Diseases%20and%20their%20causes

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Diseases and their causes

• Introduction and Viral Diseases

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What is a disease?

• A disease is an abnormal condition of an organism
  that impairs bodily functions all over.
• An acute disease is one that lasts less than six
  months.
• A chronic disease is one that last for more than
  six months sometimes for years.

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Two types of diseasesInfectious

• Infectious diseases can spread from one person to
  another and are caused by microscopic organisms
  that invade the body.

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Noninfectious

• Noninfectious diseases are not communicated from
  person to person and do not have, or are not
  known to involve, infectious agents.
• These diseases arise from inside the body as a
  result of genetic conditions or dietary
  deficiencies.
• (These diseases will be covered in a later
  presentation.)

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Types of Infectious Diseases

• Viral (caused by a virus)
• Bacterial (caused by bacteria)
• Fungal (caused by a fungus)
• Protozoan (caused by one-celled organisms)

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Worldwide mortality due to infectious diseases Worldwide mortality due to infectious diseases Worldwide mortality due to infectious diseases Worldwide mortality due to infectious diseases Worldwide mortality due to infectious diseases Worldwide mortality due to infectious diseases
Rank Cause of death Deaths 2002 Percentage ofall deaths Deaths 1993 1993 Rank
N/A All infectious diseases 14.7 million 25.9 16.4 million 32.2
1 - BACTERIA Lower respiratory infections 3.9 million 6.9 4.1 million 1
2 - VIRUS HIV/AIDS 2.8 million 4.9 0.7 million 7
3 VIRUS mostly Diarrheal diseases 1.8 million 3.2 3.0 million 2
4 - BACTERIA Tuberculosis (TB) 1.6 million 2.7 2.7 million 3
5 - PROTOZOAN Malaria 1.3 million 2.2 2.0 million 4
6 - VIRUS Measles 0.6 million 1.1 1.1 million 5
7 - BACTERIA Pertussis 0.29 million 0.5 0.36 million 7
8 - BACTERIA Tetanus 0.21 million 0.4 0.15 million 12
9 - ALL Meningitis 0.17 million 0.3 0.25 million 8
10 - BACTERIA Syphilis 0.16 million 0.3 0.19 million 11
11 - VIRUS Hepatitis B 0.10 million 0.2 0.93 million 6
12-17 Tropical diseases 0.13 million 0.2 0.53 million 9, 10, 16-18

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What is a virus?

• Viruses are tens or hundreds of times smaller
  than bacteria.
• Made up of a protein coat with genetic material
  on the inside.
• Viruses are able to survive and reproduce only in
  the living cells of a host. Once a virus invades
  a living cell, it directs the cell to make new
  virus particles. These new viruses are released
  into the surrounding tissues, and seek out new
  cells to infect.

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So, would a virus be considered a living organism?
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Diseases caused by virus

• We will look at ten viral diseases in this
  presentation. Understand, however, that there
  are many diseases that are caused by viruses.
  These ten will be those that you may most likely
  hear about.

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1. ) Influenza (Flu)
In the United States alone, approximately 25 to
50 million people contract influenza each year.
The symptoms of the flu are similar to those of
the common cold, but tend to be more severe.
Fever, headache, fatigue, muscle weakness and
pain, sore throat, dry cough, and a runny or
stuffy nose are common and may develop rapidly.
Three types Influenza A B The virus that
infects most people during the cold
months. Influenza C Very mild symptoms or none
at all. Not as severe as the A and B virus.
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• Gastrointestinal symptoms associated with
  influenza are sometimes experienced by children,
  but for most adults, illnesses that manifest in
  diarrhea, nausea, and vomiting are not caused by
  the influenza virus though they are often
  inaccurately referred to as the "stomach flu." A
  number of complications, such as the onset of
  bronchitis and pneumonia, can also occur in
  association with influenza and are especially
  common among the elderly, young children, and
  anyone with a suppressed immune system.

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2.) Common Cold

• What is it?
• caused by a virus infection located in the nose
• last on average for one week
• a milder illness than influenza
• over 100 different cold viruses. Rhinoviruses are
  the most important and cause at least one-half of
  colds
• Cold viruses live only in the noses of humans and
  not in pets

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3.) Epidemic Parotitis (Mumps)
Mumps is a relatively mild viral infection of the
salivary glands that usually occurs during
childhood. Typically, mumps is characterized by a
painful swelling of both cheeks.
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The word "mumps" comes from an old English word
meaning lumps or bumps in the cheeks.
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4.) Rabies

• The rabies virus causes inflammation of the
  brain.
• Transmitted through the saliva of the infected
  animal
• Mammals are most likely to get rabies
• In humans, if left untreated, rabies is always
  fatal.

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How dangerous is rabies?

• Worldwide, rabies kills 50,000 - 60,000 people
  each year, with over 99 percent of the victims
  being from Africa, Asia (especially Southeast
  Asia India), and South America.  Rabid stray
  dogs cause 96-98 percent of the cases in
  developing nations.  Typically, the U.S. suffers
  less than five deaths per year from rabies.  In
  recent years, most of those cases have been
  transmitted by bats, though they rank third
  behind raccoons and skunks in terms of known
  animal cases here. 

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Current map of reservoir animals that have a high
probability of having the rabies virus
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This skunk wouldnt normally attack a porcupine.
Carnivores that get rabies often do.
Be aware of wild animals that appear friendly.
One of the signs of rabies.
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5.) Hepatitis

• This virus attacks the liver
• There are about 7 different Hepatitis strains
  (Hepatitis A, B, C, D, E, F, G)

We will look only at types A and B
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Hepatitis A (Jaundice)

• Can be transmitted by consuming contaminated food
  or water and by sex. Your body will make
  antibodies that will protect you from getting it
  again after your first exposure. Symptoms
  typically last less than 6 months.

