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Lecture 21: Viscerotropic and Neurotropic Viral Diseases

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The viscerotropic viral diseases are transmitted to body tissues by what three ways?
1) Bodily fluids from infected individuals (blood, saliva, semen)

2) contaminated food/drink

3) arthropods
What four body parts do the viscerotropic viral diseases affect?
small/large intestines
liver
spleen
blood
What is the first human disease found to be caused by a virus?
yellow fever
Who identified mosquitoes as the agents of transmission of yellow fever in 1901?
Walter Reed
The causative agent of yellow fever is ____ (+-; ss,ds; RNA,DNA), icosahedral, enveloped virion
+ssRNA
The causative agent of yellow fever is from the ______ family
flaviviridae
What kind of virus is yellow fever? (transmited by arthropods)
arbovirus

arthropodborne virus
Yellow fever is _____ in tropical Central America, South America and Africa
endemic (it's there at a low level constantly)
Yellow fever is transmitted by _____ that get the virus from infected monkeys, jungle animals or humans
mosquitoes

(Aedes aegypti is a mosquito that transmits Yellow Fever)
PATHOGENICITY of yellow fever. Virus travels in blood to ______ and multiples. It then spreads to liver, ____, _____. In severe cases, _____ in infected organs. Hemorrhaging-bleeding gums, blood in vomit
lymph nodes
spleen kidneys, heart
lesions
Give an example of lesions in infected organs
hemorrhaging-- bleeding gums, blood in vomit
What are the early symptoms of yellow fever?
fever/chills then, nausea/vomiting (black vomit)
Besides fever/chills and nausea/vomiting (black vomit), what other main symptom is characteristic of yellow fever?
jaundice caused by liver damage
(biliruben levels rise)
What's the mortality rate of yellow fever?
20%
There is no proven antiviral treatment. It can be prevented by what?
attenuated virus vaccine and control of mosquito population
Infectious Mononucleosis is caused by what?
Epstein-Barr Virus
The Epstein-Barr Virus is an enveloped, icosahedral ________(ss,ds;RNA,DNA) HERPESVIRUS.
dsDNA
How is the Epstein-Barr Virus transmitted?
oropharyngeal secretions (kissing, licking, sharing fork, etc)
The Epstein-Barr Virus infects _____ and the infected cells proliferate
B-lymphocytes (mononuclear WBC)
What are Downey cells?
damaged B cells with vacuolated, granulated cytoplasm
What can be used to diagnose mononucleosis?
The Monospot Slide Test
If B-cells are infected, what will appear on the slide?
heterophile antibodies

heterophile antibodies are like other RBC, so they will cross react with other RBC of animals
Describe the process of the monospot slide test for infectious mononucleosis
A) Blood is taken from the patient.
B) The serum is separated from the cells
C) A drop of serum is placed on a slide containing guinea pig tissue extract, and the two are mixed. A rxn occurs that adsorbs any closely related antibodies in the serum.
D) Horse erythrocytes are then added, and the components are mixed.
E) If infectious mononucleosis antibodies are present in the serum, the erthrocytes will agglutinate and give a positive rxn
F) The absence of agglutination indicates an absence of mononucleosis antibodies and therefore a negative rxn.
heterophile antibodies
antibodies reacting with antigens from unrelated species
Epstein-Barr Virus causes ______ of lymph nodes and spleen
enlargement
Epstein-Barr VIrus causes enlargement of lymph nodes, spleen, fever, _____, and ____
fatigue
sore throat
Epstein-Barr Virus causes high _____ counts and _____
lymphocyte
Downey cells
Epstein-Barr Virus is a ____ disease, but EBV goes latent, patients may become carriers capable of transmitting viruses in saliva
self-limiting disease
Epstein-Barr Virus is connected with _______, a cancer of the jaw, in East Africa
Burkitts lymphoma
Epstein-Barr Virus is connected with _______, a tumor inside the nose, in South China
Nasopharyngeal carcinoma
Besides Burkitts lymphoma and nasopharyngeal carcinoma, what else is EBV connected with?
chronic fatigue syndrome, MS (multiple schelerosis)
Hepatitis is caused by several different viruses, and it results in ______
acute inflammation of the liver
Hepatitis A virus is ____(+-;ss,ds;RNA,DNA), no envelope, ocosahedral
+ssRNA
What is unique about the Hepatitis A virus?
it has no envelope
Hepatitits A belongs to what family?
picornaviridae
Hepatitis A is also known as _____
HAV or heparnavirus (hepatitits RNA-virus)
What 4 ways is hepatitis A transmitted?
1) fecal-oral
2) food (shellfish especially)
3) water contaminated w/feces
4) sexual contact
HAV is extremely resistant to ______ and is hard to get rid of
chemical or physical agents
When do symptoms appear for HAV?
symptoms appear after 2-4 weeks; short-incubation hepatitis
What are the symptoms of HAV?
initial- anorexia, nausea, vomiting, low-grade fever, abdominal pain

after 1-2 weeks, JAUNDICE
What two ways can HAV be diagnosed?
- check liver functions
- check for HAV Abs in serum

Infected individuals can be asymptomatic and contagious
What treatment is there for HAV?
No antivirals will help. No alcohol or fried food allowed
What is done to prevent HAV?
- removal of source of outbreaks
- vaccination with inactivated viruses
What is the difference between the virus that causes HepA and the virus that causes HepB?
Hep A
noneveloped
ss
RNA; heparnavirus

