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What is the main cause of viral gastroenteritis in infants and young children?
Rotavirus
Which species is Rotavirus found in?
Many mammalian species with a broad host range
Where does Rotavirus replicate?
In the cytoplasm
(without complete uncoating of the virion particle)
How many serogroups of Rotavirus are there?
7 serogroups (A-G)
Which serogroup of Rotavirus causes outbreaks in humans?
Serogroup A
How is Rotavirus transmitted?
Fecal-oral route
What is Rotavirus a significant cause of?
Severe diarrhea in infants and young children
When is the marked seasonal incidence for Rotavirus?
January through March
How long can infectious Rotavirus particles survive on surfaces?
For extended periods
Which part of the body does Rotavirus primarily infect?
Epithelial cells of the small intestine (jejunum)
Is Rotavirus resistant to stomach acid?
Yes, it is resistant to acidic pH of the stomach
What is the incubation period for Rotavirus?
48 hours or less
Can Rotavirus infections be subclinical?
Yes
What are the symptoms of a Rotavirus infection?
-Mild diarrhea/vomiting
-severe non-bloody watery diarrhea with dehydration
What is the infection rate of rotavirus worldwide?
Equal worldwide
How do Rotavirus infection outcomes vary based on global regions?
High malnutrition leads to increased severity of infection
What percentage of children in the US have Rotavirus antibodies by age 3 or 4?
90%
What is the mortality rate of Rotavirus in children? (developing vs. developed countries)
Low in younger children in developed countries
Higher in developing regions due to lack of medical care and high malnutrition
Do adults have immunity if they were infected with Rotavirus as children? What do they get?
Yes, only have a milder illness
Does breastfeeding affect the course of Rotavirus disease?
Yes, it leads to a milder disease course
What enzyme do Retroviruses contain?
Reverse transcriptase, which converts single-stranded RNA viral genome into double-stranded viral DNA
What is a unique feature of retroviruses?
They are disease-producing animal viruses
What is a major host cell protein found in the HIV virus envelope?
Major histocompatibility complex class 2 proteins (MACII)
How is HIV primarily transmitted? (4)
1) Sexually (heterosexual contact) through semen or vaginal secretion
2) Blood
3) Contaminated needles
4) Perinatally
What increases the risk of sexual transmission of HIV?
Ulcerative and nonulcerative infections
What is the chance of perinatal HIV transmission occuring without antiretroviral therapy?
15-45%
What happens if HIV is left untreated?
Leads to an immunodeficient state that allows opportunistic infections, progressing to AIDS and death
What cells are primarily infected by HIV initially?
CD4 lymphocytes
How does HIV progress?
Viral replication -> Progressive CD4 depletion -> Aids -> Death
What occurs during acute viremia in HIV infection?
High levels of virus replication in CD4 cells, with large amounts of the virus in the blood
What characterizes the latent phase of HIV?
Constant level of virus/infected cells and replacement of CD4 cells; can be clinically asymptomatic if the immune system is functional
What defines the transition from HIV infection to AIDS?
-CD4 count less than 200 AND
-Presence of a defining illness/opportunistic infection
What is AIDs?
A concurrent infection that attacks the immune system with HIV.
-release of mature virions, resulting in T cell death
What characterizes the end phase of HIV?
Encephalopathy/retinal ischemia
Name 8 AIDS-defining illnesses.
1) Candidiasis
2) Coccidioidomycosis
3) Cryptococcosis
4) CMV
5) Kaposi's sarcoma
6) Mycobacterium/tuberculosis
7) Pneumocystis pneumonia
8) Toxoplasmosis
What tests are used for HIV diagnosis and monitoring? (4)
-ELISA for screening
-Western Blot for confirmation
-PCR for identification
-Viral load and CD4 count
What is a normal viral load for HIV?
500-1500
Low: less than 200
What is PrEP and PEP in HIV treatment? What is each used for?
-PrEP is pre-exposure prophylaxis for high-risk individuals
-PEP is post-exposure prophylaxis initiated within 72 hours of a high-risk event to prevent replication of virus
What are Human T-cell Lymphotropic Viruses (HTLV)?
The first retroviruses associated with human diseases like adult T-cell leukemia and HTLV-associated myelopathy.
Which virus is associated with human disease in particular?
HTLV-1
Which strain of HTLV causes Adult T cell Leukemia (ATL)?
HTLV-1
What is HAM/TSP? What strain indicates its presence?
HTLV associated myelopathy (HAM/TSP)
– less common neurologic condition
-causing progressive weakness and ophthalmoplegia (CNS involvement indicated by presence of anti-HTLV1 antibodies in the CSF)
What is the most common transmission mode of HTLV-1 in endemic regions?
Mother-to-fetus or newborn transmission
What therapies/treatment result in a high survival rate for ATL and HAM?
Chemotherapy and Antiretroviral therapy
Traditional chemo is ineffective
True or false: Transmission of HTLV-1 varies with geographic areas and socioeconomic groups, and occurs primarily by cell associated virus
True
What are 3 ways HTLV-1 transmission occurs via cell associated virus?
1) Endemic regions - mother to fetus/newborn (most common)
2) Sexually via infected lymphocytes
3) Blood products containing intact cells
What type of leukemia is associated with HTLV-2?
Hairy cell leukemia in 5% of patients
Name that strain: Infection happens few years after infection, develops CNS involvement in a few years, causes muscular weakness and splenomegaly.
HTLV-2
What are prions?
Unconventional infectious agents
Describe prions
They're transmissible, resistant to degradation, and cause transmissible spongiform encephalopathies (TSE)
What is Bovine Spongiform Encephalopathy (BSE) commonly known as?
Mad Cow Disease
What causes Bovine Spongiform Encephalopathy?
Contaminated feed containing animal parts from diseased sheep or cattle
What is Creutzfeldt-Jakob Disease (CJD)?
A rare, rapidly progressive form of dementia that is fatal, with long incubation periods
How did CJD begin in the 1990s?
People in the UK ingested contaminated meat, or it also happened to others sporatically.
How does CJD occur in the brain? What is characteristic?
Disease protein starts to accumulate in brain creating webs/deforming gray matter which takes a characteristic spongiform appearance seen on autopsy
Early stags of ___________ are mistaken for Alzheimer's
CJD
True or false: CJD is fairly easy to fight
False. It is challenging to kill a protein that's not living!
How can Creutzfeldt-Jakob Disease be transmitted? (4)
1) Contaminated medical equipment
2) Human growth hormone injections
3) Corneal grafts
4) Transplants
What disease is often associated with fear of contact lens reuse?
CJD
Where in the eye can CJD be detected in? (3)
1) Anterior chamber
2) Vitreous
3) Cornea
All CJD patients must have rapidly progressive dementia AND how many other other signs?
2
Read this one just look it over. (In relation to CJD:)
Also need - anomalous EEG, MRI changes, brain injury protein in the CSF
What is characteristic of Kuru?
The only prion disease transmitted human-to-human
How does Kuru infection occur?
The infectious agent is acquired by an individual who was exposed to diseased brain tissue.
Where is Kuru seen?
Tribal populations practicing ritualistic cannibalism
