Viruses Transmitted by the Fecal Oral Route Flashcards
Describe the structure of Adenovirus
Naked, dsDNA viruse with an icosahedral capsid
What type of infection is Adenovirus
Can be local or systemic/generalized infection
How does Adenovirus replicate and spread?
-Most types of Adenovirus can replicate in the GI tract
-Usually they do not cause symptoms, but the virus can be spread fecal/orally as well as via respiratory spread
What can Adenovirus cause?
-There are two Adenoviruses known to cause gastroenteritis. It is common in children and can last over a week
-Can cause respiratory infections
Adeno ___ and ___, among other strains, infect military recruits and cause nasal congestion, cough, and malaise that can develop into pneumonia
4 and 7
There is a live adenovirus 4 and 7 vaccine given in the military. It is gelatin-coated to get to the GI tract, where it can replicate without symptoms, leading to protective immunity.
Adenovirus is a common cause of ___________________; the virus can last on towels and surfaces for weeks and is easily spread person-to-person
uncomplicated conjunctivitis
_______________ is found mainly in adults and is very contagious. The eye infection is accompanied by swollen lymph nodes, fever, headache, and fatigue and involves inflammation of the cornea
Epidemic keratoconjunctivitis
Describe the structure of Rotavirus
Reovirus fmaily, dsRNA, segmented, naked, icosahedral
-It is segmented and can reassort its genome
Rotavirus is very stable in:
-Detergents
-Stomach acid
-Resistant to drying and can last on surfaces for days
-A wide range of temperatures
How does Rotavirus effect children? Adults?
-Children under 5 have the most severe disease
-Rotavirus is the most likely to cause severe dehydration in young children and hospitalization
-Adults are often asymptomatic
What happens during peak infection of Rotavirus?
-Billions of virus particles/gm of stool are shed during peaking infection (infection only takes a small number of particles)
(Viral shedding continues after symptoms are gone)
Rotavirus has a (short/long) incubation time
Rotavirus is a local infection and has a short incubation time (1-3 days)
What kind of vaccine does Rotavirus have?
-Attenuated viral vaccine (recommended as part of childhood immunizations)
-This vaccine is very good at preventing severe complications from rotavirus infections resulting in hospitalizations but works less well in preventing all infections. This means some vaccinated children still get sick with rotavirus infections, but they are much less likely to end up in the hospital if they do get sick
Describe the structure of Norovirus
Calicivirus Family, ++ssRNA virus, Naked, Icosahedral
What type of infection is Norovirus and what is its incubation time?
Local infection with a short incubation time and a short course of symptoms
What age group does Norovirus affect?
-Infects and causes disease in all ages
-Usually only causes severe problems in the elderly and very young
What is Norovirus the leading cause of?
Outbreaks of acute gastroenteritis
Is Norovirus infectious?
Very infectious - millions of virus particles are shed in vomit and billions in feces
What is Norovirus resistant to?
-Resistant to drying and can remain infectious for up to 2 weeks on surfaces.
-Resistant to many common disinfectants and hand sanitizers. It needs to be heated to 140F and can withstand stomach acid
When is Norovirus shed?
-From the time of symptoms up to 2 weeks after you feel better.
-People are most contagious when sick and a few days after
Describe the structure of Picornavirus-Family
Pico-small, RNA, virus
+ssRNA, naked, icosahedral
In the Picornavirus family, there is the enterovirus genus. What does it contain?
It contains Poliovirus, Coxsackievirus A and B, Echovirus, and Enterovirus. The enteroviruses are lytic (kill the cell they infect) and can be spread both fecal/orally and through the respiratory route.
What is Picornavirus resistant to?
Like other naked viruses, picornavirus is resistant to many disinfectants, 70% Ethanol, some detergents, acidic pH, and drying
Picornaviruses have a seasonality in __________
Summer/early fall
Where do the enteroviruses of the picornavirus family replicate?
