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Introduction
Human milk, in addition to its nutritional components, contains
numerous cells, membranes and molecules whose function is to protect
newborn infants. In lactating women, the enteromammary or bronchomammary
immune system is activated when pathogens (bacteria) come in contact
with the mucous membranes of the intestine or respiratory tract
and are phagocytosed by macrophages. This stimulates T lymphocytes,
causing the differentiation of immunoglobulin A (IgA)-producing
B lymphocytes. Lymphocytes migrate to the mammary gland and, mediated
by cytokines, turn into plasma cells that produce a glycoprotein,
which binds to IgA, and eventually turns into secretory immunoglobulin
A (sIgA). This is an important and specific protective function
of human milk in newborns ().
Breastfeeding, given its benefits to mother and infant, is considered
to be the best form of nutrition for infants. However, maternal
and infant diseases may hinder breastfeeding. Under these circumstances,
the health professional should be skilled, have technical knowledge
and adopt a favorable attitude so as to properly assess the viability
of breastfeeding. When the nursing mother presents with the symptoms
of a disease, she has already exposed her infant to the pathogen
and the usual recommendation is that breastfeeding should be maintained
().
If the mother discontinues breastfeeding after symptom onset, infant
protection against diseases is decreased, and the chances of the
infant falling ill are increased, since he/she is not provided with
specific antibodies and other protective factors from human milk.
No recommendation to discontinue breastfeeding, even if temporarily,
exists in cases of mothers with urinary tract infection, bacterial
infection of the abdominal wall, episiorrhaphy, mastitis or any
other disease in which the nursing mother's physical conditions
and general state of health are not so compromised.
Although human milk contains antibodies, mononuclear cells and
other protective factors, it may be a possible source of infection
for the infant in some maternal diseases ().
The mononuclear cells in human milk, albeit providing protection,
may transfer infectious particles from the mother to the infant.
Thus, when health professionals attend to a nursing mother with
active viral infection or another infectious disease, they may become
uncomfortable about whether they should discontinue or not breastfeeding,
as their role is to promote and encourage it.
Some infectious diseases may impede breastfeeding, either on a
temporary or permanent basis, due to maternal physical conditions
such as severe cardiac, renal, and hepatic diseases, psychosis and
severe postpartum depression ().
In the present review, we discuss breastfeeding management in the
presence of common maternal diseases caused by bacteria, viruses,
parasites and fungi.
Viral infections
In several maternal viral diseases, such as hepatitis, herpes, measles,
mumps and rubella, among others, the virus may be excreted into
human milk. However, except for infections caused by retroviruses,
human immunodeficiency virus (HIV-1), human T-lymphotropic virus
type I (HTLV I) and human T-lymphotropic virus type II (HTLV II),
transmission via human milk has little epidemiological relevance.
In most maternal viral diseases, other sources of contamination
of newborns should be considered before ascribing the cause to breastfeeding
only. The risk of transmission may be enhanced in cases of acute
infection at delivery, as the milk may contain a high concentration
of viral particles and low titers of protective antibodies able
to neutralize the infectious agent. Therefore, in general, there
is no formal contraindication for breastfeeding in most cases of
viral diseases, except for diseases caused by retroviruses.
The transmission of RNA retrovirus, including HIV-1 (),
HTLV I and HTLV II ()
has already been demonstrated. HIV-2 can also be transmitted from
mother to infant, but the role of breastfeeding in the transmission
via human milk has not been clearly established yet. The Epstein-Barr
virus and herpesvirus 6 can be found in human milk, but so far,
reports on breastfed infants infected by these viruses have been
few and far between. To some extent, the fact that breastmilk is
not much more infectious is surprising, especially due to the daily
volume ingested by exclusively breastfed infants. Supposedly, there
may be other protective factors than those widely known.
Table 1 summarizes the most important infections, with possible
transmission of the virus to the infant via breastmilk, and the
corresponding breastfeeding management.
Table 1 -
Maternal viral infections and the corresponding breastfeeding management
HIV infection
HIV is excreted freely or into cells in the milk of infected women,
who may or may not present with symptoms of the disease. Approximately
65% of vertical HIV transmission occurs during labor and during
delivery; the remaining 35% occurs in utero, mainly within the last
weeks of gestation and via breastfeeding. The viral load in breastmilk
is an important determinant for the risk of transmission ().
