tetano
Editor, Senior Moderator
Public Health Agency of Canada
Risk Assessment
The public health risk posed by avian influenza A(H7N9) virus from China to Canada is considered low at this time. Cases have been reported in China from eight Provinces (Anhui, Henan, Hunan, Fujian, Jiangsu, Jiangxi, Shandong, and Zhejiang) and two Municipalities (Beijing and Shanghai). In addition, a travel-related case was reported in Taiwan. Poultry and environmental samples have tested positive for avian influenza A(H7N9) in all above mentioned provinces and municipalities, except for Hunan and Beijing. A poultry sample also tested positive for H7N9 in the Guangdong Province, but no human cases have been reportedFootnote 1.
There is still no evidence of sustained human-to-human transmission of avian influenza A(H7N9) virus. However, two family clusters suggest that limited human-to-human transmission may occur where there is close contact between cases and other people.
Updated information and risk assessments will be made available here when new evidence becomes available.
Event Summary
Cases of avian influenza A(H7N9) have been reported in the People?s Republic of China since 31 March 2013. This is the first time that a low pathogenic avian influenza virus has been associated with human fatalitiesFootnote 2.
In the most recent update on 29 May 2013, WHO reported one additional laboratory-confirmed case of human infection with avian influenza A(H7N9) virus from Beijing, and one death in a previously confirmed case. This is the first new confirmed case of human infection with avian influenza A(H7N9) since 8 May 2013, and the second confirmed case to be reported from Beijing. The laboratory-confirmed case is a 6 year old male who became ill on May 21, 2013. He was treated the same day in hospital and laboratory confirmation was received on May 28, 2013. He is currently receiving treatment and is in stable condition.
As of 5 June, 2013, the WHO has reported 132 confirmed human cases, including 37 deaths. The case fatality rate (CFR) is 28%. Currently, 18 patients are hospitalized and 76 have been discharged. With the exception of the two cases in Beijing, all other cases have occurred in adjacent regions in eastern and south eastern China, including the travel-related case in Taiwan. The majority of the cases have been reported by Zhejiang province (46), followed by Shanghai (34) and Jiangsu (26). Of the 129 cases with available demographic data the median age is 61 (range 2-91). Notably, 93 cases are male (72%) and 56 cases (43%) are ≥ 65 years of age. When stratified by age and sex, middle-aged and older men are the most affected group. The WHO?s Global Alert and Response websiteExternal Link maintains the latest updates on the total number of cases.
The source, reservoir, and communicability of the avian influenza A(H7N9) virus are currently under investigation; however, the WHO reports that human infection appears to be related to exposure to live poultry or contaminated environments for the following reasons:
The virus in humans is genetically similar to that found in animals and the environment (live bird markets).
Most human cases (approximately three out of four patients) report a history of exposure to animals, mostly chickens.
The virus has been detected in poultry in live bird markets.
The number of human cases appears to have decreased after closure of live animal markets.
In addition, monitoring and testing of more than 2,000 contacts of confirmed cases have detected few infections. Testing of more than 20,000 people with influenza-like-illness in March and April has confirmed only six infections with avian influenza A(H7N9), suggesting that milder cases are not occurring in large numbers3.
Closing of all live poultry markets appears to have been an effective control strategy in Shanghai, Jiangsu and Zhejiang as the number of reported human cases has decreased following these closures. However, this may also be the avian influenza A(H7N9) virus demonstrating a seasonal pattern, similar to other avian influenza viruses (e.g. H5N1), where human cases have been less frequent in summer months and more frequent in winter months3.
A recent scientific publication by the Infectious Diseases of Poverty indicates that it is necessary to regulate the poultry markets as long as poultry-to-poultry transmission is not well understood4. The Canadian Food and Inspection Agency (CFIA) published its ?Preliminary Assessment of the Risk to Canadian Animals from the Novel H7N9 Influenza Virus Detected in China? and highlighted that: evidence to date strongly indicates that the novel H7N9 in poultry does not differ from other Influenza A viruses common in the animal population at the global level; this novel H7N9 virus is of avian origin and does not cause any severe clinical signs in poultry; and the risk to Canadian animals from the novel H7N9 influenza virus detected in China is considered to range from negligible to very low.
No vaccine is currently available for this subtype of the H7N9 influenza virus; although preparatory work is underway should a vaccine become necessary. WHO has identified four potential candidate vaccine viruses, in addition to the wild type virus, that may be used in vaccine development. Two have have passed relevant safety testing and two-way haemagglutination inhibition (HI) tests5.
Laboratory testing has confirmed that the avian influenza A(H7N9) virus is susceptible to the neuraminidase inhibitors oseltamivir and zanamivir, two antiviral medications that are available in the National Antiviral Stockpile and National Emergency Stockpile System should they be needed to treat Canadians. . An analysis conducted on 14 patients in Shanghai showed that antivirals were able to clinically reduce viral load, however, the emergence of mutations known to confer resistance to neuraminidase inhibitors was also observed during the course of treatment in some individualsFootnote 8.
The Agency's National Microbiology Laboratory (NML) has developed diagnostic assays (tests) allowing NML to rapidly detect the novel avian influenza A(H7N9) virus. These assays have been shared with provincial/territorial colleagues allowing provinces to do their own testing should it be required.