A yellowish discoloration is often associated
with jaundice.
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Hepatitis B

• 15 of the patients cannot eliminate this virus
  after initial infection.
• Identified methods of transmission
• Blood (sharing syringes in IV drug use)
• Tattoos
• Sex
• Mother to child during pregnancy

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Patients with chronic hepatitis B have antibodies
against hepatitis B, but these antibodies are not
enough to clear the infection that establishes
itself in the DNA of the affected liver cells.
Geographic distribution of Hepatitis B
prevalence, 2005
In 2003 there were 7526 cases of Hepatitis B
reported in the United States.
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This female Cambodian patient presented with a
distended abdomen due to a hepatoma resulting
from chronic hepatitis B infection.
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6.) Varicella (Chickenpox)
After getting this highly contagious virus it
takes about 10-21 days before these symptoms
appear. The person is contagious 1-2 days before
the rash even appears. After they appear they
produce a fluid that is highly contagious. This
rash lasts about a week. Once they start crusting
over the person is no longer contagious.
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Adults can get chickenpox too!31 year-old male
Bummer.
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7.) Measles
Measles is usually a childhood infection and is
most common in the non-immunized 1-4 year old age
group. However, one can catch measles at any age.
Measles is caught through direct contact with an
infected person or through the air when the
infected person coughs or sneezes. It is highly
infectious. Measles is most infectious before the
rash appears and only trivial contact may be
sufficient for the virus to spread.
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8.) Rubella (German Measles)

• Incubation period 14-21 days
• Lasts one to five days once symptoms appear
• Children recover much quicker than adults
• Generally a mild disease
• Rare in infants and adults over 40

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Rubella (German Measles)
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9.) Smallpox

• Smallpox virus invades the small blood vessels of
  the skin (which later give rise to blisters).
• In the 18th Century smallpox was responsible for
  33 of all blindness.
• In the 20th century smallpox was responsible for
  the deaths of 300-500 million people.

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Smallpox

• This young girl in Bangladesh was infected with
  smallpox in 1973.

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The Last of Smallpox?

• The last cases of smallpox on Earth occurred in
  an outbreak of 2 cases (one of which was fatal)
  in Birmingham, England in 1978. A medical
  photographer, Janet Parker, died from the disease
  on 11 September 1978, after which the scientist
  responsible for the unit, Professor Henry Bedson,
  committed suicide. In light of this accident,
  all known stocks of smallpox were destroyed or
  transferred to one of two WHO reference
  laboratories the Centers for Disease Control and
  Prevention (CDC) in the United States and the
  State Research Center of Virology and
  Biotechnology VECTOR in Koltsovo, Russia where a
  regiment of troops guard it. In 1986, the World
  Health Organization recommended destruction of
  the virus, and later set the date of destruction
  to be 30 December 1993. This was postponed to 30
  June 1995. In 2002 the policy of the WHO changed
  to be against its final destruction. Destroying
  existing stocks would reduce the risk involved
  with ongoing smallpox research the stocks are
  not needed to respond to a smallpox outbreak.
  However, the stocks may be useful in developing
  new vaccines, antiviral drugs, and diagnostic
  tests.
• In March 2003 smallpox scabs were found tucked
  inside an envelope in a book on Civil War
  medicine in Santa Fe, New Mexico. The envelope
  was labeled as containing the scabs and listed
  the names of the patients they came from.
  Assuming the contents could be dangerous, the
  librarian who found them did not open the
  envelope. The scabs ended up with employees from
  the CDC who responded quickly once informed of
  the discovery. The discovery raised concerns that
  smallpox DNA could be extracted from these and
  other scabs and used for a biological attack.

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10.) AIDS

• Acquired
• Immune
• Deficiency
• Syndrome

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How did AIDS start?

• There is no definite answer as to how AIDS began.
  The first reported case in the U.S. was in 1981.
• AIDS is caused by the Human Immunodeficiency
  Virus (HIV)

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• HIV kills or damages cells of the body's immune
  system which decreases the body's ability to
  fight infections and certain cancers.

A picture showing the HIV (green) attacking a
white blood cell.
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• Here are the FACTS
• You cannot get HIV through casual contact such as
  shaking hands or hugging a person with HIV/AIDS.
• You cannot get HIV from using a public telephone,
  drinking fountain, restroom, swimming pool,
  Jacuzzi, or hot tub.
• You cannot get HIV from sharing a drink.
• You cannot get HIV from being coughed or sneezed
  on by a person with HIV/AIDS.
• You cannot get HIV from giving blood.
• You cannot get HIV from a mosquito bite.

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• HIV is spread through some of the body's fluids.
  HIV is in
• blood
• semen
• vaginal fluids
• breast milk
• some body fluids sometimes handled by health care
  workers (fluids surrounding the brain and spinal
  cord, bone joints, and around an unborn baby)
• HIV is passed from one person to another by
• having sex with a person who has HIV
• sharing needles with a drug user who has HIV
• during pregnancy, birth, or breast-feeding if a
  mother has HIV
• getting transfusions of blood with HIV, which is
  rare in the United States

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Interpret this graph about AIDS
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Prevalence of HIV among adults per country at the
end of 2005.
Uganda
Kenya
Zambia
Mozambique
Zimbabwe
Namibia
Botswana
South Africa
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Summary

• Diseases
• Infectious
• Viral
• Influenza
• Common cold
• Mumps
• Rabies
• Hepatitis
• Chickenpox
• Measles
• German Measles
• Smallpox
• A.I.D.S.