In newborns, the virus penetrates the nasopharyngeal and gastrointestinal
mucosae. During breastfeeding, viral transmission may occur at any
stage, but it seems to occur more often within the first weeks and
especially in most recent maternal infections. The viral load in
colostrum is significantly higher than in mature milk. Mixed breastfeeding
seems to pose more risks than exclusive breastfeeding, due to the
major injury to the gastrointestinal mucosa resulting from artificial
feeding, which favors the penetration of the virus ().
The additional risk of transmission of the virus via human milk
ranges from 5 to 20% ().
Contamination via breastmilk in women who acquired the infection
after the postnatal period was detected in 29% (15-53%) of cases
().
The presence of HIV-infected cells in breastmilk for over 15 days
after delivery is an important predictive factor for infection in
the infant ().
Retroviruses can infect mammary epithelial cells before delivery,
and can be found free or infecting monocytes in milk, which account
for 50% of cells found in breastmilk. These cells can potentially
carry the virus from the maternal bloodstream or from lymphoid tissues
to the infant's intestine. Some types of HIV use chymosin receptors
to infect macrophages. However, more studies are necessary to accurately
define the role of human milk cells in HIV infection ().
The use of antiretroviral therapy during pregnancy and delivery
and its maintenance in newborns results in a decrease in vertical
HIV transmission for up to six months after childbirth (),
even if breastfeeding is maintained. Nevertheless, HIV infection
is one of the few situations in which the contraindication for breastfeeding
is a common agreement. In Brazil, The Ministry of Health ()
recommends that HIV-infected mothers should not breastfeed. On the
other hand, the World Health Organization and UNICEF recommend that,
in poor countries, where diseases such as diarrhea, pneumonia and
malnutrition substantially contribute to high rates of infant morbidity
and mortality, the benefits of breastfeeding should be considered
in relation to the risk of HIV transmission. In these cases, and
if it is not possible to provide appropriate artificial feeding,
breastfeeding should be maintained, given its benefits to infants
who live in precarious conditions ().
Women who receive combined antiretroviral therapy have lower rates
of viral transmission ().
Preliminary information obtained from a study conducted in South
Africa considers that it is possible to reduce or prevent the risk
of postnatal transmission of HIV if the infant receives human milk
for a short period of time ().
The idea is to maintain breastfeeding for four to six months. However,
the efficacy and safety of such practice has not been demonstrated
yet, and studies still have been underway.
Another alternative is to reduce or eliminate HIV from human milk.
Infected cells can be removed from milk, but viral particles are
difficult to eliminate. The inactivation of HIV in breastmilk through
pasteurization (62.5 ºC for 30 minutes, followed by rapid cooling)
allows infants to continue receiving breastmilk without increasing
the postnatal risk of infection ().
HTLV infection
HTLV belongs to the retrovirus family, the same of HIV. They are
human T1 and T2 lymphotropic viruses called HTLV I and HTLV II.
Type I causes a rare type of leukemia, myelitis and eye infection
that may result in blindness. HTLV II is not associated with disease.
They can be transmitted via blood, infected needles, sexual intercourse
and from mother to infant by means of breastfeeding. The principal
mode of transmission is vertical, but the predominant one is via
breastfeeding.
Although HTLV affects a small portion of the population, with possible
late development of diseases in only 1 to 4% of infected individuals,
its occurrence has increased in South America, especially because
of the lack of health surveillance. As the disorders caused by these
retroviruses are severe and cannot be treated or controlled with
efficient therapy and vaccine, contraindication for breastfeeding
in infected women is a major way of reducing their vertical transmission.
In Japan, freezing the milk of HTLV I-positive mothers at -20 ºC
has been used as a way to inactivate the virus. However, the Center
for Disease Control and Prevention (CDC) establishes that every
HTLV I-infected mother should be advised not to breastfeed, and
does not have an opinion on the freezing of human milk in this situation.
CDC considers the current data on HTLV I transmission via frozen
and thawed breastmilk to be insufficient.
The amount of HTLV I-infected cells in peripheral blood is very
small compared to the number of infected T cells in breastmilk,
which explains the high risk of viral transmission via human milk.
