• Whole Body 07.05.2010


    This is part of our House MD Project series.

    Click here to read the connection to the episode (spoiler alert!)

    house-s01e07

    Danger level: High

    What is it?

    Sleeping sickness (also called human African trypanosomiasis (HAT)) is a disease caused by a parasite, which causes, among other things, disturbances in the normal sleep cycle.

    Who gets it?

    The disease, as its name implies, is confined to Africa. From there it’s imported to other countries by travelers. Worldwide, 25,000 new cases are reported to the World Health Organization (WHO) each year.

    In sub-Saharan Africa the disease threatens millions of people. In 1986, the WHO estimated that 70 million people live in areas where transmission of the disease is possible.

    What causes it?

    The disease is caused by a parasite called Trypanosoma brucei. The parasite infects a fly called a tsetse fly. From there there’s a cycle through which a human gets infected:

    trypanosoma-lifecycle

    The fly bites a human, injecting the parasite into their skin. The parasite then travels to the blood stream, from where it can travel to different organs and multiply there.

    How does the fly get infected, you may ask? It simply bites an infected human, and then the cycle goes on.

    Apart from being bitten by a fly, humans can get infected in other ways:

    1. When a sick mother is pregnant – The parasite can travel through the placenta and on to the fetus.
    2. Blood transfusion – This is rare.
    3. Sexual contact – This is how the woman on the House episode got it. We tried very hard, but couldn’t find a resource (except for Wikipedia…) that claimed this is a possible way of getting infected. So the case on House may have just been pure fiction.

    Once the parasite has gotten into the body and multiplied there, its next stop is the central nervous system (the brain), where it causes damage, leading to the symptoms of the disease.

    How does it feel?

    Sometimes the site of the fly bite can develop into a red sore, called a chancre.

    trypanosoma-chancre

    A chancre.

    From the skin bitten site, the parasite travels to the lymphatic system, which is responsible for fighting infections in our body. There they multiply, causing our lymph nodes (small organs inside the body not usually seen without an infection) to grow. In this disease, this usually happens in the back of the neck, and is called Winterbottom’s sign.

    Sometimes the infected person can also feel headaches, fever (like the woman in the episode had), weakness and joint pain. Other symptoms may follow as well.

    The final stage, as mentioned before, is infection of the brain. At that stage the person has headaches, difficulty concentrating, personality changes, psychosis, tremor, seizures, and problems walking. The symptom that gave the disease its name is a change in the sleep cycle – causing the infected person to be sleepy throughout the day. The end of this stage is usually a coma, followed by death.

    This somewhat dramatic video shows it graphically:

    How is it discovered?

    The doctor takes a sample of blood, chancre, lymph node fluid or of other tissues in the body and examines it under a microscope. Under it, the parasite can be seen.

    trypanosoma-microscope

    The parasite (in purple) under a microscope.

    Sometimes other blood tests may help discover a response to the parasite, hinting that it exists in the body.

    How is it treated?

    There are specific drugs that can be given to treat the disease, and they should be given as soon as it’s discovered, to prevent further deterioration. Names of such drugs include suramin, pentamidine, eflornithine and melarsoprol.

    What happens after treatment?

    Treating the disease on time should cure you. It’s important to note, though, that you can get infected again.


    The bottom line – How do I avoid it?

    There are some things you can do if you intend to travel to danger areas in Africa and want to protect yourself:

    1. Wear protective clothing: Including long-sleeved shirts and pants. The clothing should be thick, as tsetse flies can bite through thin fabrics. They should also be khaki or olive colored, as tsetse flies are attracted to bright and very dark colors.
    2. Use insect repellants (although they haven’t been proven to work).
    3. Use bed netting when sleeping.
    4. Inspect your vehicle for flies before entering it, and don’t ride in the back of open vehicles.
    5. Avoid bushes, as the flies use them for rest.


    What next?

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    Related posts:

    1. Neurocysticercosis – The Worm That Attacks Your Brain (As Seen on House MD)
    2. TTP Explained Again (As Seen on House MD)
    3. Wilson Disease – The Return (As Seen on House MD)
    4. Echoviruses (As Seen on House MD)
    5. Rabies – All You Need To Know (As Seen on House MD)

    Posted by Roy @ 7:55 am

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