Breast Milk Transmission of Cytomegalovirus (CMV) Infection

Abstract

Human CMV is highly species-specific, and humans are believed to be its only reservoirs¹. Seroepidemiologic surveys have found CMV infection in every population that has been tested including remote Indian tribes in the Amazon basin who lacked evidence of past measles or influenza infections^2,3. CMV infection is endemic and without seasonal variation. Climate does not affect the prevalence of the infection, and there are no known vectors in the natural transmission cycle. The prevalence of CMV infection increases with age, but according to geographic, ethnic, and socioeconomic factors. The pattern of acquisition of this infection varies widely among populations⁴. CMV is acquired earlier in life in developing countries and among the lower socioeconomic segments in developed countries. Differences between populations can be particularly striking during childhood, with rates of seropositivity in four to six year old children varying from less than 10 percent in Great Britain and certain populations in the United States, to nearly 100 percent in Africa and the South Pacific⁴. Presumably, these significant differences are the reflection of factors that account for increased exposure to CMV such as crowding, breastfeeding, sexual practices, and certain child rearing practices. Transmission occurs by direct or indirect person to person contact. Sources of virus include urine, oropharygeal secretions, cervical and vaginal secretions, semen, milk, tears, and blood^5,6. CMV is not very contagious; the spread of infection requires close or intimate contact with infected secretions.