The Epidemic of Zika Virus–Related Microcephaly in Brazil: Detection, Control, Etiology, and Future Scenarios

Abstract

We describe the epidemic of microcephaly in Brazil, its detection and attempts to control it, the suspected causal link with Zika virus infection during pregnancy, and possible scenarios for the future. In October 2015, in Pernambuco, Brazil, an increase in the number of newborns with microcephaly was reported. Mothers of the affected newborns reported rashes during pregnancy and no exposure to other potentially teratogenic agents. Women delivering in October would have been in the first trimester of pregnancy during the peak of a Zika epidemic in March. By the end of 2015, 4180 cases of suspected microcephaly had been reported. Zika spread to other American countries and, in February 2016, the World Health Organization declared the Zika epidemic a public health emergency of international concern. This unprecedented situation underscores the urgent need to establish the evidence of congenital infection risk by gestational week and accrue knowledge. There is an urgent call for a Zika vaccine, better diagnostic tests, effective treatment, and improved mosquito-control methods.

Risks associated with viral infections during pregnancy

“…This virus, a member of the family Flaviviridae, is transmitted by mosquito bite and is also potentially sexually transmitted (113)(114)(115)(116)(117). While historically an infection has been described as causing symptoms ranging from fever and rash to Guillain-Barre syndrome (118)(119)(120)(121)(122)(123)(124), during the most recent outbreak there was also a startling increase in the incidence of fetal brain and CNS abnormalities when mothers acquired the virus during pregnancy (32,(125)(126)(127)(128)(129)(130)(131)(132)(133)(134). A causal link between ZIKV and these defects was established when the ZIKV genome was identified in the amniotic fluid of women whose fetuses had microcephaly detected during fetal ultrasound (125-127, 132, 133, 135).…”

Zika vírus: desafios da saúde pública no Brasil

“…Other hypotheses, never confirmed, have been suggested to explain the increase in microcephaly cases, including the assumption that this and other malformations are associated with the use of the larvicide pyriproxyfen. In addition to evidence from recent studies that connect the neurological disorders in infants to previous infection of pregnant women by ZIKV, it is worth noting that in the epidemic in French Polynesia, in 2013-2014, in which this larvicide was not used, microcephaly cases were found in a retrospective study 11 , and that in the city of Recife, one of the areas most affected by the ZIKV epidemic and with the highest number of microcephaly cases 9 , the referred larvicide was also not used. The transmission of ZIKV in Brazil raises many concerns: the social and ecological context in the Americas, particularly in Brazil, promotes the spread of arboviruses and the occurrence of severe cases associated with viral co-circulation; the current strategy in handling the vector in most areas has proven ineffective; climate and environmental conditions are appropriate for the activity and reproduction of the vector; cities crowded with intense flow of travelers makes Brazil not only vulnerable to large outbreaks but also a dispersal point of cases for the rest of the world.…”

“…Although microcephaly is linked to many environmental and genetic exposures, drug use during pregnancy, infections such as rubella, toxoplasmosis, and cytomegalovirus, among others, the association with ZIKV infection follows the increase of cases of microcephaly and other neurological malformations in Brazil since 2015 9 . Until March 12, 2016, the Emergency Operations Center in Public Health on Microcephaly of the Brazilian Ministry of Health (MOH) announced the confirmation of 863 cases of microcephaly and/or alteration of the central nervous system (CNS), which suggest congenital infection, still based on the previous criteria for head circumference of 32 cm for newborns with 37 or more weeks of gestation 10 .…”

Zika Virus Disease: The Situation in Turkey and a Review of the Worldwide Outbreak

“…Brezilyalı yetkililer, mikrosefaliyle doğan bebek insidansında, Mayıs 2015'ten itibaren 20 kat artış bildirmişlerdir (30).…”

“…Diğer olası mikrosefali nedenleri, genetik anomaliler, gebelikte geçirilen bazı infeksiyonlar (STORCH: sifilis, toksoplazmoz, rubella, sitomegalovirus, herpes simpleks virusu, HIV ve diğer viruslar), annenin gebelikte toksinlere ve kimyasallara maruz kalması, fetal alkol sendromu, radyasyon, diabetes mellitus gibi metabolik hastalıklar, malnütrisyon, postpartum serebrovasküler ve nonvasküler (menenjit, ensefalit, bakır zehirlenmesi, kronik böbrek yetmezliği) hasarlardır (30,31). Brezilya'da 2016 itibariyle ZV'ye bağlı 3530 mikrosefali ve 46 ölüm bildirilmiş-tir (32).…”