Tuberculosis (TB), an infection caused by the organism Mycobacterium tuberculosis, can be congenital or acquired in the postnatal period.
The World Health Organization (WHO) estimates an incidence of 10.4 million new TB cases and 1.3 million TB deaths in 2016. Although congenital TB is rare, with about 350 cases reported in the English literature, the mortality rate is as high as 50%.
M tuberculosis transmission occurs via inhalation of airborne droplet nuclei, which are carried by alveolar macrophages through the lymphatic system to hilar lymph nodes. The infection can either be contained or lead to primary progressive TB. Infected macrophages interact with T lymphocytes to release cytokines that promote phagocytosis of M tuberculosis, leading to granuloma formation within 2 to 8 weeks in most individuals. Young children and immunosuppressed individuals lack host immunity and instead develop active primary progressive disease in the lung parenchyma and hilar lymph nodes. In these individuals, the characteristic fibrous granuloma capsule becomes disrupted, causing liquefactive necrosis of the central caseous material. The necrotic material can then flow into adjacent vasculature and disseminate systemically or to adjacent bronchi and spread externally via respiratory droplets. Immunosuppression and malnutrition are risk factors for reactivation of latent infection.
Vertical transmission causing congenital TB can occur due to hematogenous spread via the umbilical vein leading to a primary tuberculous lesion in the liver or lung. Alternatively, fetal aspiration or ingestion of infected amniotic fluid can lead to pulmonary or gastrointestinal TB.
The highest risk of transmission to newborns occurs via respiratory transmission from untreated mothers during the postnatal period. This is more common than congenital TB, and diagnosis of neonatal TB can lead to identification of previously unrecognized diagnosis of TB in the mother. Maternal extrapulmonary TB, such as miliary TB or tuberculous endometritis, increases the risk of congenital infection. Maternal treatment for 2 to 3 weeks in the antenatal period reduces the risk of postnatal infection. Human immunodeficiency virus (HIV) is a risk factor for maternal TB, which in turn increases the risk of mother-to-child transmission of HIV. Living in endemic areas or crowded conditions also increases the risk of TB.
Pregnancy. Pregnant women with TB tend to have fewer of the typical symptoms associated with TB. Active TB symptoms and signs include fever, cough, night sweats, anorexia, weight loss, general malaise, and weakness. Extrapulmonary TB can affect the genitourinary tract, bones and joints, meninges, lymph nodes, pleural lining, and peritoneum. Extrapulmonary TB is more common when there is co-infection with HIV. The natural history of TB is thought to be unaffected by pregnancy. Maternal TB, especially extrapulmonary disease, does increase pregnancy and perinatal complications such as preeclampsia, vaginal bleeding, early pregnancy ...