Cytomegalovirus in breast milk of Swedish milk donors

Human Breast Milk-acquired Cytomegalovirus Infection: Certainties, Doubts and Perspectives

Breast Milk (BM) is the best source of nutrition for newborns, especially if premature. In fact, its beneficial impact on short- and the long-term neonatal outcome has was deeply described. Unfortunately, BM could not be always so safe, especially due to the possible presence of maternal viruses that can be shed and transferred to the breastfed neonate. Among these, Cytomegalovirus (CMV) can potentially lead to a serious and acute illness, mostly in case of low gestational age. Some studies also report the association of CMV-acquired infection to an increased risk of structural and functional brain modifications and neurological impairment. Due to these reasons, a strategy to remove CMV from BM with a minimal or absent impact on its beneficial components would be desirable. Up to now, pasteurization, freezing, ultraviolet- C or microwave irradiation are the available techniques; they show different levels of efficacy and variable effects on BM composition, even if many studies are still needed to fully clarify these implications. In this review, we provide an update of the current evidence about these topics. We focus on the factors promoting CMV shedding through BM; moreover, the possible occurrence of a severe disease in preterm neonates is also described. Finally, we investigate the potential effects showed on BM properties by the strategies that prevent or reduce viral transmission, therefore influencing newborns' health, and the new techniques which could show a relevant role in the next future, such as metabolomics.

Primary immunodeficiency in the neonate: Early diagnosis and management

Many primary immunodeficiencies (PIDs) manifest in the neonatal period but can be challenging to diagnose and manage optimally. In part, the difficulty stems from the natural immaturity of the neonatal immune system that may mask immune deficits and/or complicate interpretation of clinical findings and laboratory assays. The great diversity of PIDs--from innate immune system defects to those that impact the humoral and/or cellular components of the adaptive immune system--and the rapid rate at which new PIDs are being discovered makes it challenging for practitioners to stay current. Moreover, recent appreciation for immune deficiencies that lead to autoinflammation and autoimmunity have broadened the spectrum of neonatal PID, adding additional complexity to an already intricate field. This article serves to highlight the deficiencies in the neonatal immune system, while providing a review of the more common PIDs that present in the neonate and guidelines for diagnosis and supportive care.

Epidemiology and transmission of Kaposi's sarcoma-associated herpesvirus

This review summarizes the current knowledge pertaining to Kaposi sarcoma-associated herpesvirus (KSHV) epidemiology and transmission. Since the identification of KSHV twenty years ago, it is now known to be associated with Kaposi's sarcoma (KS), primary effusion lymphoma, and multicentric Castleman's disease. Many studies have been conducted to understand its epidemiology and pathogenesis and their results clearly show that the worldwide distribution of KSHV is uneven. Some geographical areas, such as sub-Saharan Africa, the Mediterranean region and the Xinjiang region of China, are endemic areas, but Western Europe and United States have a low prevalence in the general population. This makes it imperative to understand the risk factors associated with acquisition of infection. KSHV can be transmitted via sexual contact and non-sexual routes, such as transfusion of contaminated blood and tissues transplants, or via saliva contact. There is now a general consensus that salivary transmission is the main route of transmission, especially in children residing in endemic areas. Therefore, there is a need to better understand the sources of transmission to young children. Additionally, lack of animal models to study transmission, gold standard serological assay and the lack of emphasis on endemic KS research has hampered the efforts to further delineate KSHV transmission in order to design effective prevention strategies.

[Review and guidelines on the prevention, diagnosis and treatment of post-natal cytomegalovirus infection]

Postnatal cytomegalovirus (CMV) infection in the newborn can occur from exposure to maternal cervical secretions during birth, ingestion of breast milk, transfusion of blood products or transmission by body fluids of infected people. Breast milk is the main source of infection, given the high rate of CMV-positive mothers excreting CMV in milk. Freezing reduces the risk of CMV transmission by breastfeeding, although it does not eliminate it completely. Pasteurisation prevents such transmission, but it can alter the immunological properties of breast milk. Postnatal CMV infection is usually asymptomatic, as it normally results from viral reactivation in the mother, and the neonate is born with protective antibodies. However, in the very low birth weight premature infant the amount of transferred antibodies is smaller and a symptomatic infection can occur. Symptomatic post-natal CMV infection in the newborn typically causes hepatitis, neutropenia, thrombocytopenia or sepsis-like syndrome. Pneumonitis and enteritis are less common, but very characteristic. Diagnosis is based on urine virus detection at the time of onset of symptoms. Postnatal CMV infection in the newborn generally resolves spontaneously without antiviral treatment. Ganciclovir should be reserved for severe cases. Unlike congenital CMV disease, post-natal CMV infection in the preterm infant does not seem to be associated with hearing loss or abnormal neuro-development in long term follow-up.

