Global spread of H5N1

Highly pathogenic H5N1
Highly pathogenic H5N1
	→  Countries with poultry or wild birds killed by H5N1.
	→  Countries with human cases of H5N1.

The global spread of (highly pathogenic) H5N1 in birds is considered a significant pandemic threat.

While prior H5N1 strains have been known, they were significantly different from the current H5N1 strain on a genetic level, making the global spread of this new strain unprecedented. The current H5N1 strain is a fast-mutating, highly pathogenic avian influenza virus (HPAI) found in multiple bird species. It is both epizootic (an epidemic in non-humans) and panzootic (a disease affecting animals of many species especially over a wide area). Unless otherwise indicated, "H5N1" in this article refers to the recent highly pathogenic strain of H5N1.

"Since 1997, studies of H5N1 indicate that these viruses continue to evolve, with changes in antigenicity and internal gene constellations; an expanded host range in avian species and the ability to infect felids; enhanced pathogenicity in experimentally infected mice and ferrets, in which they cause systemic infections; and increased environmental stability."

Tens of millions of birds have died of H5N1 influenza and hundreds of millions of birds have been slaughtered and disposed of to limit the spread of H5N1. Countries that have reported one or more major highly pathogenic H5N1 outbreaks in birds (causing at least thousands but in some cases millions of dead birds) are (in order of first outbreak occurrence): Korea, Vietnam, Japan, Thailand, Cambodia, Laos, Indonesia, China, Malaysia, Russia, Kazakhstan, Mongolia, Turkey, Romania, Croatia, Ukraine, Cyprus, Iraq, Nigeria, Egypt, India, France, Niger, Bosnia, Azerbaijan, Albania, Cameroon, Myanmar, Afghanistan, Israel, Pakistan, Jordan, Burkina Faso, Germany, Sudan, Ivory Coast, Djibouti. Highly pathogenic H5N1 has been found in birds in the wild in numerous other countries: Austria, Bulgaria, Czech Republic, Denmark, Greece, Hungary, Iran, Italy, Kuwait, Poland, Serbia and Montenegro, Slovakia, Slovenia, Spain, Sweden, Switzerland, United Kingdom. Countries with massive bird die offs that do not confirm H5N1 include: Ethiopia. Surveillance of H5N1 in humans, poultry, wild birds, cats and other animals remains very weak in many parts of Asia and Africa. Much remains unknown about the exact extent of its spread.

H5N1 has low pathogenic varieties endemic in birds in North America. H5N1 has a highly pathogenic variety that is endemic in dozens of species of birds throughout south Asia and is threatening to become endemic in birds in west Asia and Africa. So far, it is very difficult for humans to become infected with H5N1. The presence of highly pathogenic (deadly) H5N1 around the world in both birds in the wild (swans, magpies, ducks, geese, pigeons, eagles, etc.) and in chickens and turkeys on farms has been demonstrated in millions of cases with the virus isolate actually sequenced in hundreds of cases yielding definitive proof of the evolution of this strain of this subtype of the species Influenzavirus A (bird flu virus).

H5N1 caused flu outbreaks in 1959 and in 1991 but these strains were very different from the current highly pathogenic strain of H5N1. Evolution from 1999 to 2002 created the Z genotype which became the dominant strain of highly pathogenic H5N1 in 2004.

Ducks play a key role in H5N1 spread

In January 2004 a major new outbreak of H5N1 surfaced in Vietnam and Thailand's poultry industry, and within weeks spread to ten countries and regions in Asia, including Indonesia, South Korea, Japan and China. In October 2004 researchers discovered H5N1 is far more dangerous than previously believed because waterfowl were directly spreading the highly pathogenic strain of H5N1 to chickens, crows, pigeons, and other birds and that it was increasing its ability to infect mammals as well. From this point on, avian flu experts increasingly refer to containment as a strategy that can delay but not prevent a future avian flu pandemic.

The spread of avian influenza in the eastern hemisphere.

In January 2005 an outbreak of avian influenza affected thirty three out of sixty four cities and provinces in Vietnam, leading to the forced killing of nearly 1.2 million poultry. Up to 140 million birds are believed to have died or been killed because of the outbreak. In April 2005 there begins an unprecedented die-off of over 6,000 migratory birds at Qinghai Lake in central China over three months. This strain of H5N1 is the same strain as is spread west by migratory birds over at least the next ten months. In August 2005 H5N1 spread to Kazakhstan, Mongolia and Russia. On September 29 2005, David Nabarro, the newly appointed Senior United Nations System Coordinator for Avian and Human Influenza, warned the world that an outbreak of avian influenza could kill 5 to 150 million people. David Nabarro later stated that as the virus had spread to migratory birds, an outbreak could start in Africa or the Middle East. Later in 2005 H5N1 spread to Turkey, Romania, Croatia and Kuwait.

In the first two months of 2006 H5N1 spread to Africa and Europe in wild bird populations possibly signaling the beginning of H5N1 being endemic in wild migratory bird populations on multiple continents for decades, permanently changing the way poultry are farmed. In addition, the spread of highly pathogenic H5N1 to wild birds, birds in zoos and even sometimes to mammals (example: pet cats) raises many unanswered questions concerning best practices for threat mitigation, trying to balance reducing risks of human and nonhuman deaths from the current nonpandemic strain with reducing possible pandemic deaths by limiting its chances of mutating into a pandemic strain. Not using vaccines can result in the need to kill significant numbers of farm and zoo birds, while using vaccines can increase the chance of a pandemic.

By April 2006 scientists had concluded that containment had failed due to the role of wild birds in transmitting the virus and were now emphasizing far more comprehensive risk mitigation and management measures.

In June 2006 WHO predicted an upsurge in human deaths due to H5N1 during late 2006. In July and August 2006 significantly increased numbers of bird deaths due to H5N1 were recorded in Cambodia, China, Laos, Nigeria, and Thailand while continuing unabated a rate unparalleled in Indonesia.

Cumulative Human Cases of and Deaths from H5N1
As of April 11, 2007

Notes: Source WHO Confirmed Human Cases of H5N1 "[T]he incidence of human cases peaked, in each of the three years in which cases have occurred, during the period roughly corresponding to winter and spring in the northern hemisphere. If this pattern continues, an upsurge in cases could be anticipated starting in late 2006 or early 2007." Avian influenza – epidemiology of human H5N1 cases reported to WHO The regression curve for deaths is y = a + ek x, and is shown extended through the end of April, 2007.

