According to a long-awaited analysis, microcephaly screening for Zika problems in infants could miss a few birth defects. A group from Brazil reported lately that the analysis, done on the first 1,500 suspected cases in Brazil, has disclosed instances of brain damage in newborns with usual head circumference.

The biggest case series so far has been published in The Lancet, wherein Brazil researchers said that screening criteria must be adjusted to carry clues and symptoms of brain abnormalities.

In another linked research development, pathology inspection of postmortem samples from babies and fetuses from Brazil at US Centers for Disease Control and Prevention (CDC) labs have exposed Zika antigens, cell damage, but no indication of Zika beyond the central nervous system and no clue of involvement of other pathogens.

As part of the surveillance study, the researchers studied investigations concluding as of February 27 by medical teams of 1,501 live-born infants with probable microcephaly.

With the help of clinical data from Brazil's Ministry of Health, they divided the cases into five categories on the basis of neuroimaging and Zika virus lab results. The included categories ranged from definite microcephaly to discarded. The researchers also analyzed head circumference, first-week mortality, and maternal rash history.

Among the studied 1,501 cases, 899 were discarded, and in the rest 602 cases, 76 were definite, 54 were highly likely, 181 moderate likelihood, and 291 fairly probable.

In comparison to the discarded cases, definite or likely ones had tiny head circumference, and mothers were more probable to have had a rash at the time of pregnancy. Babies in the definite and probable groups also had four times more chances of dying in the first week of life.