboratory isolated samples of the virus and are working on sequencing it.
They’re looking to see if the sequence is the same as previous ones in the search for clues to the Jan. 3 death.
"Based on the genome sequence data collected to date, researchers at the [National Microbiology Laboratory] have found it to be consistent with a previously circulating H5N1 strain from China," a spokesperson said in an email Wednesday.
"The first research priority for the NML is to complete the whole genome sequence of the virus, and then analyze the data to learn more about the specific traits and characteristics of the virus. The genome analysis will help inform and guide all future research priorities."
If the sample differs from previous samples, then researchers could take a closer look.
No contact with poultry in China
The Red Deer Hospital nurse, who was in her 20s, had travelled to Beijing for a three-week visit.
Earlier this week, investigators with Alberta Health Services and the National Microbiology Laboratory provided more clinical details about the patient.
Virologist Kevin Fonseca of Alberta Health Services and his colleagues said the patient experienced symptoms of malaise, chest pain, and fever during the return flight on Dec. 27 and went to the local emergency department on Dec. 28.
One of the mysteries is that she had no known contact with poultry during her trip, public health officials said in announcing the case — the first reported death from avian flu in North America. No H5N1 outbreaks have been reported in Beijing recently.
After a chest X-ray and CT scan suggested a diagnosis of pneumonia, the woman was prescribed an antibiotic and discharged home.
The patient came back to the same emergency department on Jan. 1 with worsening inflammation of the membrane surrounding the lung, chest pain, shortness of breath, a mild headache that felt worse when she moved her head, nausea, vomiting and other symptoms, Fonseca’s team said in their posting on ProMed, an internet-based disease alert system.
On Jan. 2, the patient reported visual changes and a continuing headache. As oxygen needs increased, doctors admitted her to the ICU for intubation and ventilation.
In the early morning of Jan. 3, she had sudden tachycardia or fast heart rate and severe hypertension, followed by hypotension. Doctors took steps to keep her heart beating.
At this point, the patient’s pupils were dilated and there was no response to pain. Further tests and a neurologic exam indicated brain death.
"The attending physician felt that, while unlikely, avian influenza was possible given the travel history and neurological symptoms, and contacted the local medical officer of health on 3 Jan. 2014 to report to public health. Contact tracing of family and hospital contacts was initiated as a precaution, given the severity of the illness and its rapid progression," the team wrote.
"This case identifies a number of key issues, the first being the rapid onset and tragic death of a young, healthy traveller due to an avian influenza A(H5N1) infection. The index of suspicion was low as travel was to an area in China where there have been no recent reports of the circulation of this virus, and coupled with no obvious exposure to poultry, the diagnostic work-up and consideration for A(H5N1) infection was very low.
"The clinical course, detection of the virus in the [cerebrospinal fluid], and results of imaging studies are consistent with an infection of the brain. A review of the literature indicates that such events are uncommon in humans."
From a laboratory perspective, they said, the case also showed the value of having screening tests to identify influenza subtypes.