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Viruses
“an intracellular, infectious parasite
capable of living and replicating only
in living cells”
Viruses
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Page 386
can infect almost any living cell
a piece of genetic material wrapped in protein
contain either DNA or RNA (not both)
replicate inside living cells and use cell’s own
structures to reproduce more infected cells
• some of the smallest human pathogens
• lack enzymes such as ATP for producing
energy
Inactivation of Viruses
• some are sensitive to disinfectants due to
lipids in their coverings
• detergents and ether dissolve their lipid
coverings
• e.g. HIV can be inactivated by a solution of
10% sodium hypochlorite (household bleach)
in water
Dermatropic (Skin) Diseases
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Page 387
Smallpox: vaccination ended in the 1970s
Monkeypox: Page 389 Figure 27 - 2
Measles: Page 390
Readings question #1: What is the virus
responsible for measles? What is the only
reservoir for this virus?
• MMR vaccine (measles, mumps, rubella)
Dermatropic Diseases (cont’d)
• German Measles: Page 390
• Readings question #2: What is the virus that is
responsible for the disease known as German
measles? How is it spread?
• Color Plate 61
• Chickenpox and Shingles: Page 392
• Color Plate 62
• Shingles rarely occurs in people under the age of
20 and highest incidence is in the elderly
• Color Plate 63
Reye’s Syndrome
• severe complication of chickenpox, influenza and
some other viral diseases
• persistent vomiting
• signs of brain dysfunction
• coma and death
• survivors: neurological damage
• children and teenagers
• use of aspirin to lower fever in chickenpox and
influenza increases chance of acquiring this
Dermatropic Diseases (cont’d)
• Herpes Simplex 1 and 2: Page 392
Readings question #3: What is caused by the
Herpes Simplex 1 virus and how is it
transmitted? What is caused by the Herpes
Simplex 2 virus and how is it transmitted?
• Color Plate 64
• Figure 27 - 6
Pneumotropic (URT) Diseases
• Page 394
• Influenza: strains are “antigenic shifts”
- vaccines are usually “multivalent”
- pandemic 1918-1919
- 2 new drugs: zanamivir (Relenza)
oseltamivir phosphate (Tamiflu)
Pneumotropic Diseases (cont’d)
• Common Cold:
• Hantavirus Pulmonary Syndrome (HPS):
– Rodents especially mice
• Severe Acute Respiratory Syndrome (SARS):
– Asia, North American and Europe
– fever greater than 100.4 degrees
– close person-to-person contact, resp. droplets
Neurotropic (CNS) Diseases
• Page 396
• Rabies: rhabodovirus
– shaped like a bullet
– spread by “bite” or “aerosols”
– colonizes in skeletal muscle and connective tissue
– immune system cannot suppress infection
because lymph does not circulate in the brain and
spinal cord (CSF)
– “hydrophobia”
Neurotropic Diseases (cont’d)
• Poliomyelitis: (polio virus) Page 396
• ingestion of feces contaminated water
• path of the poliovirus once it is ingested:
– throat – small intestine- lymph nodes (neck
and ileum) – blood (viremia) – final stages:
CNS
• vaccines: Salk (injection) and Sabin (oral)
Neurotropic Diseases (cont’d)
• Viral Encephalitis: Page 397
- inflammation of the brain
- arthropod-borne arbovirus (mosquitoes)
- EEE (Eastern Equine Encephalitis); WEE
(Western Equine Encephalitis); SLE; CE; LCE
etc.
- control of large populations of mosquitoes
to decrease spread
Neurotropic Diseases (cont’d)
• West Nile Virus: Page 397
– can infect humans, birds, mosquitoes,
horses etc.
– causes mild flu-like disease with no longterm health effects
– spread limited through mosquito control
– Elderly: can cause fatal encephalitis or
polio-paralysis
Viscerotropic (Visceral) Diseases
• Hepatitis:
Hepatitis A (HAV) “infectious”
Hepatitis B (HBV) “serum”
• Readings question #4: According to OSHA’s
Blood-borne Pathogen Rule, what are the
rights of funeral home employees regarding
the HBV vaccine?
• Hepatitis C (HCV): “silent epidemic”
– 100,000 people infected/year in the U.S.
Viscerotropic Disease (cont’d)
• Infectious Mononucleosis: Page 400
• Epstein-Barr virus (EBV) through transfer of saliva
• replicates in parotid salivary glands
• Cytomegalovirus: “inclusion bodies” “owls eyes”
• Shed in body secretions
• 80% of population are carriers
• Common in day-care settings
• Epidemic Parotitis (Mumps)
• Figures 27 – 9 and 27 - 10
Immunological Disease
• Page 402
• HIV (Human Immunodeficiency Virus)
– transmitted in bodily fluids; multi-drug resistant
– affects “T” cells within the immune system
– “opportunistic infections”
Readings question #5: What is the major
threat to embalmers when embalming AIDS
victims? What can the embalmer do to
protect him/herself?