Human and bird cases

Confirmed human cases and mortality rate of avian influenza (H5N1) 2003–2024

Country
Australia
Azerbaijan
Bangladesh
Cambodia
Canada
Chile
China
Djibouti
Ecuador
Egypt
India
Indonesia
Iraq
Laos
Myanmar
Nepal
Nigeria
Pakistan
Spain
Thailand
Turkey
United Kingdom
United States
Vietnam
Total

2003			2004			2005			2006			2007			2008			2009			2010			2011			2012			2013			2014			2015			2016			2017			2018			2019			2020			2021			2022			2023			2024			Total
cases	deaths	CFR	cases	deaths	CFR	cases	deaths	CFR	cases	deaths	CFR	cases	deaths	CFR	cases	deaths	CFR	cases	deaths	CFR	cases	deaths	CFR	cases	deaths	CFR	cases	deaths	CFR	cases	deaths	CFR	cases	deaths	CFR	cases	deaths	CFR	cases	deaths	CFR	cases	deaths	CFR	cases	deaths	CFR	cases	deaths	CFR	cases	deaths	CFR	cases	deaths	CFR	cases	deaths	CFR	cases	deaths	CFR	cases	deaths	CFR	cases	deaths	CFR
																																																															1	0	0%	1	0	0%
									8	5	62.5%																																																							8	5	62.5%
															1	0	0%							2	0	0%	3	0	0%	1	1	100%				1	0	0%																												8	1	12.5%
						4	4	100%	2	2	100%	1	1	100%	1	0	0%	1	0	0%	1	1	100%	8	8	100%	3	3	100%	26	14	53.8%	9	4	44.4%																									6	4	66.7%	10	2	20.0%	72	43	59.7%
																														1	1	100%																																		1	1	100%
																																																												1	0	0%				1	0	0%
1	1	100%				8	5	62.5%	13	8	61.5%	5	3	60.0%	4	4	100%	7	4	57.1%	2	1	50.0%	1	1	100%	2	1	50.0%	2	2	100%	2	0	0%	6	1	16.7%																			1	1	100%	1	0	0%				55	32	58.2%
									1	0	0%																																																							1	0	0%
																																																									1	0	0%							1	0	0%
									18	10	55.6%	25	9	36.0%	8	4	50.0%	39	4	10.3%	29	13	44.8%	39	15	38.5%	11	5	45.5%	4	3	75.0%	37	14	37.8%	136	39	28.7%	10	3	30.0%	3	1	33.3%																						359	120	33.4%
																																																						1	1	100%										1	1	100%
						20	13	65.0%	55	45	81.8%	42	37	88.1%	24	20	83.3%	21	19	90.5%	9	7	77.8%	12	10	83.3%	9	9	100%	3	3	100%	2	2	100%	2	2	100%				1	1	100%																						200	168	84.0%
									3	2	66.6%																																																							3	2	66.6%
												2	2	100%																																					1	0	0%													3	2	66.7%
												1	0	0%																																																				1	0	0%
																																																1	1	100%																1	1	100%
												1	1	100%																																																				1	1	100%
												3	1	33.3%																																																				3	1	33.3%
																																																									2	0	0%							2	0	0%
			17	12	70.6%	5	2	40.0%	3	3	100%																																																							25	17	68.0%
									12	4	33.3%																																																							12	4	33.3%
																																																						1	0	0%				4	0	0%				5	0	0%
																																																									1	0	0%				13	0	0%	14	0	0%
3	3	100%	29	20	69.0%	61	19	31.1%				8	5	62.5%	6	5	83.3%	5	5	100%	7	2	28.6%				4	2	50.0%	2	1	50.0%	2	2	100%																						1	0	0%				1	1	100%	129	65	50.0%
4	4	100%	46	32	69.6%	98	43	43.9%	115	79	68.7%	88	59	67.0%	44	33	75.0%	73	32	43.8%	48	24	50.0%	62	34	54.8%	32	20	62.5%	39	25	64.1%	52	22	42.3%	145	42	29.0%	10	3	30.0%	4	2	50.0%	0	0	0%	1	1	100%	1	0	0%	2	1	50.0%	6	1	16.7%	12	4	33.3%	25	3	12.0%	907	464	51.1%

Updated 1 September 2024

Source: World Health Organization Global Influenza Program Cumulative Cases Report ·

1959-2003

A highly pathogenic strain of H5N1 caused flu outbreaks with significant spread to numerous farms, resulting in great economic losses in 1959 in Scotland in chickens and in 1991 in England in turkeys. These strains were somewhat similar to the current pathogenic strain of H5N1 in two of its ten genes, the gene that causes it to be type H5 and the gene that causes it to be N1. The other genes can and have been reassorted from other subtypes of the bird flu species (their ease at exchanging genes is part of what makes them all one species). Evolution by reassortment of H5N1 from 1999 to 2002 created the Z genotype which became the dominant strain of highly pathogenic H5N1 in 2004 and is now spreading across the entire world in both wild and domestic birds.

"The precursor of the H5N1 influenza virus that spread to humans in 1997 was first detected in Guangdong, China, in 1996, when it caused a moderate number of deaths in geese and attracted very little attention."

In 1997, in Hong Kong, 18 humans were infected and 6 died in the first known case of H5N1 infecting humans.

"Human disease associated with influenza A subtype H5N1 re-emerged in January 2003, for the first time since an outbreak in Hong Kong in 1997." Three people in one family were infected after visiting Fujian province in mainland China and 2 died.

By midyear of 2003 outbreaks of poultry disease caused by H5N1 occurred in Asia, but were not recognized as such. That December animals in a Thai zoo died after eating infected chicken carcasses. Later that month H5N1 infection was detected in 3 flocks in the Republic of Korea.

H5N1 in China in this and later periods is less than fully reported. Blogs have described many discrepancies between official China government announcements concerning H5N1 and what people in China see with their own eyes. Many reports of total H5N1 cases exclude China due to widespread disbelief in China's official numbers.

2004

January 2004: A major new outbreak of H5N1 surfaced in Vietnam and Thailand's poultry industry, and within weeks spread to ten countries and regions in Asia, including Indonesia, South Korea, Japan and China. Intensive efforts were undertaken to slaughter chickens, ducks and geese (over forty million chickens alone were slaughtered in high-infection areas), and the outbreak was contained by March, but the total human death toll in Vietnam and Thailand was twenty three people.

February 2004: "The Ministry of Public Health in Thailand has confirmed the country’s tenth case of H5N1 infection."

July 2004: Fresh outbreaks in poultry were confirmed in Ayutthaya and Pathumthani provinces of Thailand, and Chaohu city in Anhui, China. Research identifies the dominant strain of H5N1 as the "Z genotype".

August 2004: Avian flu was confirmed in Kampung Pasir, Kelantan, Malaysia. Two chickens were confirmed to be carrying H5N1. As a result Singapore has imposed a ban on the importation of chickens and poultry products. Similarly the EU has imposed a ban on Malaysian poultry products. A cull of all poultry has been ordered by the Malaysian government within a 10km radius of the location of this outbreak. These moves appear to have been successful and since then, Singapore has lifted the ban and Malaysia has requested the OIE declare Malaysian poultry bird flu free .

September 2004: More cases of H5N1 in humans in Thailand.

