The baby who had contracted the yellow fever infection had no history of herpes infections in family members and had not had any vaccinations prior to his symptoms.
Also, the baby showed no sign of insect bites, had not been in contact with sick people, was not exposed to animals.
The authors further state, "This probable case of yellow fever virus further supports the current recommendations for avoidance of yellow fever vaccination in lactating mothers of infants under nine months of age. While there may be situations in which the mother will have unavoidable and significant risk of yellow fever exposure, the risk to the infant due to maternal vaccination must be weighed against the risk of wild-type virus infection."
The authors conclude that traveling women should adjust their plans to reduce or limit their risk of exposure to yellow fever infection or postpone their trip entirely until their infant is no longer breastfeeding or is old enough to be vaccinated.