SITREP - WHO | Avian influenza A(H5N1) - update 13: China confirms spread of infection in poultry

Avian influenza A(H5N1) - update 13: China confirms spread of infection in poultry, Development of an H5N1 vaccine for humans: need for samples and viruses, Protection of workers involved in culling operations

30 January 2004

China confirms spread of infection in poultry

Health and agricultural authorities in China have today informed WHO of further outbreaks of highly pathogenic H5N1 avian influenza in poultry. The outbreaks, which are laboratory confirmed, have been detected in Hunan and Hubei provinces.

A confirmed outbreak of highly pathogenic H5N1 avian influenza at a duck farm in Guangxi province was announced on 27 January.

As announced today, outbreaks of disease in poultry have also been detected at farms in Anhui, Shanghai, and Guangdong provinces. According to the authorities, highly pathogenic H5N1 avian influenza is the suspected cause. Samples from birds in these outbreaks are being tested, in China, to confirm the causative agent.

Local authorities in the affected provinces have undertaken immediate culling operations and quarantining of farms. Compulsory vaccination of poultry is being introduced.

At present, no human cases of H5N1 infection have been detected in China.

Development of an H5N1 vaccine for humans: need for samples and viruses

With the confirmed spread of H5N1 infection in poultry in China, WHO is again stressing the need for access to samples and viruses from all countries currently experiencing H5N1 outbreaks. Such materials are needed to support laboratory studies being conducted by the WHO Global Influenza Surveillance Network.

Up to now, laboratories in the WHO network have analyzed viruses from the current outbreaks made available by authorities in Cambodia, Japan, the Republic of Korea, and Viet Nam. Viruses from the outbreaks in Indonesia, Laos, and Thailand are expected to be available for analysis soon.

Network laboratories are now working to develop a prototype virus that can be recommended by WHO for use by companies in the production of a human vaccine effective against H5N1 influenza strains. Both human and avian viruses are needed. Information from these viruses will help WHO and its partners ensure that a fully tested and licensed vaccine for humans is available as soon as possible.

Protection of workers involved in culling operations

As more countries announce plans for the mass slaughter of poultry, WHO continues to stress the need for personal protection of these workers. Targeted administration of seasonal influenza vaccine to high-risk groups, such as cullers and poultry workers, is being recommended as one of several measures that reduce opportunities for the emergence of a new influenza virus subtype with pandemic potential. Guidelines for the use of seasonal influenza vaccine in humans at risk of H5N1 infection have been issued today.

WHO Avian influenza A(H5N1) - update 13: China confirms spread of infection in poultry, Development of an H5N1 vaccine for humans: need for samples and viruses, Protection of workers involved in culling operations

SITREP - WHO | Avian influenza A(H5N1) in humans - update 12

Avian influenza A(H5N1) in humans - update 12: Prevention of further cases of H5N1 disease in humans,Investigation of the origins of the current outbreaks in poultry

29 January 2004

Prevention of further cases of H5N1 disease in humans

In response to outbreaks of highly pathogenic H5N1 avian influenza in poultry, several countries are currently conducting the mass slaughter of millions of chickens. Such action is the major line of defence for preventing further human cases of H5N1 infection and possibly averting the emergence of a new influenza virus with pandemic potential.

WHO continues to stress the need for personal protection of these workers, who are at high risk of exposure to a virus that has demonstrated its capacity to cause severe disease and deaths in humans. Recommendations about safety measures that should be in place before the mass destruction of poultry begins have been issued. Adherence to these recommendations will reduce the likelihood that measures aimed at preventing the further spread of H5N1 infection in poultry might lead to increased transmission of the virus to humans.

Those organizing culling operations in affected countries need to ensure that WHO recommendations are followed as strictly as possible. The recommendations spell out the appropriate personal protective equipment, which includes goggles and preferably N95 respirator masks, as well as specific types of protective clothing that can be either disinfected or discarded after use. Frequent handwashing is strongly recommended.