October 2004: Researchers discover H5N1 is far more dangerous than previously believed. "In the past, outbreaks of highly pathogenic avian influenza in poultry began following the primary introduction of a virus, of low pathogenicity, probably carried by a wild bird. The virus then required several months of circulation in domestic poultry in order to mutate from a form causing very mild disease to a form causing highly pathogenic disease, with a mortality approaching 100%. Only viruses of the H5 and H7 subtypes are capable of mutating to cause highly pathogenic disease. In the present outbreaks, however, asymptomatic domestic ducks can directly introduce the virus, in its highly pathogenic form, to poultry flocks." Limiting this conclusion to domestic waterfowl proved to be wishful thinking, as in later months it became clear that nondomestic waterfowl were also directly spreading the highly pathogenic strain of H5N1 to chickens, crows, pigeons, and other birds and that it was increasing its ability to infect mammals as well. From this point on, avian flu experts increasingly refer to containment as a strategy that can delay but not prevent a future avian flu pandemic.

November 2004: The U.S.'s National Institutes of Health's (NIH) National Institute of Allergy and Infectious Diseases's (NIAID) Influenza Genome Sequencing Project to provide complete sequence data for selected human and avian influenza isolates begins.

December 2004: "[F]irst human case of H5N1 [is] detected in Viet Nam since early September" .

2005

January 2005: An outbreak of avian influenza affected thirty three out of sixty four cities and provinces in Vietnam, leading to the forced killing of nearly 1.2 million poultry. Up to 140 million birds are believed to have died or been killed because of the outbreak.

February 2005: "Surveillance stepped up in province where Cambodia's first human avian influenza case was detected".

March 2005: Vietnam and Thailand have seen several isolated cases where human-to-human transmission of the virus has been suspected in care-givers of H5N1 patients, including a mother of a girl who died from H5N1 and two nurses.

April 2005: "The Ministry of Health in Vietnam has provided WHO with official confirmation of an additional eight human cases of H5N1 avian influenza. Two of the cases were recently detected, between 2 and 8 April, in Hung Yen and Ha Tay Provinces, respectively. Both patients are alive. The other six cases are thought to have been detected prior to 2 April. WHO is seeking further details from the authorities on this six cases." There is an unprecedented die-off of over 6,000 migratory birds at Qinghai Lake in central China during April, May and June. This strain of H5N1 is the same strain as is spread west by migratory birds over at least the next ten months. "The RNA sequence of the Qinghai virus reveals that three of its eight genes are almost identical to those of a virus isolated from a chicken in Shantou in 2003. The other five genes resemble those of viruses found in southern China earlier in 2005, which belong to the "Z genotype" virus circulating across east Asia."

May 2005: "Since January 2004, when human cases of H5N1 avian influenza were first reported in the current outbreak, 97 cases and 53 deaths have been reported in Vietnam, Thailand and Cambodia. Vietnam, with 76 cases and 37 deaths, has been the most severely affected country, followed by Thailand, with 17 cases and 12 deaths, and Cambodia, with 4 cases and 4 deaths."

June 2005: "[T]esting of clinical specimens by international experts working in Vietnam provided further suggestive evidence of more widespread infection with the virus, raising the possibility of community-acquired infection" but "the detection of H5N1 in clinical specimens is technically challenging and prone to errors" so team members and supplies from "institutes in Australia, Canada, Hong Kong SAR, Japan, the United Kingdom, and the United States of America having extensive experience in the testing of avian influenza viruses in human clinical specimens" investigated and concluded that "no laboratory evidence suggesting that human infections are occurring with greater frequency or that the virus is spreading readily among humans."

July 2005: A death in Jakarta was the first confirmed human fatality in Indonesia. On July 28, avian influenza was reported to have killed two more people in Vietnam, raising the death toll to sixty .

August 2005: On August 3 2005, WHO said it was following closely reports from China that at least 38 people have died and more than 200 others have been made ill by a swine-borne virus in Sichuan Province. Sichuan Province, where infections with Streptococcus suis have been detected in pigs in a concurrent outbreak, has one of the largest pig populations in China. The outbreak in humans has some unusual features and is being closely followed by the WHO. In early August, an avian outbreak of H5N1 flu was confirmed in Kazakhstan and Mongolia, suggesting further spread of the virus . Later in August, the virus was found in western Russia, marking its appearance in Europe. As a result, Dutch authorities ordered that free-range chickens would have to be kept indoors. EU officials chose not to impose a similar policy on member countries.

September 2005: On September 29 2005, David Nabarro, the newly appointed Senior United Nations System Coordinator for Avian and Human Influenza, warned the world that an outbreak of avian influenza could kill 5 to 150 million people. Also, due to a bipartisan effort of the United States Senate, $4 billion dollars was appropriated to develop vaccines and treatments for Avian influenza. David Nabarro stated that as the virus had spread to migratory birds, an outbreak could start in Africa or the Middle East. Agricultural ministers of Association of South East Asian Nations announced a three-year plan to counter the spread of the disease.

October 2005: On 13 October 2005 the EU Health Commissioner Markos Kyprianou confirmed that tests on the dead turkeys found on farms in Kiziksa, Turkey, showed that they had died from the H5N1 strain. Even before the test results were available, some 5,000 birds and poultry have been culled in the area. It is believed that the disease had spread from migratory birds that land at the Manyas bird sanctuary (a few miles from the infected farm) on their way to Africa. On 15 October 2005, the British Veterinary Laboratory in Weybridge confirmed that the virus detected in Ciamurlia, Romania is H5N1. On 19 October 2005, China announced a fresh outbreak of bird flu, saying 2,600 birds have died from the disease in Inner Mongolia. The deaths, at a farm near the region's capital of Hohhot, were due to the H5N1 strain, the Xinhua news agency said. On 26 October 2005, Croatia announced H5N1 strain was found in dead swans . On 31 October 2005, Russia confirmed previously suspected H5N1 bird flu in ten rural communities across Russia. The confirmed outbreak sites are in the central areas of Tula and Tambov, as well as in the Urals province of Chelyabinsk and in Omsk and Altai, in Siberia.

November 2005: Kuwait has reported positive testing of two birds, one infected with H5N1, and the other with the H5N2 virus, making them the first cases of infection in the Middle East. A flamingo holding the H5N1 virus was found dead by the sea, as the source reports, it was killed by authorities and did not die from the virus.

December 2005: "China confirms its third human death from bird flu. That brings the death toll [...] to 74, comprising 14 victims in Thailand, four in Cambodia, 11 in Indonesia, 42 in Vietnam and three in China."

2006

January

January 5 2006

• A second Turkish child from the same family died from bird flu on Thursday at a hospital in eastern Turkey where she was being treated, a regional governor said. Her brother, 14-year-old Mehmet Ali Kocyigit, had already died of the H5N1 strain of bird flu, officials said on Wednesday, confirming the first human death from the disease outside China and southeast Asia. "We lost Fatma Kocyigit this morning," Niyazi Tanilir, governor in the eastern province of Van, said on the CNN Turk news channel. Newspapers said Fatma was 15-years-old. She died around 6:30 a.m. (0430 GMT).