..
http://www.phac-aspc.gc.ca/eri-ire/h7n9/risk_assessment-evaluation_risque-eng.php
Risk Assessment
The public health risk posed by avian influenza A(H7N9) virus from China to Canada is considered low at this time. Cases have been reported in China from eight Provinces (Anhui, Henan, Hunan, Fujian, Jiangsu, Jiangxi, Shandong, and Zhejiang) and two Municipalities (Beijing and Shanghai). In addition, a travel-related case was reported in Taiwan. Poultry and environmental samples have tested positive for avian influenza A(H7N9) in all above mentioned provinces and municipalities, except for Hunan and Beijing. A poultry sample also tested positive for H7N9 in the Guangdong Province, but no human cases have been reportedFootnote 1.
There is still no evidence of sustained human-to-human transmission of avian influenza A(H7N9) virus. However, two family clusters suggest that limited human-to-human transmission may occur where there is close contact between cases and other people.
Updated information and risk assessments will be made available here when new evidence becomes available.
Event Summary
Cases of avian influenza A(H7N9) have been reported in the People?s Republic of China since 31 March 2013. This is the first time that a low pathogenic avian influenza virus has been associated with human fatalitiesFootnote 2.
In the most recent update on 29 May 2013, WHO reported one additional laboratory-confirmed case of human infection with avian influenza A(H7N9) virus from Beijing, and one death in a previously confirmed case. This is the first new confirmed case of human infection with avian influenza A(H7N9) since 8 May 2013, and the second confirmed case to be reported from Beijing. The laboratory-confirmed case is a 6 year old male who became ill on May 21, 2013. He was treated the same day in hospital and laboratory confirmation was received on May 28, 2013. He is currently receiving treatment and is in stable condition.
As of 5 June, 2013, the WHO has reported 132 confirmed human cases, including 37 deaths. The case fatality rate (CFR) is 28%. Currently, 18 patients are hospitalized and 76 have been discharged. With the exception of the two cases in Beijing, all other cases have occurred in adjacent regions in eastern and south eastern China, including the travel-related case in Taiwan. The majority of the cases have been reported by Zhejiang province (46), followed by Shanghai (34) and Jiangsu (26). Of the 129 cases with available demographic data the median age is 61 (range 2-91). Notably, 93 cases are male (72%) and 56 cases (43%) are ≥ 65 years of age. When stratified by age and sex, middle-aged and older men are the most affected group. The WHO?s Global Alert and Response websiteExternal Link maintains the latest updates on the total number of cases.
The source, reservoir, and communicability of the avian influenza A(H7N9) virus are currently under investigation; however, the WHO reports that human infection appears to be related to exposure to live poultry or contaminated environments for the following reasons:
The virus in humans is genetically similar to that found in animals and the environment (live bird markets).
Most human cases (approximately three out of four patients) report a history of exposure to animals, mostly chickens.
The virus has been detected in poultry in live bird markets.
The number of human cases appears to have decreased after closure of live animal markets.
In addition, monitoring and testing of more than 2,000 contacts of confirmed cases have detected few infections. Testing of more than 20,000 people with influenza-like-illness in March and April has confirmed only six infections with avian influenza A(H7N9), suggesting that milder cases are not occurring in large numbers3.
Closing of all live poultry markets appears to have been an effective control strategy in Shanghai, Jiangsu and Zhejiang as the number of reported human cases has decreased following these closures. However, this may also be the avian influenza A(H7N9) virus demonstrating a seasonal pattern, similar to other avian influenza viruses (e.g. H5N1), where human cases have been less frequent in summer months and more frequent in winter months3.
A recent scientific publication by the Infectious Diseases of Poverty indicates that it is necessary to regulate the poultry markets as long as poultry-to-poultry transmission is not well understood4. The Canadian Food and Inspection Agency (CFIA) published its ?Preliminary Assessment of the Risk to Canadian Animals from the Novel H7N9 Influenza Virus Detected in China? and highlighted that: evidence to date strongly indicates that the novel H7N9 in poultry does not differ from other Influenza A viruses common in the animal population at the global level; this novel H7N9 virus is of avian origin and does not cause any severe clinical signs in poultry; and the risk to Canadian animals from the novel H7N9 influenza virus detected in China is considered to range from negligible to very low.
No vaccine is currently available for this subtype of the H7N9 influenza virus; although preparatory work is underway should a vaccine become necessary. WHO has identified four potential candidate vaccine viruses, in addition to the wild type virus, that may be used in vaccine development. Two have have passed relevant safety testing and two-way haemagglutination inhibition (HI) tests5.
Laboratory testing has confirmed that the avian influenza A(H7N9) virus is susceptible to the neuraminidase inhibitors oseltamivir and zanamivir, two antiviral medications that are available in the National Antiviral Stockpile and National Emergency Stockpile System should they be needed to treat Canadians. . An analysis conducted on 14 patients in Shanghai showed that antivirals were able to clinically reduce viral load, however, the emergence of mutations known to confer resistance to neuraminidase inhibitors was also observed during the course of treatment in some individualsFootnote 8.
The Agency's National Microbiology Laboratory (NML) has developed diagnostic assays (tests) allowing NML to rapidly detect the novel avian influenza A(H7N9) virus. These assays have been shared with provincial/territorial colleagues allowing provinces to do their own testing should it be required.
..
http://www.phac-aspc.gc.ca/eri-ire/h7n9/risk_assessment-evaluation_risque-eng.php