WHO also recommends that effective antiviral drugs be readily available for the treatment of suspected H5N1 respiratory infections in cullers and farm workers.

N95 masks and prophylactic treatment with antiviral drugs were used to protect thousands of poultry workers and cullers during an outbreak of highly pathogenic H7N7 avian influenza in the Netherlands in 2003. During that outbreak, nearly 30 million poultry were destroyed. Although avian influenza virus caused mild illness in 89 poultry workers and members of their families, the single death in that outbreak occurred in a veterinarian who was not adequately protected.

Investigation of the origins of the current outbreaks in poultry

Countries currently experiencing outbreaks of highly pathogenic H5N1 avian influenza in poultry have provided numerous samples and viruses to laboratories in the WHO Global Influenza Surveillance Network. WHO is grateful for the high level of international collaboration of all affected countries and influenza experts around the world.

Laboratory characterization of several viruses from humans and different species of birds has helped to compare, retrospectively, H5N1 viruses taken from infected birds and humans in January 2004 with viruses obtained from birds several months ago. Results indicate that the virus now causing severe disease in poultry and some humans has been circulating in parts of Asia for longer than initially presumed.

Presently available evidence from these studies is not sufficient to support any speculations about the geographical origins of the current outbreaks of highly pathogenic H5N1 avian influenza.

Up to now, laboratories in the WHO network have analyzed viruses from the current outbreaks made available by authorities in Cambodia, Japan, South Korea, and Viet Nam. Viruses from the outbreaks in Indonesia, Laos, and Thailand are expected to be available for analysis soon.

WHO Avian influenza A(H5N1) in humans - update 12: Prevention of further cases of H5N1 disease in humans,Investigation of the origins of the current outbreaks in poultry

SITREP - WHO | Avian influenza A(H5N1) in humans - update 11

Avian influenza A(H5N1) in China - update 10

27 January 2004

The Ministry of Health in China has today confirmed the presence of highly pathogenic H5N1 avian influenza in poultry in the southern province of Guangxi. The H5N1 strain was detected in samples taken from a duck farm.

Testing is under way of samples from poultry outbreaks in the adjacent Hunan and Hubei provinces. Ducks are involved in the outbreak in Hunan, and chickens are involved in Hubei.

Strict measures to control all outbreaks, including culling and quarantine, have been undertaken.

No cases of human illness linked to these outbreaks have been detected to date.

WHO Avian influenza A(H5N1) in humans - update 11: Note to national authorities, Situation in Viet Nam, Rapid - and safe - culling of infected poultry: the first line of defence for protecting international public health

SITREP - WHO | Avian influenza A(H5N1) in China - update 10

Avian influenza A(H5N1) in China - update 10

27 January 2004

The Ministry of Health in China has today confirmed the presence of highly pathogenic H5N1 avian influenza in poultry in the southern province of Guangxi. The H5N1 strain was detected in samples taken from a duck farm.

Testing is under way of samples from poultry outbreaks in the adjacent Hunan and Hubei provinces. Ducks are involved in the outbreak in Hunan, and chickens are involved in Hubei.

Strict measures to control all outbreaks, including culling and quarantine, have been undertaken.

No cases of human illness linked to these outbreaks have been detected to date.

WHO Avian influenza A(H5N1) in China - update 10

SITREP - WHO | Avian influenza A(H5N1) in humans - update 9: Situation in Thailand, Overview of the current situation

Avian influenza A(H5N1) in humans - update 9: Situation in Thailand, Overview of the current situation

27 January 2004

Situation in Thailand

The Ministry of Public Health in Thailand has today confirmed a second death caused by human infection with the H5N1 strain of avian influenza virus.

The fatal case is a 6-year-old boy from Sukhothai province, whose infection with H5N1 was confirmed yesterday. He died today. He was Thailand?s third confirmed case of H5N1 avian influenza and the country?s second death from this disease.