January 7 2006

• Two more children in Turkey are hospitalized after contracting bird flu like symptoms then later test positive for H5N1. They are both from the same area as the prior three children that died from H5N1 bringing the total number of cases in Turkey to 5, with 2 of them fatal. 76 people have died since the outbreak began in 2003.

January 8 2006

• Three people are hospitalized after developing suspected H5N1 in the Turkish capital.

January 10 2006

• A woman is diagnosed with bird flu, as Turkey struggles to contain the outbreak.
• China announces that two more people had died of bird flu before 2006 began.
• Indonesia confirms that a 29 year old woman has died from suspected bird flu.
• Birds begin dying in Nigeria. It is not known until February that it is an H5N1 outbreak.

January 16 2006

• A 15-year-old Indonesian girl from Indramayu, Java, dies of bird flu.

January 18 2006

• China and Turkey each confirm another human death from H5N1.
• A 13-year-old boy dies in Indonesia, he is the brother of the girl who died on January 16.
• Donor nations pledge 1850 million US dollars to combat bird flu at the two day International Pledging Conference on Avian and Human Influenza held in China.

January 21 2006

• The WHO confirms that the two Indonesian children died of H5N1.

January 29 2006

• H5N1 is found in dead birds in northern Cyprus. The European Commission freezes transfers of animals and animal products from the north of the island through the green line to the areas controlled by the Republic of Cyprus and to the rest of the European Union.

January 30 2006

• According to WHO:

The Ministry of Health in Iraq has confirmed the country’s first case of human infection with the H5N1 avian influenza virus. The case occurred in a 15-year-old girl who died on 17 January following a severe respiratory illness. Her symptoms were compatible with a diagnosis of H5N1 avian influenza. Preliminary laboratory confirmation was provided by a US Naval Medical Research Unit located in Cairo, Egypt. The girl’s 39-year-old uncle, who cared for her during her illness, developed symptoms on 24 January and died of a severe respiratory disease on 27 January. Both patients resided in the town of Raniya near Sulaimaniyah in the northern part of the country, close to the border with Turkey. Poultry deaths were recently reported in their neighbourhood, but H5N1 avian influenza has not yet been confirmed in birds in any part of the country. Poultry samples have been sent for testing at an external laboratory. A history of exposure to diseased birds has been found for the girl. The uncle’s source of infection is under investigation. The Ministry of Health has further informed WHO of a third human case of respiratory illness that is under investigation for possible H5N1 infection. The patient is a 54-year-old woman, from the same area, who was hospitalized on 18 January. Specimens are on their way to a WHO collaborating laboratory in the United Kingdom for diagnostic confirmation and further analysis. An international team, including representatives of other UN agencies, is being assembled to assist the Ministry of Health in its investigation of the situation and its planning of an appropriate public health response. WHO staff within Iraq have been directly supporting the government’s operational response, which was launched shortly after the girl’s death. Iraq is the seventh country to report human H5N1 infection in the current outbreak. The first human case occurred in Viet Nam in December 2003.

February

February 4 2006

• Indonesia confirms three new cases, two of which were fatal.
• A dead swan near the city of Vidin, Bulgaria is found to contain the H5 strain. Further testing begins to determine if the bird died from the H5N1 type of the disease. Over 20 dead birds are found along the Danube and in lakes near the Black Sea.

February 6 2006

• Preliminary report is sent from Nigeria to OIE on a massive bird die off that began January 10. Report was sent by Dr. Junaidu A. Maina, Acting Director, Department of Livestock and Pest Control Services, Federal Ministry of Agriculture and Rural Development, Abuja, Nigeria.

February 7 2006

• OIE/FAO Reference Laboratory for avian influenza and Newcastle disease in Padova, Italy, confirmed highly pathogenic avian influenza virus subtype H5N1 in Nigerian isolates from samples taken January 16.

February 8 2006

• The Nigeria situation is announced to the world. Nigeria is the first African country to have an H5N1 outbreak confirmed. It affected a commercial chicken farm (owned by Nigeria's sports minister, Saidu Samaila Sambawa) in which ostriches and geese were also kept, in Jaji village in Igabi administrative division (local government area or LGA) in Kaduna State in Nigeria. The control measures said to be used include killing poultry, quarantining poultry, poultry movement control, and disinfection; however there are complaints that these measures are in fact not being carried out. 40,000 out of 46,000 caged chickens died of H5N1 despite being treated by their owner with broadspectrum antibiotics. The remaining 6,000 have been killed to try to control spread of the disease.

February 9 2006

• Four new farms in Nigeria are confirmed to have H5N1 outbreaks: two in Kano State, one in Plateau State and a second farm in Kaduna State.
• Veterinarians from Onderstepoort Veterinary Institute, Faculty of Veterinary Science, University of Pretoria in South Africa have offered their expertise to assist in tracking occurrence of the virus in Nigeria and elsewhere in Africa.
• The United States, OIE and WHO are sending experts, supplies and money to Nigeria to help with this H5N1 crisis.
• H5N1 flu in Africa is expected to spread and create a very severe situation.
• Farmers in northern Nigeria are rushing to sell dead chickens at cut-price rates before government bans are put into place. Promised measures to contain the disease are still not in place.
• European countries are facing an increased probability that spring bird migrations from Africa will bring H5N1.
• Countries in Africa near to Nigeria are responding with "dread" and import restrictions.

February 10 2006

• Officials in Azerbaijan say H5N1 virus has been identified in wild birds floating dead in the Caspian Sea near Baku .

February 11 2006

• The government of Italy confirms that H5N1 has been found in wild swans in Sicily and elsewhere in the country. It is also found in wild birds in Greece and Bulgaria.

February 12 2006

• The government of Slovenia confirms that the virus subtype H5 has been found in a wild swan by the Drava river near Maribor. The samples have been sent to the United Kingdom to determine if it is the deadly H5N1 strain.

February 13 2006

• Nihat Kabil, Bulgaria's Minister of Agriculture and Forestry, confirms a second case of a swan with the H5 virus. While the first case was in Vidin (in the country's northwest), the second one was near Krajmorie, a Black Sea port in the Burgas region (in the country's southeast), about 3.5 km (2 mi) from an egg farm. Several other cases have been reported in other parts of the country, and Mr. Kabil has said that there is a high probability that Bulgaria will have its first mass case within days.

February 14 2006

• Health authorities report the first case of the H5N1 virus in Austria. 2 dead Swans at Mellach near Graz were found to be carrying the virus.
• Following the discovery of four dead swans suspected of carrying the H5N1 virus on the island of Rügen in North-east Germany, authorities in Germany and several other EU countries make it compulsory for all poultry to be kept inside enclosures effective as of February 20.

