12_STDs caused by Viruses Flashcards

1
Q

STD: define

A
  • sexually transmitted diseases (aka STIs and Venereal disease)
  • illnesses that ahve a significant probability of transmission b/w humans through sexual behavior, incl:
    • vaginal intercourse
    • anal sex
    • oral sex
  • ~20M new cases of STIs every year
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2
Q

other ways STIs can be contracted

(other than sexually transmitted)

A

can be contracted by using IV drug needles as well as through incident involving the contact of a wound w/ contaminated blood or through childbirth or breast feeding

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3
Q

named the major viral STDs

A
  • Herpes simplex virus
  • Human papilloma virus
  • Zika virus
  • Hepatitis
  • Human immunodeficiency
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4
Q

Herpes simplex virus (HSV)

  1. family
  2. infects
  3. structure
  4. symptoms
A
  1. herpesvirus family (Herpesviridae) - HSV-1 and HSV-2
  2. infects humans; ubiquitous and contagious
  3. core of ds-DNA surrounded by protein coat in icosahedral symmetry; nucleocapsid surrounded by an envelope
  4. symptoms
    1. HSV-1 –> causes oral herpes (cold sores)
    2. HSV-2 –> genital herpes
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5
Q

what is the most prevalent STD in the US?

A

genital herpes (HSV-2)

(45 M cases; 1M new genital herpes infxns per year)

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6
Q

epidemiology:

oral herpes and genital herpes

A
  • >100 M Americans have oral herpes;
  • > 45 M Americans have genital herpes
  • annually, 776,000 people in the US get new herpes infxns
  • genital herpes infxn is common; 16% of persons 14-49 y/o have HSV-2 infxn
  • inc. # of genital herpes infxns are caused by HSV-1
  • increases genital HSV-1 infxn have been found in patient population worldwide
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7
Q

how do people get genital herpes?

(through contact w/ what?)

can it be caught from skin that looks normal?

A
  • thru contact w/ lesions, mucosal surfaces, genital secretions, or oral secretions
  • HSV-1 and HSV-2 can both be shed from skin that looks normal;
    • in pts w/ asymptomatic HSV-2 infxns, genital HSV shedding occurs on 10% of days
  • generally a person can only get HSV-2 infxn during sexual contact w/ someone who has genital HSV-2 infxn
  • herpesviruses are highly contagious
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8
Q

symptomology of herpes simplex?

A
  • typically a blister or multiple blisters around infected areas –
    • usually the mouth, genitals, or rectum
  • blisters break –> leaving tender sores
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9
Q

describe the recurrence of herpes infection:

  1. what is the process?
  2. what triggers this?
  3. how do sxs differ from primary episodes?
A
  1. after lesions heal –> virus retreats up nerve fibers and remains dormant in nerve cells of spinal column
    • flare-ups: when virus moves down along fibers to genitals/lips
  2. triggers:
    • stress, anxiety, depression
    • acidic food, UV light, fever, poor nutrition, fatigue
    • general illness (mild to serious conditions)
    • immunosuppression due to AIDS or such medications as chemotherapy or steroids
  3. sxs are generally milder than primary episode and heal more quickly
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10
Q

how to reduce risk of transmission of genital herpes?

A
  • Use condoms – virus can’t pass thru latex condoms
    • During outbreak, avoid sexual contact w/ lesion area (even w/ condom - can become infected)
    • B/w outbreaks - use condoms still bc there can be asymptomatic viral shedding
  • medications are availabel to reduce asymptomatic viral shedding b/w outbreaks –> reduces risk of transmission
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11
Q

herpes complications for:

  1. women, and
  2. both sexes?
A
  1. women:
    • inc. incidence of cervical cancer - women w/ herpes should get pap smears every 6-12 months
    • newborn baby can be infected by passage through birth canal – can cause severe damage or death
      • C-section recommended for women w/ active symptomatic disease
  2. both sexes: ocular herpes infection can occur if virus is transferred from a sore to the eye
    • must be treated quickly to avoid eye damage
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12
Q

how to prevent and treat herpes?

A
  • prevent: reduce frequency of outbreaks
    • suppressive therapy: daily med taken to prevent recurrent outbreaks; reduces asymptomatic viral shedding b/w outbreaks
  • treat symptoms of outbreaks, and speed healing
    • episodic therapy: medication taken to tx outbreaks when they occur
  • using antiviral drugs –> reduce viral shedding & duration/severity of outbreaks
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13
Q

3 antiviral drugs used to tx herpes?

A
  • acyclovir
  • valacyclovir
  • famiclovir
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14
Q

human papilloma virus:

  1. family
  2. infect what?
  3. symptomology
A
  1. papillomavirus family; DNA virus
  2. establish productive infections only in keratinocytes of the skin or mucous membranes
  3. symptoms
    • most HPV infxns are subclinical and cause no physical symptoms
    • some subclinical pts –> can become clinical and cause benign papillomas or cancers of the cervix, vulva, vagina, penis, oropharynx, and anus
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15
Q

clinical symptoms (if present) of HPV

A
  • cause benign papillomas (such as warts [veruccae] or squamous cells papilloma)
  • cancers of the cervix, vulva, vagina, penis, oropharynx, and anus
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16
Q

Low-risk HPV types, and their effects

A
  • HPV 6, 11, among others
  • Leads to benign cervical changes, and/or genital warts
17
Q

HIGH-risk HPV types, and their effects

A
  • HPV 16, 18
  • lead to:
    • precancerous cervical changes,
    • cervical cancer,
    • anal and other cancers
18
Q

What about the HPV genome allows the virus to be associated w/ cancer?

