Infections during breastfeeding

4.15.1

Common infections

4.15.2

Cytomegaly

Cytomegalovirus (CMV) is a ubiquitous DNA herpesvirus that causes a wide variety of clinical manifestations. The human cytomegaly virus (HCMV) is widespread, and its prevalence varies in different populations between 40 and 100%. During the pregnancy, with a fresh HCMV infection, there may be an intrauterine infection in 40–50% of cases, while 1 to 3% is the most common congenital infection. Seven to 10% of the congenitally infected children show hematological, neurological or sensory abnormalities. A perinatal infection is not significant. Infection via the mother’ milk has been documented with a reactivation of the HCMV of up to 90% in the mammary glands. HCMV-DNA has been detected in the milk, and infection of breastfed children is known. However, its course in full-term babies is asymptomatic as a rule, probably due to the passive intrauterine immunization through the placenta with IgG antibodies when a mother has had the infection. For this reason, there is no limitation on breastfeeding babies born after the 32nd week of pregnancy. Of more concern is breastfeeding or giving mother’s milk to extremely prematurely born infants (<32 SSW, <1,500 g), because they have not yet developed sufficient immune competency and have not received adequate passive immunization. Inactivation by Holder pasteurization (30 minutes at 62°C) and the gentler brief pasteurization (10 seconds at 72°C) has been documented. A good alternative seems to be brief pasteurization for 5 seconds at 62°C, which was recently tested in a German study. This makes possible certain inactivation of the HCMV-virus and, at the same time, protection of the immune factors in mother’s milk ( ). Freezing at −20°C for 24 hours or longer reduces, but does not eliminate HCMV ( , , ). The infection rate of premature infants after feeding, both with previously frozen as well as fresh milk, has been evaluated in many studies – with a range from 5 to 38% ( , , ). Four to 50% of the infected babies showed symptoms, while a case series described five seriously ill premature infants, among them one death (24+5 SSW) ( ). In other studies, the babies with symptomatic infections mostly had mild courses of hematologic ( thrombocytopenia , neutropenia ) or hepatological (transaminase increase, cholestasis ) ( , ). All of these babies recovered well with no lasting effects. In a recent meta-analysis, among 299 infants fed untreated breast milk, 19% acquired CMV infection and 4% developed CMV-associated sepsis-like syndrome ( ). Among 212 infants fed frozen breast milk, there were only slightly lower rates of CMV infection, but similar rates of sepsis-like syndrome.

Long-term studies after 2 to 4 years did not find any differences in hearing tests, motor or speech development and no neurological abnormalities with CMV-infected premature infants ( , , , ).

To date, there are no clear guidelines nor a unified procedure for breastfeeding management of premature infants of HCMV-positive mothers ( ). Recommendations of pediatric societies vary from avoiding breastfeeding, through pasteurization or freezing, to feeding with fresh mother’s milk.

4.15.3

Dengue virus

Dengue viruses are members of the family Flaviviridae genus Flavivirus. They are small enveloped viruses containing a single-strand RNA genome of positive polarity. Dengue is transmitted between humans by mosquitoes. Dengue virus can be vertically transmitted to the fetus in utero or to the infant at parturition ( ).

A case report describes breast milk as a possible route of transmission ( ). The mother was hospitalized for preterm labor and appeared to be infected with the Dengue virus during pregnancy. The preterm infant was fed with expressed milk from day 2, then breastfed. Dengue virus was detected in the breast milk (RT-PCR positive) and the breastfeeding was stopped. On day 4 the infant developed fever and his serum tested positive for the Dengue virus. Cord blood tested negative for the Dengue virus as well as the infant’s blood samples collected from day 0 and day 2. Although other routes of transmission cannot be excluded, transmission of Dengue virus through breastfeeding might be possible. Significant breast milk viral loads and breastfeeding transmission route have been described for other flavaviruses.

4.15.4

Hepatitis A

Hepatitis A virus (HAV) is a non-enveloped, icosahedral, positive-stranded RNA virus classified in the Heparnavirus genus of the Picornaviridae family. HAV is mostly spread via the fecal-oral route. Although HAV RNA can be detected in breast milk in lactating mothers with acute HAV infection, there is no indication that breastfeeding contributes to transmission of HAV from an infected mother to her child ( ).

4.15.5

Hepatitis B

Hepatitis B virus (HBV) is an enveloped DNA virus that is a member of the Hepadnaviridae family. Vertical transmission is one of the most important causes of chronic HBV infection and is the most common mode of transmission worldwide ( ). Hepatitis B is only rarely transmitted via the placenta. Breastfeeding does not appear to increase the risk of transmission, therefore, newborns whose mothers are HBsAg- and HBeAg-positive are simultaneously immunized immediately after birth. Children of HBeAg-positive mothers have a higher risk of becoming ill. HBsAg, HBeAg and HBV-DNA have been detected in mother’s milk, with the viral load correlating with that in the maternal serum ( , ). No studies have shown an increased risk of illness for the infant through breastfeeding when the mother was exclusively HBsAg positive ( , ). Among some 100 breastfeeding mothers with a chronic infection, of which 22% (11/51) were HBeAg positive, there was no indication of an infection via mother’s milk following simultaneous immunization of the infant ( ). The authors qualified their recommendation on the safety of breastfeeding with reference to the relatively small number of mother–child pairs studied, and the uncertainty of transmission with the greater infectiousness of the HBeAg-positive mothers.

4.15.6

Hepatitis C

Hepatitis C virus (HCV) is a positive-strand RNA virus. Most HCV infections are acquired through percutaneous exposure to infected blood. Sexual and household transmission of HCV does occur ( ). Mother-to-child (vertical) transmission is now the main route of infection in children ( ). Fourteen cohort studies with a total of nearly 3000 mother-infant pairs found no association between breastfeeding by women infected with HVC and the risk for transmission to infants ( ).

The guidelines of the European Paediatric Hepatitis C Virus Network, American Academy of Pediatrics, the Centers for Disease Control and Prevention, and the US Preventive Services Task Force see no evidence for hepatitis C transmission through breastfeeding, though a minimal risk cannot be ruled out ( , ). They recommend not advising against breastfeeding.