Some risk factors have been considered in the transmission of HTLV
I and II via human milk: breastfeeding for over three months, advanced
maternal age, antigen levels in maternal blood and high titers of
HTLV I antibodies in the nursing mother ().
However, Van Dyke et al. ()
report that the transmission of HTLV II from mother to infant may
occur regardless of the type of feeding the infant receives in similar
rates to those of HTLV I, thus showing that the virus can be transmitted
to the infant in the absence of breastfeeding.
Hepatites A, B and C
Hepatitis A, B and C viruses can be transmitted to the infant during
pregnancy, delivery or postnatal period. Viruses transmitted by
the oral-fecal route, as in hepatitis A, have a higher chance of
being transmitted to the infant at delivery.
The hepatitis A virus can be excreted into human milk in the acute
phase of the disease. When delivery occurs in this phase of the
disease, the infant should receive anti-hepatitis A immunoglobulin
at the dose of 0.02 ml/kg as prophylactic measure. This prophylaxis
is indicated for all infants, regardless of whether they are being
breastfed or not, and provides protection that outweighs the risk
of the infant acquiring the disease. Thus, breastfeeding is not
contraindicated ().
Hepatitis B and C viruses are transmitted hematogenously and sexually.
Hepatitis B surface antigen (HBsAg) has been detected in the milk
of HBsAg-seropositive women, and possibly, small amounts of blood
might be ingested by the newborn infant during breastfeeding, from
nipple injuries, even if these injuries are small. However, the
major mode of transmission is infant exposure to maternal blood,
which occurs throughout labor and delivery ().
In case of HBsAg-seropositive mothers during pregnancy, the infant
should receive the first dose of the vaccine immediately after delivery
and hepatitis B hyperimmune immunoglobulin (0.5 ml IM) in the first
12 hours of life, given concomitantly, but in different sites. This
practice has an efficiency of 95% and eliminates the occasional
risk of transmission via breastmilk ().
When the mother has not been tested for HBsAg or if this information
is not available, the test should be requested immediately after
delivery. While the test result is not available, the newborn should
receive the first dose of the vaccine. If the test yields a positive
result, immunoglobulin should be given as soon as possible, within
the first seven days after delivery. However, if HBsAG testing is
not possible, giving all newborns immunoglobulin is not recommended,
since the vaccine alone is quite efficient in preventing the disease
in 70 to 90% of cases ().
In cases of HBsAg-positive mothers, newborns should be thoroughly
washed, in order to remove all traces of blood or maternal fluids.
Breastfeeding is not contraindicated even if the mother has a bleeding
nipple fissure.
The Brazilian Society of Pediatrics recommends that preterm newborns
weighing less than 2,000 g born to an HBsAg-positive mother should
receive four doses of the vaccine (at birth, at 1, 2 and 6 months
of life) besides immunoglobulin ().
If the first dose is not administered in the neonatal period, then
the infant should receive the three conventional doses of the vaccine.
In all situations, breastfeeding should be recommended. In mothers
with an infant aged less than one year and with hepatitis B diagnosed
during the breastfeeding period, breastfeeding should be maintained
and the infant should be tested for HBsAg, since he/she received
the vaccine at birth. If the result of the test is negative, the
infant should be revaccinated and the prophylactic measures for
the case should be followed, that is: administer hepatitis B immunoglobulin
(HBIG) intramuscularly at the dose of 0.04 ml/kg, or standard gammaglobulin
at the dose of 0.12 ml/kg IM ().
Although hepatitis C virus has been detected in the milk of HCV-positive
mothers, its transmission via breastmilk has not been confirmed.
Therefore, breastfeeding is not contraindicated in HCV-positive
mothers. However, the prevention of nipple fissures is very important,
as it has not been yet determined whether the infant's contact with
maternal blood can facilitate the transmission of the disease. The
American Academy of Pediatrics Committee on Infectious Diseases
recommends that mothers be informed of the theoretical (but yet
not confirmed) risk of transmitting the virus via breastmilk. The
decision to breastfeed should be analyzed on a case-by-case basis,
assessing the role of breastfeeding in the infant's life, since
the definite role of breastfeeding in the transmission of hepatitis
C virus to the infant is not known ().