Hep B
enveloped
ds
DNA; hepadnavirus
Symptoms for Hepatitis B are more severe than Hep A and occur in ____; therefore, it is called ____
4wks-6months
long-incubation hepatitis
THe initial symptoms of Hepatitis B include _____, _____, ______.
fatigue, anorexia, taste changes
The initial symptoms of Hepatitis B include fatigue, anorexia, taste changes. Then, ____, ____, ____
dark urine, weird color stools, jaundice
The initial symptoms of Hepatitis B include fatigue, anorexia, taste changes. Then, dark urine, weird color stools, jaundice. If chronic liver infection, then there is a possibility of ______
heaptocarcinoma
Hepatitis B is transmitted mostly by _____ and _____. It is considered an ____
blood and bodily fluids
STD
What are 6 methods for the transmission of Hepatitis B?
1) nonsterile tatooing needles
2) contaminated dialysis equipment
3) contaminated vaccination eequipment
4) nonsterile dental practices
5) contaminated drug needles
6) nonsterile body piercing equipment
What does the Ebola virus cause?
Ebola Hemorrhagic Fever
The Ebola virus is a ___(+-;ss,ds;RNA,DNA)
ssRNA
The Ebola virus is what kind of virus?
filovirus
Natural host of Ebola is unknown, and it is thought to be transmitted by contact with human blood. What are the symptoms of Ebola Hemorrhagic fever?
Massive internal bleeding
blood spurts from patients
organs turn to liquid
PATHOGENICITY of Ebola Hemorrhagic Fever. The Ebola virus encodes at least two ____
glycoproteins
One glycoprotein attaches to _____
endothelial cells lining the veins and arteries

it encourages viral entry. Viral replication and damage to the cells WEAKEN THE BLOOD VESSELS, causing them to LEAK; catastrophic bleeding follows
The second glycoprotein attaches to _____
neutrophiles (types of white blood cells)

thereby LIMITING PHAGOCYTOSIS and the IMMUNE RESPONSE. Thus the patient bleeds to death internally before a reasonable immunological defense can be mounted. 90% MORTALITY
WHat are the 5 viscerotropic diseases?
1) Yellow Fever (arbovirus)
2) Infectious Mononucleosis (Epstein-Barr Virus)
3) Hepatitis A (heparnavirus)
4) Hepatitis B (hepadnavirus)
5) Ebola Hemorrhagic Fever (filovirus)
West Nile Fever is a member of the _____ family
flaviviridae
West NIle Fever is a member of the Flaviviridae family and is a _____(+-;ss,ds;RNA,DNA) icosahedral, enveloped virus
+ssRNA
In most cases, West Nile Fever is transmitted by ____
mosquitoes
West Nile Fever is transmitted by mosquitoes. Mosquitoes become infected when feeding on infected _____. Then, mosquitoes ____
birds
bite and infect humans
In some cases, West Nile Fever is transmitted by _____
blood transfusions
organ transplants
breast-feeding
pregnancy (mother to child)
How is West Nile Fever not spread?
not spread by contact such as touching or kissing an infected person
The incubation period for west nile fever is 3-14 days. THe virus multiplies in bloodstream and then travels to the ___
brain
People of what age group are more likely to develop serious symptoms of WNV?
>50
What are some symptoms of WNV?
fever, headache, nausea, vomiting, sometimes swollen lymph glands, and/or skin rash on chest, stomach and back
Some ppl (about 1 in 150) will develop _____ or _____
encephalitis
meningitis
Some ppl (about 1 in 150) will develop encephalitis or meningitis, resulting in _____
stiff neck
disorientation
coma convulsions
vision loss
paralysis

neurological effects may be permanent
What is the treatment for WNV?
No specific treatment, just prevention
What shape is the Rabies virus?
helical
The Rabies Virus is ___(+-,ss,ds,RNA,DNA) enveloped w/ spikes virion
ssRNA
The Rabies Virus is a helical, enveloped w/ spikes ssRNA virion of the ______ family
Rhabdoviridae
The rabies virus has how many genes?
5
The rabies virus can occur in most warm-blooded animals. There is no rabies in what four land-locked places?
Australia
Great Britain
New Zealand
Hawaii
What is unique about the rabies virus mortality rate?
highest mortality rate of any human disease once symptoms have fully materialized
How is the rabies virus transmitted?
transmitted by fluid (blood, saliva, urine) of infected animal
The rabies virus enters tissue from saliva of infected animal. _____ in muscle tissue near bite.
Viral replication
The rabies virus enters tissue from saliva of infected animal. Viral replication in muscle tissue near bite. Virus moves up peripheral nervous system (undetected by immune system) to ____
CNS
When the rabies virus moves up the spinal cord to the brain, it can cause fatal ______
encephalitis
Besides entering tissue, the rabies virus can also enter _____
salivary glands, other organs
After getting bit, there are mild symptoms at first, then when CNS is involved, what are 4 major symptoms?
1) spasms/ paralysis of pharyngeal muscles (DRIPPING SALIVA)
2) Hydrophobia (afraid of water)
3) Inability to swallow
4) Death from respiratory paralysis
furious rabies
excitable, restless animal that bites anything
Dumb rabies
lethargic (cat), docile
How is Rabies treated?
Vaccine, IgG

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