Avian Influenza A (H5N1) Activity in Asia - Update 17

Updated: February 13, 2004

The Public Health Agency of Canada continues to closely monitor occurrences of avian influenza A (H5N1) or "bird flu" outbreaks in several Asian countries. Outbreaks have been confirmed in Japan, South Korea, Vietnam, Thailand, Cambodia, China and Indonesia. The outbreaks have affected millions of chickens in these countries combined, as well as several human cases in Vietnam and Thailand. In addition, reports indicate that ducks have also been infected.

As a public health measure, culling has been taking place in the countries listed above in order to prevent further spread of the H5N1 virus in animal populations and to reduce the likelihood of human transmission.

To date, twenty-seven human laboratory confirmed cases of avian influenza A (H5N1) have been reported in Vietnam and Thailand . In Vietnam, nineteen cases have been reported, including fourteen deaths. The cases have been reported from various parts of the country, including: seven cases in Hanoi (four children and three adults), seven cases in Ho Chi Minh City (three children and four adults), two cases in Thai Binh province (two sisters, aged 19 and 20), and two cases from Southern Provinces (aged 16 and 17). Details on the remaining case are not currently available.

Thailand has reported eight human cases, six of whom are deceased. The first case was a 6-year-old boy from Kanchanaburi. The second case was a 7-year-old boy from Suphanburi province. The third case was a 6-year-old child from Sukothai province. The fourth case was a 58-year-old woman. The fifth case was a 6-year-old boy from Kanchanaburi province. The sixth case occurred in a 13-year-old boy from Chaiyaphum Province. The two cases reported today occurred in a 2-year-old boy from Suphanburi province and a 27-year-old woman from Uttaradit Province. Both cases have fully recovered and were discarged from hospital this week.

The relationship between the human and poultry outbreaks of avian influenza A(H5N1) in Vietnam and Thailand is not fully understood at present. The World Health Organization and the Ministries of Health of these countries are continuing investigations to determine the source of the human cases.

A laboratory investigation was held by the World Health Organization to determine whether there was human to human transmission between the two sisters from Thai Binh province, Vietnam. The results demonstrated that the influenza genes found in the H5N1 virus strain found in the sisters were of avian (i.e. animal) in origin. There were no human influenza genes present. While this cannot definitively exclude the possibility that human-to-human transmission may have occurred, the absence of further cases related to these cases indicates that the virus does not spread easily or rapidly among humans.

Due to the simultaneous occurrence in several countries, the H5N1 strain may be more widely established in bird populations and the environment in Asia than presently thought. The Public Health Agency of Canada and its partners will continue to monitor outbreaks as they occur.

Source:

World Health Organization World Organization for Animal Health

Avian influenza A (H5N1) is an influenza virus that until 1997 was seen only in birds, including chickens and ducks. Human cases were reported for the first time in 1997. That outbreak occurred in Hong Kong, where 18 human cases and six deaths led to a mass slaughter of chickens in the regions, which were thought to have been the source of the virus.

Mild cases of avian flu occurred in Hong Kong in 1999 (two cases) and the Netherlands experienced an outbreak of H7N7 avian influenza in April 2003 where 83 people were affected. In the latter outbreak, evidence demonstrated that human to human transmission occurred. The symptoms were mainly conjunctivitis in this outbreak, with one human fatality.

In March 2003, Hong Kong confirmed two cases of influenza A (H5N1) - one case was a 9-year-old boy who recovered, and a second, his 33-year-old father, who later died as a result of pneumonia.

The recent outbreaks in poultry in South Korea marks the first time the illness has affected that country.

Until this year, there had been no reports of avian influenza in Japan since 1925.

It is important to note that while avian influenza has been shown in some cases to affect humans, this disease should not be confused with human influenza, a common human disease. Avian influenza A (H5N1) is primarily a virus that affects animals - particularly birds. However, if contracted by humans, the virus has the capacity to cause severe disease with high mortality in humans.

Current influenza vaccines do not provide protection against the A (H5N1) strain, and no H5N1 vaccine is available at this time. Certain anti-viral drugs are effective against influenza A viruses. However, it is not yet known whether these anti-virals are effective against the current H5N1 strain.

While severely affected birds will stop laying eggs, eggs laid in the early phase of the outbreak could contain the avian influenza virus in the albumen, yolk and/or on the egg surface. The virus can penetrate cracked or intact shells or, more significantly, contaminate egg containers.

Recommendations

The Public Health Agency of Canada is aware that China, Cambodia, Thailand, Vietnam, South Korea, Japan and Indonesia are aggressively culling affected poultry. However, the Public Health Agency of Canada has not been able to confirm whether egg products are being recalled.

While to date there has been no evidence that the virus is transmitted through contaminated food, as a precaution, and until further information is available, the Public Health Agency of Canada advises that travellers to China, Cambodia, Thailand, Vietnam, South Korea, Japan and Indonesia not consume undercooked poultry, raw eggs or lightly cooked egg products (such as runny eggs).

Travellers should ensure that all food products listed above be well cooked before being consumed, as evidence suggests the virus becomes inactive when cooked.

Travellers should be aware that it is possible for the avian influenza virus to stick to hair and clothing, and may be inhaled. The Public Health Agency of Canada recommends that travellers avoid unnecessary contact with live poultry. This includes poultry farms as well as markets where live animals such as chickens, ducks and pigs are sold, as these animals have been found to be carriers of the avian influenza virus. Research has shown that the risk of direct transmission of H5N1 infection from birds to humans is greatest in persons having close contact with live, infected poultry.

Travellers are advised to not bring poultry or egg products from these affected countries into Canada.

Travellers are further advised to maintain high standards of hygiene, including thorough hand washing, particularly after having contacted eggs or undercooked poultry and egg products. Using hot, soapy water and lathering for at least 20 seconds is the single most important procedure for preventing infections. This is because disease-causing micro-organisms can frequently be found on the hands. Alternatively, travellers can use waterless, alcohol-based antiseptic hand rinses. If there is visible soiling, hands should be washed with soap and water before using waterless antiseptic hand rinses. If soap and water are unavailable, cleanse hands first with detergent-containing towelettes to remove visible soil.

As is routinely done, the Public Health Agency of Canada recommends that travellers to Asia seek an individual risk assessment consultation with their personal physician or travel medicine clinic at least 6 to 8 weeks prior to travel. The Public Health Agency of Canada also recommends that travellers obtain the influenza vaccine before travel.

The Public Health Agency of Canada recommends that travellers who become sick or feel unwell with respiratory or flu-like symptoms on their return to seek a medical assessment with their personal physician. Travellers should inform their physician without being asked, that they have been travelling or living outside of Canada, and where they have been.

Canadian Food Inspection Agency recommendations to prevent the introduction of avian flu into Canada's animal population:

Travellers who have visited a farm while in an affected country should ensure that clothing and footwear worn on the farm are free from soil and manure before entering Canada. Clothing should be laundered and footwear should be disinfected after arrival. More information is available at the Canadian Food Inspection Agency  web site.

For more information:

The Public Health Agency of Canada produces weekly FluWatch reports, summarizing influenza surveillance activities in Canada and abroad. At this web site, you will find Questions and Answers on avian influenza developed by the Public Health Agency of Canada.

For previous avian influenza travel health advisories, visit the Travel Medicine Program's Travel Advisory Archives.

The World Health Organization has developed an avian influenza fact sheet. 

For international reports of the flu, visit the World Health Organization influenza web site.

For international reports of infected animals by country, visit the World Organization for Animal Health.