Study shoots down uncertainty that dengue boosts threat of microcephaly connected with Zika

Publicado em 20 julho 2021

An expectant female contaminated by Zika infection does not encounter a higher threat of bring to life a child with microcephaly if she has actually formerly been subjected to dengue infection, according to a Brazilian research study that contrasted information for expectant females in Rio de Janeiro as well asManaus

A Zika epidemic burst out in Brazil in 2015-16 in locations where dengue is native. Both infections are transferred by the insect Aedes aegypti. Some of the states influenced by the Zika epidemic reported an increase in instances of microcephaly, an uncommon neurological condition in which the infant’s mind falls short to create entirely. Others saw no such surge.

According to this brand-new research study by Brazilian scientists, 2 aspects describe the surge in microcephaly in just some locations: The high Zika assault price, as well as the mommy’s having actually acquired the infection in the very first trimester of maternity. The term assault price in public health describes the variety of instances split by the overall populace.

The research study was sustained by FAPESP through 2 jobs (16/15021 -1 as well as 13/21719 -3), as well as was performed under the aegis of the Network for Research on Zika Virus in São Paulo (Rede Zika). The outcomes are explained in a short article in Viruses, a peer-reviewed open-access journal released by the Multidisciplinary Digital Publishing Institute (MDPI). The write-up showed up in late April in an unique problem on Zika as well as maternity.

“The discrepancies between regions in terms of the numbers of reported cases of microcephaly during the Zika epidemic were puzzling. One of the hypotheses was that prior exposure to dengue might make Zika more severe, but in the state of São Paulo there weren’t many adverse effects of Zika even though the region is highly endemic for dengue, so we decided to try to find out what could explain the differences,” stated virologist Maurício Lacerda Nogueira, a teacher at the São José do Rio Preto Medical School (FAMERP) in São Paulo, as well as co-principal private investigator for the research study together with Patrícia Brasil, a scientist at Oswaldo Cruz Foundation (FIOCRUZ) in Rio de Janeiro.

According to Nogueira, their interest was attracted to the assault price when they evaluated the information for both state resources. In Rio de Janeiro, where lots of instances of microcephaly were reported, the variety of individuals contaminated by Zika infection represented 10 per 10,000 occupants, while in Manaus, where reasonably couple of children were birthed with microcephaly, the assault price was 0.6 per 10,000.

“Microcephaly caused by Zika is a rare phenomenon, but when there are many cases of Zika in an area it becomes more apparent. It had been suggested earlier that contracting Zika in the first trimester of pregnancy might be relevant, and now we’ve proved that it was,” Nogueira stated.


The scientists laid out to comprehend the distinctions in the damaging end results of maternity as well as in the children of both populaces by examining 114 expectant females contaminated by Zika infection in between September 2015 as well as June 2016. Infection was validated by RT-qPCR screening of blood and/or pee examples. The topics were hired at Heitor Vieira Dourado Tropical Medicine Foundation (FMT-HVD), a transmittable condition health center in Manaus, as well as FIOCRUZ’s severe febrile health problem facility in Rio de Janeiro.

Prior direct exposure to dengue was evaluated by serological examinations to find counteracting antibodies, to name a few. The objective was to discover prospective organizations in between maternity end results as well as the Zika assault price, specified as the variety of instances formally reported throughout the research study duration split by the populace of each city.

Overall, 31 females had damaging end results (27 in Rio as well as 4 in Manaus). In this team, 4 children passed away prior to birth as well as 27 were birthed with mind abnormalities. “Only Zika attack rates and infection in the first trimester of pregnancy were associated with adverse pregnancy and infant outcomes. Pre-existing immunity to dengue was not associated with outcomes (normal or abnormal) in patients with Zika during pregnancy,” the writers of the write-up state in the Abstract.

And they end, “The strengths of our study include a careful classification of infant outcomes, made possible through detailed assessments at birth by a multidisciplinary team. […] In addition, the use of a highly sensitive and specific [plaque reduction neutralizing antibody] assay to characterize pre-existing dengue immunity and the use of sera collected during the acute phase of RT-PCR-confirmed Zika infection lend credibility to our results. […] Our main limitations are the modest sample size and convenience sample selection.”

An earlier research study led by Nogueira in 2017 revealed that clients contaminated by Zika after direct exposure to dengue did not end up being a lot more drastically ill than other individuals. It was the very first clinical research study to reveal this in people. Prior research study entailing cells as well as rats had actually recommended the reverse.


Microcephaly is an uncommon neurological problem in which a baby’s head as well as mind are dramatically smaller sized than regular as an outcome of changes in the development of the nerves throughout advancement in the womb. Children with microcephaly generally experience hampered or obstructed psychological, physical as well as electric motor advancement.

The source of microcephaly consist of hereditary aspects as well as direct exposure to chemicals, microorganisms as well as infections. Scientists have actually lately revealed that Zika got while pregnant can harm fetal advancement.

During the epidemic in Brazil, Zika influenced individuals of every ages as well as was connected with the event of a lot of instances of microcephaly. In November 2015, Brazil stated a public wellness emergency situation due to the climbing variety of instances. The World Health Organization (WHO) after that provided an epidemiological alert, emphasizing the opportunity of genetic neurological malformations in children birthed to females contaminated by Zika.

In 2015 alone, greater than 2,400 instances of microcephaly were reported inBrazil They happened in concerning 540 districts in 20 states. In the duration 2010-14, the overall variety of reported instances was 781.

In 2016 there were some 214,000 potential instances ofZika The number was up to 17,000 in 2017 as well as 8,000 in 2018. In the very first 3 months of this year, it was 448, according to the Ministry of Health’s epidemiological publication.

The signs and symptoms of Zika resemble those of dengue. In most contaminated individuals, it triggers high temperature, migraine, red eyes, joint discomfort as well as breakout. On standard, the signs and symptoms go away in 10 days.

The scientists are waging their evaluation of the communications in between Zika as well as dengue, specifically to see if Zika regulates infection by dengue infection. Nogueira additionally takes part in a worldwide team that is working with designs to anticipate upsurges of Zika, dengue as well as yellow high temperature.