Cytomegalovirus infection
Cytomegalovirus (CMV) can be intermittently excreted in saliva,
urine, genital secretions and human milk for several years after
the primary infection and in case of reactivation of its latent
forms. Infant or fetal infection may be acquired from mothers with
primary infection or during reactivation of the infection, occurring
more frequently while the baby passes through the birth channel
or in the postnatal period. However, due to the transplacental transfer
of antibodies, this disease is not common among newborns.
In postnatal infection, the correlation with breastfeeding is evident,
although the virus may be acquired from the contact with other seropositive
individuals who share the same household. Studies show that 30%
of breastfed infants born to seropositive mothers acquire the infection
in the first years of life, amounting to 70% of the cases when the
virus is isolated in breastmilk. Nevertheless, symptomatic infections
or late sequelae have not been observed in babies, possibly due
to the transfer of specific maternal antibodies that protect the
infant against systemic disease. Early contamination of the breastfed
infant seems to be preferred, because if contamination occurs later
on, the risk for symptomatic disease is higher. These data confirm
that breastfeeding should not be contraindicated ().
However, special attention should be given to preterm babies, especially
those with a lower gestational age. The decision to breastfeed preterm
infants of CMV-positive mothers should be considered in terms of
risk of transmission of the disease versus breastfeeding benefits.
Preterm babies might not have protective antibodies and have symptomatic
infections. However, the virus can become inactive by pasteurization
of human milk and the viral load can be reduced by freezing the
milk at -20 ºC ().
A recent study with preterm infants who acquired infection in the
early postnatal period, via breastmilk of CMV-positive mothers,
has shown that neurological development and hearing were not compromised
in the infants. Nevertheless, given the small number of assessed
infants, follow-up studies with preterm infants with infections
acquired in the postnatal period are necessary ().
Varicella
A mother who presents with varicella up to five days before or
two days after delivery may transmit the disease to the infant in
its severe form, when the risk for viremia is high. In these cases,
the mother should be isolated during the contagious phase of lesions
up to the crust phase, and VZIG (varicella-zoster immunoglobulin)
at the dose of 125 intramuscular units or a 2-ml single IM dose
of standard immunoglobulin should be given to the infant as soon
as possible, although the value of the latter medication is arguable
().
The infant should be observed up to the 21st day of life. It is
unclear whether the virus can be found in human milk and whether
it could infect the infant. Thus, during this period, breastmilk
can be expressed and given to the infant. However, if the infant
develops the disease during this period, acyclovir therapy should
be implemented ().
A mother with varicella whose onset of the disease occurred more
than five days before delivery or after the third day postpartum
can produce and transfer antibodies to the infant, transplacentally
or via breastmilk. In this case, the infant may develop the mild
form of the disease, with no need for isolation or prophylaxis.
The mother can breastfeed the infant, provided that precautions
such as handwashing, wearing of a mask and covering of lesions are
properly taken ().
Herpes simplex
Newborn infants can be contaminated with herpes simplex in utero
via a hematogenous transplacental route, during delivery (more frequent)
or in the postnatal period. The risk of neonatal contamination is
higher for primary infection or non-primary infection if it occurs
in the last month of gestation. However, in the last week before
delivery, transmission rates are low for recurrent disease.
The risk of viral transmission via breastmilk is very low. In nursing
mothers with herpes, breastfeeding should not be interrupted, except
when the herpetic vesicles are located on the breasts. Active lesions
in other body parts should be covered, and the nursing mother's
hygiene should not be overlooked so that breastfeeding can be maintained.
Extra precaution should be taken if vesicles are present on the
face and fingers, as well as with other sources of herpes simplex
virus, such as gingivostomatitis in other family members. If there
is suspicion or confirmation that the infant is infected with herpes
simplex, he/she should be isolated from other infants but not from
his/her mother. There is a case report of a 15-month-old who was
contaminated with the disease by a five-year-old sibling who had
gingivostomatitis. Both of the mother's breasts were contaminated
by the infant during breastfeeding ().
Rubella
Acute exanthematic disease caused by a virus that can be eliminated
in respiratory secretions between 10 days before and 15 days after
the appearance of the exanthema. Most cases are asymptomatic or
subclinical, but may transmit the infection. No data exist that
contraindicate breastfeeding in a nursing mother with rubella. In
case of vaccination against rubella, breastfeeding may be maintained
as well ().
