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Monday, December 13, 2010

AIDS = Aquired Immune Defficiency Syndrome

AIDS is a disease which is caused by HIV - Human Immunodeficiency Syndrome - which has infected over 33 million people worldwide in 2010 and killed approximately 5% of its prey. The figure bellow shows how people living with HIV are spread around the world (source: wikipedia).


Before we start to get into the scientific discussion on this syndrome, we must understand the true meaning of the two terms mentioned above- HIV and AIDS. HIV is the virus which after entering the body will attack mainly the white blood cells of the body which are the human body's soldiers. The virus will feed off and use the energy of the host cell and eventually destroy it. So, the role of the Human Immunodeficiency Virus is to damage the Immune System of the human body - as quiet visibly seen in the name of the virus. To be more precise, the virus attacks the CD4 cells, which are immune cells. The normal concentration of these in a healthy body with a reliable and strong immune system is between 450 and 1200 in a cubic millimetre of blood. But as the virus attacks more and more of the CD4 cells, the immune system will become weaker and weaker and increasingly vulnerable to "opportunistic infections".

AIDS is known as the stage in which the concentration of the CD4 cells has fallen bellow 200 per 1 cubic millimeter of blood. This means that the body's defence system has become extremely weak and is literally an open target for any bacteria or virus that's floating past.

It usually takes 10 to 12 years on average after being infected with the Human Immunodeficiency Virus for the symptoms of AIDS to start showing up. But the mentioned figure can vary largely depending on the clinical situation of a person, the diet of the person, the race of the person or the age of the person. Those with other infections such as Tuberculosis are also at a higher risk.

The Human Immunodeficiency Virus can be spread in various ways which will be examined later on, but it's only logical to see where the virus originated from first.  According to the Centers for Disease Control and Prevention (CDC), the source of HIV has been tracked down to a specie of chimpanzee in Africa. Scientists believe that the chimpanzee's version of the Immunodeficiency Syndrome called the Simian Immunodeficiency Virus (SIV) was passed onto humans when they were hunted and eaten and therefore came into contact with the primate's infected blood. It is believed that the virus spread to the other countries of the world in the following decades.

Now that we have a hypothesis on how the virus was derived, we can pay more attention to the methods through which the Virus - not necessarily the Syndrome - is transmitted. HIV can be transmitted through sexual relations, misuse of syringes, unsafe and un-sterilized dental procedures or clinical injections, unsafe tattooing and even through being bitten by a person infected with the virus. HIV can be passed on from mother to child during breastfeeding. It must be kept in mind though that HIV cannot be transmitted through water, saliva, tears, handshakes, mosquitoes or sharing eating tools ie spoons, forks, plates,...
To understand the symptoms caused by AIDS we must realize that what the HIV does is weakening the immune system and therefore killing the body's soldiers. In this case, bacteria, viruses and fungi can affect the patients body dramatically. The systematic symptoms to infection such as weight loss, fever, sweating and weakness may be observed. Also, the body becomes vulnerable to many cancers such as the immune system cancer called lymphomas and others such as Kaposi's sarcoma.

There is no vaccine nor cure for HIV or AIDS and the best solution is to prevent the virus from entering the body. If a patient is diagnosed with HIV, an antiretroviral treatment can take place. Again this is not a publicly available solution and the hunt for better methods must continue.

Saturday, December 11, 2010

Tuberculosis: a consuming disease

This essay will be an overlook of the disease that has reached out to one third of the world's population and affected millions of people; some relevant to the media-attracted ear include Niels Abel and Edward Baker Lincoln son of Abraham Lincoln.

Tuberculess bacillus or Tuberclosis or TB was once known as "consumption" as literally one's body will be consumed by the bacteria which cause this disease. The main cause of TB is a bacteria from the myobacterium family. The bacteria enters the body through inhaling infected air and therefore enters the body through the gate of the Respiratory System. When these bacteria have entered the lungs they can multiply and cause a local inflamation or infection which is known as pnemonia.

The body will respond to this unwanted guest by isolating the bacteria and not allowing them to spread throughout the body. The immune system does this by forming scar tissue in a process known as fibrosis around the bacteria to bloak the passages. These scar tissues may harden over time due to calcification of the tissue by the calcium floating in the blood stream. This state of the disease is called Primary or in-active TB. People with in-active tuberculosis, will not experience the range of symptoms experienced by those suffering active TB and will also not be infectious- meaning cannot distribute the disease.

