V8 Flashcards
How many Herpes viruses infect humans?
8
Name the Herpes viruses that infect humans
- Herpes simplex type 1 & 2 (HSV)
- Varicella Roster virus (VRV)
- Cytomegalovirus (CMV)
- Epstein-Barr virus (EBV)
- Human herpesvirus 6, 7 & 8 (HHV)
- Kaposi’s sarcoma-associated herpesvirus (HHV-8, KSHV).
What are the stages of herpesviruses?
- Initial (primary) infection
- Latent infection
- Reactivated infection
What occurs during the primary stage of herpesvirus infections?
- May be asymptomatic or subclinical
- Always leads to latency
What occurs during the latent stage of herpesvirus infections?
No viral replication, life-long
What occurs during the reactivated stage of herpesvirus infections?
- Virus reactivates from latent stage again causing active infection (= production of progeny virus).
- Reactivations may be asymptomatic (and thus go
unnoticed) - Shedding of infectious virus particles = potential
source of transmission
Describe Primary oral HSV infection
- Painful but happens only once in a lifetime
- Gingivostomatitis with painful mucosal ulceration
- Typically occurs during childhood.
Describe the latent phase of HSV infection
Virus remains dormant in nerves of CNS
Describe a recurrent infection of HSV
- Most common manifestation.
- Typical, recurrent mucocutaneous lesions.
- Caused by reactivated infection.
- Can be “triggered” (stress, sun exposure, diet)
How is HSV diagnosed?
Do lumbar puncture, genome testing to diagnose
What are complications of HSV?
- Herpes simplex encephalitis.
- Ocular: dendritic corneal ulcus; acute retinal necrosis.
- Neonatal herpes.
What is the main difference between HSV type 1 and 2?
- HSV-1 lies dormant in nerve cells near the base of the neck when outbreaks occur, will appear on the face or neck
- HSV-2 lies dormant in nerve cells near the base of the spine, when outbreaks occur, will appear around the genitals
How is Varicella Zoster diagnosed?
Very typical, don’t need to do lab tests to confirm
How is Varicella zoster prevented?
Vaccines
What are the different stages of VSV?
- Primary infection with VZV causes varicella (chicken pox)
- The virus remains latent in the dorsal root ganglia
- Herpes zoster, also known as shingles, is caused by the reactivation of the VZV
What is the impact of VZV in adults compared to children?
- Adults: Infection in childhood, then Shingles (zoster) is normal; however Varicella more severe
- Children: If shingles in young people – query, could be HIV/cancer; Varicella more clinically benign
What is CMV disease?
A rare manifestation of CMV infection
How does CMV disease present?
Febrile illness, hepatitis, pneumonitis, retinitis
Which groups are most at risk for CMV disease?
Patients with impaired immunity and Infants.
What are possible sources of CMV infection in newborn babies?
- Intrauterine (transplacental)
- Intrapartal (sub partu)
- Through breastfeeding
- Nosocomial / transfusion
Describe the stages of infection of CMV
- Primary infection clinically mostly unrecognised
- Lifelong persistence (true latency?): CMV detectable in most tissues and transmissible through blood and organs.
- Reactivations frequent but also normally inapparent
What diseases are caused by EBV?
EBV can cause disease ranging from harmless illness to cancer
Describe primary infection of EBV
infectious mononucleosis (glandular fever, “kissing disease“, “student disease“)
EBV is an aetiologic agent for which cancers?
Burkitt’s lymphoma and nasopharyngeal carcinoma
What are the 2 patterns of influenza epidemiology?
epidemic and pandemic influenza
What is the pattern of endemic influenza?
Regularly occurring seasonal epidemics of varying magnitude:
Tropics: throughout the year.
Temperate and colder areas: in winter months
What is the pattern of pandemic influenza?
Occasional global pandemics
E.g] 1918 Spanish flu
What are the mechanisms behind epidemic influenza?
- Caused by influenza A and B viruses.
- Antigenic drift: Influenza viruses undergo continuous, subtle antigenic changes in their surface antigens, hemagglutinin (HA) and neuraminidase
(NA)
What are the mechanisms of action of pandemic influenza?
- Pandemic influenza occurs at irregular and unpredictable intervals.
- Only by influenza A viruses by a newly emerged “human“ virus subtype
- Antigenic shift: leads to a virus strain with a
hemagglutinin gene encoding a different subtype from those previously circulating in the human population
What is a zoonotic source? (and which influenza is an example of this?)
A disease caused by animal viruses that cross the animal-human divide to infect people. Influenza A viruses are originally animal viruses.
What are clinical features of influenza?
- Droplet infection, incubation period 48 hours
- Abrupt onset with fever, headache, photophobia, shivering, dry cough, malaise, myalgia, and dry throat.
- Uncomplicated influenza: lasts approx 7 days
- Cough and weakness may persist for some weeks
How is measles and rubella transmitted?
Transmitted via aerosol and droplets (coughing, sneezing, talking)
How can measles and rubella be prevented?
Both preventable by live-attenuated vaccines (if combined with mumps: MMR vaccine)
How long is the incubation period of measles?
8 – 10 days to first signs, 2 weeks until rash appears
What is the Contagion index of measles?
almost 100, practically everyone who is exposed will become infected
What are the complications of measles?
- Interstitial (giant cell) pneumonia.
- Immunosuppression → bacterial superinfections: pneumonia, otitis media.
- Exacerbated by Vitamin A deficiency.
- Cancrum oris
- Encephalitis: 3 forms:
>1. Inclusion body enc.
>Post-infectious enc.
>Subacute sclerosing panencephalitis (SSPE).
What is the incubation period of Rubella?
12 – 23 days until rash appears
What are the Signs and symptoms of rubella?
rash, swollen lymph nodes, arthralgia of small joints (esp. in women), serious complications rare
What is the main problem with rubella?
teratogenic, esp. early in pregnancy
What is the Classical Congenital Rubella Syndrome (CRS) triad?
cataracts, heart defects, and sensorineural deafness; however numerous other abnormalities may also occur
