The Zika virus has been affecting a large part of the Brazilian population since 2014, and its pathology has raised questions on the transmission route, symptoms ,prevention, and treatment, as well as on neurological changes, which were previously not associated with the disease. To clear doubts on the transmission of the virus during breastfeeding, this study aimed to review and analyze studies, published from January 2014 to April 2017, regarding the relationship between breastfeeding and Zika virus exposure and focusing on the importance of breastfeeding. A search was performed in main databases, resulting in 85 articles, of which 38 were selected based on search criteria. All articles reported on the presence of Zika virus RNA in human milk. Among them, 34.21% had no stance on breastfeeding, 28.94% supported it, 18.42% did not recommend it, while 18.42% explained the need for further studies on the subject. The World Health Organization recommends breastfeeding for all mothers infected with Zika virus because the benefits of breastfeeding outweigh the risks of disease transmission, and there is no scientifically proven case of transmission through this route.

Breastfeeding, Nursing, Newborn, Infant

Marinatti T, Bartha M, Gomes Junior SC, Lopes Moreira ME (2017) Breastfeeding and Vertical Exposure to Zika Virus: A Literature Review. JSM Women’s Health 2(2): 1007.

ZIKAV: Zika virus; PCR: polymerase chain reaction; WHO: World Health Organization

In November 2014 and early 2015, the Zika virus (ZIKAV), a new virus transmitted by the Aedes aegypti mosquito, started to spread in Brazil. The manifestations were similar to those of dengue fever, with low fever, itching exanthema in the body, and conjunctivitis. Other symptoms included myalgia and mild joint pain [1,2]. A higher prevalence of microcephaly cases and central nervous system abnormalities was observed, associating cases of neurological changes with the virus [3,4].\

ZIKAV originated from Asia and Africa and spread throughout French Polynesia in 2013, with some cases in Chile [5]. In May 2015, 1.5 million people were affected by ZIKAV in the northeastern region of Brazil. The virus spread throughout South America, Central America, and the Caribbean, alarming the Pan American Health Organization. More than 4,500 microcephaly cases were confirmed in February 2016, and a worldwide epidemic of ZIKAV was announced, with confirmed cases in Europe [6]. The idea of correlating ZIKAV with microcephaly began as a result of a surge in the number of infected cases and newborns with reduced cephalic perimeter with no apparent cause, which initiated research and notification

The viral transmission can either be vectored or non-vectored. The vectored route occurs through the bite of Aedes aegypti or other mosquitoes of the same species, which reproduce in clean standing water in unsealed water tanks, plant dishes, and tires, among other places [7]. The non-vectored form occurs without direct contact with the agent, such as sexual transmission through semen [7-9] and perinatal transmission, or transmission of the virus from the mother to the newborn during childbirth [4,10,11]. Blood transfusion is also a form of transmission [7,12]; asymptomatic blood donors with ZIKAV were detected, with 80% not showing clinical alterations [13]. Transplacental transmission can also occur through a pregnant woman affected by ZIKAV, transmitting the virus to the fetus through the placenta at any time during pregnancy [14].

Diagnosis is through polymerase chain reaction (PCR) and virus segregation in blood samples. The PCR technique allows to accurately identify the causative agent’s DNA in the patient’s blood samples. It operates by amplifying a specific fragment of the DNA molecule thousands of times in just a few hours [5,13]. 

The ZIKAV epidemic has raised questions about the transmission, prevention, and consequences of the disease, including some questions about breastfeeding and reproduction planning. Due to the extent and diversity of the cases, infected infants need to undergo an interdisciplinary follow-up by neurologists, pediatricians, speech therapists, physiotherapists, occupational therapists, psychologists, and social workers, to address different issues. Moreover, early evaluation and stimulation of neuropsychomotor function are essential to provide a better prognosis [5,15].

Considering the increased incidence of ZIKAV in Brazil and the association of swallowing disorders in newborns with congenital ZIKAV syndrome, a speech pathologist is necessary to evaluate the baby’s feeding problems and stomatognathic functions, stimulate these functions, and design an appropriate intervention plan for each case, following the recommendation of the World Health Organization (WHO) [16], which is exclusive breastfeeding in the first 6 months of life for the overall development of the newborn and food security.

Considering the controversy surrounding the pathology of ZIKAV with unknown means of transmission, this literature review was conducted to build knowledge for action, allowing a stance on breastfeeding in ZIKAV cases and providing basis for both professional recommendations and performance of the mother regarding breastfeeding.

This literature review aimed to group knowledge about breastfeeding and ZIKAV exposure in articles published between January 2014 and April 2017. The following combined keywords in English, Portuguese, and Spanish were used to identify articles on the topic in the Medline, SciELO, Bireme, Cochrane, and Embase databases: fonoaudiologia “Zika e amamentação”, “Zika e aleitamento materno”, “Zika e alimentação”, “Zika and breastfeeding”, “Zika and feeding”, “Zika y lactancia materna”, and “Zika y alimentacion”.

We found 85 studies published in English and Portuguese in Medline, Bireme, and Embase, as shown in Figure 1. No studies were found in SciELO and Cochrane. Furthermore, no studies on ZIKAV related to speech therapy were found in any of these scientific databases. Among the 85 articles, the following were excluded: duplicate articles (13), nonscientific publications (9), articles not related to the subject (20), and unavailable articles (5). Thus, 47 articles were excluded, and the remaining 38 articles that addressed the subject of ZIKAV and breastfeeding were selected (Figure 1).