February 15 2006

• Slovenian Ministry of Agriculture, Forestry and Food declares entire Slovenia a bird-flu high risk zone after tests confirmed the dead swan (found on 9th February) was carrying H5. It is sent to Great Britain for further subtype determination.
• Avian influenza H5N1 is identified in some dead swans in Hungary. Not known until the end of February whether they carried the human-infecting strain (genotype Z) of H5N1.
• Iran reports cases in wild birds.

February 17 2006

• The presence of H5N1 in Slovenia is confirmed.
• Egypt has detected its first cases in several parts of the country, the government detailed three separate sites where birds where found carrying the virus.
• France has recorded a case of a duck infected with the H5 virus in Ain, near Lyon. It was later confirmed that the duck was infected with the H5N1 strain of the virus. A swan earlier tested negative for the disease.
• Iraq confirms a second person has died of H5N1 - he was the uncle of the country's initial death.

February 18 2006

• Officials in India's western Maharashtra state are planning a poultry cull after the country reported its first cases of the deadly H5N1 strain of bird flu.

February 19 2006

• First suspected bird flu human death reported from Surat, Gujarat, India.

February 20 2006

• Croatia has recorded a new case of a swan infected with the H5 virus in Čiovo, near Trogir. In the same time, H5 is confirmed in dead swan found in Jajce, Bosnia and Herzegovina.
• A United Kingdom laboratory confirms the three cases of H5N1 in dead swans found near the cities of Dobrich, Varna and Burgas, in Bulgaria's northeastern and southeastern regions. The previous H5N1 case was recorder near Vidin in the northwest.

February 21 2006

• The Malaysian government confirms 40 chickens died of H5N1 in Selangor.
• The dead swans that were found in Hungary on February 15 are confirmed to be H5N1.
• Croatia confirmed the previous day's case to be H5N1.
• Professor Neil Ferguson, Imperial College London biologist, says:

"This is a disease which doesn't go away so we are going to be living with H5N1 in Western Europe, I believe, in wild bird populations - even endemic in wild bird populations - for decades perhaps, or even sporadically in those populations every year."

• The respected science journal Nature says:

"The virus is highly likely to become endemic, says Peter Openshaw, head of the respiratory viral infections section at the National Heart and Lung Institute in London, UK. We have to change the way poultry are farmed. [...] Jan Slingenbergh, an animal health expert at the United Nation's Food and Agriculture Organization (FAO) in Rome, Italy, points out that H5N1 may survive in icy lake waters over European winters, potentially infecting any migratory birds that subsequently arrive. The virus could also become established in permanently resident European birds; Openshaw notes that H5N1 has so far been able to infect a wide range of species. If this happens, farming practices will have to be changed, says Neil Ferguson, an epidemiologist at Imperial College London, UK, who is advising the British government on how to deal with possible future outbreaks."

February 23 2006

• Slovakia has become the latest EU nation to confirm cases of the virulent H5N1 bird flu strain. One of the dead birds was found in the capital, Bratislava, the other in Gabcikovo, southwestern Slovakia

February 25 2006

• France For the first time a EU farm becomes infected and 80% of the more than 11 thousand birds die for the H5N1 flu in the previous week .

February 27 2006

• Niger confirms a case of H5N1 bird flu in a flock of ducks near the border with Nigeria .
• Switzerland says a dead swan has been found on Lake Geneva which the H5 virus.
• Bosnia's veterinary office said that tests at the European Union reference laboratory confirmed its first case of the deadly H5N1 bird flu virus in two wild swans near Jajce. Thousands of birds were culled.

February 28 2006

• Confirmed case of highly pathogenic H5 in Sweden
• Finland: The 20 dead ducks and 1 crow at Kotka, Sapokka park, were confirmed not to be carriers of H5N1. The reason for the deaths remains to be solved. On March 13th an insecticide, parathion was confirmed to be the reason for deaths. The toxin is life-threatening to humans, too. The use of parathion has been banned in Finland since 1992.

March

March 1 2006

• Scientists have confirmed that the dead swan found on Lake Geneva on the February 27 had the H5N1 virus. It is the first confirmed case of H5N1 in Switzerland.
• A second case of H5 bird flu has been found in Switzerland, this time on Lake Constance, near the town of Egnach, Thurgau.
• Greece confirms three new cases of H5N1 in swans found the northern part of the country, bringing the total number of cases in the country to 19.
• 8 Quebec farms are quarantined after receiving live poultry from France. The province braces itself for its first H5N1 cases.

March 2 2006

• A chicken from a farm, 175 km south from Addis Ababa, is being tested for the possibility of having H5N1 in Ethiopia, the first possible case in East Africa.
• Serbia detected the bird flu in a dead swan that was found in northwest Serbia (near Croatia)
• Tests on live ducks imported France to Quebec have come back negative for H5N1.

March 3 2006

• Sweden confirms eight new cases of H5 bird flu virus
• Azerbaijan confirms first case of H5N1 bird flu in poultry

March 4 2006

• H5N1 was found in a wild goose near Lüneburg, Lower Saxony, Germany, making it the sixth federal state in the country to report a case of the disease.
• Austria's cases of H5N1 rise to 29 with three ducks, a seagull, and a grebe found with the disease in Vorarlberg.

March 5 2006

• Poland has reported its first case of H5N1 in a wild swan found dead two days ago in Toruń, a city in northern Poland.
• A man in the southern Chinese province of Guangdong has died of H5N1. This is the eighth death in the country caused by avian flu.
• A new case of H5N1 was reported in Buzău, Romania in a wild goose found dead a week ago.

March 6 2006

• Poland confirms H5N1 in two swans.

March 8 2006

• Albania has reported its first case of H5N1, found in a domestic chicken in the village of Cukes, near Sarandë, in the south of the country.
• Myanmar found H5N1 in chickens after an HPAI outbreak on March 8.

March 9 2006

• Serbia (and by extension, Serbia and Montenegro) has confirmed that a wild swan found dead near Sombor carried the deadly H5N1 bird flu, the first confirmed case in the country.

March 10 2006

• Poland has confirmed that a wild swan found dead near Lublin carried the H5 bird flu, it was the second confirmed case in the country.

March 12 2006

• Cameroon reports its first outbreak of the H5N1 in a duck farm in Maroua, in the Far North Province.

March 14 2006

• Azerbaijan reports three deaths from the H5N1 virus.

March 15 2006

• Sweden has confirmed its first case of H5N1 in two wild ducks found near the Baltic Sea port city of Oskarshamn.
• Culling begins in Jalgaon, Maharastra, India.

March 16 2006

• Denmark has confirmed its first case of H5N1 in one Common Buzzard found dead at a beach near the city of Næstved.
• Afghanistan finds deadly H5N1 virus.

March 17 2006

• H5N1 bird-flu strain had been found in tens of thousands of poultry in Israel.

March 18 2006

• Egypt has confirmed the first human death caused by H5N1 virus.

