Lecture 14- Viral GIT Infections Flashcards
Viral infections
Virus causing waterborne infections = important
^ cause of GIT infections
Rotaviruses= cause of viral diarrhoea in children
Gastroenteritis
Causes by;
Rotaviruses- young children
Caliciviruses, Astroviruses, Adenoviruses
Seasonal variations; norovirus - winter vomiting disease
Rotavirus
Spherical in appearance with prominent glycoprotein spikes
-common cause of infant associated gastroenteritis
Vaccination; self limiting when supported with fluid replacement + electrolytes
Viral entry and replication
Infects and replicates in mature enterocytes
Enter into the cell via endosome; endosomes = indicate transportation into the cell + lysosomes= involved with degradation
Endosomes= releases the viral particle into the cytoplasm
Lipid droplets= help the formation of a viroplasm in which the new viral particles are produced
Symptoms- slide 10
Calciviruses - Norovirus (aka- winter vomiting virus)
Group of viruses
Cause of gastroenteritis
Belong to the family caliciviridae
Usually spread from person-to-person from the contaminated surroundings
Sometimes can be in; mussels, oysters + filter feeders
^shellfish also linked to a number of outbreaks
-contaminated= most likely to have originated from treated/untreated sewage
Fresh produce- leafy green veg + berry fruits- known to spread norovirus
^outbreaks linked with frozen berries
Use of contaminated water for agricultural/hygiene purposes
Norovirus cont
Infection;
Small infective dose
Incubation period for 15-48 hrs
Symptoms persist for 1-2 days; mild- more serious in diff ages
Symptoms;
-suddenly feeling sick
-vomiting + watery diarrhoea
Raised temp, headaches, cramps + aching limbs
Full recovery within a few days
Spread;
Illness may be very short
Vomit- high levels of infectious virus
Contaminate the environment= infection risk
Preventing the spread;
Infected people= avoid handling food
Transmitted= touching contaminated surfaces/food
Don’t share towels/food
Disinfect surfaces that an infected person has touched
Don’t go to A+E, Sch
Hepatitis E virus
Own family
Infects the liver through faecal oral route- enteric hepatitis
Fatalities associated with pregnant women; hormonal + immunological changes associated either 3rd trimester + placental replication
Astroviruses + Enteroviruses
Astroviruses;
Cause diarrhoea but no vomiting
Less prevalent in adults
Mild symptoms lasting around 1-4 days
Infection= common
Enteroviruses;
Large fam of viruses; spread by water + cause additional intestinal symptoms
Seasonal incidence in temp countries; summer + autumn
Important = poliomyelitis virus
Echo viruses + coxsackie virus
Polioviruses + Echovirus
CNS virus
Can be spread through contaminated water
3 serotypes + 4 conditions;
*asymptomatic infection- 90% of infections
*minor polio- temp fever, malaise + sore throat
*nonparalytic polio- invades CNS, muscle spasms + back pain
*paralytic polio- invades spinal cord + motor cortex of brain, paralysis
Echovirus;
Enteric Cytopathogenic Human Orphan Virus
Transferred through the faecal oral route
Causes colds + viral meningitis
Coxsackieviruses
Coxsackie A
-associated with lesions + fever= lasts days-weeks - self limiting
-several serotypes cause lesions of the mouth + pharynx
-sore throat, pain in swallowing + vomiting
-hand foot + mouth disease
Coxsackie B
-transmitted through the mouth
-associated with myocarditis rather than GI tract
-invasion to the pancreas can cause diabetes through the cellular destruction of the insulin production
Hepatitis A
Transmitted through faecal oral route
Not cytolytic
Survives for long periods on surfaces
1 month incubation; fever, fatigue, nausea + anorexia
^jaundice due to liver issues- patients own immune system kills infected cells
Viral replication
Enters through endocytosis
Poorly understood how virus is released from endosomes; is released as viral RNA
Host ribosome- used to synthesise protein
^proteins= promote the synthesis of new viral RNA + complete particles
Symptoms- outbreaks
Damage caused to the intestinal villi - water loss + diarrhoea
Villi is repopulated with cells to repair damage but immature cells= lack function
May impact on individuals with T cell defect + may spread to other systems
