See Influenza for details about the illnesses and Influenza A virus subtype H5N1 and Influenza A virus subtype H3N2 for details about the causative agents.
Fujian flu refers to flu caused by either a Fujian human flu strain of the H3N2 subtype of the Influenza A virus or a Fujian bird flu strain of the H5N1 subtype of the Influenza A virus. These strains are named after Fujian, a coastal province in Southeast China.
A/Fujian (H3N2) human flu (from A/Fujian/411/2002(H3N2) -like flu virus strains) caused an unusually severe 2003–2004 flu season. This was due to a reassortment event that caused a minor clade to provide a haemagglutinin gene that later became part of the dominant strain in the 2002–2003 flu season. A/Fujian (H3N2) was made part of the trivalent influenza vaccine for the 2004-2005 flu season and its descendants are still the most common human H3N2 strain.
A/Fujian (H5N1) bird flu is notable for its resistance to standard medical countermeasures and its rapid spread. This variant of the H5N1 virus also illustrates the continuing evolution of the H5N1 virus, and its emergence has caused political controversy.
Terminology A variety of names were used before being standardized. Phrases used to identify the flu or the causative agent include "Fujian-like" and "Fujian virus"Medical News Today article H5N1 Bird Flu Virus Is Changing, FAO And OIE Recommend Increased Surveillance When Vaccinating published 10 November 2006 for the H5N1 version and "Fujian-like" for the H3N2 version.
Both are also sometimes specified as "Type A Fujian flu" or "A/Fujian flu" referring to the species Influenza A virus. Both are also sometimes specified according to their species subtype: "Fujian Flu (H3N2)" or "Fujian Flu (H5N1)". Or both, example: "A-Fujian-H3N2".
"A/Fujian/411/2002-like (H3N2)" and "Influenza A/Fujian/411/02(H3N2)-lineage viruses" are examples of using the full name of the virus strains.
A/Fujian (H3N2) In the 2003-2004 flu season the influenza vaccine was produced to protect against A/Panama (H3N2), A/New Caledonia (H1N1), and B/Hong Kong. A new strain, A/Fujian (H3N2), was discovered after production of the vaccine started and vaccination gave only partial protection against this strain. Nature magazine reported that the Influenza Genome Sequencing Project, using phylogenetic analysis of 156 H3N2 genomes, "explains the appearance, during the 2003–2004 season, of the 'Fujian/411/2002'-like strain, for which the existing vaccine had limited effectiveness" as due to an epidemiologically significant reassortment. "Through a reassortment event, a minor clade provided the haemagglutinin gene that later became part of the dominant strain after the 2002–2003 season. Two of our samples, A/New York/269/2003 (H3N2) and A/New York/32/2003 (H3N2), show that this minor clade continued to circulate in the 2003–2004 season, when most other isolates were reassortants."
In January 2004, the predominant flu virus circulating in humans in Europe was influenza A/Fujian/411/2002 (H3N2)-like.EISS - Weekly Electronic Bulletin article Influenza activity on the rise in the east of Europe dated 23 January 2004
As of 15 June 2004, CDC had antigenically characterized 1,024 influenza viruses collected by U.S. laboratories since 1 October 2003: 949 influenza A (H3N2) viruses, three influenza A (H1) viruses, one influenza A (H7N2) virus, and 71 influenza B viruses. Of the 949 influenza A (H3N2) isolates characterized, 106 (11.2%) were similar antigenically to the vaccine strain A/Panama/2007/1999 (H3N2), and 843 (88.8%) were similar to the drift variant, A/Fujian/411/2002 (H3N2).CDC article Update: Influenza Activity --- United States and Worldwide, 2003–04 Season, and Composition of the 2004–05 Influenza Vaccine published 2 July 2004
The 2004-2005 flu season trivalent influenza vaccine for the United States contained A/New Caledonia/20/1999-like (H1N1), A/Fujian/411/2002-like (H3N2), and B/Shanghai/361/2002-like viruses.
