Influenza A virus subtype H5N1 facts for kids

Kids Encyclopedia Facts

Quick facts for kids Influenza A virus subtype H5N1

A close-up picture of H5N1 flu viruses (in gold) inside cells (in green).
Virus classification
(unranked):	Virus
Realm:	Riboviria
Kingdom:	Orthornavirae
Phylum:	Negarnaviricota
Class:	Insthoviricetes
Order:	Articulavirales
Family:	Orthomyxoviridae
Genus:	Alphainfluenzavirus
Species:	Influenza A virus
Serotype:	Influenza A virus subtype H5N1
Notable strains
Goose Guangdong virus A/Fujian (H5N1)

Influenza A virus subtype H5N1 (A/H5N1) is a type of influenza A virus. It causes the influenza (flu) illness, mostly in birds. This virus is commonly found in many bird groups. It can also spread widely among different animal species.

The A/H5N1 virus can also infect mammals, including humans. This happens if they are near sick birds. When mammals get infected, the illness is often very serious or even deadly.

Infected birds spread the A/H5N1 virus through their spit, snot, and poop. Other infected animals can spread it through breathing or other body fluids like milk. The virus can quickly spread through chicken farms and among wild birds. About half a billion farm birds have been killed to try and stop the virus from spreading.

What is H5N1 Flu?
Symptoms
- In Birds
- In Humans
How to Prevent H5N1
- Vaccines
- Public Health Efforts
Treating H5N1
H5N1's Impact on Society
See also

What is H5N1 Flu?

The symptoms of A/H5N1 flu can be different. It depends on the specific type of virus and the animal that gets sick. Scientists classify bird flu as either Low Pathogenic Avian Influenza (LPAI) or High Pathogenic Avian Influenza (HPAI). This is based on how sick it makes domestic chickens. It doesn't always show how sick other animals will get.

Chickens with LPAI A/H5N1 might show mild signs or no signs at all. But HPAI A/H5N1 causes serious breathing problems, a big drop in egg laying, and sudden death.

In mammals, including humans, A/H5N1 flu is rare. Symptoms can be mild or severe. They include fever, diarrhea, and a cough. Since 1997, human infections with A/H5N1 have been reported in 23 countries. About half of these cases led to severe lung problems and death. As of May 2024, 889 human cases were found worldwide, with 463 deaths. This means about 50% of reported cases were deadly. However, it's possible that many mild cases were not reported.

The A/H5N1 flu virus was first found in farm birds in southern China in 1996. Between 1996 and 2018, A/H5N1 was one of several flu types in birds. But since then, the very strong HPAI A(H5N1) type has become the main one worldwide. Some H5N1 types that are very harmful to chickens have changed. They now cause mild symptoms in ducks and geese. This allows them to spread quickly when birds migrate. Mammals like cows, seals, goats, and skunks have also been infected with H5N1.

HPAI A(H5N1) is very deadly and spreads easily. It is found all over the world. It can infect more and more types of animals. It also keeps changing its genetic code. Because of this, the H5N1 virus is seen as the biggest threat for a future worldwide flu pandemic. Farm birds can sometimes be protected from certain types of the virus by getting vaccinated. If a serious H5N1 flu outbreak happens in humans, health groups have "candidate" vaccines ready. These could help prevent infection and control the outbreak. But it might take several months to make enough vaccines for everyone.

Symptoms

In Birds

Signs of H5N1 in birds can be mild. These include fewer eggs, runny nose, coughing, and sneezing. They can also be severe. Birds might lose coordination, energy, and appetite. Their eggs might be soft or oddly shaped. Parts of their body like wattles, head, eyelids, combs, and hocks might turn purple. They can also have diarrhea. Sometimes, the first sign is sudden death.

In Humans

Humans who catch a human flu virus (type A) usually have certain symptoms. These include fever, cough, sore throat, muscle aches, and eye irritation. In serious cases, they can have breathing problems and pneumonia, which can be deadly. How severe the infection is depends on the person's immune system. It also depends on whether they have been exposed to that flu type before.

The bird flu virus prefers to attach to certain cells in the body. This means that when H5N1 infects humans, it mostly grows in the lower parts of the lungs. This can cause viral pneumonia. As of April 2024, there is no H5N1 flu that has fully adapted to humans. So, all humans who have caught it so far got the bird version of H5N1.

How to Prevent H5N1

Vaccines

There are several H5N1 vaccines for different types of bird H5N1. But H5N1 keeps changing, which makes these vaccines less useful. While vaccines can sometimes protect against similar flu types, the best protection would be from a vaccine made specifically for a new pandemic flu virus. Experts say that a "pandemic vaccine" can only be made once a pandemic starts.

However, "pre-pandemic vaccines" have been developed. These are being improved and tested. They show some promise for research and preparing for the next pandemic. Vaccine makers are encouraged to produce more vaccines. This way, if a pandemic vaccine is needed, there will be enough facilities to make large amounts quickly.

Public Health Efforts

Many countries and organizations are working together to deal with H5N1. The United States works with groups like the World Health Organization (WHO) and the Food and Agriculture Organization of the United Nations (FAO). They also work with 88 other governments. They plan, monitor, and share information about bird flu outbreaks.

These groups encourage countries to watch for outbreaks in poultry and many deaths in wild birds. They also push for quick actions to stop the spread. Different U.S. government agencies are working together on international response plans.

Together, they are taking steps to "lower the risk of further spread in animals." They also aim to "reduce the risk of human infections" and "support planning for a pandemic."

Experts from various organizations are constantly watching and studying H5N1 outbreaks in humans and animals. They share their findings to help control the virus.

Treating H5N1

There is no very effective treatment for H5N1 flu. But a medicine called oseltamivir (also known as Tamiflu) can sometimes stop the flu virus from spreading inside the body. This medicine has become important for governments and groups preparing for a possible H5N1 pandemic.

In 2006, the company Roche announced that three million doses of Tamiflu were ready for the World Health Organization. These would be used if a flu pandemic happened. Roche also gave two million doses to the WHO for use in developing nations. These are countries that might be affected but cannot buy large amounts of the drug.

Studies on animals and in labs suggest that Relenza (zanamivir), another flu medicine, might also work against H5N1. In a study from 2000, zanamivir helped treat bird flu viruses that could infect mammals. Also, mouse studies show that a mix of zanamivir, celecoxib, and mesalazine looks promising. This mix helped 50% of mice survive, while none survived without it.

While no one knows if zanamivir will help with a future H5N1 pandemic strain, it might be good to have it ready, along with oseltamivir. However, neither oseltamivir nor zanamivir can be made in large enough amounts once the virus starts spreading easily among humans. In 2006, a WHO scientist said that some H5N1 types had become resistant to Tamiflu. Tamiflu-resistant types have also appeared in the EU, but they are still sensitive to Relenza.

H5N1's Impact on Society

H5N1 has greatly affected human society. This includes how people, governments, and businesses react to actual and predicted deaths in birds, humans, and other animals. Billions of dollars are being raised and spent to research H5N1. This money also helps prepare for a possible avian influenza pandemic. Over $10 billion has been spent, and more than 200 million birds have been killed to try and stop H5N1.

People have bought less chicken, causing poultry sales and prices to drop. Many individuals have also stored supplies for a possible flu pandemic. International health officials say that many questions about the disease are still unanswered.

Dr. David Nabarro, a United Nations expert on bird flu, has expressed concern about H5N1's potential impact on humans. He once said that bird flu could kill 150 million people. He compared bird flu to AIDS in Africa. He warned that underestimating the problem could lead to wrong research and actions.