Cytomegalovirus transmission to extremely low-birthweight infants through breast milk

AIM

To determine the incidence, timing and clinical significance of acquired postnatal cytomegalovirus (CMV) in extremely low-birthweight (ELBW) infants.

METHODS

Prospective, longitudinal surveillance study. ELBW infants were recruited in the first week of life. Maternal blood was tested for CMV-specific IgG antibodies. Weekly urine samples were obtained from infants for CMV culture and rapid antigen testing. Data were collected regarding clinical course and breast milk intake.

RESULTS

Of 181 eligible infants, 119 infants, born to 101 mothers, were enrolled. Eighty of the 101 mothers had their serum checked for CMV status. Seventy percent of those tested were seropositive for CMV. Of the 65 infants born to seropositive mothers, 94% received breast milk during their hospital stay. Complete urine collection was obtained in 92 infants. CMV was cultured from the urine of only four infants, all of whom were born to seropositive mothers. Only one of these four infants was symptomatic. The range at which CMV was first detected was between 48 and 72 postnatal days of age.

CONCLUSIONS

Despite a very high CMV seropositivity rate in mothers of ELBW infants, and the previously reported high rate of CMV excretion into breast milk, the incidence of postnatal CMV transmission was extremely low in our study.

Cytomegalovirus transmission from breast milk in premature babies: does it matter?

There is evidence that CMV is commonly present in breast milk and is often transmitted to babies. CMV infection acquired postnatally can cause serious disease in very premature babies. Interventions to remove CMV from breast milk are possible but may damage other important constituents.

Breast milk transmission of viral disease

Breast milk transmission of maternal viral infection is well established for CMV and HIV-1. In the case of CMV, this usually does not pose a risk to the infant since serious disease is prevented by placentally transferred maternal antibody. However, in HIV infection, breast-feeding increases the risk of maternal-fetal transmission by about 25% with late breast-feeding (after six months of age) constituting a particular risk. In other maternal viral diseases, e.g., other herpes viruses, parvovirus, hepatitis A, B and C, and rubella, the virus is often demonstrated in the breast milk, but transmission is very rare. The highest risk is during an acute viral infection at the time of birth, since the breast milk has a high titer of virus, and a lack of antibody to neutralize the organism.

Transmission of cytomegalovirus to preterm infants through breast milk

OBJECTIVE

To evaluate the rate of virus excretion through breast milk and the incidence and significance of postnatal cytomegalovirus (CMV) transmission from mothers to premature infants.

DESIGN

Prospective study of mother-child pairs after preterm delivery before 32 weeks or birth weight < 1500 g. Exclusion of donor breast milk and of CMV-seropositive blood. Material used was maternal CMV serostatus, ear swab of the infants at birth, sequential screening of breast milk and children's urine. Methods used were CMV-DNA PCR and viral cultures on fibroblasts.

RESULTS

During a 12-month period 56 mother-infant pairs with 67 preterm infants were studied. Twenty-seven women (48%) were CMV-seronegative at birth; breast milk samples and the infants' urine remained CMV-negative. Twenty-nine women were CMV IgG-seropositive; 23 of 27 seropositive breast-feeding mothers excreted CMV through milk (85%); 25 of 27 (93%) had CMV DNA-positive results. CMV infection occurred in 17 of 67 infants (25%). CMV transmission was exclusively found in infants of seropositive mothers who excreted CMV and breast-fed their infants; 17 of 29 exposed infants became infected (59%). In 12 patients (gestational age, 29.9 +/- 1.8 weeks) CMV was detected at a postnatal age beyond 8 weeks; 5 of these infants had mild signs of a viral infection. However, 5 extremely low birth weight infants (gestational age, 24.4 +/- 0.5 weeks) were infected at an age of 4 to 7 weeks; 4 of these infants had marked symptoms of an acute CMV infection.

CONCLUSION

In mothers of preterm infants a high incidence of CMV excretion into breast milk was detected. There is evidence that the most immature infants are at the greatest risk to acquire an early and symptomatic CMV infection.

