Infectious Diseases Flashcards
Definition latent TB
Persistent immune response to previously acquired TB without clinical evidence of infection
Percentage of the world population with latent TB
1/3
Percentage of people with TB who will progress to active disease, and timeframe for progression
10%- usually in the first 5 years after infection
Young children at particular risk for progression with high risk of disseminated TB (miliary and meningitis)
Definition of a country with significant incidence of TB
Incidence of >40 per 100,000 population
Testing for latent TB
Tuberculin skin test
> 5 years:
- >15mm if normal host with normal immune system and no TB risk factors
- >10mm if close contact/travel to a high incidence country for > 3 months
- >5mm HIV/immunocompromised
<5 years:
- >10mm if low risk and BCG, >5mm if high risk or no BCG
Interferon gold- less likely to have false positive on children who have received BCG vaccine
Assessment of child with TB contact (<5 years)
If <2 years and close contact with case of active TB- LTB treatment
TST- if positive exclude active TB (CXR and physical exam)
Assessment of child with TB contact (>5 years)
TST/Interferon gold- if positive exclude active TB
If negative and contact < 12 weeks, repeat in 12 weeks
If still negative consider BCG vaccine
Assessment of child with TB contact (immunocompromised)
Exclude active TB, treat for LTB
Treatment LTB
Main side effect
3/12 izoniazid and rifampicin (or 6/12 isoniazid alone if rif contrainidication eg. on antiretrovirals)
Add pyridoxine for BF baby, HIV, malnourished- reduced risk neuropathy
Main side effect hepatotoxicity
If a child is symptomatic, isoniazid and rifampicin should be discontinued if aminotransferase values are three times the upper limit of normal. If the child is asymyptomatic, therapy should be ceased if aminotransferases exceed five times the upper limit of normal. Rifampicin can be cautiously reintroduced when hepatotoxicity has abated. A four month regimen of rifampicin monotherapy would be appropriate
Ongoing surveillance of LTB after treatment
Not required
Incidence congenital CMV Aus
4/100 000 live births
Leading cause of congenital infections
Fetal Ix fo CMV
Fetal US- sens 30-50%, low specificity Amnio with CMV PCR: - <20 weeks 45% sens, high spec - >21 weeks 80-100% sens, high spec Sensitivty increased by waiting >6 weeks post maternal infection
Fetal US features associated with congenital CMV (9)
Microcephaly Hydrocephalus IUGR Poly or oligohydramnios Intracranial calcification, abdominal calcification Fluid- pleural or pericardial effisoons, ascites, hydrops Hepatomegaly Hyperechogenic bowel Pseudomeconium ileus
CMV transmission to fetus
Primary- 30% risk of transmission
- 10-15% symptomatic congenital CMV –> 50% risk of sequelae
- 85-90% asymptomatic congenital CMV –> 10-15% risk of sequelae
Non-primary 1% risk of transmission
- Symptomatic <1%
Transmission fo CMV across trimesters
First half of pregnanct- severe adverse neurological outcome
Second half- acute visceral disease (hepatitis, pneumonia, purpura, thrombocytopenia)
