HPV DNA has been detected in breast milk but its origin has remained obscure. The aim of the study was to analyze the prevalence and persistence of HPV in breast milk during the first 6 month follow-up (FU) of the Finnish Family HPV cohort study. The association of breast milk HPV persistence with women’s oral and genital HPV status as well as with oral HPV status of her infant was further evaluated.
We included 308 mothers and their newborns to the study. Mothers collected the milk samples manually at day 3, month 2 and 6. Cervical and oral samples were taken before delivery, and at month 2 and 6. Oral samples from newborns were taken at delivery, day 3 and, at month 2 and 6. HPV testing was done with nested PCR and Luminex-based Multimetrix kit.
Breast milk HPV DNA was found in 10.1% (31/308), 20.1% (39/194) and 28.8% (17/59) at day 3, month 2 and 6, respectively. Of the HPV genotypes, HPV16 and HPV6 was found at day 3, HPV16 and HPV33 at month 6, while at month 2 HPV 16,18,45,53,56,59,66 and 82 were detected. Breast milk HPV persisted among 5.5% (9/164) of the women. 77.8% (7/9) of these breast milk HPV persistent infections were a single or co-infection with HPV16. At baseline, these breast milk persistors were HPV6 seropostive and HPV16 seronegative except one. Their oral samples were always HPV-negative as were cervical samples except one. 55.6% (5/9) of the breast milk persistors’ children got an incident oral HPV infection during the FU. Among these children two had a persistent oral infection with HPV16. Due to the small number of breast milk persistors no significant associations were detected between the persistent breast milk and the children’s oral incident or persistent HPV infection.
To conclude, HPV16 can persist in breast milk independent of the mother’s oral HPV status. The breast milk might have an effect on the breast milked children’s future oral HPV status.