The other fatal case in Thailand was another 6-year-old boy from Kanchanaburi province. He died on 25 January.

Overview of the current situation

To date, only two countries, Viet Nam and Thailand, have reported laboratory confirmed cases of H5N1 infection in humans. Viet Nam has reported 7 cases, 6 of them fatal. Thailand has reported 3 cases, 2 of them fatal.

The cases and deaths in humans coincide with outbreaks of highly pathogenic H5N1 avian influenza in poultry populations in these two countries and several others in Asia. The disease in poultry is widespread in both Viet Nam and Thailand. WHO teams, drawn from the Global Outbreak Alert and Response Network, are in both countries to support national authorities. Laboratories in the WHO Global Influenza Surveillance Network have been providing diagnostic and investigative support. WHO is collaborating closely with FAO and the World Organisation for Animal Health (OIE).

Over the past few days, several countries in Asia have detected deaths in poultry flocks, and testing to determine the causative agent is under way.

The possible transmission of highly pathogenic H5N1 avian influenza from animals to humans is of great concern. Testing for the presence of this particular strain takes several days and must be performed in specially equipped laboratories.

WHO Avian influenza A(H5N1) in humans - update 9: Situation in Thailand, Overview of the current situation

SITREP - WHO | Avian influenza A(H5N1)- update 8: Situation in Thailand, Advice to international travellers

Avian influenza A(H5N1)- update 8: Situation in Thailand, Advice to international travellers

26 January 2004

Situation in Thailand

The Ministry of Public Health in Thailand has today announced laboratory confirmation of the country?s third human case of H5N1 avian influenza infection. The patient, who remains alive, is a 6-year-old child from Sukhothai province.

Health officials in Thailand have also confirmed the death of a 6-year-old boy from Kanchanaburi province. The boy, whose infection with the H5N1 strain was announced on Friday, died Sunday night. He had been hospitalized in Bangkok with severe pneumonia and acute respiratory distress syndrome.

The other case previously announced in Thailand is a 7-year-old boy from Suphanburi province.

Advice to international travellers

WHO does not at present recommend any restrictions on travel to any country currently experiencing outbreaks of H5N1 avian infection in poultry flocks, including countries which have also reported cases in humans.

At this time, WHO recommends that travellers to areas experiencing outbreaks of this disease in poultry should avoid contact with live animal markets and poultry farms. Large amounts of the virus are known to be excreted in the droppings from infected birds.

Since mid-December, outbreaks of H5N1 infection have been detected in the poultry populations of the Republic of Korea, Japan, Viet Nam, Thailand and Cambodia. Additional countries have detected deaths in poultry flocks, and the cause is currently under investigation.

The outbreak in Japan was limited to a single farm in Yamaguchi Prefecture. The outbreak was reported on 12 January, and no further spread to other farms has been detected. All 34,600 chickens at the infected farm had either died or been destroyed by 20 January.

Some human cases and deaths caused by the same H5N1 virus strain have been reported in two of these countries, Viet Nam and Thailand. Most of these cases have been linked to direct contact with diseased birds. At present, WHO has no information that the disease is spreading from person to person.

Influenza viruses are destroyed by heat. As a precaution, consumers should ensure that all foods from poultry, including eggs, have been thoroughly cooked.

WHO Avian influenza A(H5N1)- update 8: Situation in Thailand, Advice to international travellers

SITREP - WHO | Avian influenza A(H5N1)- update 7: Two further cases confirmed in Viet Nam,

Avian influenza A(H5N1)- update 7: Two further cases confirmed in Viet Nam, Overview of the current situation, Implications for food safety

24 January 2004

Two further cases confirmed in Viet Nam

Laboratory tests have confirmed two additional human cases of H5N1 avian influenza in Viet Nam. The cases, both in Ho Chi Minh City, are two children, an 8-year-old girl and a 13-year-old boy. The boy died on 22 January. The girl is hospitalized in stable, but critical condition.

