Zika virus has been topping the news lately, particularly its effect on the fetus during pregnancy. Here are some quick facts about the Zika virus.
- It is carried by the Aedes species mosquito, which is the common mosquito in the Americas. However, researchers have identified the virus in 10 different species of mosquitos. The Aedes mosquito is common in Africa.
- Incubation period is unknown but thought to be a few days.
- Symptoms are usually very mild and may include fever, skin rashes, muscle and joint pain, malaise and headache. Symptoms usually last 2-7 days.
- Microcephaly in infants is associated with Zika infection during pregnancy. Further research is required to verify this association but rates of microcephaly increased dramatically in association with increases in Zika virus infections in Brazil.
- Increases in incidence of Guillain-Barre was associated with the recent outbreak of Zika in Brazil. A previous outbreak in French Polynesia did not show this increase in incidence of Guillain-Barre.
- Sexual transmission of Zika virus has been described in 2 cases and presence of the Zika virus in semen in 1 other case.
While the association between Zika virus infection and microcephaly has not been proven, it is concerning enough that measures should be taken to avoid exposure during pregnancy. Further work is underway to evaluate the association. Concern has also arisen lately about breastfeeding when potentially infected with Zika, and particularly in association with use of donor milk. French Polynesia has actually had the largest outbreak of Zika anywhere with an estimated 28,000 cases or about 11% of the population in 2013-2014. Researchers from this area reported on the transmission of Zika virus in breast milk, albeit a very small sample of two. They measured and reported results of the milk of two mothers for active or replicative Zika virus. This was negative in these two samples but PCR for these samples was positive. The World Health Organization states that “In light of available evidence, the benefits of breastfeeding for the infant and mother outweigh any potential risk of Zika virus transmission through breast milk.” (http://apps.who.int/iris/bitstream/10665/204473/1/WHO_ZIKV_MOC_16.5_eng.pdf?ua=1 Feb 2016).
While the Zika virus RNA has been detected in the two women in the report above, there is no evidence that infant infection with Zika postnatally results in neurologic or other long-term detrimental outcomes. The CDC also recommends that women who have been exposed or potentially exposed to Zika breast feed their infant (http://www.cdc.gov/zika/transmission/).
But what about the use of donor milk that has become so common for NICU infants who are also at highest risk for immune deficiency? The Human Milk Banking Association of North America (HMBANA) has issued a statement about donor milk. First, all donors are carefully screened for all infectious diseases and secondly, the milk is pasteurized using a process known as Holder pasteurization. This process is known to render inactive the heat sensitive Zika virus (www.HMBANA.org).
The rapid spread of Zika virus is perhaps the most worrisome piece of this epidemic. Zika was first discovered in 1947 in Uganda, was only seen in the Americas less than a year ago, and has already infected thousands of people (http://foreignpolicy.com/2016/01/28/the-zika-virus-isnt-just-an-epidemic-its-here-to-stay-world-health-organization/). This may be the new West Nile Virus and be permanently a part of our environment. Ongoing research will aid in identification of risk for pregnant women and infants. Care to avoid Zika high-risk areas during pregnancy is currently advised, as well as testing of pregnant women who have been to areas with Zika virus infestation. At present, only the CDC and some state health departments have testing ability for Zika virus.
Looking for more on the topic of human milk? Read this article on
Human Milk: The Original Personalized Medicine
Besnard M, Lastere S, Teissler A, Cao-Lormeau, VM, Musso, D. Evidence of perinatal transmission of Zika virus, French Polynesia, December 2013 and February 2014. Rapid Communications. www.eurosurveillance.org.