Infectious disease Flashcards

1
Q

What type of virus is Hep B virus?

A

Enveloped DNA virus

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2
Q

What is the definition of chronic hepatitis B?

A

HBsAg positive for > 6 mo AND absence of anti-HBs antibody

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3
Q

What is the most common route of transmission of HBV?

What are the other routes?

A

Vertical is the MOST common route of transmission

High prevalence areas –> perinatal transmission

Intermediate prevalence –> horizontal (child to child) in early childhood

Low prevalence –> Unprotected sex, IDU

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4
Q

Is breastfeeding contra-indicated in HBV?

A

No, HBV is not spread through breast milk

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5
Q

What is the significance of HBeAg?

A

Active replication of the virus

(CAUTION: 30 % have mutation that prevent HBeAg expression)

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6
Q

What is the rate of neonatal transmission of hep B with and without PEP?

A

With: 2 %

Without:

  • 90 % (mother HbeAg+)
  • 15 % (mother HbeAg-)
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7
Q

Name factors that increase perinatal transmission of Hep B (5)?

A

HbeAg +

High viral load (DNA)

Genotype

Resistant virus

Altered timing of PEP

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8
Q

What is the single strongest factor driving perinatal transmission of Hep B?

A

HBV DNA viral load

(Often in viral load > 200 000 ≈106)

Even in the presence of appropriate neonatal PE

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9
Q

Does Hep B increase adverse pregnancy outcomes?

A

Chronic: None (no increase in SAB, PTB etc)

Acute:

Low birth rate

Prematurity

Increased perinatal transmission:

  • 10 % if maternal infection in early pregnancy
  • 60 % if maternal infection at or near the time of delivery
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10
Q

In cases of pre-natal serologies positive for HBsAg, what other test should you order?

A

HBeAg

HbeAb (anti-HBe)

HbcAb (anti-HBc)

Hbc IgM (Anti-HBc IgM)

HBV DNA levels

Liver enzymes, bili, coags, CBC

Ultrasound of the liver

Hepatology/ ID consult

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11
Q

What the indications for HBV treatment in pregnancy?

A

1- Maternal reasons

2- Prevent transmission

HBV viral load > 200 000 (>106)→ start treatment at 28+32 weeks

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12
Q

What is the PEP regimen to prevent Hep B transmission to newborn

A

HBIG 0.5 mL IM

+

Hep B vaccine 0.5 mL IM (1st of 3 doses)

Given within 12h of birth

**f baby is preterm or wt < 2000g, needs 4 doses of vaccination (vs 3)**

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13
Q

What additional testing does complicated VVC warrant?

A

Testing for HIV and DM

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14
Q

What is the definition of complicated VVC?

A

Recurrent (> 4 episodes in 12 month)

Associated with severe symptoms

Non-albicans species

Present in immunocompromised host

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15
Q

Laboratory findings in Candida infections (3)

A

pH < 4.5

Wet mount: Budding yeast and pseudohyphae

Gram stain: polymorphonuclear cells, budding yeast, pseudohyphae

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16
Q

What are the RF for yeast infection (4)?

A

Sexual activity

Recent abx use

Pregnancy

Immunosuppression (HIV, poorly controlled DM)

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17
Q

What are the options to treat non albicans VVC?

A

Boric acid insert

Flucytosine cream

Amphotericin B suppository

Nystatis suppository

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18
Q

What is the other name for strawberry cervix and what is it associated to?

A

Colpitis macularis

Associated to trichomonas

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19
Q

Describe the Amsel criteria (4)

A

3 out of 4 for BV diagnosis

  • Adherent and homogenous vaginal discharge
  • Vaginal pH > 4.5
  • Detection of clue cells on saline wet mount
  • Positive wiff test (amine odour after addition of K hydroxide)
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20
Q

Name the reasons to prescribe supressive treatment for HSV (5)?

A

At least 6 recurrences per year

Less than 6 recurrences but significant complications with recurrences

Need to lower risk of transmission to partner, fetus, neonate

Problem with QoL

Social or sexual dysfunction

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21
Q

What are the treatment schemes for herpes ?

A

1- Episodic treatment

2- Supressive treatment (only effective during treatment)

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22
Q

What is the classic triad of NEONATAL HSV infection

A

Skin lesions

Chroniretinitis

CNS abnormalities (seizures, lethargy etc)

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23
Q

What is the risk of neonatal HSV infection in :

1- Primary infection

2- Recurrence

What is the risk of post-natal infection without prevention?

