After dropping in last week's report to its lowest level (n=105) since the crisis began, the number of new suspect microcephaly cases added to this week's report rebounded slightly to 130.
This is still roughly half the rate reported by the MOH only a couple of weeks ago.
The cause of this drop is unknown, although a few possible factors include:
- Brazil recently adopted a more stringent definition for microcephaly
- Much of Brazil was still in their winter dry season (with presumably fewer mosquitoes) when this week's birth cohort were in their 1st trimester
- Brazil's mosquito control efforts and mosquito protection awareness efforts were starting to ramp up at that time as well
The number of confirmed microcephaly cases shot up by 102, while the number of discarded cases increased by 273, leaving 4,046 still under investigation.
Also in this week's report, early information on a case control study conducted in Paraiba which suggests maternal infection during the 1st trimester was most apt to produce microcephalic birth defects.
This is preliminary data from an unpublished study, so we'll have to weigh these results carefully. Additionally, microcephaly is not necessarily the only negative result of maternal Zika infection, although it is easily the most immediately apparent.
In any event, a translation of a portion of last night's report follows:
Data are from research conducted by the Ministry of Health and the US CDC in Paraiba. The new release are 4,046 cases microcephaly research, 1,046 confirmed and 1,814 discarded
The case-control study in Paraíba shows preliminarily that mothers who had the Zika virus in the first trimester of pregnancy were more likely to have children with microcephaly. The Ministry of Health, in partnership with the Government of Paraiba and Center for Disease Control and Prevention of Diseases (CDC) of the United States, continues with the analysis of blood samples collected from the mothers and babies paraibanos. Only after this phase, the final results will be announced.
The initial result of the study, presented in João Pessoa (PB), also found no association of microcephaly with the exhibition of products such as insecticides, for example.
"It's part of this study to investigate people who were not affected by microcephaly. Only after processing the collected blood samples, comparing cases and controls, can we estimate more clearly the risk of being affected by the disease and Zika's relationship with microcephaly, "said the aide Surveillance Secretariat of Health the Ministry of Health, Eduardo Hage, highlighting the commitment of the teams in the field phase of the research. "The study gave an agile, ethical and effective manner. The teams have taken important steps in the search for answers to the problem that concerns the world, "the Secretary of Health Surveillance, Ministry of Health, Antonio Nardi.
The research, which began on 22 February, featured the work of eight teams - composed by the institutions involved - who investigated the proportion of infants born with microcephaly associated with Zika, and the risk of virus infection in 56 municipalities state. Overall, respondents were 165 cases of mothers who had babies with microcephaly and 446 control (mothers and babies in the same area without microcephaly). Among the babies, 52% are female and 48% male, in the age group 0-7 months.