Human Diseases Caused by Viruses and Prions Flashcards
Airborne Diseases
How do humans transmitted airborne diseases?
viruses are propelled from the respiratory tract by coughing, sneezing, or vocalizing
routes of viral transmission
- airborne
- arthropods
- direct contact
- food and water
- zoonotic
Airborne Diseases
examples of airborne diseases
- chickenpox
- flu
- measles
- mumps
- RSV
- rubella
- smallpox
Chickenpox (varicella)
Chickenpox is a DNA virus, a member of…
herpesviridae
Chickenpox (varicella)
Humans serve as a….
reservoir and source
Chickenpox (varicella)
How is chickenpox acquired?
droplet inhalation into respiratory system
Chickenpox (varicella)
Describe chickenpox
- result from initial infection
- individuals that recover are immune, but not free of the virus
- vaccine prevents or shortens illness
Shingles (herpes zoster)
What is shingles?
a reactivated form of chickenpox
Shingles (herpes zoster)
Where does the shingles virus reside?
episome in cranial and sensory neurons
- reactivation – virus migrates down neuron
Shingles (herpes zoster)
How is shingles treated?
supportive; acylovir and others
Influenza
What is influenza?
a respiratory system disease caused by influenza virus
Influenza
What type of virus is influenza?
RNA virus; segmented genome
Influenza
What are the 3 genera?
A, B, and C
Influenza
How is influenza acquired?
by inhalation or ingestion of respiratory secretions
Influenza
Subtypes of influenza are based on…
hemagluttinin (HA) and neuraminidase (NA)
Influenza
What are NA and HA?
membrane surface glycoproteins
Influenza
What are HA and NA functions?
part of viral attachment and virulence
Influenza
How many antigenic forms do HA and NA have?
- 18 HA
- 11 NA
Influenza
antigenic drift
due to accumulation of mutations in a strain
- vaccine mismatch
Influenza
antigenic shift
due to reassortment of genomes when two different strains of flu viruses (from humans and animals) infect the same cell and are incorporated into a single new capsid
- epidemics
Arboviruses
What are arboviruses?
viruses transmitted by bloodsucking arthropods from one vertebrae host to another
Arboviruses
What are arboviruses capable of doing?
multiply in tissues of vector without producing disease
- vector acquires a lifelong infection
Arboviruses
What three clinical syndromes can arboviruses be placed into?
- undifferentiated fevers, with or without rash
- encephalitis-inflammation of the brain; fatality rate is usaully high
- hemorrhagic fevers - frequently severe and fatal
Arboviruses
What are treatment options available for arboviruses?
supportive treatment, no vaccine
Arboviruses
What are some examples of arboviruses?
- chikungunya
- dengue
- west nile virus
- zika
Dengue and Dengue Hemorrhagic Fever
What type of virus is dengue?
enveloped RNA virus
- worldwide distribution, endemic in over 100 countries where mosquito vectors are found
Dengue and Dengue Hemorrhagic Fever
What are the dengue serotypes?
DENV-1 through DENV-4
Dengue and Dengue Hemorrhagic Fever
What are symtpoms of dengue?
- fever
- rash
- joint and bone pain
- muscle aches
- mild bleeding of the gums
- easy bruising lasting 3 to 10 days
Dengue and Dengue Hemorrhagic Fever
What does the first infection with one serotype DENV result in?
(ex. DENV-1)
the formation of neutralizing antibody, which limits infection
Dengue and Dengue Hemorrhagic Fever
What does the second infection with a different DENV serotype result in?
(ex. DENV-2)
the binding of anti-DENV-1 antibody
- this opsonizes rather than neutralizes the virus, which uses phagocytic immune cells as productive cells
Dengue and Dengue Hemorrhagic Fever
antibody-dependent enhancement
occurs if an individual is later bitten by a mosquito carrying any of the other serotypes
- antibodies will recognize the E protein of the serotype even though it is structurally distinct, leading to DHF
Zika
What type of virus is zika?
enveloped RNA virus in the Flaviviridae
Zika
How can zika be transferred?
- transmitted by many species of Aedes mosquitoes
- can be transmitted person to person in bodily fluids like breast milk and semen
Zika
What are symptoms of zika?
- mild fever
- rash
- joint pain
- conjuntivitis that resolves in 3 to 7 days
Zika
What percentage of people are symptomatic with zika?
only about 18% of people
Zika
What birth defect in zika known to cause?
microcephaly
Direct Contact Diseases
How are direct contact disease transmitted?
through direct personal contact
Direct Contact Diseases
What are examples of direct personal contact?
- touching
- kissing
- sexual contact
- contact with body fluids
- contact with open wounds
Direct Contact Diseases
What are some examples of direct contact diseases?
- HIV
- cold sores
- common cold
- herpes
- mononucleosis
- poliomyelitis
- herpes
- hepatitis
What does the phrase “food and water are vehicles for viral disease” mean?
several viruses cause common food-borne and waterborne diseases
Gastroenteritis (Viral)
What is acute viral gastroenteritis?
inflammation of stomach or intestines
Gastroenteritis (Viral)
What demographic is affected by acute viral gastroenteritis?
important disease of infants and children
- leading cause of childhood death in developing countries
Gastroenteritis (Viral)
How is acute viral gastroenteritis transmitted?
fecal-oral route
Gastroenteritis (Viral)
What are the major virus groups that cause acute viral gastroenteritis?