Measles
Highly contagious exanthematic disease caused by a virus transmitted
by respiratory secretions few days before and during the course
of the disease. The measles virus has not been isolated in human
milk yet, but, on the other hand, specific antibodies were found
in the milk of immunized women. If measles is confirmed in a nursing
mother, the infant should receive immunoglobulin, and the mother
should be isolated up to 72 hours after the appearance of the exanthema.
However, expressed breastmilk can be given to the infant because
secretory IgA begins to be secreted after 48 hours of the appearance
of the exanthema in the mother ().
Mumps
Viral disease transmitted by direct contact with respiratory droplets
or fomites. Infection is rare in infants younger than one year due
to the passive transfer of antibodies via placenta. If a susceptible
nursing mother is infected, she should continue breastfeeding because
exposure occurred seven days before the development of parotiditis
and IgAs in human milk may help mitigate the symptoms in the infant
().
Bacterial infections
Tuberculosis
Breastfeeding recommendations for mothers with tuberculosis depend
on the time at which diagnosis was made. According to the World
Health Organization, it is not necessary to separate the mother
from the infant and, under no circumstance, should breastfeeding
be discontinued ().
Koch's bacillus is exceptionally excreted into breastmilk, and if
the infant is infected, the respiratory tract usually serves as
a portal of entry. Thus, a mother with extrapulmonary tuberculosis
does not require any special care to breastfeed.
According to the American Academy of Pediatrics, an infant of a
mother with pulmonary tuberculosis in the contagious phase, untreated
or with less than three weeks on antitubercular drugs at delivery,
should be separated from the mother but fed with expressed human
milk, as transmission often occurs via the airways. The mother's
sputum should be submitted to the acid-fast smear test, and she
should only be allowed to be in contact with her infant after the
test yields negative results ().
The infant should receive chemoprophylaxis with isoniazid, at the
dose of 10 mg/kg/day for three months and then be submitted to the
tuberculin skin test. If the test result is positive, the disease
should be traced by clinical and radiological examination. If no
active infection is detected, surveillance and chemoprophylaxis
should be maintained up to the sixth month, when intradermal BCG
is applied. If the tuberculin test is negative at three months of
life, chemoprophylaxis may be interrupted and intradermal BCG applied,
and clinical surveillance should be maintained. Situations in which
there may be risks of not following up the infant on isoniazid therapy,
concomitant intradermal BCG vaccination is recommended ().
According to the WHO, breastfeeding should be maintained, but the
close contact between mother and infant should be reduced, and the
following precautions should be taken: a mask or similar device
should be worn while breastfeeding, hands should be carefully washed,
and those infected with the disease, especially household members,
should be identified. The infant should be treated with hydrazide
(INH) at the dose of 10 mg/kg, once a day for six months. After
chemoprophylaxis is over, the infant should receive intradermal
BCG. Breastfeeding should not be discontinued in any of these phases
().
There are no restrictions on breastfeeding for mothers who are
in the non-contagious phase of tuberculosis, whose treatment began
more than three weeks ago, and in this case, the baby should be
vaccinated with intradermal BCG at birth. In cases in which the
diagnosis of maternal tuberculosis was established after the onset
of breastfeeding, the infant should be regarded as potentially infected
and should receive chemoprophylaxis.
Breastfeeding should not be discontinued because the administration
of antitubercular drugs in the mother is not a contraindication
for breastfeeding.
Table 2 shows the WHO recommendations for tuberculosis cases and
the management of breastfeeding, considering the possibility of
not using the tuberculin skin test.
Table 2 -
WHO recommendations for tuberculosis cases and the management of
breastfeeding according to the time at which diagnosis was made
It is paramount to underscore that all infants should be monitored
as to their weight gain and health status. Special attention should
be given to infants whose mothers have risk factors for multidrug-resistant
tuberculosis. In this case, the separation of mother and infant
may be necessary, as the mother, under this circumstance, shows
increased infectiousness and takes longer to respond to therapy.
Breastfeeding may be maintained provided that expressed milk is
used, thus reducing the respiratory contact between mother and infant
().