In the respiratory tract and GI tract before they enter the blood and go to target organs. IgG in the blood can prevent the virus from entering the blood and from going to target organs, which prevents the severe consequences of infection
(If you have IgG antibodies against the virus, you can stop the disease. The virus cannot go to its target organ. This virus however, is still replicating and can spread fecal/orally and via respiratory spread)
Most picornavirus-poliovirus infections are (symptomatic/asymptomatic)
Asymptomatic
-The majority who had symptoms were sick for about a week, some progressing to meningitis, but all recovered completely
About 1% of all picoronavirus-poliovirus infections had ___________
paralytic poliomyelitis
-They appeared to get better from the febrile illness, but polio traveled through the motor neurons to the anterior horn, killed the cells, and symptoms of spinal polio occurred with limb paralysis.
-Some also had weakness of muscles involved in swallowing and breathing
-There was higher mortality than spinal polio
-Most recovered the use of their limb, but some remained paralyzed for life
The ________ polio vaccine is an attenuated virus. This vaccine is no longer used in the US
Sabin/Oral
What happens if you’re exposed to wild-type polio and vaccinated with the Sabin vaccine?
-You do not get infected with wild-type polio
-The Sabin/oral polio vaccine prevents infection, disease, and no wild-type poliovirus is spread to others if exposed
The _______ polio vaccine is an inactivated virus vaccine that prevents polio and is used in the US
Salk/Inactivated Polio Vaccine (IPV)
What happens if you are exposed to wild-type polio and vaccinated with the Salk vaccine?
-You can become infected, but the IgG present in the blood prevents disease
-The Salk/Inactivated vaccine prevents disease but not all infections with wild-type polio. This means that although the exposed don’t develop the disease, they can still become infected, excrete wild-type polio, and spread it fecal/orally
______ are the number one cause of viral meningitis
Enteroviruses
Echovirus, enterovirus, coxsackievirus A, and coxsackievirus B can all cause meningitis
When is meningitis most common?
It can occur at any age but is very common in children
How does viral meningitis resolve?
Unlike bacterial meningitis, viral meningitis resolves on its own, with most having no lasting side effects
Enteroviruses can also cause _______
encephalitis
However, most recover completely if the encephalitis occurs outside of the neonate stage
What are symptoms of Hand, Foot, and Mouth disease (HFMD)?
-Oral and pharyngeal ulcerations occur first. Lesions then appear on the soles of the feet and palms
-Complications are rare, and almost everyone recovers completely
-Enterovirus 71 (EV-71) can cause severe neurologic complications but only rarely
What age group is HFMD common in?
children
What is the leading cause of HFMD?
Coxsackievirus A
Describe the lesions seen in Herpangina?
-Lesions are similar to HFMD but are limited to the posterior of the oral cavity. There is no involvement in the rest of the body
What causes Herpangina?
Coxsackievirus A
__________ is one of the viruses that cause infectious myocarditis/pericarditis
Coxsackievirus B
What does Coxsackievirus B start as?
Starts as a respiratory infection but can, on rare occasions, cause myocarditis
When can generalized infections of newborns occurs?
Can happen if the mother has an enteroviral infection during the last week of pregnancy or if a newborn gets an enteroviral infection shortly after birth
What happens if a newborn gets an enteroviral infection?
The virus can spread to multiple organs with a high mortality rate
T/F: With generalized infections, if the pregnant person can form antibodies and transfer them to the fetus, the baby will be protected from the virus spreading in the blood to target organs
True! This is why the timing of the infection in pregnancy matters. If symptoms occur over a week before delivery, maternal antibodies can make and transfer, and the baby will be protected from the generalized infection
T/F: Rhinovirus is a picornavirus and can be transmitted by the fecal-oral route
False - It is a picornavirus but it CANNOT be transmitted by the fecal-oral route. Low pHs inactivate the virus
The picornavirus-rhinovirus prefers to grow at 33 degrees making it ideal for ________
the upper respiratory tract
T/F: There are many types of rhinovirus and most people are frequently reinfected and symptomatic throughout life
True!
_______ is the primary cause of the common cold
Rhinovirus
How long does rhinovirus stay infectious on a surface?
Like other naked viruses, it can stay infectious on surfaces for several hours
Where are high amounts of the rhinovirus found?
In nasal secretions
What is a significant route of infection of rhinovirus?
hand-to-face
