viral infxns 2 Flashcards
what kind of virus is polio? what conditions is it stable in?
- picornavirus, RNA genome
- virons stable in hi pH-why it can survive in stomach acid
how is polio transmitted and what’s it’s incubation time? what’s important to note about the majority of the people infected?
- fecal/oral
- inc time= 6.20 days
- most people are asymptomatic
countries with endemic polio virus?
Pakistan, Nigeria and Afghanistan
what are the three clinical manifestations of polio?
1) absortive poliomyelitis- respiratory and gi probs
2) Nonparalytic aseptic meningitis- 1-2%, stiffness in back, neck and legs that last 2-10 days
3) flaccid paralysis in less than 1% of infections
diagnosis of polio
- shed in stool
- sequenced and determined if wild type or vaccine strain
what’s important to know about the Sabin strain polio vaccine?
-it was used from 1963-2000 and was a live attenuated oral polio vaccine that replicates in GI tract
1/2million doses of the vaccine strain reverted to more neurtropic strain that caused CNS pros and Vaccine Associated paralytic poliomyelitis (VAPP)
what occurred in 2000 -referring to polio vaccine
- an inactivated form used with all three antigens-inactivated via formaldehyde
symptoms of gastroenteritis
- vomiting, diarrhea, nausea
viral or bacterial gastroenteritis: in developing countries vs in poor hygiene/sanitation areas
viral
viral or bacterial gastroenteritis: bloody diarrhea
bacterial (inflammatory)
viral or bacterial gastroenteritis: a few hrs to 7 days incubation vs 1-3 days incubation
viral
viral or bacterial gastroenteritis: vomiting often only presenting feature
viral
viral or bacterial gastroenteritis: diagnosis of exclusion
-viral (can also do immunoassays for rotavirus and adenovirus) - culture for bacteria
signs of severe dehydration
- lack of tears
- sunken eyes
- weak pulse
- rapid
- skin tenting
- lack of urination
rotavirus target pop? type of virus and what family what percentage of kids are infected by 5 years of age age of most sever cases?
- infects mainly kids
- double stranded RNA/ rioviridae family
- 95%
- 3-24 months old
what’s important to note about the structure of rotaviruses
- they have their genome that is confined to the core and never leaves
- completely circular virus at transmission and then when inside host morph into something that has pores that transfer needed material to core of the virus (genome there)
rotavirus- incubation period? symptoms and how long they last? fever? HIV?
- 1-3 days
- symptoms- vomiting and diarrhea for 4-7 days
- fever- 1/3 of people get fever
- not major opportunistic pathogen more HIV pt
Rotavirus pathogenesis
- ingested virus infects cell at tip of microvilli in small intestine and spreads to infect large numbers of cells
-release of virus particles into lumen
-infected cells damaged and lost leaving immature cells with decrease absorptive capacity for sugar, water and salts
-fluid accumulation in lumen + rotavirus toxin NSP4 that causes loss of Ca2+ release
= diarrhea
2 things that cause diarrhea in rotavirus infection
- NSP4 toxin that increases Ca2+ release and
- destruction of infected epithelial cells and their microvilli =villi blunting
diagnosis, prevention and treatment of rotavirus
- diagnosis- via enzyme immunoassay from stool (cuz shed tons of virions, pcr
- treat- rehydration- oral, iv
- prevention- prevent oral/fecal contamination, IgA in breast milk also provides protection, vaccine
what are the two rotavirus vaccines and how are they different? recommended vaccination time for infants?
- rotateq and rotatrix- both live, attenuated oral vaccines
- rotateq -human/bovine protective against strains g1-4 and g9
- rotatrix- human
- vaccinate within 12 wks of birth- no intussusceptions noted
Norovirus target pop- incubation incidence fever? pathology symptoms
- infects all age groups
- incubation- 24-60 hr
- comprises 96% of outbreaks of non-bacterial gastroenteritis
- fever in half of pt
- path- similar to rotavirus
- nausea, vomiting and diarrhea
family of Norovirus and type of bacteria
caliciviradae family
non-enveloped
ssRNA genome
what is a strain of norovirus and what type of cells does it like infecting and why?
Norwalk virus- likes infecting people with type B blood b/c attaches to those antigens on RBCs
transmission of noroviruses?
- oral-fecal
- contact with contaminated food/prep
- fomites
- personal contact
- droplets from vomitus
- waterborne
where are noroviruses the most prevalent?
-long term care facilities
adenovirus typeof virus capsid? what serotypes cause gastroenteritis? incubation per? symptoms? population season?
- ds DNA (aDEN- dna)
- no capsid
- serotypes 40-41
- incubation- 8-10 days
- symptoms- vomiting, diarrhea (NON-BLOODY), fever
- population- kids
- no seasonal variation
diagnosis of adenovirus
-antibody based
sapovirus
-related to calciviridea family (like norovirus)
astrovirus
- star-shaped
- ssRNA
- kids, elderly or healthy adults exposed to contaminated food/drink
