Transcript Viral Diseases

Common Cold
 Most common infection
 Caused by group of viruses called:
* Rhinoviruses – RNA viruses
 Virus infects the cells of the Respiratory tract
 Other viruses that may cause a cold are:
* Adenovirus
* Coronavirus
* Influenza A and B
Virus is spread by droplets from nose and throat
from coughs, sneezing or direct contact
 Person may feel sick from 2 – 4 days
 There is no cure or vaccines for cold
 Treatment of a cold includes relieving
the symptoms:
* Grandma’s chicken soup
* Aspirin
* Throat lozenges
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Known as the “FLU”
 Highly contagious infection
 In the respiratory tract:
* Nose
* Lungs
 Named by the proteins on
the surface of the virus:
H = Haemagglutinin
N = Neuraminidase
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H5N1
Type/strain of Influenza A
Called “Avian” flu
Most wild ducks are the
natural carries of the virus
How did it end up infecting humans?..........
When poultry, such as chickens and
turkeys became infected
The virus is found in chicken droppings…….
Farmers needs to wash their hands
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H1N1: Influenza A
Normally only infects pigs, but…
The virus is able to mutate as it travels from host
to host for years……..
Then, if it happens to infect a
human host, it can mutate……
This is not good! Why?................
Once it mutates in the human host then it can be
transmitted from one person to another and
our immune system can’t fight the virus off
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Bird flu remains a threat:
(AFP) – Mar 24, 2010
“Bird flu outbreaks that have killed seven people
in several countries so far this year show the virus
remains a threat to humans”
“Last week, a three-year-old Vietnamese girl
stricken with the virus died of severe lung infection,
authorities there said.”
“Fatality rate for humans infected with bird flu
remains high at 59 percent”
 Luckily, we can’t get the
virus by eating cooked
chicken or eggs
 It has not been proven that
the virus can be spread from person to person
 Most common in Asia and Indonesia
 No cases have been seen in USA or
North America
 At present time there is no affective
vaccine against H5N1. WHY?.......
 Regular Flu vaccine doesn’t work
 Known as the “Spanish Flu”
 Killed close to 50 million people
worldwide
 That’s more than the Black
Death
Bubonic Plague from 1347 to 1351
 An estimated 675,000 Americans died
during the pandemic
 What is a “Pandemic” ?...........
When an infectious disease
spreads worldwide
Origin of the Spanish Flu is not known
 Interestingly it killed healthy adults, not the usual
population such as:
* Young children
* Elderly
* The Sick
 WHY?..............
 Do to their healthy, strong immune system, the
the system overreacted to the virus destroying
healthy tissues and organs as well
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 Some Scientists believe that the H1N1 virus of
today is the mutated version of the 1918 Flu virus
 Also, interestingly enough, it was not the virus
itself that caused so many deaths, BUT?..........
 A secondary bacterial infection in the LUNGS!!!
 In the past 300 years there have been two other
Flu pandemics:
1. The Asian Flu of 1957
2. The Hong Kong Flu of 1968
The word “herpein” comes
from Greek word “to creep”
 There are more that
100 herpes viruses but only
8 infect human host
 Most adults worldwide are infected
 DNA virus
 “Hidden” virus
 Once infected, it is your buddy for LIFE!!!
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HSV – 1
HSV – 2
HSV-1 infects the cells in the mouth,
skin and cornea of the eye
HIGHLY CONTAGIOUS by direct contact
Cause cold sores and severe
blistering of the skin
HSV- 2 is type of STD – also Highly contagious
Causes 2 distinct diseases:
 Chicken pox –Varicella
* Common in children
* In adults it is very serious
* Virus remains dormant or
“Hidden” in nerve cells of spinal cord
 Shingles – Herpes zoster
* Common in adults
* Reactivation of Chicken pox virus
* Virus becomes “Active” again
EBV
 Causes Mononucleosis or the “Kissing Disease”
 Transmitted in saliva from person to person
 Virus infects cells in the mouth
 Next, virus infects B – cells
* Type of white blood cells
* Virus “Hides” in B – cells
 More than 90% of people become infected
 Can cause Cancer:
* Burkitt’s Lymphoma - cancer of B-cells
* Nasophyrangeal CA – nose and throat
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 6 strains of Hepatitis virus:
* A B C D E and F
 Only 3 can make us sick:
* A B and C
 Infects the Liver
 Each type/strain is transmitted differently:
* Contaminated food or water
* Blood
* Sexually /STD
 Causes Jaundice – yellowing of skin and eyes
 HVA
 Type of RNA virus
 More common in developing
countries with poor sanitation
 Highly contagious – found in feces
 Spreads by eating and drinking
contaminated food and water
 Children have mild or no symptoms
* They develop life - long immunity
 75 % of adults develop jaundice
 HVB
 DNA virus
 Close to 400 million are infected world - wide
 Spread by contaminated blood by drug users
sharing needles
 Body fluids - STD
 Health care workers
 90% of people recover
 But……
 10% of people develop chronic hepatitis
 HVC
 RNA virus
 Mainly spread via
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contaminated blood
75% of infected people develop Chronic
Hepatitis
Only 50% of people with chronic hepatitis
recover
There is no vaccine for HVC
Luckily, There is vaccine for HVA and HVB