March 19 2006

• Egypt has reported its second human case of bird flu, a 30-year-old man who worked on a chicken farm in the province of Qalyoubiya.

March 20 2006

• Kazakhstan has reported another outbreak of H5N1 in the western part of the country, found in a wild swan.
• Another outbreak of H5N1 in Malaysia resulted in the death of six chickens in the province of Seberang Perai, in the state of Penang.

March 21 2006

• Pakistan confirms its first cases of H5N1 at chickens in two farms in the North-West Frontier Province.

March 24 2006

• A dead wild buzzard is found to be the first case of H5N1 in Berlin, Germany.
• H5N1 confirmed in the Gaza Strip, the West Bank and Jordan.

March 26 2006

• A peregrine falcon in the Tin Shui Wai area of Hong Kong has been confirmed to have died as a result of H5N1 infection.

March 29 2006

• The Czech Republic confirms its first case of H5N1 in a swan on the Vltava River, near Hluboká nad Vltavou.
• The EU reference laboratory in Weybridge, Great Britain confirms the first case of H5N1 found in Denmark a few weeks ago.

March 31 2006

• A dead swan confirmed to have H5N1 is found in the city of Grudziądz in northern Poland.
• First human case of the bird flu was announced in Jordan.

April

April 4 2006

• Burkina Faso has detected H5N1 in poultry on the outskirts of the capital, Ouagadougou, making the West African country the fifth nation on the continent to report the disease. Nigeria, Niger, Cameroon and Egypt have already confirmed the virus in Africa.
• The World Health Organization confirmed four cases of bird flu in Egypt over the past month, including two fatalities, the first reports of human deaths due to H5N1 in Africa.

April 5 2006

• H5N1 is detected in domestic poultry near Liepzig, Germany.

April 6 2006

• H5N1 is detected in a wild migratory swan (Whooper Swan Cygnus cygnus) in Cellardyke in Fife, Scotland.

April 7 2006

• British authorities declare a 1,000 mile wild bird risk area around Cellardyke.

April 10 2006

• Over one hundred outbreaks have been reported in Myanmar since March 13, the first time since 2004 that H5N1 has been detected in the country.
• A wild swan found in the Sava River, near the Croatian capital of Zagreb, is confirmed to have H5N1.

April 11 2006

• "The Scientific Seminar on Avian Influenza, the Environment and Migratory Birds met from 10-11 April 2006 at UN Office in Nairobi, Kenya. The Seminar was organized by the United Nations Environment Programme (UNEP) Division of Early Warning and Assessment (DEWA) in cooperation with the Convention on Migratory Species of Wild Animals (CMS) and its Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA). [...] Hepworth identified the Seminar’s objectives to: stimulate debate on the role of wild birds in transmitting the virus; provide up-to-date status reports and advice for decision-makers; increase awareness of the recent multilateral environmental agreement (MEA) resolutions among all governments; promote further research on virus behavior and transmission; and encourage international technical cooperation and risk mitigation." The seminar concluded with reaffirmations to disseminate the Seminar’s findings and to manage the risks associated with HPAI.

April 12 2006

• PDF from The Panel on Animal Health and Welfare (AHAW) of the European Food Safety Authority (EFSA) containing a scientific statement on the role of migratory birds in the spread of the H5N1 form of avian influenza (AI) amongst domestic and wild bird populations in the European Union (EU) issued and summerized here and here. Intro reproduced here.

April 18 2006

• Sudan reports its first case of H5N1 at a poultry farm in Khartoum, as well as the state of Al Jazirah.

April 27 2006

• "Ivory Coast prepared to slaughter chickens and tightened restrictions on movements of poultry on Thursday after reporting outbreaks of bird flu in two heavily populated neighbourhoods of its main city Abidjan. The World Organisation for Animal Health (OIE) said late on Wednesday a total of 17 birds infected with the deadly H5N1 strain of avian flu had been found in separate outbreaks in the Marcory Anoumabo and Treichville suburbs of Abidjan."

May

May 11 2006

• "Djibouti said on Thursday that one person had tested positive for the deadly H5N1 avian influenza virus in the first confirmed human case in the Horn of Africa."

May 13 2006

• WHO investigated possible H5N1 human cluster in North Sumatra. According to local tests, five members of an extended family have died of bird flu in the past few days.

May 15 2006

• According to local tests, a sixth member of an extended family have died of bird flu in the past few days in North Sumatra.

May 16 2006

• According to UN officials, bird flu was found on the western half of the island of New Guinea.

May 21 2006

• The H5 strain of Bird flu is confirmed in the Romanian capital Bucharest.
• An eighteen year old shuttlecock maker from East Java has died of bird flu. It appears that he was not in direct contact with live birds.

May 23 2006

• WHO reports cluster of seven victims connected only by each other indicating possible human to human spreading of H5N1

May 25 2006

• 56 outbreaks of H5N1 have been found in Romania since the virus reemerged there 12 days ago. "The recent outbreaks have involved some large commercial farms and some poultry in Bucharest, the capital, triggering quarantine orders for some neighborhoods this week."

May 30 2006

• The WHO publishes the WHO pandemic influenza draft protocol for rapid response and containment, detailing a proposed method for stopping the spread of a pandemic strain of H5N1 at the source.

June

June 2 2006

• Indonesian tests say that a girl on the outskirts of Jakarta died of bird flu. Her brother died on May 30 with similar symptoms, but died before he could receive medical treatment, and was buried before testing could be performed.

June 17 2006

• The EU reference laboratory confirm the presence of the H5N1 viral strain in birds sent from the Kiskunmajsa region of Hungary for analysis.

June 23 2006

• A family in Indonesia were confirmed to have had human-to-human spread of H5N1. A mutated strain was found, but it had not mutated into an easily-transmisable strain.

June 30 2006

• "This week’s issue of the Weekly Epidemiological Record, published online by WHO, sets out results from the first analysis of epidemiological data on all 205 laboratory-confirmed H5N1 cases officially reported to WHO by onset date from December 2003 to 30 April 2006. Data used in the analysis were collected for surveillance purposes. Quality, reliability and format were not consistent across data from different countries. Despite this limitation, several conclusions could be reached.

1. The number of new countries reporting human cases increased from 4 to 9 after October 2005, following the geographical extension of outbreaks among avian populations.
2. Half of the cases occurred in people under the age of 20 years; 90% of cases occurred in people under the age of 40 years.
3. The overall case-fatality rate was 56%. Case fatality was high in all age groups but was highest in persons aged 10 to 39 years.
4. The case-fatality profile by age group differs from that seen in seasonal influenza, where mortality is highest in the elderly.
5. The overall case-fatality rate was highest in 2004 (73%), followed by 63% to date in 2006, and 43% in 2005.
6. Assessment of mortality rates and the time intervals between symptom onset and hospitalization and between symptom onset and death suggests that the illness pattern has not changed substantially during the three years.
7. Cases have occurred all year round. However, the incidence of human cases peaked, in each of the three years in which cases have occurred, during the period roughly corresponding to winter and spring in the northern hemisphere. If this pattern continues, an upsurge in cases could be anticipated starting in late 2006 or early 2007."

