How Useful is Screening of Donor Breast Milk?
Two of our recent posts have looked at donor breast milk for infants: one from February found that donor milk reduced rates of necrotizing enterocolitis in very low birth weight infants, and the other found that 10% of breast milk purchased over the internet contained some cow’s milk. A recent publication by Bloom looked at the frequency of potential infectious agents and contaminants in donated breast milk from screened donors.
Donor breast milk is used primarily for preterm infants who are likely to do better on breast milk, however their mothers cannot supply them with enough. There are strict screening criteria that are used for potential donors, the donors themselves are screened for several infectious diseases, and their incoming milk undergoes drug, adulteration and dilution testing, and DNA present in the milk is matched back to the donor. Milk is then pasteurized to reduce bacterial numbers in the milk.
The criteria for donating milk are rather strict, and there is some variation between milk banks. To be honest, some criteria are not related to the quality or safety of milk and seem overly restrictive, however others are understandable. For example, the Tiny Treasures Milk Bank and the National Milk Bank both require the donor mother to be generally healthy, non-smokers, not taking “medication” on a regular basis, and the infant should be doing well. Potential donors should not carry or have had intimate contact with people with the two viral diseases known to be contracted through breast milk, namely HIV and human T-lymphotropic virus 1 (HTLV-1). Some reasons for exclusion are related to the virtually non-existent risk of transmitting Creutzfeldt-Jakob Disease via breast milk, a phenomenon that has never before been seen and is mechanistically impossible, such as living in Europe for more than five years. One milk bank also does not want to include donors who have ever been infected with Human Papilloma Virus, which would presumably apply to 80% of the population (Antonsson), or around 25% of women if restricting HPV to those of genital origin (Dunne). Use of any dietary supplements for longer than 2 weeks is a potential cause for exclusion, as is consumption of products containing caffeine. Even though smoking is not a reason for mothers not to breast feed, the sensitive nature of preterm infants means that women who smoke or live with a smoker may not donate milk.
However, screening based on questionnaires requires that potential donors understand the questions properly, are completely aware of their current health status, and are honest with their answers. Despite careful screening, it was found that 0.8% of donors who did not receive financial compensation for their milk and 0.6% of compensated donors tested positive for one of the diseases for which they were screened: hepatitis B or C, HIV, HTLV-1 or syphilis. Two samples did not match the DNA of the donors, which was traced back to a mix-up in the NICU. The drug screening came back negative for illicit drugs, 0.3% of the donors failed tests for nicotine residues in milk (cotinine) and 2 were taking prescription painkillers that were not allowed. 0.7% of samples from non-compensated donors compared to 2% of samples from compensated donors were diluted, posing an infection risk.
All-in-all, it seems that only a small proportion of women are passing the screening but fail one of the blood or milk tests, and this may not be deliberate. The infectious disease tests are for diseases that have a long latent period or can be asymptomatic, and it’s possible that the women themselves were not aware that they had the diseases for which they received a positive test. The small proportion of the milk that tested positive for nicotine (cotinine) could be due to passive smoking. Even so, the higher proportion of diluted milk from women paid for expressing milk may be deliberate and due to the financial incentive for providing milk, and is a cause for concern.
Although the series of analyses performed were different to those reported in a series of articles on the safety and quality of breast milk samples purchased via the internet from Geraghty and Keim (see four articles below), the risks from carefully screened donor milk appear to be smaller than for those from milk from the internet, especially given that donor milk is pasteurized before use. The study shows that extensive screening for potential contaminants is useful to ensure the safety of pasteurized donor milk from a milk bank for use in preterm infants.
Barry T Bloom. Safety of donor milk: a brief report. Journal of Perinatology 36, 392-393 (May 2016) doi:10.1038/jp.2015.207
Antonsson, A., Forslund, O., Ekberg, H., Sterner, G., & Hansson, B. G. (2000). The Ubiquity and Impressive Genomic Diversity of Human Skin Papillomaviruses Suggest a Commensalic Nature of These Viruses. Journal of Virology, 74(24), 11636–11641. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC112445/
Dunne EF, Unger ER, Sternberg M, et al. Prevalence of HPV Infection Among Females in the United States. JAMA. 2007;297(8):813-819. doi:10.1001/jama.297.8.813. http://jama.jamanetwork.com/article.aspx?articleid=205774
Geraghty SR, McNamara K, Kwiek JJ, Rogers L, Klebanoff MA, Augustine M, Keim SA. Tobacco Metabolites and Caffeine in Human Milk Purchased via the Internet. Breastfeed Med. 2015 Nov;10(9):419-24. doi: 10.1089/bfm.2015.0096. Epub 2015 Sep 22. http://www.ncbi.nlm.nih.gov/pubmed/26394021
Keim SA, Hogan JS, McNamara KA, Gudimetla V, Dillon CE, Kwiek JJ, Geraghty SR. Microbial contamination of human milk purchased via the Internet. Pediatrics. 2013 Nov;132(5):e1227-35. doi: 10.1542/peds.2013-1687. Epub 2013 Oct 21. http://www.ncbi.nlm.nih.gov/pubmed/24144714
Keim SA, Kulkarni MM, McNamara K, Geraghty SR, Billock RM, Ronau R, Hogan JS, Kwiek JJ. Cow's Milk Contamination of Human Milk Purchased via the Internet. Pediatrics. 2015 May;135(5):e1157-62. doi: 10.1542/peds.2014-3554. Epub 2015 Apr 6. http://www.ncbi.nlm.nih.gov/pubmed/25847797
Keim SA, McNamara K, Kwiek JJ, Geraghty SR. Drugs of Abuse in Human Milk Purchased via the Internet. Breastfeed Med. 2015 Nov;10(9):416-8. doi: 10.1089/bfm.2015.0098. Epub 2015 Oct 13. http://www.ncbi.nlm.nih.gov/pubmed/26460596