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An ancient Japanese legend promises that the gods will grant a wish to anyone who folds a thousand origami cranes. These birds became a symbol of peace in Japan due to the story of Sadako Sasaki, a girl who was two years old on August 6, 1945. It was the date that the pilot Paul Tibbett of the United States Air Force , flew the Enola Gay bomber over the city of Hiroshima to drop an atomic bomb called “Little Boy”.
By the end of 1945, the bomb had killed 166,000 people in Hiroshima, although only half died on the day of the bombing. Sadako, with her mother and brother, escaped the fires and survived the impact of the bomb.
But after a while he became ill with leukemia, attributed to exposure to radioactive black rain that fell on the city.
Sadako was admitted to the hospital, but she remained optimistic and resilient. Inspired by the history of origami cranes, she began to collect hundreds of pieces of paper to fold hundreds of birds and wish to heal completely.
After folding her thousandth crane, Sadako made a wish to be okay again. Unfortunately, it did not come true and she passed away at the age of twelve surrounded by family and with 1,300 origami cranes in her room.
Cranes, symbolic birds for many cultures
Throughout Asia, the crane is a symbol of happiness and eternal youth. The beauty of cranes and their spectacular mating dances have made them symbolic birds in many cultures. Crane mythology is widespread and we can find references to these animals in areas such as the Aegean, South Arabia, China, Korea, Japan and in the native cultures of North America. The crane appears in Aesop’s Fables, Pliny the Elder wrote about them, and Aristotle described the migration of these birds in the History of Animals.
The massive migrations carried out by cranes are extraordinary and spectacular. Each year between 400,000 and 600,000 sandhill cranes, 80% of all the cranes on the planet, congregate along an 80-mile stretch of the central Platte River in Nebraska. They do so to fatten off the waste grains from harvested corn fields, in preparation for the journey to their arctic and sub-arctic nesting grounds.
Twice a year, more than 500 million birds, of more than 400 species, pass through the Lake Park / Hula Valley area in Israel, while migrating from Europe to Africa and vice versa. This place is one of the ten most important sites for bird watching in the world. According to the Society for the Protection of Nature in Israel (SPNI), around 100,000 common cranes arrive there each year from Russia and eastern Scandinavia, and about 40,000 of them stay for the winter.
A new outbreak of bird flu in Israel’s birds
Unfortunately, in recent days, more than 5,000 migratory cranes have died in the Hula Nature Reserve, in what has been the worst blow to wildlife in Israel’s history, according to the country’s environment minister. , Tamar Zandberg.
The most serious damage to wildlife in the history of the country. 5000 cranes die from bird flu in the sick reedbed, and the extent of the damage is still unclear. I visited there today with representatives of the Nature and Parks Authority and the Jewish National Fund pic.twitter.com/i0Qb4CzQAJ
– Tamar Zandberg @ (@tamarzandberg) December 26, 2021
The culprit has been the H5N1 avian flu virus
The zoonotic threat of the H5N1 avian influenza virus remains high due to the spread of the virus between birds. The events of mass bird deaths, such as the cranes in Israel, are concerning. Although the overall pandemic risk associated with H5N1 is not considered to have changed compared to previous years.
In any case, the WHO recommends that the Member States remain vigilant whenever outbreaks of this type appear. In addition, it is convenient that they consider mitigation measures to reduce human exposure to potentially infected birds to reduce the risk of additional zoonotic infections.
What are the risks of bird flu for humans?
The highly pathogenic H5N1 avian influenza virus (HPAI) of Asian origin is highly contagious and particularly deadly among poultry. The virus was first detected in 1996 in geese in China and for the first time in humans in 1997 amid a poultry outbreak in Hong Kong.
Globally, from 2003 to 2021 there have been 863 cases of human infection due to the influenza A (H5N1) virus that have been reported in 18 countries. Of these 863 cases, 456 were fatal, showing a fatality rate of 53%. The last case was reported in July 2021 in India.
There are four types of seasonal flu viruses, which are called influenza A viruses, influenza B viruses, influenza C viruses, and influenza D viruses. The ancestral reservoir for all influenza type A viruses is waterfowl. In particular, those included in the order Anseriformes (to which geese or ducks belong) and in the order Charadriiformes (where gulls are found).
All known flu pandemics have been caused by influenza A flu viruses. Influenza A viruses are solely responsible for avian flu, as well as being the causative agents of the common human flu and swine and equine flu.
Viruses with a high mutation rate
Influenza viruses have a high mutation rate and a phenomenon known as genetic rearrangement that allows the virus to generate many different combinations. Type A influenza viruses can be divided into different subtypes depending on the genes that make up the surface proteins, hemagglutinin (H) and neuraminidase (N).
These proteins constitute the main antigenic recognition sites by the host’s immune system. There are 18 hemagglutinin subtypes and 11 different neuraminidase subtypes, from H1 to H18 and from N1 to N11 respectively, so there are potentially dozens of combinations of the influenza A subtype and H5N1 is one of them. It is noteworthy that within each subtype there is considerable genetic, antigenic and phenotypic variability, which affects the pathogenicity of the strain.
Most human pathogenic influenza virus subtypes originate from birds and pigs. The latter are considered an ideal recombination vessel for variants of various origins.
This is how it reaches humans
In waterfowl, mainly of the orders Anseriformes and Charadriiformes, influenza A viruses replicate and are eliminated from the digestive tract. This allows water transmission.
In humans, swine, and other mammalian models, influenza viruses replicate in the upper or lower respiratory tract, due to the presence of the necessary sialic acid receptors, which favors the airborne transmission.
The most important zoonotic subtypes of influenza A virus belong to the hemagglutinin 5 and 7 protein subtypes. Of the two known highly pathogenic subtypes (H5 and H7), almost all fatal cases in humans have been caused by the Eurasian H5N1 lineage.
The epidemiological characteristics of the H5N1 avian influenza virus, including host variety, survival in the environment, minimal infectious dose, pathogenicity, and excretion rates, appear to support its large-scale endemicity in some ecosystems, thus For our sake, it is prudent to monitor and monitor bird outbreaks of this virus.
Raúl Rivas González. Professor of Microbiology, University of Salamanca.
This article was originally published on
The Conversation.
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