Rates of diarrhoea associated with early weaning among infants in the Kisumu breastfeeding study
Polly Clayden, HIV I-Base
The Kisumu Breastfeeding Study (KiBS) in Kenya is an ongoing study to assess the effect of HAART from 34 weeks gestation through 6 months postpartum on HIV transmission and infant health. Women in KiBS are encouraged to wean at 6 months and over 2 weeks before HAART is discontinued. Mothers are instructed to use local foods while weaning. 
Timothy Thomas and coworkers compared rates of diarrhoea and related hospitalisations during the first year of life of HIV-negative infants in KiBS with HIVnegative infants of HIV -positive mothers in a vertical transmission study conducted from 1996 to 2001 in Kisumu. In this study no infant nutrition intervention was promoted; infants were fed according to traditional feeding practices, which often involves introduction of complementary foods and water by 2 to 3 months and breastfeeding beyond 12 months.
The investigators reported that when the two studies were compared, overall diarrhoea incidence over the 12 months was significantly lower in KiBS (5.7 episodes/100 infant-months of observation) than in the vertical transmission group (8.7; RR = 0.66; 0.55 to 0.79). They found KiBS diarrhoea rates peaked during the peri-weaning period at 6 and 7 months and then declined in contrast to vertical transmission rates, which remained elevated after 3 months. Serious diarrhoea resulting in hospitalisations peaked in KiBS at 6 months and was significantly higher overall than in vertical transmission (RR = 3.60; 2.31 to 5.63). There were 2 HIV KiBS infant deaths due to diarrhoea (ages 7 and 12 months).
The investigators suggested that the peak in diarrhoea rates at 6 and 7 months would appear to reflect: loss of maternal antibodies in the infant; increased exposure to pathogens during weaning or as infants become more mobile and put things in their mouths. They noted that the decline in diarrhoea rates at 8 to 12 months requires further evaluation. And despite significant differences in reported infant feeding practices there was no difference in overall diarrhoea rates for the first year of life between the two studies.
Table 1: Rates of diarrhoea associated with early weaning among infants in the Kisumu breastfeeding study
|All diarrhoea, KiBS (n=144)||2.6||3.6||5.0||5.6||6.5||9.6||3.9||4.0||3.6||4.7||3.1||5.7|
|All diarrhoea, vertical transmission (n=347)||3.0||4.5||9.7||9.7||5.7||11.6||9.6||11.2||9.7||11.5||8.7|
|Hospital, KiBS (n=44)||0.4||0.9||0.5||0.9||1.9||6.6||3.8||2.0||1.0||1.5||1.0||0.5||1.8|
|Hospital, vertical transmission (n=34)||0.1||0.3||0.2||0.5||1.2||0.5||0.4||0.8||0.6||0.8||0.5||0.5||0.5|
- Thomas T, Masaba R, van Eijk A et al. Rates of diarrhoea associated with early weaning among infants in Kisumu, Kenya. 14th CROI, 25-28 February 2007, Los Angeles. Abstract 774.