Highly pathogenic H5N1 Countries that have reported deaths of poultry or wild birds linked to highly pathogenic H5N1 infection as of March 2023. Countries that have reported human cases of highly pathogenic H5N1 infection. The global spread of H5N1 influenza in birds is considered a significant pandemic threat. While other H5N1 influenza strains are known, they are significantly different on a genetic level from a highly pathogenic, emergent strain of H5N1, which was able to achieve hitherto unprecedented global spread in 2008. The 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 timeline refers to the 2008 highly pathogenic strain of H5N1.
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): South 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, Hungary, United Kingdom, Kuwait, Bangladesh, Saudi Arabia, Ghana, Czech Republic, Togo, Nepal, Bhutan, the Philippines, and Chile.
Highly pathogenic H5N1 has been found in birds in the wild in numerous other countries: Austria, Belgium, Bulgaria, Denmark, Greece, Iran, Italy, Poland, Serbia and Montenegro, Slovakia, Slovenia, Spain, Sweden, Switzerland, and Uruguay. 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 parts of 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).
According to Robert G. Webster:
On July 25, 2008, the Food and Agriculture Organization (FAO) released an Avian Influenza Disease Emergency Situation Update, reporting that H5N1 pathogenicity was continuing to gradually rise in endemic areas but the avian influenza disease situation in farmed birds was being held in check by vaccination. Eleven outbreaks of H5N1 were reported worldwide in June 2008 in five countries (China, Egypt, Indonesia, Pakistan and Vietnam) compared to 65 outbreaks in June 2006 and 55 in June 2007.
Human cases
Timeline 1959–1997
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. On December 28 to 29, 1997, 1.3 million chickens were killed by the government of Hong Kong. The government also suspended the import of chickens from mainland China.
2003 In 2003 the first cases in humans since 1997 were diagnosed. 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 mainland Chinese government announcements concerning H5N1 and what people in mainland China see with their own eyes. Many reports of total H5N1 cases exclude mainland China due to widespread disbelief in mainland China's official numbers.
2004
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, especially ducks, 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 influenza experts increasingly refer to containment as a strategy that can delay but not prevent a future avian flu pandemic.
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. 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."
2005
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 2005, it was discovered that H5N1 "could be infecting up to half of the pig population in some areas of Indonesia, but without causing symptoms [...] Chairul Nidom, a virologist at Airlangga University's tropical disease center in Surabaya, Java, was conducting independent research earlier this year. He tested the blood of 10 apparently healthy pigs housed near poultry farms in western Java where avian flu had broken out, Nature reported. Five of the pig samples contained the H5N1 virus. The Indonesian government has since found similar results in the same region, Nature reported. Additional tests of 150 pigs outside the area were negative."CIDRAP article Indonesian pigs have avian flu virus; bird cases double in China published May 27, 2005
2006
In the first two months of 2006 H5N1 spread to other Asian countries (such as India), north 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. 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 or early 2007 following a summer/fall lull in most countries, as H5N1 appears to be somewhat seasonal in nature. 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. In June, there was a human outbreak in Indonesia when 8 members of a family in Sumatra became infected and 7 died. The WHO reported that this may have been the first recorded instance of human-to-human transmission. In September, Egypt and Sudan joined the list of nations seeing a resurgence of bird deaths due to H5N1. In November and December, South Korea and Vietnam joined the list of nations seeing a resurgence of bird deaths due to H5N1 February/March 2006 - A dead cat infected with the H5N1 bird flu virus was found in Germany. 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: February 2006 - H5N1 infection killed up to five cats and 51 chickens in Iraq. Authors all part of US Naval Medical Research Unit No. 3, Cairo, Egypt
2007
In January, Japan, Hungary, Russia, and the United Kingdom joined the list of nations seeing a resurgence of bird deaths due to H5N1. In February, Pakistan, Turkey, Afghanistan, and Myanmar joined the list and Kuwait saw its first major outbreak of H5N1 avian influenza.
In March Bangladesh and Saudi Arabia each saw their first major outbreak of H5N1 avian influenza and Ghana in May.
As H5N1 continued killing many birds and a few people throughout the spring in countries where it is now endemic, in June Malaysia and Germany saw a resurgence of bird deaths due to H5N1, while the Czech Republic and Togo experienced their first major outbreak of H5N1 avian influenza.
In July France and India also saw a resurgence of bird deaths due to H5N1.
January 24, 2007 "Chairul Anwar Nidom of Airlangga University in Surabaya, Indonesia, told journalists last week that he had taken blood samples from 500 stray cats near poultry markets in four areas of Java, including the capital, Jakarta, and one area in Sumatra, all of which have recently had outbreaks of H5N1 in poultry and people. Of these cats, 20% carried antibodies to H5N1. This does not mean that they were still carrying the virus, only that they had been infected - probably through eating birds that had H5N1. Many other cats that were infected are likely to have died from the resulting illness, so many more than 20% of the original cat populations may have acquired H5N1."
2008
January