- rotaviruses
- adenoviruses
- astroviruses
- bocaparvoviruses
- caliciviruses
- parechoviruses
Gastroenteritis (Viral)
How many cases of norovirus caused acute gastroenteritis cases are there per year in the US?
20 million cases/year
Gastroenteritis (Viral)
T/F: Acute gastroenteritis due to norovirus is usually self-limited disease.
TRUE
Gastroenteritis (Viral)
What are treatment options for acute gastroenteritis due to norovirus?
for symptomatic patients there is supportive therapy
Gastroenteritis (Viral)
For gastroenteritis caused by rotavirus what are treatment options?
vaccination
- vaccination has reduced number of hospitalizations and deaths
Zoonotic Diseases
What are zoonotic diseases?
human viral infections in animal reservoirs before transmission to and between humans
Zoonotic Diseases
What are some examples of zoonotic diseases?
- ebola and marburg diseases
- hantavirus pulmonary syndrome
- rabies
Ebola Hemorrhagic Fever
What type of virus is it?
member of single-stranded, negative sense RNA family called the Filoviridae
Ebola Hemorrhagic Fever
How is it transmitted?
direct contact with ebola victim, body fluids or clinical samples
- bats are a natural reservoir
Ebola Hemorrhagic Fever
What is it?
severe multisystem syndrome in which the host vascular system is damaged leading to vascular leaking (hemorrhage) and dysfunction (coagulopathy)
Ebola Hemorrhagic Fever
What are treatment options?
supportive therapy; no treatment available
Hantavirus Pulmonary Syndrome (HPS)
What type of virus is it?
single-stranded, negative sense RNA virus in Bunyaviridae family
Hantavirus Pulmonary Syndrome (HPS)
How is it transmitted?
to humans by inhalation of virus particles shed in urine, feces, or saliva of infected rodents
Hantavirus Pulmonary Syndrome (HPS)
Are there any mortality risks for this?
potentially deadly for humans but do not cause disease in their reservoir (rodent) hosts
Hantavirus Pulmonary Syndrome (HPS)
What are the treatment options?
supportive therapy; no specific treatment avaibable
Rabies
What type of virus is it?
negative-strand, bullet-shaped, RNA virus
- highly neurotropic
Rabies
How are rabies transmitted?
primarily by bites of infected animals
Rabies
How frequently are rabies seen in the US?
fewer than 10 cases per year in the US
Rabies
First rabies…
enter the host cell and multiply.
Rabies
After multiplication, rabies then…
enter nervous system and spread to the spinal cord
- first specific symptoms may occur
Rabies
Rabies rapidly progresses into ?? as the virus spreads through the ??.
- encephalitis
- central nervous system
Rabies
Rabies finally spreads to the ??; including ?? where it is…
- peripheral nerves
- salivary glands
- shed in saliva
Rabies
What are the symptoms of rabies?
- pain or paresthesia at wound site
- anxiety
- irritability
- depression
- fatigue
- loss of appetite
- fever
- sensitivity to light and sound
Rabies
How soon do the symptoms of rabies appear?
2 to 16 weeks after exposure
Rabies
What does rabies quickly progress to?
- paralysis
- death via destruction of brain regions that regulate breathing
Rabies
How is rabies diagnosed?
- previously by microscopy
- currently direct immunofluorescent antibody (DFA), serology for antirabies antibody, and by PCR testing
Rabies
How are rabies treated?
- postexposure vaccination
- preexposure vaccination of individuals with high risk of exposure, dogs, and cats
Prions and Disease Induction Over Time
prions
protein infectious particles
- abnormally folded proteins which induce normal forms of protein PrPC to abnormally fold
Prions and Disease Induction Over Time
BSE agent
another name for prions
Prions and Disease Induction Over Time
T/F: BSE agent survives GI passage and is neurotropic.
TRUE
Prions and Disease Induction Over Time
What is a primary symtpom of prions?
dementia
Prions and Disease Induction Over Time
What are prion infections usually accompanied with?
motor dysfunction
Prions and Disease Induction Over Time
When do prion symptoms typically appear?
after prolonged incubation
- lasts from months to years prior to death
Prions and Disease Induction Over Time
What are the effects of prions on the brain?
- produce spongiform brain degeneration
- deposition of amyloid plaques
Prions and Disease Induction Over Time
What disease do prion infections share a lot of similarities with?
alzheimer’s disease
Prions and Disease Induction Over Time
How are prion disease categorized?
- familial (inherited) types
- sporadic types
- acquired types
Prions and Disease Induction Over Time
TSEs
transmissible spongiform encephalopathies
Prions and Disease Induction Over Time
What are TSEs?
fatal neurodegenerative disorders caused by prions
Prions and Disease Induction Over Time
TSEs remain ?? for months or years.
clinically silent
Prions and Disease Induction Over Time
How do TSEs typically end?
in profound disability or death
Prions and Disease Induction Over Time
What are some disease examples of TSEs?
- Kuru
- Creutzfeldt-Jakob (CJD) disease
- variant CJD
- bovine spongiform encephalopathy (BSE)
- scrapie
- FFI
Prions and Disease Induction Over Time
How are prion disease transmitted?
- medical procedures
- genetic
- food-borne