A

1- Primary infection: 30 - 50 %

2- Recurrence: < 1 %

Post-natal infection without prevention: 15 %

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24
Q

Describe CONGENITAL neonatal HSV

A

Microcephaly, hydrocephaly, ventriculomegaly

Hepatosplenomegaly

Echogenic bowel

Spasticity, flexed extremities

IUGR

IUFD

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25
Q

What is the treatment of maternal primary HSV infection?

A

Non severe maternal disease

Acyclovir 400 mg po tid × 7–10 days

Valacyclovir (Valtrex) 1 g po bid × 7–10 days

Severe maternal disease

Acyclovir 5-10 mg/ kg q 8h until clinical improvement then PO tx x 10 days

Prophylactic regimen at 36 weeks

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26
Q

How do you manage a HSV discordant couple (male infected, mother non infected) in pregnancy?

A

Type specific serologies in the mother before or as soon as pregnant

Repeat maternal serologies at 32 -34 weeks

Abstinence for any relations

Condom + supressive therapy in partner

27
Q

What are the different types of HSV infection?

A

Primary infection

(flu like, lesions, tender LN + miction)

Non-primary first episode

(infection with other virus type)

Recurrent

Asymptomatic shedding

28
Q

What are the tests to diagnose HSV (2+2) + (2)?

A

1- Viral identification tests

  • Viral culture
  • Viral NAAT
  • Immunofluorescent staining (lack sensitivity)
  • Tzanck test (lack sensitivity)

2- Serologies (good negative predictive value)

  • Type specific
  • Non type specific
29
Q

Name risk factors to HSV infection (8)

A

Female

Older age

Non-caucasian

Immunocompromised

Hx of any STI

Hx of genital lesions in self or partner

Multiple sexual partners

Low socio-economic level

30
Q

What kind of organism is Trichomonas Vaginalis?

To what kind of cells does it adhere?

A

Anaerobic parasitic protozoan (flagellated)

Adheres to epithelial cells

31
Q

What is the most common non viral STI?

A

Trichomonas vaginalis

32
Q

Describe symptoms of Trichomonas

A

Asymptomatic 60 - 90 %

Symptomatic

Significant increase in vaginal discharge

Green, yellow, Malodorous, Frothy appearance

Pruritus: Vulvitis, vaginitis

Dysuria, Dyspareunia

Colpitis macularis on genital mucosa and cervix (strawberry cervix)

33
Q

Describe the 3 diagnostic methods for Trichomonas vaginalis

A

- Wet mount (direct visualization of parasite)

- Vaginal culture

- Antigen testing (most specific/sensitive)

NAAT or immunoassays

34
Q

What is the treatment of Trichomonas?

A

Flagyl 500 mg PO BID x 7 days

OR

2g PO x 1

35
Q

What are the treatment options for Trichomonas resistant to Flagyl?

A

Tinidazole 2 g PO x 1

Longer/ higher doses of flagyl

36
Q

Is a test of cure required for Trichomonas?

A

NO according to SOGC Guidelines

UpToDate

Between 2 weeks - 3 months after completion of treatment

High re-infection rate (20%)

37
Q

Should you treat the partner of a patient with trichomonas?

A

Yes - even without testing them

38
Q

What is the recommended treatment for BV ?

A

Flagyl 500 mg PO BID x 7 days

Flagyl gel 0.75 % - 5g PV daily x 5 days

Clinda cream 2 % - 5 g PV daily x 7 days

Alternative

Flagyl 2g PO x 1

Clinda 300 mg PO daily x 7 days

39
Q

What are the indications for long term supressive BV therapy?

What are the treatment regimen?

A

> 3 documented episodes in 12 months

  • Metronidazole gel 0.75 %
  • Oral nitroimidazole x 7-10 days then twice weekly gel x 4-6 mo
  • Clinda gel less effective but ok if allergic to flagyl – can also desensitize
40
Q

What is the treatment of vaginal warts in pregnancy?

A

TCA only

41
Q

What therapies are effective for treating vaginal warts (4)?

A

TCA

BCA

Interferons

Laser ablation

42
Q

When should you test for HIV status is pregnancy (3)?

(# 185)

A

At first appointment (tx initiated at 15 -19 wks)

In every trimester if HIV neg but high risk behaviours

In labour if HIV status unknown (if high risk, offer prophylaxis + fetal tx)

43
Q

Name high risk behaviours for HIV (5)?