Hansen's disease
Hansen's disease is a chronic infectious disease with high infectiousness
and low pathogenicity. Its clinical course varies, basically depending
on the individual's cellular immune response. The disease is transmitted
by person-to-person contact, especially long contact, by means of
nasal and cutaneous secretions. The bacillus can be isolated in
breastmilk in cases of untreated Hansen's disease, as well as in
patients treated during less than three months with sulfone (dapsone
or clofazimine) or less than three weeks with rifampicin. Skin lesions
on the breast can be a source of infection for the infant.
There is no contraindication for breastfeeding if the mother is
receiving proper treatment ().
The infant should be treated as early as possible, simultaneously
with the mother. The drugs used are the same ones used in the mother
and may cross into human milk at low concentrations, but there is
no report of severe side effects. The infant should be followed
up and submitted to regular clinical exams for early detection of
possible signs of the disease. Moreover, the following is recommended
before and during breastfeeding: careful handwashing, wearing of
a mask while handling the infant and covering of breast lesions.
The contagious mother (untreated or treated for less than three
months with sulfone or three weeks with rifampicin) should avoid
contact with her baby, except to breastfeed; she should wear a mask
or similar device, wash her hands carefully before handling the
infant and disinfect nasal secretions and baby wipes ().
Syphilis
Syphilis is a disease that is basically sexually transmitted; however,
other modes of transmission exist, such as contact with people with
active lesions in mucous membranes, genital region and breasts.
There is no evidence of transmission via human milk, without breast
lesions. A nursing mother with primary or secondary syphilis with
breast involvement can infect the infant through the contact of
lesions with the mucous membranes. If there are lesions on the breasts,
especially on the areola, breastfeeding or use of expressed milk
is contraindicated until full treatment and regression of lesions.
Twenty-four hours after penicillin therapy, the infectious agent
(spirochete) is seldom detected in the lesions. Thus, there is no
contraindication for breastfeeding after proper treatment ().
Brucellosis
Detection of Brucella melitensis in human milk has been reported,
and so have cases of brucellosis in exclusively breastfed infants.
This confirms the possibility of brucellosis being transmitted via
breastmilk.
In the acute phase of severe disease in the mother, breastfeeding
should be avoided, but the use of expressed and pasteurized human
milk is allowed. Breastfeeding may be restored as soon as the disease
is treated with antimicrobials and the nursing mother shows clinical
improvement ().
Parasitic infections
Malaria
Since malaria is not transmitted among humans, breastfeeding may
be maintained if the mother's clinical conditions allow so. There
is no evidence indicating that malaria can be transmitted via breastfeeding
().
For mothers who need to be treated, chloroquine, quinine and tetracycline
are recommended. Sulfonamides should be avoided in the first month
of breastfeeding ().
Therefore, a nursing mother with malaria may breastfeed during the
treatment with specific drugs.
Chagas' disease
Studies show that Trypanosoma cruzi can be isolated in human milk
in acute and chronic forms of Chagas' disease. There was a case
report of acute infection in a two-month-old infant breastfed by
an infected mother ().
Although late sequelae may develop, acute disease in the infant
tends to be benign. This, combined with the remote possibility of
transmission of the disease, is reason enough for maintaining breastfeeding
in women with the chronic form of the disease, except if the nipples
bleed and have fissures ().
In cases of acute disease, breastfeeding should be contraindicated
().
Lab experiments using samples of human milk contaminated with the
protozoan and tested under different conditions demonstrate that
milk pasteurization prevents the transmission of the disease. Rats
orally and intraperitoneally inoculated with human milk containing
the parasite were infected; however, the control group with animals
inoculated with pasteurized milk was not infected ().
Animal experiments using human milk heated to 63 oC in a household
microwave oven (7 minutes, 45% power) proved efficient in reducing
the transmission of Trypanossoma cruzi ().
Fungal infections
Paracoccidioidomycosis
Systemic granulomatous disease caused by a fungus, whose transmission
occurs via respiratory secretions. There is no contraindication
for breastfeeding. However, it should not be forgotten that cotrimoxazole,
commonly used for the treatment of paracoccidioidomycosis, is excreted
into breastmilk and may produce severe side effects in the infant
().
Cryptococcosis
Fungal disease with worldwide distribution. Immunocompromised patients,
including those with HIV/AIDS, are at greater risk for cryptococcosis.
The transmission of particles in the environment occurs via aerosol
droplets, and no documentation exists of person-to-person transmission.
Therefore, breastfeeding is not contraindicated ().
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