But this natural immunization won't hold back the myobacterium forever. If the immune system of the body weakens due to cancer, other clinical diseases, drugs capable of affecting the immune system such as medications for arthritis and inflammatory bowel disease, the bacteria will break free and spread around the body. This is a much more vast and effective operation as the immune system is literaly switched off. This state of the disease is called active TB. Some symptoms of this active state of tuberculosis include night sweats, weakness, tiredness, weightloss and fever. If the inflamation and infection in the lungs becomes more severe, coughing, chest pain, coughing up sputum (matter emmited from the lungs) or even blood as well as shortness of breath can be experienced. If the bacteria spread to other organs of the body, depending on the specific organ being attacked, further symptoms may unveil.

Now that we have talked about the different types of tuberculosis, their source and symptoms, let's have a glance at how TB can be prevented, distinguished and treated.

It is important to know that 8 million people are added to the long list of the "TB affected" anually. It is estimated that about 10-15 million people are suffering TB just in the U.S. The only way this disease can be passed on is via air particle transmition. Of course there are a few factors that can increase the vulnerability of a person in regards with TB. Some of these factors may include alcohol and drug intake, poor immune system, diabetics, those with AIDS, and also some races. Unlike AIDS which is transmitted via contact, TB is transmitted only if infected air particles are inhaled. And because noone is aware of the clinical situation of all the surounding people and noone can detect if the atmosphere is TB infected or not, anyone can fall in the footpath of TB.

But the search for vaccines had started as early as the early 19th century and even untill now, many countries use the BCG vaccination programme when a child is born. The BCG aids the body very weakly in terms of TB and although it can prevent minor damage, it is not a reliable programme. But studies are taking place and new and much more effective vaccines are on the verge of flowing through the body of the public; such as the MVA85A.

TB is caused by a bacteria and if diagnosed on time, can be dealt with by using antibiotics over a stretched period of time. If any of the symptoms above take place or you just want to make sure you are free of this disease, a skin test can be taken. A fluid - tubercullin - is injected into the skin of the forearm and after 2 or 3 days the amount of swelling around the area is examined. Further examinations will involve X-ray images that will show exactly where the bacteria have attacked and if the TB is at an active or in-active state.

Wednesday, December 8, 2010

Katydids sing for lunch!

Cicadas are small insects found in many parts of the world but largely in Australia. There are about 2500 species of cicadas. There are many facts that can be discused about this tiny creature but this essay pinpoints on the cicadas mating strategy and an interesting twist discovered by cicada experts Dave Marshal and Kathy Hill of the University of Connecticut.

Male cicadas have very loud "noise makers" called tymbals on the sides of their abdominal base. Unlike in grasshoppers in which the sound is created through stridulation (rubbing of one body part against another), the sound created by male cicadas is due to the contraction and relaxing of the muscle obn their abdominal base. The sound created can be as simple as a "click" or very complicated and including a chorus. So only male cicadas have "sound makers" but both the sexes have "sound detectors" called tympana which are literally the cicada's ears. An interesting note is that male cicadas have the capability to "disable" their earing instruments when they are creating a sound. This is a very useful strategy because cicada sounds are the loudest among all insects. If the cicada were laid on a human's shoulder - close to the ear - and created a sound, the human would be permanatly deaf. Some of the notes created by cicadas are so high pitched that the human ear can't even detect. (pictured above is a group of cicadas)

When a male cicada is looking for "love", he starts creating a sound. It is timely to mention that each specie of cicada has a unique type of sound; this aids the female cicada in detecting whether the male cicada calling out is her type or not. Cicadas love heat and "sing" their most spirited "songs" in the hotter days of the year.

If the female cicada responds to the song of the male cicada, that's a sign that he has been chosen. The singing and responding will continue untill the male finds the female cicada.

Researcher such as Hill and Marshall have found that snapping your fingers can attract the attention of the male cicada. But it is all in the timing. The female cicada responds to the male's signal in about 70 miliseconds which means seven hundredth of a second. If the timing is right, the male cicada will be fooled.

So, what's the twist?

On a journey which led Marshal, Hill and Max Moulds to Queensland, Australia, the researchers came upon a very interesting note. After hearing the reply of ehat seemed to be a female cicada, one of the researchers tracked down the source of the sound and was amazed at what he observed. The source of the reply wasn't a female cicada but a well camouflagued Katydid.

Katydids or Bush-crickets are an excelent example of mimicry and camouflague. As seen in the example above, the katydid mimics the sound of a female cicada in order to attract the male cicada towards itself and gobble it up. (pictured above is a katydid)

The researcher also foreshadowed that "Captive Katydids respond to almost any sharpand short sound, like the clik of two coins or even the sound of a car's indicator."


Reference: New Scientist magazin, 26 September 2009, page 44-7  visit: http://www.newscientist.com/