Bird Flu Is Back

Naomi Brown

Recently there have been numerous reports of the rapid spread of avian flu across Europe. With the memories of previous outbreaks that caused widespread devastation across poultry farms and fatalities in humans, there are concerns that this time it could be worse.

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Image Credit: Flickr

What is avian flu?

Avian flu is a type of influenza virus adapted to live in birds.  A virus is made up of genetic material, such as DNA or RNA, covered by a protective protein coat. Flu viruses are constantly changing, which means they have the ability adapt to become the best at infecting hosts. This is why they have the potential to cause pandemics (the spread of an infectious disease that has spread through human populations across a large region).   

Upon the discovery of the influenza virus the first parts to be identified were two proteins on the virus surface called hemagglutinin and neuraminidase. This lead the naming system still used today: ‘H’ for hemagglutinin and ‘N’ for neuraminidase. The types of virus were numbered as they were discovered, for example: the first virus identified was H1. However, there are six other genes present in flu viruses. This means that although strains have the same name, they have six genes that could be different. Therefore, it is possible that two viruses with the same name could either cause mild symptoms or be highly contagious.

It is worth noting that most types of avian flu do not infect humans. However, a number of the ones that do, cause serious infection. The strains of the virus that can cause fatalities in poultry are the H5 and H8.

The Last Outbreak

The current strain, H5N8, has evolved from H5N1, which was first recorded in a goose on a Chinese farm in 1996.  H5N1 is highly pathogenic, meaning it is contagious and so spreads quickly. This led to the rapid spread of the disease across Asia, Europe and Africa; hundreds of birds died, significantly impacting the poultry markets. The disease spread to humans from contact with these birds causing 452 deaths.

This Time

The H5N1 virus has had the opportunity to hybridise with other types of flu because the migrating birds congregate in North-Central Asia during the warm summer months before dispersing all over Africa, Europe and Asia.  This the first time that wild birds have died because this H5N8 strain has picked up new genes from flu in wild birds. There is a high likelihood of more H5N8 outbreaks in both wild bird populations – such as geese, ducks and gulls – and farmed animals, due to the migration of wild birds.

The first case of infection report in Europe was on a farm in Germany where there was swift response; a 3 km2 quarantine was set up and 30,000 chickens were culled. There have been further reports of infected birds from Austria, Lake Geneva in Switzerland and Romania.  

So far, no humans have been affected. A report from the World Health Organisation has concluded that the risk of human infection is low but cannot be excluded. H5 flu viruses rarely infect humans however one similar strain, H5N6, has caused 6 fatalities out of the 14 reported cases of infection in humans.  The disease has only been transmitted to humans when a person has come into contact with infected poultry, and there is no evidence that eating infected meat that has been cooked correctly can cause transfer of the disease.

If you’re worried about Avian flu, their advice is to avoid contact with dead or sick birds, wash your hands thoroughly after any contact with livestock and make sure to cook poultry thoroughly.

 

Where Did AIDS Come From?

Katie Jones

AIDS stands for Acquired Immune Deficiency Syndrome and is a disease characterised by an extremely weak immune system. It eventually leads to the patient dying from infection or cancer if left untreated. HIV (Human Immunodeficiency Virus) causes AIDS by attacking and invading cells of the immune system and using them as a safe space to grow and increase in number.

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Image Credit: Wikimedia Commons

Once there are lots of virus particles, they will erupt from the invaded cell and kill it. The virus then travels around the body in the blood to the next immune cell. Therefore, it can hide from the body’s immune system, and kill it at the same time. HIV is spread through the transfer of bodily fluids from one person to another, most commonly through unprotected sex, sharing needles, or across the placenta to a baby during pregnancy.

Over the years, there have been a few theories regarding the origin of AIDS and how it spread throughout the human population.

The most outlandish of these it that HIV is a manmade virus. The first reported cases of HIV were around 1920. At that time scientists had nothing close to the knowledge or technology necessary to produce their own virus. Developing a virus from scratch would require an understanding of genetic manipulation and in the 1920s this information just wasn’t known.

The theory that was probably the most controversial was fronted by the once well-respected retrovirus expert Peter Duesberg from The University of California at Berkeley. He believes that HIV does not cause AIDS. In the 1980s, during the initial height of the AIDS pandemic (the spread of a disease across the world), Duesberg championed The Drug Hypothesis.

The hypothesis suggested that the increase in the use of a variety of drugs, including sex-enhancing recreational drugs such as amyl nitrate (poppers) to HIV-inhibiting drugs like AZT, were what caused HIV. Despite there being a correlation between the people who used these drugs and the incidence of HIV, no causal link was ever found.

The universally accepted theory as to how HIV came to infect humans is that there was a species jump from SIV (a virus closely related to HIV) in primates to humans. It’s suggested that it came from the slaughtering and butchery processes involved in eating ‘bushmeat’, meat from non-domesticated animals, in western Africa.

The butchery process could easily lead to blood and other secretions from infected primates (especially sooty mangabeys) entering open wounds on the human skin. It’s thought that the first transmission of SIV to HIV in humans took place around 1920 in the Democratic Republic of Congo (DRC), and spread to the neighbouring Republic of Congo in 1937.

As urbanisation increased and people moved from rural to more densely populated areas, HIV increased within the population. Throughout the second half of the 20th century, as transport networks improved and long haul flights became popular, HIV spread around the world.

By the 1980s, there was a high incidence of HIV in Haiti. During the 1960s, a lot of Haitian professionals were working in the DRC, many people blamed them for the spread of HIV and the subsequent pandemic. This lead to the Haitian people suffering from severe racism, stigma and discrimination.

Huge numbers of people still suffer from AIDS because it’s practically impossible to make a vaccine against HIV. The virus mutates so quickly that there are a massive number of strains each requiring a different vaccine; sometimes more than one strain can infect just one person. Also, HIV invades and can remain dormant in the body’s own immune system. Therefore, an attack on the virus could become a simultaneous attack on the body’s healthy cells.

Real and effective treatments for HIV were first released in 1987: a drug called AZT that prevents the virus from replicating and making more viruses. Then in 1992, combination therapies became popular, which reduced the numbers of people dying from AIDS even further. Protease inhibitors (drugs that block the activity of an enzyme that would normally help to make new viruses) were first used in 1995 and this lead to a dramatic drop in death rates.

Looking forward, its high mutation rates mean a vaccine to HIV is probably not the most viable solution – but never say never, who knows what new technologies are around the corner? Instead, a possible solution would be to decrease an HIV-positive person’s viremia (the number of viruses in the blood) to a point where the individual is no longer infective. Therefore, this would lead to a decrease in the spread of HIV, eventually to the point where there are no longer any individuals with the virus.

It’s hugely important that people still remember that anyone can become infected with HIV and that there are many things that we can all do to keep safe and remain informed. The simplest thing that people can do to prevent becoming infected is to practice safe sex and wear a condom; as well as going for regular sexual health tests.

Intravenous drug users are at a high risk of becoming infected with HIV through sharing needles with other people. There are loads of free needle exchanges in most towns and cities across the country. In Sheffield alone, there are 20 chemists participating in the Sheffield Syringe Needle Exchange Scheme.

Developments in our knowledge and technology mean that an HIV-positive diagnosis is no longer a death sentence. Hopefully, further advances in treatment will mean that one day HIV and AIDS will be completely eradicated and millions of lives will be saved as a result.