Date of Award

January 2018

Document Type


Degree Name

Medical Doctor (MD)



First Advisor

Albert Ko



Adeolu Aromolaran, B.Sc., Joseph Lim, Ph.D., Federico Costa, Ph.D., Albert Ko, M.D. Department of Epidemiology of Microbial Diseases, Yale University School of Public Health, New Haven, CT.

In 2015, Brazil experienced an outbreak of Zika-associated microcephaly that disproportionately affected the states in the northeast. These states have very low socioeconomic status (SES) when compared to other regions in Brazil. Multiple hypotheses have been proposed to explain this geographic cluster (site of introduction of Zika virus (ZIKV), environmental factors, interaction with other viruses and lower socioeconomic status). However, there is a paucity of data regarding the link between SES and Zika-associated microcephaly. Therefore, we aim to describe and compare the burden of microcephaly at a public hospital (hospital 1) which serves patients of low SES and a private hospital (hospital 2) with a patient population of high SES. We implemented active surveillance at both hospitals to investigate microcephaly cases from October 1, 2015 – January 31, 2016. Clinical evaluation and diagnostic tests were performed for 85 infants with microcephaly and serological screening was performed on their mothers. We also conducted a serosurvey of 362 mothers of non-microcephaly controls. We found that maternal (ZIKV) seroprevalence varied widely between the hospitals in this period. Hospital 1 had a high sample adjusted prevalence of 63.9% (95%CI-60.3-67.5) when compared to hospital 2, 18.7% (95%CI-15.9-21.5) (p<0.01). ZIKV exposed mothers in hospital 1 also had a significantly higher microcephaly prevalence of 17.8% (95%CI-14.3-22.1) than hospital 2 in which prevalence was 5.6% (95%CI-2.8-11.3) (p<0.01). Analysis of the cases of microcephaly suggests that their presentations were uniformly severe across both hospitals. Among these infants, 49% had severe microcephaly and 71% of infants evaluated had evidence of Congenital Zika Syndrome (CZS). In conclusion, we found that patients at the public hospital experienced a higher burden of Zika-associated microcephaly than the private hospital. Resources that are aimed at the care and prevention of CZS-associated microcephaly should focus on vulnerable populations with low SES.


This thesis is restricted to Yale network users only. It will be made publicly available on 06/25/2100