The two cases are the first to be confirmed in the south of the country. They bring the total number of confirmed H5N1 cases in Viet Nam to seven, including five in Hanoi. Of the seven cases in Viet Nam, six (five children and one 30-year old woman) have died since 30 December 2003.

A WHO team is in Viet Nam working closely with health authorities to assess the current situation, conduct epidemiological investigations, and identify the most appropriate control measures.

Overview of the current situation

Yesterday, health authorities in Thailand announced laboratory confirmed H5N1 infection in two boys. Additional patients with respiratory symptoms that might signal H5N1 infection are being tested, and results are expected next week.

At present, Viet Nam and Thailand are the only two countries in which human cases of H5N1 avian influenza are known to have occurred in the current outbreak. The first recorded outbreak of H5N1 infection in humans occurred in Hong Kong in 1997, when 18 persons developed serious disease and six died.

The present human cases in Viet Nam and Thailand coincide with an historically unprecedented spread of highly pathogenic H5N1 avian influenza in the poultry populations of Asian countries. Since mid-December 2003, outbreaks of H5N1 disease in poultry have been confirmed in the Republic of Korea, Viet Nam, Japan, Thailand, and Cambodia. Additional countries have detected deaths in poultry flocks, and the cause is currently under investigation.

In Viet Nam, H5N1 infection in poultry has now been detected in 23 of the country?s 64 provinces. Since 23 December 2003, about 2.9 million poultry stock have either died or been destroyed because of the disease.

WHO has identified the rapid culling of H5N1 infected or exposed poultry as the major line of defence for preventing further human cases and possibly averting the emergence of a new influenza virus capable of causing an influenza pandemic.

At present, WHO has no evidence that person-to-person transmission is occurring.

Laboratories in the WHO Global Influenza Surveillance Network are characterizing avian and human viruses obtained from the current outbreaks. Preliminary results indicate that these viruses are significantly different from other H5N1 strains isolated in Asia in the recent past, thus necessitating the development of a new prototype strain for use in vaccine manufacturing.

Viruses are needed from all areas currently experiencing outbreaks in either infected birds or humans. Information from these viruses will then be used by WHO network laboratories to develop H5N1 prototype strains for vaccine manufacturers. Information about viruses from all outbreak sites is needed to ensure that the vaccine composition recommended by WHO will protect humans against all currently circulating H5N1 strains.

Implications for food safety

Since 1997, when the H5N1 avian influenza virus strain is first known to have caused infections in humans, fewer than 30 laboratory-confirmed cases have been documented worldwide. The 1997 outbreak in Hong Kong has been extensively studied. However, data about this disease in humans and its modes of transmission are limited by the small number of cases.

Investigations of the Hong Kong outbreak determined that close contact with live infected poultry was the source of human infection in all 18 cases. For this reason, the practice of marketing live poultry directly to consumers should be discouraged in areas currently experiencing outbreaks of highly pathogenic H5N1 avian influenza among poultry.

While trade restrictions have been put in place by some countries to protect animal health, on the basis of presently available data, WHO does not conclude that any processed poultry products (whole refrigerated or frozen carcasses and products derived from them) and eggs in or arriving from areas currently experiencing outbreaks of avian influenza H5N1 in poultry flocks pose a risk to public health.

It is well known that influenza viruses are killed by adequate heat. WHO continuously emphasizes, and in this particular situation reiterates, the importance of good hygiene practices during handling of poultry products, including hand washing, prevention of cross-contamination and thorough cooking (70�C).

WHO Avian influenza A(H5N1)- update 7: Two further cases confirmed in Viet Nam, Overview of the current situation, Implications for food safety

SITREP - WHO | Avian influenza A(H5N1) in humans in Viet Nam and in poultry in Asian countries - update 2

Avian influenza A(H5N1) in humans in Viet Nam and in poultry in Asian countries - update 2

16 January 2004

As detailed in a fact sheetissued yesterday, epidemics of highly pathogenic avian influenza, recently reported in some Asian countries, need to be watched very closely because of their potential significance for human health. All reported bird epidemics, in the Republic of Korea, Viet Nam, and Japan, are now known to have been caused by an H5N1 strain of avian influenza viruses.

