Incidence and risk factors for newborn umbilical cord infections on Pemba Island, Zanzibar, Tanzania.

Background: Few community-based data exist on the frequency of cord infection signs in low resource settings, especially in Sub-Saharan Africa. We developed simple sign-based definitions of omphalitis and estimated incidence and risk factors for infection over a range of severity among neonates in Pemba, Zanzibar, Tanzania.
Methods: Infants' umbilical stump was assessed on days 1, 3, 5, 7, 10, and 14 after birth for presence of pus, redness, swelling, and foul odor. Infection incidence and proportion of affected infants was estimated for 6 separate combinations of these signs. Two definitions were examined for associations between infection and selected potential risk factors using multivariate analysis.
Results: Nine thousand five hundred fifty cord assessments (in 1653 infants) were conducted. The proportion of affected infants ranged from 16 (1.0%, moderate to severe redness with pus discharge) to 199 (12.0%, pus and foul odor), while single signs were observed in >20% of infants. Median time to onset of infection was 3 to 4 days; 90% of infections occurred by age 7 days. Breast-feeding within the first hour after birth was associated with lower risk of infection in multivariate analyses, while other maternal, and infant and care practices were generally not associated.
Conclusions: Signs of omphalitis occur frequently and predominantly in the first week of life among newborns in Pemba, Tanzania. Infection definitions relying on single signs without classifying severity level may overestimate burden. Redness with pus or redness at the moderate or severe level if pus is absent is more appropriate for estimating burden or during evaluation of interventions to reduce infection.