Figure (1): Exclusion and selection criteria.

We established a guiding question, “What is the stance of the existing literature on breastfeeding in cases of ZIKAV exposure?” After article selection, we observed and analyzed the 38 articles, and classified the approach of each study based on the guiding question, as follows: has no stance on breastfeeding, is in favor, is against, and explains the need for further studies on the subject.

Among the analyzed studies are shown in Table 1, 34.21% [5,10,14,17-26] investigated the presence of ZIKAV RNA in breast milk but had no stance on breastfeeding or lactation.

However, 28.94% [16,27-36] were in favor of breastfeeding and explained that despite the presence of ZIKAV in human milk, there is no scientific evidence of infants being infected through breastfeeding. Meanwhile, 18.42% [6,37-42] affirmed the possibility of contamination and were against breastfeeding, whereas 18.42% [43-49] explained the importance of further studies in this area (Figure 2).

Figure 2: Evidences found in articles selected.

In this literature review, a large proportion of the articles reported that breastfeeding is essential in all nations and should be treated as a public policy based on the benefits it brings in the short, medium, and long term, being advantageous to both the baby and the mother [16,27,36,50,51].

The WHO guidelines on breastfeeding reinforce that even in cases of suspected or confirmed ZIKAV infection, breastfeeding should be supported and encouraged. Exclusive breastfeeding is recommended from 1 hour after childbirth up to 6 months of age, to be continued with complementary foods up to 2 years of age or more [16,17,36]. Mothers and infants may need help in the breastfeeding process, and newborns with congenital ZIKAV syndrome may have swallowing disorders, requiring speech therapy to start and continue breastfeeding.

One study analyzed the milk of a mother with confirmed ZIKAV infection [18] and showed virus replication in breast milk. However, the newborn was not infected even though it was breastfed. Due to this study, some authors [6,37-42] supposed that breastfeeding may be a transmission vector, knowing that some diseases caused by flaviviruses of the same family with ZIKAV, such as dengue fever and other diseases, can be transmitted through breastfeeding [46]. However, until recently, there is no scientific evidence of this transmission route for ZIKAV.

This research shows that 28.94% of the studies analyzed [16,28-37] agreed with the recommendation of exclusive breastfeeding. Although ZIKAV RNA was detected in human milk, there was no virus replication in the culture, and the virus did not infect infants [9]. Nevertheless, this remains a controversial subject.

Breastfeeding helps in cognitive, affective, and social development, besides being a species/specific food, that is, “a living substance of great complexity, with specific composition for human species, containing fats, proteins, vitamins, water, sugar, enzymes, iron, antibodies and iron in exact proportions for the nutritional needs of the human baby” [52], which is easily digested and absorbed. Breastfeeding also contributes to the reduction of infant mortality and has prevented 823,000 deaths annually from children under 5 years of age by increasing their immunity and preventing diseases such as diarrhea and respiratory problems, otitis, and malocclusions [50,51] Breastfeeding is also an economic policy that is sustainable, since it does not generate expenses or pollute the environment. It is renewable, natural, and free [50,51]. Current evidence suggests that the benefits of breastfeeding outweigh the risks of ZIKAV transmission through breast milk.

During breastfeeding, mothers and babies require assistance, as they commonly have difficulties establishing this practice [53]. Speech therapists have the competence to accompany the mother and baby in their feeding mishaps, evaluate their stomatognathic functions, encourage them, and tailor the intervention plan for each case [54]. Because of these findings, we searched the databases for any correlation between the work of speech therapists, breastfeeding, and ZIKAV infection; however, the search showed no studies focused on this correlation. Although this area is a “recent” subject, the search result encourages further research.

In Brazil, the region most affected by ZIKAV has been the southeast, followed by the northeast, midwest, south, and north [55]. The recommended/performed approaches throughout Brazil encourage breastfeeding, multidisciplinary follow-up, and early neuropsychomotor stimulation. The innovations in this pathology has promoted the search for new knowledge and approaches.

The institution of a ZIKAV epidemic protocol became a crucial step to foster research funding and enable clarification on the infection, forms of transmission, and whether breastfeeding is a possible transmission vector, providing information for the population of pregnant women and newborns with congenital ZIKAV syndrome.

ZIKAV is detected in breast milk, but breast milk has not been considered a transmission vector due to the lack of virus replication studies that prove this relationship. The guidelines for mothers with suspected or confirmed ZIKAV infection and for newborns with congenital ZIKAV syndrome have been as follows: breastfeeding, early stimulation of neuropsychomotor development, and follow-up with a speech therapist and a multidisciplinary team [56].

Due to the lack of research addressing speech pathology in the follow-up of these cases, we suggest that research be conducted on this approach, building theoretical knowledge produced by clinical practice and considering the generation of microcephaly cases that may occur due to the ZIKAV epidemic in recent years.

Further studies are needed to clarify whether breastfeeding is a possible transmission vector. The virus’ RNA has already been identified in breast milk, but there is no proven case of this route of infection. Moreover, we suggest long-term research to clarify the dynamic process of breastfeeding and to better understand questions regarding the duration of RNA presence in human milk, viral load, and long-term follow-up for breastfed babies.

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