Earlier this week, laboratory tests confirmed the presence of the H5N1 variant in samples taken from three patients hospitalized with severe respiratory disease in Hanoi, Viet Nam. Today, laboratory tests have confirmed the presence of H5N1 in an additional Vietnamese patient. All four confirmed cases have been fatal.

Several other patients with respiratory illness are under investigation in Hanoi. A case definition of avian influenza in humans is being introduced to facilitate the detection of further cases in Viet Nam, and surveillance is improving as a result.

Apart from its severe impact on bird populations, this H5N1 variant has properties that make it a potential risk to human health of considerable significance. H5N1 virus recently isolated from Asian birds has been shown to mutate rapidly and has a known tendency to acquire genes from influenza viruses affecting other species.

Moreover, the simultaneous occurrence of large and highly fatal outbreaks of H5N1 in birds is considered unprecedented. WHO is concerned that these events may indicate that H5N1 is becoming established in birds in this part of the world. Because comprehensive surveillance to detect all cases in bird species is difficult, the true geographical occurrence of the avian epidemic may not be fully appreciated at present.

The outbreak in Viet Nam is of particular concern as it suggests the presence of many conditions that are known to have favoured the start of influenza pandemics in the past. Foremost among these is the co-circulation of human influenza viruses with an avian strain that is prone to mutate and has high pathogenicity. H5N1 has, on two occasions in the recent past, caused severe disease with high fatality in humans, and has done so again during the past three weeks.

Widespread epidemics in birds increase opportunities for human exposure. Increases in the number of infections in humans increase opportunities for the avian and human strains to exchange genetic material. If a new virus subtype emerges as a result, and if that virus proves capable of spreading easily and sustainably from person to person, then the conditions for the start of an influenza pandemic will have been met.

The H5N1 variant isolated from fatal human cases in Viet Nam was partially sequenced earlier this week. All genes are of avian origin, indicating that the virus had not yet acquired genes from the human influenza virus. The acquisition of such genes increases the likelihood that a virus of avian origin can be readily transmitted from person to person.

In response to these concerns, WHO and its partners have intensified activities needed to reach three main objectives: to reduce death and disease among humans due to H5N1, to reduce opportunities for a new influenza pandemic to emerge, and to initiate urgently needed international and national research. Specific lines of research will allow a better scientific assessment of the significance of ongoing epidemics in birds for human health in affected countries, and possibly elsewhere.

Laboratories in the WHO global influenza network are now conducting studies, at the molecular level, of viruses isolated from infected birds in the different countries, and from the human cases. Such molecular ?detective work? can help identify the origins of currently circulating viruses, determine how they might be related, and thus shed considerable light on how the viruses are evolving.

Despite the seriousness of the current outbreak in humans, WHO believes that it can be controlled, provided decisive measures are taken to eliminate the animal reservoir for human infections. Surveillance for human respiratory disease in this part of the world has been intensified. WHO has alerted countries regarding the need to intensify surveillance for animal infections. Culling of infected or potentially exposed poultry flocks is a standard control measure that has proved effective in halting past epidemics of avian influenza in several countries.

H5N1 is the only one of the 15 subtypes of avian influenza that has, to date, caused severe outbreaks in humans. In Hong Kong in 1997, H5N1 caused disease in 18 persons, of whom 6 died. In February, 2003, H5N1 infected two persons, causing the death of one.

Three incidents of human infection with other avian subtypes, namely H7N7 and H9N2, were documented in 1999 and 2003, but caused only mild illness and altogether only 1 death.

During the 1997 outbreak of H5N1 influenza in humans, the culling ? within three days ? of Hong Kong?s entire poultry population is thought, by many experts, to have averted an influenza pandemic.