July

July 5 2006

• "Nigeria has been infected multiple times with H5N1 bird flu probably carried by migratory birds from southern Russia and northern Europe or introduced by imported chickens, scientists said on Wednesday. After analysing samples from infected birds on two farms in south-western Nigeria they found the viruses were genetically distinct from each other and from H5N1 found in the north of the country. So rather than one strain spreading through the country, different strains had been introduced on separate occasions, which could make controlling the spread of the virus more difficult. [...] The analysed samples were similar to strains found in southern Russia and northern Europe but not from southeast Asia"

July 7 2006

• "A Spanish laboratory has confirmed the country's first case of H5N1 bird flu after analyzing a sample taken from a wild migratory water bird" (the Great Crested Grebe).

July 22 2006

• "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."

July 26 2006

• The World Health Organization (WHO) confirmed on July 26, 2006 that a 17-year-old boy who died on July 24, 2006 in the Phichit province of northern Thailand had H5N1 avian influenza, marking the country's first case this year. H5N1 was recently detected in 31 dead chickens in Phichit province. Thai health officials have placed several other people from Phichit province under quarantine. "The country's agriculture minister recently announced bans on poultry imports and the transport of birds [and] the Phichit Provincial Livestock Office declared the Bang Mulnarg district an avian flu–infected area, which allows officials to conduct full-scale disease control efforts, including culling, quarantine, screening, and disinfection of affected sites."

July 28 2006

• Due to H5N1, about 2,500 chickens died on the Dongbang poultry farm in Xaythany district, Laos beginning July 18, 2006. This is the country's first major outbreak since 2004. "The government of Laos has taken immediate action to control the spread of the virus by culling all chickens in the farm, disinfecting the farm and imposed movement restrictions within the five kilometre surveillance zone," said Wantanee Kalpravidh, FAO regional coordinator for Avian Influenza Projects.

August

August 5 2006

• A German zoo and a Vietnam theme park both report highly pathogenic H5N1 in their birds.

August 10 2006

• "Experts tracking the dangerous and economically devastating H5N1 virus have been concerned about Indonesia, where inadequate control methods have led to widespread outbreaks across the vast and densely populated archipelago. Indonesia trailed other affected Asian countries in developing human cases, marking its first in July 2005. But since then cases in Indonesia have cropped up at a rate unparalleled elsewhere. And the country's H5N1 death toll recently surpassed that of Vietnam to make Indonesia the country that has lost the most lives to the virus. Indonesia has logged 56 confirmed human cases, 44 of which have been fatal. Globally 236 cases of H5N1 infection have been confirmed in 10 countries since late 2003 and 138 of those people have died."

August 12 2006

• "Cambodia has suffered its second outbreak of bird flu this year in the same province where the H5N1 virus killed a boy in April, officials said on Saturday. The virus was confirmed in more than 1,300 ducks that died in Prey Veng province, 70 km (45 miles) southeast of Phnom Penh, but there were no immediate reports of human infections, they said. Yes, bird flu is back, senior Agriculture Ministry official Nou Muth said."

August 18 2006

• On August 18, 2006, the World Health Organization (WHO) changed the H5N1 avian influenza strains recommended for candidate vaccines for the first time since 2004. "Many experts who follow the ongoing analysis of the H5N1 virus sequences are alarmed at how fast the virus is evolving into an increasingly more complex network of clades and subclades, Osterholm said. The evolving nature of the virus complicates vaccine planning. He said if an avian influenza pandemic emerges, a strain-specific vaccine will need to be developed to treat the disease. Recognition of the three new subclades means researchers face increasingly complex options about which path to take to stay ahead of the virus."

August 25 2006

• CIDRAP reported on August 25, 2006 on a new US government Web site that allows the public to view current information about testing of wild birds for H5N1 avian influenza which is part of a national wild-bird surveillance plan that "includes five strategies for early detection of highly pathogenic avian influenza. Sample numbers from three of these will be available on HEDDS: live wild birds, subsistence hunter-killed birds, and investigations of sick and dead wild birds. The other two strategies involve domestic bird testing and environmental sampling of water and wild-bird droppings. [...] A map on the new USGS site shows that 9,327 birds from Alaska have been tested so far this year, with only a few from most other states. Last year officials tested just 721 birds from Alaska and none from most other states, another map shows. The goal of the surveillance program for 2006 is to collect 75,000 to 100,000 samples from wild birds and 50,000 environmental samples, officials have said."

September

September 7 2006

• Indonesian officials reported on September 7, 2006 that a 14-year-old Indonesian girl who died in June was infected with bird flu. The case was discovered during routine surveillance of blood samples from people who had exhibited flu symptoms. In a change of policy, Health Minister Siti Fadillah Supari reported that "we did not send (the samples) to the WHO (World Health Organisation) because our positive results are usually positive results at the WHO." IOL reports that "until now, Indonesia has always sent blood and tissue samples from suspected human bird flu cases to a WHO laboratory in Hong Kong for confirmation," but that "under a new arrangement Jakarta could confirm infections after two local tests showed the person to have contracted H5N1."

September 13 2006

• Sudan authorities announced that all the samples taken from chickens in southern Sudan in August and sent to the United Kingdom for further tests had proven positive for the deadly H5N1 bird flu virus.

Pig cases

Pigs can harbor influenza viruses adapted to humans and others that are adapted to birds, allowing the viruses to exchange genes and create a pandemic strain.

Avian influenza virus H3N2 is endemic in pigs ("swine flu") in China and has been detected in pigs in Vietnam, increasing fears of the emergence of new variant strains. Health experts say pigs can carry human influenza viruses, which can combine (i.e. exchange homologous genome sub-units by genetic reassortment) with H5N1, passing genes and mutating into a form which can pass easily among humans. H3N2 evolved from H2N2 by antigenic shift and caused the Hong Kong Flu pandemic of 1968 and 1969 that killed up to 750,000 humans. The dominant strain of annual flu in humans in January 2006 is H3N2. Measured resistance to the standard antiviral drugs amantadine and rimantadine in H3N2 in humans has increased to 91% in 2005. A combination of these two subtypes of the species known as the avian flu virus in a country like China is a worst case scenario. In August 2004, researchers in China found H5N1 in pigs.

Felidae (cats)

Domestic cats can get H5N1 from eating birds, and can transmit it to other cats and possibly to people.

