Cow's milk and the emergence of group B streptococcal disease in newborn babies.

BACKGROUND: Group B streptococcus (GBS), the most significant cause of neonatal bacterial sepsis, is thought to have emerged in the 1960s. GBS also causes mastitis in cows, and there is indirect evidence that human GBS is derived from a bovine ancestor.
OBJECTIVE: A major change in the collection of milk from farms, using bulk tanks rather than churns, occurred in the 1960s. We sought to define the temporal relationship between this change in farming and the emergence of GBS neonatal disease.
METHODS: We searched PubMed for reports of GBS disease from 1930 until 1980 to more exactly determine the time of emergence of neonatal infection and supported this data with UK hospital admission statistics for GBS infections. We identified the dates of the change from churns to bulk tanks by searching the internet and books for information on the history of milk transportation, farming and milk collection in the UK.
RESULTS: There are no PubMed reports of neonatal GBS disease between 1930 and 1950, and reports from the UK only emerged in the mid-1960s, confirming the notion that GBS neonatal infection was a newly emergent disease in the 1960s. No national data on hospital admissions are available around this time, but the Oxford Record Linkage Study, with admission data available for Oxford from 1968, showed no cases of neonatal disease until 1974. Cow's milk collection in the UK switched to bulk tank between 1960 and 1979, and publications relating to GBS disease emerged soon after.
CONCLUSIONS: There is a temporal relationship between the emergence of neonatal GBS disease reports in the UK in the 1960s and a change in cow's milk collection. This finding may be a temporal coincidence or may add support to the notion that human GBS was historically derived from a bovine ancestor.