A

contains an oncogene (gene which in certain circumstances can transform a cell into a tumor cell.

also has major viral transforming proteins (E6 and E7)

19
Q

how does productive HPV infxn progress to malignancy?

A
  • productive life-cycle (2-3 weeks)
    • 1-2 years pass
  • persistent infxn (lack of immune clearance)
    • up to 20 years
  • HPV-induced malignancy (oncogene activation +/- integration)
20
Q

genital warts (GW):

  • prevalence
  • transmission
  • sxs
  • treatment
A
  • prev: >15% of Americans/ 6M new US cases/yr
  • transmission: sexual contact
    • condoms don’t prevent infxn in genital areas not covered by condoms
    • HPV is most commonly transmitted by asymptomatic patients
  • sxs: *most are asymptomatic
    • if visible warts appear, incubation for 3-8 wks after contact
      • Women - GW appear in lower vaginal opening, perineum, labia, inner vaginal walls, and cervix
      • In men, usually on glans, foreskin, or shaft of penis
      • BOTH sexes: can occur on anus
    • appear pink/red and soft w/ cauliflower-like appearance in moist areas, OR hard/yellow-gray in dry areas
  • tx: visible warts removed by cryotherapy (freezing) or chemical tx –> larger warts may need minor surgery
21
Q

does cryotherapy and/or surgery prevent recurrence of genital warts?

A
  • removal doesn’t necessarily prevent recurrence
  • warts may disappear on their own
22
Q

what is the underlying cause of cervical cancer?

when was this connection discovered, and by which groups?

A

HPV is the underlying cause

discovered in 1996 by NIH and WHO

23
Q

HPV infxns: Summary

(persistent low-risk –>

persistent high -risk –> )

24
Q

how to prevent cercial cancer?

A
  • screening for precancerous changes (and tx if problems found)
  • vaccination against HPV
25
Hx of the conventional pap smear
* by George Papanicolaou in 1940's * most common cancer screening is pap smear * key part of annual gynecological exam * has greatly reduced cervical cancer mortality in US
26
**HPV vaccine:** * strains it protects against * function * consists of what? * appropriate age and series
GARDASIL vaccine * protects against: type **16, 18, 6, 11** (high- and low-risk strains) * function: **prevents HPV infxn, but doesn't tx existing infxn** * highly effective * very few serious side effects * consists of: **virus-like particles** * administered before puberty; requires 3 injections
27
**zika virus:** * family/lineages * structure
* genus: **Flavivirus,** family: **Flaviviridae** * African lineage * Asian lineage * **enveloped icosahedral, single-stranded RNA virus**
28
what is Zika virus closely related to? where have outbreaks occurred?
* closely related to **Dengue fever** (~43% homology & extensive Ab cross-reactivity) * 1st strain isolated from Rhesus monkey in Zika Forest, Uganda * Outbreaks in Africa, Asia, and recent outbreaks in Latin/South America
29
how is Zika virus transmitted?
* vector borne or * mosquito (from monkey) * non-vector borne * accidental lab exposure * blood trasnfusion * organ transplant * monkey bite * sexual transmission
30
what can Zika virus cause in newborns?
* **microcephaly** (small head)
31
possible neurological and ophthalmic complications of Zika?
* Ophthalmic: * Conjunctivitis * Retinal atrophy * Neurological: * Meningitis, Meningoencephalitis, myleitis * Guillain-Barre syndrome (not confirmed)
32
what is **Guillain-Barre syndrome?** can Zika cause this?
strongly associated w/ Zika, but connection is not confirmed
33
**zika virus:** * testing/diagnosis * primary prevention
* test/dx * culture for virus * acute phate (more than 7 days after onset) * chronic phase (more than 4 days, lasts for months) * primary prevention * no vaccine, so prevent mosquito exposure * people w/ active infxn should avoid exposure to mosquitoes to prevent further spread
34
**hepatits**: * cause * prevalence * transmission
* caused by **hepatitis virus (types A, B, C, D, E) --\> attacks liver** * **HepC is most** * prevalence: \>170M people have HepC worldwide, 5M in US * transmission: * HepA - fecal-oral, oral-anal sexual contact; infected food handlers * all can be by sexual contact (HepB is more often by sex) * HepC - \*needle sharing * from infected mother --\> fetus/infant
35
which types of Hep viruses cause Chronic liver disease? transmission and sxs of the various Hepatitis strains?
* B, C, D, E all can cause Chronic liver disease
36
**Hepatitis**: * sxs * sequelae * tx * vaccines?
* sxs: *vary* * asymptomatic * mild flu-like sxs * high fever, vomiting, severe abdominal pain * jaundice/yellowing of whites of eyes or skin due to inc. breakdown of RBC * sequelae: **chronic infxn w/ HepB or HepC --\> risk of liver cancer** * **HepC --\> severe liver complications such as cirrhosis, liver failure (**20-25% of patients) * tx: * HepA: bed rest, fluid intake * HepB: same as A, but since can be chronic --\> may be tx w/ antiviral drugs * HepC: more serious --\> tx w/ antiviral drugs for some strains * vaccines? * Available for HepA and HepC patients