Zika Screening and Outcomes in Pregnant Women in Leganés (Madrid, Spain)

Introduction: By the end of 2015, an international alert for Zika virus was generated in numerous countries, mainly in Latin America. Potential serious consequences on the fetus were described, due to its capacity for vertical transmission during pregnancy, leading to congenital malformations such as microcephaly. Spain is one of the European countries with the highest possibility of imported infections, due to the significant flow of travelers and residents from risk areas. Since January 2016, Severo Ochoa University Hospital (HUSO), in Leganés, Madrid, has been performing Zika virus infection (ZIKV) screening in pregnant women at risk.

Materials and Methods: Data collected within the screening program performed in the HUSO between January 2016 and December 2017 were analyzed. This program included all women from endemic area or who had ever traveled to an endemic area during their pregnancy, whether they had symptoms (during the trip or in 15 days after their return) or not. The total number of pregnant women included in the screening program was 41. They underwent ZIKV serology (immunoglobulin M [IgM], immunoglobulin G [IgG]). If serologic test was positive, the plaque-reduction neutralization testing (NNT) was performed. In addition, in those pregnant women with suspected recent infection (return from the endemic region in the past month), ZIKV PCR was performed in serum and urine. Confirmed cases were defined if IgM and IgG were positive or if IgG and NNT were positive. Discarded cases were those with IgM and IgG negative. When IgM was negative, IgG positive and NNT were indeterminate, we defined those as indeterminate cases, as we could not confirm or rule out the infection in the mother.

Results: The most frequent origin of the 41 pregnant women studied was from Colombia and the Dominican Republic (19.5% in both cases), followed by Ecuador (12.2%). In nine of them (with a history of recent stay in an endemic area), serum and urine PCR were performed, being negative in all cases. In 46.3% (19) of the pregnant women, the ZIKV IgG was positive; 4.8% (2) women had a confirmed infection (one with IgM positive and the other with NNT positive). In the other women with IgG positive, seven cases (17% of the total) had indeterminate NNT, so were cataloged as indeterminate cases. Both in the cases of confirmed and indeterminate infection, newborns were studied and followed up. All of them presented IgG positive and IgM negative at birth. None presented microcephaly and the cranial ultrasound, funduscopic exam and audiology testing were normal. During follow-up, one of the children had IgG negative at 12 months of age, ruling out Zika infection. The others currently continue to be followed up and for the moment no infection has been confirmed in any of them ([Fig. 1]).

Conclusion: Since the role of Zika virus in fetal neurodevelopment is known, ZIKV screening is recommended in all those women who have ever been during pregnancy in a region in which virus circulation has been detected, even in the absence of symptoms. In those cases of ZIKV confirmed in a pregnant woman, multidisciplinary follow-up of the child should be performed because long-term consequences of the infection in the fetus are not yet fully known. Due to the limitations of the available serological tests, in cases of indeterminate neutralization tests, since the ZIKV infection cannot be ruled out in the mother, the same follow-up should be performed on the newborn as in the confirmed cases.

Keywords: Zika virus, pregnant women, serology, plaque-reduction neutralization testing, microcephaly

Fig. 1 Zika screening and outcomes in pregnant women in Severo Ochoa University Hospital.