Flu Watch reported for 13 to 19 February 2005 that: "The National Microbiology Laboratory (NML) has antigenically characterized 516 influenza viruses: 470 influenza A (H3N2) and 46 influenza B viruses. Of the 470 influenza A (H3N2), 427 (91%) were A/Fujian/411/2002 (H3N2)-like and 43 (9%) A/California/7/2004-like viruses. Of the 46 influenza B, 45 were B/Shanghai/361/02-like and one B/HongKong/330/2001-like virus. Although the A/California/7/2004 (H3N2)-like isolates have reduced titres to the A/Fujian/411/2002-like antisera, the H3N2 component of the current vaccine is still expected to provide some level of protection against this new variant. The WHO has recommended that the vaccine for the 2005/06 northern hemisphere season contain the A/California/7/2004 (H3N2)-like virus."Flu Watch 13 to 19 February 2005
A/Fujian (H5N1)
Specific H5N1 isolates labeled as Fujian include A/Fujian/1/2005 and A/DK/Fujian/1734/05 (or A/Ck/Fujian/1734/2005).washington.edu Ministry of Health, P.R.China 2006-1-20
A/Fujian (H5N1) bird flu is notable for its resistance to standard medical countermeasures, its rapid spread, what it tells us about the continuing evolution of the H5N1 virus, and the political controversy surrounding it. CIDRAP says "A new subtype of H5N1 avian influenza virus has become predominant in southern China over the past year, possibly through its resistance to vaccines used in poultry, and has been found in human H5N1 cases in China, according to researchers from Hong Kong and the United States. The rise of the Fujian-like strain seems to be the cause of increased poultry outbreaks and recent human cases in China, according to the team from the University of Hong Kong and St. Jude's Children's Research Hospital in Memphis. The researchers also found an overall increase of H5N1 infection in live-poultry markets in southern China."CIDRAP article Study says new H5N1 strain pervades southern China published 3 November 2006CIDRAP article Chinese promise H5N1 samples, deny claim of new strain published 10 November 2006Reuters article China scientists call bird flu paper "unscientific" published 7 November 2006WHO PDF
Resistance to countermeasures According to the New York Times: "[P]oultry vaccines, made on the cheap, are not filtered and purified [like human vaccines] to remove bits of bacteria or other viruses. They usually contain whole virus, not just the hemagglutinin spike that attaches to cells. Purification is far more expensive than the work in eggs, Dr. Stöhr said; a modest factory for human vaccine costs $100 million, and no veterinary manufacturer is ready to build one. Also, poultry vaccines are "adjuvated" – boosted – with mineral oil, which induces a strong immune reaction but can cause inflammation and abscesses. Chicken vaccinators who have accidentally jabbed themselves have developed painful swollen fingers or even lost thumbs, doctors said. Effectiveness may also be limited. Chicken vaccines are often only vaguely similar to circulating flu strains – some contain an H5N2 strain isolated in Mexico years ago. 'With a chicken, if you use a vaccine that's only 85 percent related, you'll get protection,' Dr. Cardona said. 'In humans, you can get a single point mutation, and a vaccine that's 99.99 percent related won't protect you.' And they are weaker [than human vaccines]. 'Chickens are smaller and you only need to protect them for six weeks, because that's how long they live till you eat them,' said Dr. John J. Treanor, a vaccine expert at the University of Rochester. Human seasonal flu vaccines contain about 45 micrograms of antigen, while an experimental A(H5N1) vaccine contains 180. Chicken vaccines may contain less than 1 microgram. 'You have to be careful about extrapolating data from poultry to humans,' warned Dr. David E. Swayne, director of the agriculture department's Southeast Poultry Research Laboratory. 'Birds are more closely related to dinosaurs.'" Researchers, led by Nicholas Savill of the University of Edinburgh in Scotland, used mathematical models to simulate the spread of H5N1 and concluded that "at least 95 per cent of birds need to be protected to prevent the virus spreading silently. In practice, it is difficult to protect more than 90 per cent of a flock; protection levels achieved by a vaccine are usually much lower than this."SciDev.Net article Bird flu warning over partial protection of flocks published 16 August 2006
Referring to the Fujian-like strain, an October 2006 National Academy of Sciences article reports: "The development of highly pathogenic avian H5N1 influenza viruses in poultry in Eurasia accompanied with the increase in human infection in 2006 suggests that the virus has not been effectively contained and that the pandemic threat persists. [...] Serological studies suggest that H5N1 seroconversion in market poultry is low and that vaccination may have facilitated the selection of the Fujian-like sublineage. The predominance of this virus over a large geographical region within a short period directly challenges current disease control measures." The research team tested more than 53,000 birds in southern China from July 2005 through June 2006. 2.4% of the birds had H5N1, more than double the previous 0.9% rate. 68% them were in the new Fujian-like lineage. First detected in March 2005, it constituted 103 of 108 bird hosted isolates tested from April through June 2006, five Chinese human hosted isolates, 16 from Hong Kong birds, and two from Laos and Malaysia birds. Chickens in southern China were found to be poorly immunized against Fujian-like viruses in comparison with other sublineages. "All the analyzed Fujian-like viruses had molecular characteristics that indicated sensitivity to oseltamivir, the first-choice antiviral drug for H5N1 infection. In addition, only six of the viruses had a mutation that confers resistance to amantadine, an older antiviral drug used to treat flu."
Rapid spread "China's official Xinhua news agency says a new bird flu outbreak has killed more than 3,000 chickens in the northwest. The Ministry of Agriculture told Xinhua that the July 14 outbreak in Xinjiang region's Aksu city is under control. No human infections have been reported. Saturday's report says the deadly H5N1 virus killed 3,045 chickens, and nearly 357,000 more were destroyed in an emergency response. Xinhua says the local agriculture department has quarantined the infected area. The government's last reported outbreak was in the northwestern region of Ningxia earlier this month."
The October 2006 National Academy of Sciences article also says: "Updated virological and epidemiological findings from our market surveillance in southern China demonstrate that H5N1 influenza viruses continued to be panzootic in different types of poultry. Genetic and antigenic analyses revealed the emergence and predominance of a previously uncharacterized H5N1 virus sublineage (Fujian-like) in poultry since late 2005. Viruses from this sublineage gradually replaced those multiple regional distinct sublineages and caused recent human infection in China. These viruses have already transmitted to Hong Kong, Laos, Malaysia, and Thailand, resulting in a new transmission and outbreak wave in Southeast Asia."
H5N1 evolution The first known strain of HPAI A(H5N1) (called A/chicken/Scotland/59) killed two flocks of chickens in Scotland in 1959; but that strain was very different from the current highly pathogenic strain of H5N1. The dominant strain of HPAI A(H5N1) in 2004 evolved from 1999 to 2002 creating the Z genotype. This e-book is under constant revision and is an excellent guide to Avian Influenza It has also been called "Asian lineage HPAI A(H5N1)".