This is a quick summary of the points taken from the TOG article which was published in July 2023. It is an important exam topic so must be covered thoroughly.
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Introduction
- Tuberculosis (TB) is one of the leading infectious causes of overall mortality
- Highest disease burden in low-resource countries
- >2/3 cases in Africa and Southeast Asia
- Co-infection of TB & HIV in reproductive years is significant
- In UK — increasing due to immigration
- Can have adverse effects on mother & fetus
Epidemiology
- Global incidence - 1990-2020 — 9.9 million with 1.3 million deaths worldwide
- Major contributors to the resurging global TB epidemic — Poverty, HIV Coinfection, Drug resistance
- In 2020 UK had 4700 cases = 6.9 per 100 000
- Risk of new migrant women having active TB highest in first 5 years of migration
- Exact worldwide TB prevalence in pregnancy - Uncertain & depends on area
- Low-prevalence countries 0.06-0.25%
- High-prevalence countries
- 0.07-0.5% (in HIV negative)
- 0.7-11% (in HIV-positive)
Pathophysiology
- Causative organism — Mycobacterium tuberculosis (non-spore-forming, aerobic & non-motile bacteria)
- Primarily airborne infection
- Can also occur through ingestion of unpasteurised milk or direct implantation
- TB particles range from 1-5 microns in size, carried to terminal alveoli and multiply there
- Alveolar macrophages ingest & destroy most of the particles, but few survive and continue to multiply
- A granuloma is formed by macrophages around the bacilli
- Usually, the immune system clears the infection, but if it fails, it remains dormant without clinical manifestations or may cause symptoms.
- ~10% immunocompromised with latent TB will develop reactivation of TB
- ~10% healthy acquire infection during their life
- Most common form of clinical TB — Pulmonary disease
- 20% active TB can present as extrapulmonary TB with cervical nodes being most common site (31%).
- Other sites are CNS, spinal cord, abdomen, pericardium (more common in immunocompromised & HIV-positive)
- Latent TB
- Primary TB (within 2 years)
- Secondary TB
Clinical Presentation
- Suspect TB if h/o exposure to patients with chronic cough or recent visits to endemic areas
- Symptoms except for Fever same as non-pregnant — weight loss, night sweats, chills, appetite loss, tiredness & weakness
- Latent disease will be asymptomatic & non-infectious but can have reactivation
- Four-symptom screening for TB suggested by WHO