WHO Avian influenza A(H5N1) in humans in Viet Nam and in poultry in Asian countries - update 2

SITREP - WHO | Avian influenza A(H5N1) in humans in Viet Nam and poultry in Asia - update

Avian influenza A(H5N1) in humans in Viet Nam and poultry in Asia - update

14 January 2004

Investigation of cases of acute respiratory illness are continuing in Viet Nam with support from WHO staff. The investigation has been undertaken in response to concerns over the laboratory confirmation, on Sunday, of the presence of avian influenza virus H5N1 in three patients who died of severe respiratory illness in late December and early January.

The H5N1 strain implicated in the outbreak has now been partially sequenced. All genes are of avian origin, indicating that the virus that caused death in the three confirmed cases had not yet acquired human genes. The acquisition of human genes increases the likelihood that a virus of avian origin can be readily transmitted from one human to another.

Investigations are focusing on the source of infection and possibilities of human-to-human transmission.

An outbreak of highly pathogenic H5N1 avian influenza was detected in southern Viet Nam in the beginning of January. The outbreak is now known to have spread to other provinces in the country. Reports indicate that pigs and ducks have also been infected.

Yesterday, officials in the Republic of Korea announced the spread of H5N1 avian influenza to an additional farm. Japan is also experiencing an outbreak in poultry caused by the H5N1 virus.

In response to these developments, WHO has initiated a series of activities. These include support to national authorities in investigating the outbreaks and enhanced surveillance activities in Asia. WHO has also initiated the development of candidates and reagents for vaccine production, and antigenic and genetic assessments of the H5N1 strain to provide up-to-date diagnostic tests to national influenza centres.

The WHO Global Influenza Network will receive virus and clinical specimens shortly. As a precautionary measure, network laboratories will immediately begin work on the development of a strain that can be used to produce a vaccine.

WHO Avian influenza A(H5N1) in humans in Viet Nam and poultry in Asia - update

SITREP - WHO | Human influenza A(H3N2) activity remains widespread in many countries - update 7

Human influenza A(H3N2) activity remains widespread in many countries - update 7

13 January 2004

Summary (to 3 January 2004)

Influenza activity associated with A/Fujian/411/2002-like viruses continued to be widespread in some countries in Europe (Croatia, Denmark, Finland, France, Norway and Switzerland) and in the USA. Compared with the significant increase in previous weeks, influenza A(H3N2) activity seemed to be levelling off although, in several central and eastern European countries (Croatia, Latvia and Switzerland), it continued to increase. So far this season influenza B activity has been low and reported only from Asian countries (Republic of Korea and Thailand).

Most influenza infections this season have been attributed to influenza A(H3N2) viruses. The majority of A(H3N2) viruses antigenically characterized so far have been A/Fujian/411/2002-like; the others have been A/Panama/2007/99-like.

Following last week?s update on the A(H5N1) outbreak in the Republic of Korea, no more farms have been reported to be infected by avian influenza A(H5N1) viruses. The National Influenza Centre in the Republic of Korea has finished sampling sera from persons in contact with suspect infected animals and nearby residents, and will start serological studies shortly.

Avian influenza virus A(H5N1) has been identified as the cause of an outbreak of avian influenza in two southern provinces of Viet Nam; there is also information on outbreaks of avian influenza in other provinces. The virus, which spreads rapidly and has a mortality approaching 100% in chickens, has resulted in the deaths of 40 000 chickens and the culling of 30 000 more. Pigs and ducks are also reported to have been infected.

Since the end of October 2003, hospitals in Hanoi and surrounding provinces have admitted 14 persons with severe respiratory illness ? 13 children and one adult (the mother of a deceased child). To date, 11 of the children and the adult have died. The National Institute of Hygiene and Epidemiology in Viet Nam and the National Influenza Centre in Hong Kong Special Administrative Region of China (Hong Kong SAR) confirmed that three of these cases were infected with avian influenza A(H5N1) viruses. At present, there is no evidence that human-to-human transmission is occurring, and no health care workers have been infected. More information is available on the WHO web site.

