What are AIDS, Sars, Avian Flu, Ebola?

Why do each of them scare scientists?

These are all infections that kill and there are no known cures for them that are approved by the FDA to treat these in th United States.

those sicknessess are not curable...

These are all diseases caused by viruses to which there is no cure.

AIDS is caused by HIV. AIDS is basically a syndrome in which your body immune system has been destroyed and your body cannot fight infections. AIDS do not kill people but a simple cold or flu can kill. They are also at an increase risk for cancer. HIV is virus that scientist are having a very difficult time finding a cure for. THe virus mutates so fast that it has developed ways to counter act the medications that are made.
SARS is also cause be a virus. It is a kind of flu virus, but is more lethal than your normal flu but not by much. I would not say that scientists is scared of this virus though.
Avian flu is another disease cause by a virus. It is also like the flu virus but mainly in birds. What happens is that birds usually transfer the virus to a human and they get sick. What scientists are worried about is the virus mutating and being able to be passed on from one human to another.
Ebola is a very dangerous virus that will kill most people. It basically liquifys your tissue and it is a very dangerous and painful killer. there is no cure for this either.

These are contagious diseases caused by strain of mutated viruses unknown to be neutralized, but can be prevented.

--- Acquired immune deficiency syndrome or acquired immunodeficiency syndrome (AIDS or Aids) is a collection of symptoms and infections resulting from the specific damage to the immune system caused by the human immunodeficiency virus (HIV) in humans, and similar viruses in other species (SIV, FIV, etc.). The late stage of the condition leaves individuals susceptible to opportunistic infections and tumors. Although treatments for AIDS and HIV exist to decelerate the virus's progression, there is currently no known cure. HIV, et al., are transmitted through direct contact of a mucous membrane or the bloodstream with a bodily fluid containing HIV, such as blood, semen, vaginal fluid, preseminal fluid, and breast milk. This transmission can come in the form of anal, vaginal or oral sex, blood transfusion, contaminated hypodermic needles, exchange between mother and baby during pregnancy, childbirth, or breastfeeding, or other exposure to one of the above bodily fluids. (a)

--- SARS :Severe Acute Respiratory Syndrome --is a respiratory disease in humans which is caused by the SARS coronavirus. symptoms are flu like and may include: fever, myalgia, lethargy, gastrointestinal symptoms, cough, sore throat and other non-specific symptoms. The only symptom that is common to all patients appears to be a fever above 38 掳C (100.4 掳F). Shortness of breath may occur later. Symptoms usually appear 2鈥?0 days following exposure, but up to 13 days has been reported. In most cases symptoms appear within 2鈥? days. About 10鈥?0% of cases require mechanical ventilation. (b)

--- Ebola Virus : The Ebola virus first emerged in 1976 in simultaneous outbreaks in Sudan and Zaire. Ebola is considered to be the deadliest virus of all time, but it is not as well known as Smallpox because Ebola outbreaks have been limited mainly to remote areas of the world.
--- Ebola hemorrhagic fever is potentially lethal and encompasses a range of symptoms including fever, vomiting, diarrhea, generalized pain or malaise, and sometimes internal and external bleeding. Mortality rates are extremely high, with the human case-fatality rate ranging from 50% - 89%, according to viral subtype. The cause of death is usually due to hypovolemic shock or organ failure.
(c)

--- Avian influenza: sometimes Avian flu, and commonly bird flu refers to "influenza caused by viruses adapted to birds.
--- "Bird flu" is a phrase similar to "Swine flu", "Dog flu", "Horse flu", or "Human flu" in that it refers to an illness caused by any of many different strains of influenza viruses that have adapted to a specific host.
--- The highly pathogenic Influenza A virus subtype H5N1 virus is an emerging avian influenza virus that has been causing global concern as a potential pandemic threat. It is often referred to simply as "bird flu" or "avian influenza" even though it is only one subtype of avian influenza causing virus.
(d)

--- These diseases scare scientists and disease control officials because they all have the potential to become a pandemic. AIDS already has, though AIDS moves rather slowly. That is because AIDS and HIV are transmitted only via infected bodily fluids.
---Ebola, Avian Flu, and SARS are considered much more serious because they infect via airborne transmission as well as body fluids. This combined with their rapid onset and high mortality rate and terrible symtoms make them very real and feared candidates for the next great pandemic. What they are afraid of is another "white flu" or "spanish flu" pandemic like the one in 1918.
---The influenza pandemic of 1918-1919 killed more people than the Great War, known today as World War I (WWI), at somewhere between 20 and 40 million people. It has been cited as the most devastating epidemic in recorded world history. More people died of influenza in a single year than in four-years of the Black Death Bubonic Plague from 1347 to 1351. Known as "Spanish Flu" or "La Grippe" the influenza of 1918-1919 was a global disaster. (e)
---I highly recommend that you visit the Stanford 1918 pandemic page. It is well worth the reading. You will get and idea of what a epidemic really is. It is a well done site.
---I footnoted the stanford page (e) as well as the others in the source box.

All are deadly Viruses which will kill you...avoiding certain life styles or inappropriate behaviors or traveling will prevent most of these deadly pathogens! There is no vaccine, pill nor treatment for any...only one cure for all...Death