Implications of Zika virus and congenital Zika syndrome for the number of live births in Brazil

Abstract

SignificanceZika virus (ZIKV) was discovered 70 years ago, and since then small isolated outbreaks occurred without major complications being reported. When ZIKV hit Brazil, however, a public health emergency was declared, given its link with microcephaly. Knowledge on ZIKV has advanced, but demographic impacts remain poorly understood. This study uses data from Brazil to assess whether a decline in births occurred after the onset of ZIKV. Forecasts show significant birth declines, particularly after April 2016. No significant changes in fetal death rates and no pattern of increase in hospitalizations due to abortion complications were observed, although hospitalizations occurred later in some states. We argue that postponement of pregnancy and abortions, primarily, likely affected fertility, with implications for women’s reproductive health.

Experimental Infection of Mid-Gestation Pregnant Female and Intact Male Sheep with Zika Virus

“…The number of the placentomes of each ewe was within normal limits, but all infected animals had at least some degree of placentome inversion ("advanced") morphology ( Figure 3; Table 1). Mineralization present in the FM sometimes around small vessels closer to the CE, rarely within the PL 7 1 No significant findings (NSFs), 2 Fetal mesenchyme (FM), 3 Chorionic epithelium (smooth chorion) (CE), 4 Lymphoid aggregates composed of macrophages surrounded by multiple layers of lymphocytes and plasma cells, 5 Multinucleated giant cells (MNGCs), 6 Interplacentomal endometrium (IPE), 7 Placentomal limbus (PL).…”

“…Results from both experiments indicate that mid-gestation ewes can be infected with ZIKV with subsequent disruption of fetal development and that intact male sheep are susceptible to ZIKV infection and viral dissemination and replication occurs in highly vascular tissues (including those of the male reproductive tract).Viruses 2020, 12, 291 2 of 23 and negative gestational outcomes when infection occurs during pregnancy. In humans, ZIKV is believed to result in trimester-specific effects to the fetus [2][3][4][5][6][7]. Established animal models of ZIKV infection during pregnancy that result in vertical transmission include non-human primates (NHP) and type-1 interferon/interferon receptor deficient mice.…”

Association of past dengue fever epidemics with the risk of Zika microcephaly at the population level in Brazil

“…So far, microcephaly ratios as high as in the Brazilian NE region have not been described in any other region in the world that had undergone a Zika epidemic [7][8][9] . Several reasons for this discrepancy were suggested -poor data quality [10][11][12] , the unreliability of secondary data sources 13,14 , virus genetic variation 15 , socioeconomic factors 16 , dengue immunity profile of the population 17 , and women postponing pregnancy or having abortions [18][19][20] .…”

Understanding the sexual and reproductive health needs in Brazil's Zika‐affected region: placing women at the center of the discussion

“…Among the most affected populations are underserved women, most of them young Afro‐Brazilians with little education, living in one of the poorest regions of the country . From January 2015 to November 2016, most of the infection‐related microcephaly cases were concentrated in the northeast region of Brazil and 83% of women who had a child with CZS were Afro‐Brazilian and/or Native Brazilian, whereas only 49% of the female Brazilian population falls within these groups . Moreover, northeast Brazil was disproportionately affected by the Zika epidemic: this geographical region ranks lowest among the country's macro‐regions on the Human Development Index…”

“…The link between the discovery and public announcement of the consequences of ZIKV epidemic with the decline of live births in Brazil has been discussed elsewhere . From September 2015 to December 2016 a total of 3 820 304 births were reported in Brazil.…”