Data or Zika. Briefly, Zika is a vector borne disease, spread by Aedes Aegypti and the news channel loves it. Were the news channels reporting wrong numbers? or were the Brazilians under-reporting their cases previously, as a result now leading to a sudden surge in reported Zika cases linked to microcephaly. Let me take you through this discussion.
I came up with a general information and a hypothetical question on Zika previously:
My main objective in writing this blog is to allow us to think critically and analytically. As public health physicians, it is important for us to digest this data before we conclude an association / correlation or causative-effect of an issue.
Currently Public Health authorities are suggesting that the two (Zika & Microcephaly) are more than coincidental. In other words, women who contract Zika in Brazil “may find” their newborns suffering from misshapen of the skull.
Let me rephrase and make things clear here. Brazil had cases of microcephaly even before Zika was reported.
America’s North Shore Journal stated that a study published in 2015, of 94 children in a Brazilian orphanage, they found that 17 percent had fetal alcohol spectrum disorders and do you know that 80% of children with Fetal Alcohol Syndrome usually have microcephaly and behavioral abnormalities.” (Stromlandet al., 2015)
These tables below use a variety of different sources with differing microcelphaly incidence rates to predict the “normal” number of microcephaly cases for both the United States and Brazil.
America’s North Shore Journal explained that Brazilians have claimed their national incidence for microcephaly is 0.5:10000. That suggest they have an estimated 148 cases of the birth defect yearly. However, a study on the prevalence of toxoplasmosis in Brazil suggested that as many as 927 births every year suffer “neurological disease”, including cases of microcephaly (Dubbed etal., 2012). This, alone, seems to indicate that Brazil has under-reported its case count.
Lets go back to the basic principles of Public Health Medicine. What is an outbreak? A disease outbreak is the occurrence of cases of a disease in excess of what would normally be expected in a defined community, geographical area or season.
The key word here is occurrence of cases in excess is considered an outbreak. So did Brazil actually experience an excess of microcephaly cases? or was it under-reported the whole time and now damage control is been done…. I will leave it to you to decide.
I believe it is important for us to know the preexisting microcephaly rates before we conclude, correlate or associate microcephaly with another problem (Zika).
I quote from the America’s north shore Journal “In a Jan. 26 article in Nature, Declan Butler explores the possibility that the increase in reported microcephaly cases in Brazil is unrelated to an outbreak of Zika viral illness”
Latin American Collaborative Study of Congenital Malformations (ECLAMC) reported that the Brazilian authorities are using an unproven criteria for microcephaly. The government has changed the diagnostic criteria to reflect that all children with a head circumference of less than 33 cm should be reported as a case of microcephaly.
More than one study has noted that the WHO charts vary from those produced by the CDC. “For children in industrial countries, the mean OFC (occipital-frontal circumference) is larger than that indicated in the WHO standard values, which are based on measurements taken from about 8500 children in Brazil, Ghana, India, Oman, and the USA.” (Hagen et al., 2014).
Food for thought…. We must have a clear definition of a particular disease in an outbreak, determine its baseline rates and crunch those numbers to get the best answers out of it. Lets not jump the gun and create panic and chaos of a newly emerging infectious disease.
Von der Hagen, M., Pivarcsi, M., Liebe, J., von Bernuth, H., Didonato, N., Hennermann, J. B., Bührer, C., Wieczorek, D. and Kaindl, A. M. (2014), Diagnostic approach to microcephaly in childhood: a two-center study and review of the literature. Developmental Medicine & Child Neurology, 56: 732–741. doi: 10.1111/dmcn.12425