Vertical transmission of Mycobacterium tuberculosis in KwaZulu Natal: impact of HIV-1 co-infection

Abstract

Background: Increases in perinatal TB have paralleled the exacerbation of the TB epidemic in KwaZulu Natal. The exact risks for vertical transfer of Mycobacterium tuberculosis (VTRTB) to the baby are unknown, as is the impact of HIV-1 co-infection, which frequently accompanies maternal TB disease in the region.

Design: Prospective case series study of 82 HIV-1-infected and 25 non-infected pregnant mothers, King Edward VIII Hospital, KwaZulu Natal, South Africa.

Results: Perinatal mortality in HIV-1/TB diseased mothers was 85/1000 and associated with maternal anaemia (P = 0.02); 46% of newborns were premature, 66% low birth weight and 49% intrauterine growth restricted. These were significantly higher than overall hospital rates (P < 0.01, OR 4.8, 95%CI 3.2-7.0). Sites of detection of maternal TB, distribution of bacteriologically-proven TB, obstetric comorbidity and perinatal morbidity were similar in HIV-1-infected and non-infected mothers. VTRTB was detected in 16 newborns (16%), occurring similarly in bacteriologically-proven and suspected maternal TB disease, with no difference between HIV-1-infected and non-infected mothers. Eleven newborns with VTRTB were HIV-1 exposed; 64% acquired HIV-1 and died from rapidly progressive disease by 10 months of age. HIV-1-infected mothers and their exposed newborns had significantly lower CD4 counts. No association between perinatal maternal viral load, CD4 count or VTRTB was detected.

Conclusion: Mothers with TB disease in pregnancy are at risk for significant perinatal morbidity, mortality and VTRTB.