Zika virus infection during pregnancy and microcephaly occurrence: a review of literature and Brazilian data

Abstract

In November of 2015, the Ministry of Health of Brazil published an announcement confirming the relationship between Zika virus and the microcephaly outbreak in the Northeast, suggesting that infected pregnant women might have transmitted the virus to their fetuses. The objectives of this study were to conduct a literature review about Zika virus infection and microcephaly, evaluate national and international epidemiological data, as well as the current recommendations for the health teams. Zika virus is an arbovirus, whose main vector is the Aedes sp. The main symptoms of the infection are maculopapular rash, fever, non-purulent conjunctivitis, and arthralgia. Transmission of this pathogen occurs mainly by mosquito bite, but there are also reports via the placenta. Microcephaly is defined as a measure of occipto-frontal circumference being more than two standard deviations below the mean for age and gender. The presence of microcephaly demands evaluation of the patient, in order to diagnose the etiology. Health authorities issued protocols, reports and notes concerning the management of microcephaly caused by Zika virus, but there is still controversy about managing the cases. The Ministry of Health advises notifying any suspected or confirmed cases of children with microcephaly related to the pathogen, which is confirmed by a positive specific laboratory test for the virus. The first choice for imaging exam in children with this malformation is transfontanellar ultrasound. The most effective way to control this outbreak of microcephaly probably caused by this virus is to combat the vector. Since there is still uncertainty about the period of vulnerability of transmission via placenta, the use of repellents is crucial throughout pregnancy. More investigations studying the consequences of this viral infection on the body of newborns and in their development are required.

Zika Virus NS4A and NS4B Proteins Deregulate Akt-mTOR Signaling in Human Fetal Neural Stem Cells to Inhibit Neurogenesis and Induce Autophagy

“…Individuals infected by ZIKV typically develop a mild or unapparent dengue-like disease (Duffy et al, 2009). However, mounting evidence has linked ZIKV infection to neurological defects in newborns (De Carvalho et al, 2016). Furthermore, ZIKV was detected in the amniotic fluids of pregnant women as well as in the brain tissues of microcephalic fetuses, suggesting that ZIKV can potentially cross the placental barrier to infect fetuses (Calvet et al, 2016; Mlakar et al, 2016).…”

Zika virus infection reprograms global transcription of host cells to allow sustained infection

“…Emerging evidence suggests that ZIKV causes mild symptoms in non-pregnant individuals, but it has also been associated with neurological abnormalities and Guillain–Barré syndrome. 8, 9, 10, 11 …”

Epidemiology, Diagnosis and Preventive Measures of Zika Virus Infection: A Review Update

“…After 5-10 days, ZIKV can be found in the mosquito's saliva, which can then infect humans. If the mosquito's saiva is inoculated into humal skin, the virus can infect epidermal keratinocytes, skin fibroblasts in the skin and Langerhans cells 10 31 . The major advantage of a serology test is that it remains positive for several months or longer after infection.…”

“…Moreover, it is particularly important to make an early diagnosis of microcephaly and recognize possible brain dysfunctions to guide the patient to a health care unit that can implement early brain stimulation measures. It is known that the brain of microcephalic patients is proportionally smaller, thus about 90% of the cases are associated with some degree of intellectual disability 31 . Therefore any suspected case of microcephaly caused by ZIKV should be immediately notified to health authorities.…”