Belgium. Influenza A(H3N2) activity declined in week 1 (28 December 2003 to 3 January 2004) in terms both of the number of viruses identified and of the influenza-like illness (ILI) consultation rate.

Canada. In week 1, widespread influenza activity was reported in Ontario, Quebec, Newfoundland and some parts of British Columbia. Overall ILI consultation rate dropped from 79 cases per 1000 consultations in week 52 of 2003 to 36 cases per 1000. Of the 456 influenza viruses antigenically characterized by the National Microbiology Laboratory to date, 429 (94%) were A/Fujian/411/2002-like, 25 (6%) were A/Panama/2007/99-like, one was an A/New Caledonia/20/99 (H1N1)-like virus and one was A(H1N2).

Croatia. Influenza A(H3N2) activity increased significantly in week 1, with 6 influenza A(H3N2) and 9 A non-subtyped viruses identified.

Czech Republic. Influenza A(H3N2) activity remained localized in week 1, with ILI consultation rate below the baseline level.

Finland. Influenza A(H3N2) activity remained widespread in week 1, but with a significant decrease in the number of laboratory-confirmed influenza cases since week 52 of 2003.

France. Influenza activity continued to decline in France, although widespread influenza A(H3N2) activity still persisted in many regions.

Denmark. Influenza A(H3N2) activity was reported as widespread in week 1, when the ILI consultation rate declined after being above the epidemic threshold for 3 weeks.

Germany. A continuing slight increase of regional influenza activity was observed in week 1.

Israel. Influenza activity has been in decline since week 51 of 2003.

Latvia. Influenza activity remained at a low level, but with a slight increase since week 49 of 2003.

Norway. After a peak in weeks 49 and50, clinical and virological indicators showed that influenza A(H3N2) activity, while still widespread in most parts of the country, declined gradually in week 1. Of 882 influenza A virus detected so far, 187 have been subtyped as A(H3) and 26 as A(H1). All A(H3) strains antigenically characterized were A/Fujian/411/2002-like, and all A(H1) strains were A/New Caledonia/20/99-like.

Portugal. Influenza activity remained sporadic in week 1 with 1 influenza A(H3N2) virus detected.

Republic of Korea. Influenza B activity has been reported since week 49.

Romania. Influenza A(H3N2) activity has declined rapidly since week 52 and was reported as sporadic in week 1.

Switzerland. Influenza A(H3N2) activity was reported as widespread in week 1, with an increase in the ILI consultation rate in all regions of the country.

United Kingdom. Influenza activity continued to decline in week 1, with a falling ILI consultation rate reported in Northern Ireland, Scotland and Wales. In England, the ILI consultation rate increased slightly, probably because of the disruption of service over the Christmas and New Year period. During week 1, no influenza virus was detected. Of the viruses antigenically characterized, 102 (95.3%) have been confirmed as A/Fujian/411/2002-like, 3 as A/Panama/2007/99-like and 2 as B/Hong Kong/330/2001-like.

United States. The overall ILI consultation rate (6.2%) decreased for the first time this season; the percentage of specimens testing positive for influenza and the number of states reporting widespread influenza activity also decreased. However, pneumonia and influenza mortality (9.4%) continued to increase and exceeded the epidemic threshold (8.0%). Widespread influenza activity was reported in 38 states, New York City and the District of Columbia, and regional activity was reported in 9 states during week 1. Of the specimens tested, 20.7%were positive for influenza, with 635 influenza A viruses and 6 B viruses identified. Since week 40, the Centers for Disease Control and Prevention in Atlanta have antigenically characterized 2 influenza A(H1) viruses, 454 A(H3N2) viruses and 5 B viruses from the USA. Of the 454 A(H3N2) viruses characterized, 98 (21.6%) were A/Panama/2007/99-like and 356 (78.4%) are A/Fujian/411/2002-like.