(#185)

A

Sharing needles during IV drug use

Unprotected sex with multiple partners

Unprotected sex with a known HIV-positive individual

Unprotected sex with a partner from a known endemic area

Unprotected sex with a partner participating in known high risk behaviours

44
Q

After how long on cART is it considered safe to have condomless intercourse?

(#354)

A

Minimum: on cART for a minimum of 3 months AND 2 negative viral loads one month apart

Ideal: viral load negative x 6 months

Acceptable: viral load negative x 3 months

45
Q

Are HCV medication safe during pregnancy?

(#354)

A

Not safe in pregnancy and immediate pre-conception

Should treat (and cure) HCV pre-conceptin

For male, new HCV Rx are safe during pre-conception except for Ribavarin (to stop 6 months before)

46
Q

What are the outcomes of HIV + patients in fertility treatments (4)

(#345)

A

↓ implantation

↓ clinical pregnancies

↓ birth rates

Possible tubal factors for non IVF pregnancies

47
Q

When should you refer a HIV + couple to fertility ?

(#345)

A

After 6- 12 months of attempts at home (condomless sex, home insemination)

48
Q
A
49
Q

What is the riskf of HIV transmission through breast milk ?

(# 310)

A

Approx 10 %

9.3 (3.8 - 14.8)

50
Q

What are the criteria to plan a elective CS for HIV infected mother?

(#310)

A

Unknown viral load

Viral load > 1000 copies/mL

No cART during pregnancy, regardless of viral load

** Only benefit is for scheduled CS (not in labour)

51
Q

What medication should be given to HIV + mother that present in labour?

(#310)

A

IV ZVD = Zidovudine (2 mg/kg/h then 1 mg/kg/h) - to everyone

+/-

Nevirapine 200 mg PO x 1 – if no cART

If unknown status and high risk, give ZVD Nevirapine

52
Q

What is the only pre-requisit for a SVD in HIV + patient?

(#310)

A

Viral load < 1000 within 4 weeks of delivery

53
Q

Which cART should be stopped in labour and why?

(#310)

A

Stavudine (d4T) as it interacts with ZVD= Zidovudine

54
Q

What blood work HIV related should you ask for at the first visit?

(#310)

A

CD4 count

HIV Viral load

HIV genotype drug resistance

HLA-B*5701 at baseline

55
Q

What common obstetrics Rx should not be used in combination to cART?

(#310)

A

PPH: Ergotamine

Stop breast milk : Bromocriptine + Cabergoline (borth derivative of ergot)

Ergotamine causes exaggerated vasoconstriction in patients on Protease inhibitors

56
Q

When should you test an infant for HIV infection ?

(#310)

A

Basic testing with HIV PCR

  • At birth
  • 4 weeks
  • 3-4 months

To exclude HIV

2 HIV virological test non reactive:

  • After 4 weeks of age and
  • > 4 weeks after end of prophylactic antiretrovirals
57
Q

How long can mother’s HIV AB stay in infant’s blood?

(#310)

A

18 -24 months

58
Q

What is the gloves and socks rash associated with ?

(# 316)

A

Parvo B19

Mostly in adults - Children get Slap cheeks rash

59
Q

What is the most common symptom in adults with parvo B19?

(#316)

A

Arthropathy

Symmetric polyarthralgia (hands, wrists, ankles, knees)

May last weeks to months

60
Q

What are the different presentations maternal and fetal of parvo infection (5 + 3)

A

Maternal

  • Asymptomatic
  • Erythema infectiosum
  • Arthralgia
  • Anemia + transcient aplastic crisis
  • Myocarditis

Fetal

  • Anemia (+ hydrops)
  • Myocarditis
  • Fetal loss
61
Q
A
62
Q

How long can IgM remain positive in Parvo/ CMV/Toxo?

A

Parvo : 6 months

Toxo: years

CMV: months

63
Q

% Spontaneous resolution of hydrops in Parvo ?

A

30 % over course of 4+6 weeks

(more common in older fetuses as immune sme more developped)

64
Q

Name reasons to perform amnio in Toxo infection (3)

(285)

A
  • Confirmed diagnosis of maternal infection
  • Cannot confirm or exclude maternal infection by serologic testing
  • Abnormal US findings (Intracranial calcifications, microcephaly, hydrocephalus, ascites, hepatosplenomegaly, severe IUGR)