The purpose of this study is to understand how breast milk may protect infants from infection and promote favorable immunological, growth and development outcomes. By following mothers and their infants, we will evaluate the important interactions between infant immune responses and infectious disease events in relation to breast milk composition and feeding patterns. Our aim is to identify a set of predictive factors corresponding to healthy early infant growth and development in this setting in Northern Tanzania.

Inclusion Criteria:

• Informed consent provided by mothers, and parental consent on behalf of their infants
• Confirmed maternal HIV status (HIV-1, HIV-2 or HIV-Dual seropositive or HIV-seronegative)
• Stated intention to remain in the clinic catchment area ≥6 months post-partum
• Singleton birth

Exclusion Criteria:

• None

HIV+ and HIV- mothers and their infants attending a semi-rural clinic and/or rural dispensaries from birth to 6 months of infant age in north western Tanzania.