What happens in chickenpox, exactly?

What is it?

Chickenpox is a very contagious viral disease. It is known for the small, itchy blisters it causes. Other common symptoms include fever, tiredness and headache.

Chickenpox is very common – in 2013 about 140 million cases occurred worldwide. However, practically everyone went through the disease before the chickenpox vaccine was developed, and the vaccine is thought to protect as much as 90% of people from the disease. Chickenpox is quite harmless with death occurring in 1 per 60 000 cases, but given how common it is, in 2013 it caused 7000 deaths.

What causes it?

Chickenpox is caused by a virus called varicella zoster virus (VZV). It spreads easily with the coughs and sneezes of someone infected. It can also spread through direct contact with the skin blisters.

What happens during it?

Viruses are practically just protein cells containing genetic information. They reproduce by invading a living cell, releasing their genetic material inside it and forcing it to become a virus factory. The cell produces new virus parts according to the viruses instructions for a while, and then the new viruses are put together and released and the cell dies.

The chickenpox virus invades the body through the respiratory tract. They first reproduce inside the cells outlining the respiratory tract, and then they move on to the lymph nodes. When they are released from the lymph nodes and start to spread around the body in the blood stream, the body realizes that there’s something wrong and starts a full-blown immune reaction. This causes many of the more generic symptoms associated with chickenpox such as fever.

The viruses are then carried by infected white blood cells to the skin. The formation of blisters is important in order for the viruses to spread from a person to another. The viruses apparently manage to manipulate the functions of cells so that the blisters, filled with lots of viruses ready to attack whoever comes into contact with them, appear.

If you have had chickenpox before or if you have been vaccinated against it, you have a very small chance of developing the disease. That’s because our immune system has a memory. For example, we have cells called B cells that produce proteins called antibodies that mark pathogens like viruses for destruction if they come into contact with them. When a pathogen first invades our body, it takes time to figure out the proper constitution of that antibody as they are different to each pathogen. Once our body has done this, it never forgets it. Our B cells produce enormous amounts of antibodies all the time. If the virus tries to invade us again, the odds are that there are a few of these antibodies circulating in our body and when they find the viruses they stop it right in it’s tracks.

How can it be treated?

The treatment of chickenpox consists mostly of alleviating the symptoms. It’s a good idea to stay at home, both to get some rest and to avoid infecting others. The blisters can be very itchy so keeping your nails short and maybe even wearing gloves minimizes the chance of doing some unnecessary damage by scratching. Paracetamol can be helpful in reducing the fever, and in severe cases, medications that attack the viruses can also be used.



Sources: en.wikipedia.org/wiki/Chickenpox, https://en.wikipedia.org/wiki/Varicella_zoster_virus, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4066823/



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