October 2004: Variants have been found in a number of domestic cats, leopards and tigers in Thailand, with high lethality. "The Thailand Zoo tiger outbreak killed more than 140 tigers, causing health officials to make the decision to cull all the sick tigers in an effort to stop the zoo from becoming a reservoir for H5N1 influenza (ProMED-mail, 2004i; ProMED-mail, 2004w). A study of domestic cats showed H5N1 virus infection by ingestion of infected poultry and also by contact with other infected cats (Kuiken et al., 2004)." The initial OIE report reads: "the clinical manifestations began on 11 October 2004 with weakness, lethargy, respiratory distress and high fever (about 41-42 degrees Celsius). There was no response to any antibiotic treatment. Death occurred within three days following the onset of clinical signs with severe pulmonary lesions."

On February 28 2006 a dead cat infected with the H5N1 bird flu virus was found in Germany.

On March 6 2006 Hans Seitinger, the top agriculture official in the southern state of Styria, Austria announced that several still living cats in Styria have tested positive for H5N1:

It was announced in the August 2006 CDC EID journal that while literature describing HPAI H5N1 infection in cats had been limited to a subset of clade I viruses; a Qinghai-like virus (they are genetically distinct from other clade II viruses) killed up to five cats and 51 chickens from February 3 to February 5, 2006 in Grd Jotyar (≈10 km north of Erbil City, Iraq). Two of the cats were available for examination.

"An influenza A H5 virus was present in multiple organs in all species from the outbreak site in Grd Jotyar (Table). cDNA for sequencing was amplified directly from RNA extracts from pathologic materials without virus isolation. On the basis of sequence analysis of the full HA1 gene and 219 amino acids of the HA2 gene, the viruses from the goose and 1 cat from Grd Jotyar and from the person who died from Sarcapcarn (sequence derived from PCR amplification from first-passage egg material) are >99% identical at the nucleotide and amino acid levels (GenBank nos. DQ435200–02). Thus, no indication of virus adaptation to cats was found. The viruses from Iraq are most closely related to currently circulating Qinghai-like viruses, but when compared with A/bar-headed goose/Qinghai/65/2005 (H5N1) (GenBank no. DQ095622), they share only 97.4% identity at the nucleic acid level with 3 amino acid substitutions of unknown significance. On the other hand, the virus from the cat is only 93.4% identical to A/tiger/Thailand/CU-T4/2004(H5N1) (GenBank no. AY972539). These results are not surprising, given that these strains are representative of different clades (8,9). Sequencing of 1,349 bp of the N gene from cat 1 and the goose (to be submitted to GenBank) show identity at the amino acid level, and that the N genes of viruses infecting the cat and goose are >99% identical to that of A/bar-headed goose/Qinghai/65/2005(H5N1). These findings support the notion that cats may be broadly susceptible to circulating H5N1 viruses and thus may play a role in reassortment, antigenic drift, and transmission."

The spread to more and more types and populations of birds and the ability of felidae (cats) to catch H5N1 from eating this natural prey means the creation of a reservoir for H5N1 in cats where the virus can adapt to mammals is one of the many possible pathways to a pandemic.

Mammals in general

Martens and an unknown number of other mammals can catch H5N1, illustrating the unprecedented ability of H5N1 to survive and spread.

H5N1 has been transmitted in laboratories to many species including mice and ferrets to study its effects.

H5N1 was transmitted in the wild to three civet cats in Vietnam in August 2005 and a stone marten in Germany in March 2006.

The BBC reported that a stray dog in Azerbaijan died from the disease on March 15 2006.

Experts believe more work is needed to determine the role of mammals in the epidemiology of H5N1. Officials are not doing enough to monitor cats, dogs and other carnivores for their possible role in transmitting H5N1. People living in areas where the A(H5N1) virus has infected birds are advised to keep their cats indoors. "Cats can be infected through the respiratory tract. Cats can also be infected when they ingest the virus, which is a novel route for influenza transmission in mammals. But cats excrete only one-thousandth the amount of virus that chickens do [...] The concern is that if large numbers of felines and other carnivores become infected, the virus might mutate in a series of events that could lead to an epidemic among humans. Dogs, foxes, seals and other carnivores may be vulnerable to A(H5N1) virus infection, Dr. Osterhaus said. Tests in Thailand have shown that the virus has infected dogs without causing apparent symptoms."

Expected mortality from pandemic

If H5N1 mutates so that it can jump from human to human, while maintaining a relatively high level of mortality, how many people could die? Risk communication analysts Peter M. Sandman and Jody Lanard give a round-up of the various estimates:

Worldwide mortality estimates range all the way from 2–7.4 million deaths (the “conservatively low” pandemic influenza calculation of a flu modeling expert at the U.S. Centers for Disease Control and Prevention) to 1000 million deaths (the bird flu pandemic prediction of one Russian virologist). The estimates of most H5N1 experts range less widely but still widely. In an H5N1 pandemic, the experts guess that somewhere between a quarter of us and half of us would get sick, and somewhere between one percent and five percent of those who got sick would die — the young and hale as well as the old and frail. If it’s a quarter and one percent, that’s 16 million dead; if it’s a half and five percent, it’s 160 million dead. Either way it’s a big number.

Perhaps the most extreme maximum has come from renowned virus expert, Robert Webster, who believes H5N1 has the capacity to mutate into a form that could kill a third of the human population .

See also

• Reporting disease cases

Further reading

General information

• Nature Magazine focus on the global spread of H5N1
• Bird Flu Fears: Is There a Better Way to Develop Drugs? (Center for Economic and Policy Research) October 2005 (PDF)
• Q&A: What is Bird Flu and Who's At Risk?
• Nature Magazine: Avian flu special: The flu pandemic: were we ready!? - Fictional account of flu epidemic from Nature magazine
• The Threat of Pandemic Influenza: Are We Ready? Workshop Summary (2005) - Online book by Board on Global Health (BGH) from the Institute of Medicine of The National Academies
• Emergency Measures Avian flu is on the rise in Vietnam and is now endemic in much of Asia. Can heightened vigilance keep it at bay?
• Flu Wiki
• FluTrackers

• FAO's map of overlapping flyways for migratory waterfowl worldwide
• Google Earth updated maps of avian flu spread in poultry and humans
• Department of Health and Human Services Pandemic Planning Update A Report from Secretary Michael O. Leavitt March 13, 2006This report outlines how the 3.3 billon dollar funding is being used to help achieve HHS’s five primary objectives around Pandemic Response.
• Factory Farms Blamed for Spread of Bird Flu
• H5N1 Facts and Timeline

News

• Blauer's Bird Flu and H5N1 News Overview using Reuters and Yahoo News
• Current status (Google news of "H5N1")
• Bird Flu news updates
• Bird Flu News Focus from SciDev.Net, regularly updated with the latest news stories
• University of Pittsburgh scientists say they've genetically engineered an avian flu vaccine that has proven 100 percent effective in mice and chickens. from physorg.com
• Special report on avian flu & its effect on UK agriculture from Farmers Weekly Interactive
• Diplomacy Monitor - Bird Flu
• News Now: Bird Flu, updated every five minutes with news from over 22,000 sources
• Bird Flu H5N1 Daily Reports