Other reports. Low influenza activity was reported in Greece, Hong Kong SAR, Italy and Japan. Argentina and Poland reported no influenza activity.

WHO Human influenza A(H3N2) activity remains widespread in many countries - update 7

SITREP - WHO | Avian influenza A(H5N1) in humans and poultry in Viet Nam

Avian influenza A(H5N1) in humans and poultry in Viet Nam

13 January 2004

Laboratory results received on Sunday have confirmed the presence of avian influenza virus strain A(H5N1) in samples taken from humans. The samples were taken from two children and one adult admitted to hospital with a severe respiratory illness in Hanoi.

Since the end of October, hospitals in Hanoi and surrounding provinces have admitted 14 persons with severe respiratory illness. The cases are in thirteen children and one adult, the mother of a deceased child. To date, eleven of the children and the adult have died.

It is not known whether all of these cases were caused by the same pathogen. At present, there is no evidence that human-to-human transmission has occurred. No reports indicate that health care workers have been infected.

The presence of avian influenza A(H5N1) in samples from three of these cases was confirmed by Hong Kong?s National Influenza Center, which is a member of the WHO Global Influenza Surveillance Network. Samples have also been sent for analysis to Japan?s National Institute for Infectious Diseases, another member of the WHO influenza network. Results are awaited shortly.

WHO is providing support to Vietnamese health authorities in their investigation of the cases and in the prevention of further spread to humans.

Avian influenza strains normally infect birds exclusively.

The first cases of human infection with avian influenza A(H5N1) were identified in 1997 in Hong Kong. The virus infected 18 persons and caused 6 deaths. Genetic studies subsequently linked the outbreak in humans to an outbreak of highly pathogenic avian influenza in poultry. The immediate culling of around 1.5 million poultry in Hong Kong is thought to have averted a larger outbreak in humans.

Other recent outbreaks of avian influenza in humans have caused limited disease. An outbreak of H5N1 in Hong Kong in February 2003 caused 2 cases and 1 death. An outbreak of H7N7 avian influenza in the Netherlands caused the death of one veterinarian in April 2003, and mild illness in 83 humans. Mild cases of avian influenza A(H9N2) in children occurred in Hong Kong in 1999 (two cases) and in mid-December 2003 (one case).

Highly pathogenic avian influenza in poultry

Last week, avian influenza virus A(H5N1) was identified as the cause of an outbreak of highly pathogenic avian influenza in two southern provinces of Viet Nam. To date, the virus, which spreads rapidly and has a mortality in chickens approaching 100%, has resulted in the deaths of 40,000 chickens and the culling of 30,000 more.

The relationship between the human and poultry outbreaks of avian influenza A(H5N1) in Viet Nam is not fully understood at present. WHO and Viet Nam?s Ministry of Health are undertaking investigations to determine the source of the human cases and whether human-to-human transmission has occurred. The situation is also being followed closely by the country?s Ministry of Agriculture and Rural Development.

An outbreak of avian influenza A(H5N1) occurred in South Korea in December 2003. On Monday, Japanese authorities announced the death of 6,000 chickens at a single farm as due to infection with the same strain of the virus. These outbreaks mark the first cases of avian influenza in South Korea, and the first cases in Japan since 1925.

No human cases of infection with the avian influenza virus have been reported in either of these outbreaks.

WHO regards every case of transmission of an avian influenza virus to humans as a cause for heightened vigilance and surveillance. The circulation of highly pathogenic avian influenza viruses in large numbers of poultry in a growing number of countries is of particular concern. Influenza viruses are highly unstable. The co-circulation of highly pathogenic animal viruses with human viruses could create opportunities for different species-specific viruses to exchange genetic material, giving rise to a new influenza virus to which humans would have little, if any, protective immunity.

WHO Avian influenza A(H5N1) in humans and poultry in Viet Nam