Role of milk whey in the transmission of human cytomegalovirus infection by breast milk

Breast-fed infants are susceptible to human cytomegalovirus (HCMV) infection via breast milk. In our previous study, HCMV was isolated more frequently from breast milk at later than one month after delivery than from colostrum or early breast milk. To clarify the role of milk cells and whey in vertical infection by breast feeding, we separated breast milk into milk cells and whey and examined each fraction for the presence of HCMV. We collected breast milk from mothers who breast-fed their infants (aged from 3 days to 2 months). The breast milk was centrifuged and separated into the middle layer (layer of milk whey) and the pellet (containing milk cells). We attempted to isolate HCMV from whey and to detect HCMV immediate early (IE) DNA in both milk whey and cells. HCMV was isolated from 7 out of 35 (20.0%) whey samples and HCMV IE DNA was detected from 15 out of 35 (42.9%) whey and/or milk cells. Detection rates of HCMV IE DNA in the whey layer and milk cells were 39.1% (25 out of 64) and 17.2% (11 out of 64), respectively. HCMV IE DNA was not detected in colostrum, but was detected in breast milk samples one month after delivery. Therefore, cell-free HCMV shed into milk whey may have a more important role in vertical infection by breast milk than cell-associated HCMV in the milk.

Prevalence of antibodies to herpes simplex virus types 1 and 2, Epstein-Barr virus and cytomegalovirus in teenage girls

Seropositivity to herpes virus type 1 (HSV-1), herpes virus type 2 (HSV-2), cytomegalovirus (CMV) and Epstein-Barr virus (EBV) was estimated in a group of 98 16-year-old Swedish girls. Antibodies to HSV-1 were seen in 41% of the girls and to HSV-2 in 1%, and antibodies to CMV in 45 and to EBV in 82%. In girls with coitus experience, there was significantly higher prevalence of HSV-1 and EBV antibodies, compared with girls with no sexual contact. The age of coitarche or number of coitus partners did not affect the rate of seropositivity. During 2 years of follow-up, 13 girls seroconverted. All but one EBV-seroconverting girl, were sexually active, and no girl converted for more than one type of virus. We concluded that transmission of herpes viruses is common in adolescence, and sexuality, even with regard to its close association with kissing, is one important determinant.

Detection of human cytomegalovirus DNA in breast milk by means of polymerase chain reaction

Three hundred and twenty-five breast milk samples were examined for the occurrence of human cytomegalovirus (HCMV) by cell culture method. Virus was isolated from the milk in 1 of 177 samples collected within 6 days after delivery, 2 of 115 samples collected during the period of 7 days to 1 month after delivery, 10 of 33 samples collected over 1 month after delivery. Next, we tried to amplify HCMV DNA from the breast milk samples from HCMV seropositive mothers and seronegative mothers at 1 month after delivery by polymerase chain reaction. HCMV DNA was detected in 12 of 13 samples from seropositive mothers and in none of 7 samples from seronegative mothers. It was thought that all women seropositive for HCMV principally shed the virus into their breast milk at 1 month after delivery.

Early acquisition of cytomegalovirus infection

Two hundred and fifty three infants were screened for cytomegalovirus (CMV) in the urine at birth and were followed up at regular intervals for one year. Twelve per cent (of 249) were excreting virus at 3 months, and 20% (of 234) at 12 months. In all cases infection was subclinical. The major factors determining risk of acquiring infection were the mother's serological state and whether the infant was breast fed. There was no association with social class, mother's age, or whether the child had been in a special care baby unit or a postnatal ward. By one year 33% (of 123) of infants of seropositive mothers had acquired CMV infection compared with 4% (of 123) born to seronegative mothers. Twenty per cent (17) of seropositive women who breast fed had virus isolated from their breast milk on at least one occasion, and 76% (13) of their infants became infected. In four mother-infant pairs comparison of CMV isolates from the mother's milk and the child's urine was made by restriction endonuclease digestion; in each pair infection had apparently occurred with the same strain of virus. All 13 infected infants followed up for three years were still shedding virus. Infection with CMV is common in infancy, and virus shedding persists for years. Congenital infection cannot be distinguished from acquired infection unless the presence of CMV in the urine is identified within three or four weeks after birth, even when clinical problems suggestive of congenital infection are present.