Spatiotemporal Analysis of the Population Risk of Congenital Microcephaly in Pernambuco State, Brazil
Neal D E Alexander1, Wayner V Souza2, Laura C Rodrigues1
1Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK.
Abstract:
Since an outbreak in Brazil, which started in 2015, Zika has been recognized as an important cause of microcephaly. The highest burden of this outbreak was in northeast Brazil, including the state of Pernambuco. The prevalence of congenital microcephaly in Pernambuco state was estimated from the RESP (Registro de Eventos em Saúde Pública) surveillance system, from August 2015 to August 2016 inclusive. The denominators were estimated at the municipality level from official demographic data. Microcephaly was defined as a neonatal head circumference below the 3rd percentile of the Intergrowth standards. Smoothed maps of the prevalence of microcephaly were obtained from a Bayesian model which was conditional autoregressive (CAR) in space, and first order autoregressive in time. A total of 742 cases were identified. Additionally, high and early occurrences were identified in the Recife Metropolitan Region, on the coast, and in a north-south band about 300 km inland. Over a substantial part of the state, the overall prevalence, aggregating over the study period, was above 0.5%. The reasons for the high occurrence in the inland area remain unclear.
Insights
Zika virus caused a significant microcephaly outbreak in Brazil, particularly in Pernambuco state. Researchers mapped congenital microcephaly prevalence using a Bayesian model, revealing high rates along the coast and inland.
Area of Science:
- Epidemiology
- Public Health
- Neurology
Background:
- Zika virus outbreak in Brazil (2015) recognized as a major cause of microcephaly.
- Northeast Brazil, specifically Pernambuco state, experienced the highest burden.
- Congenital microcephaly prevalence requires detailed spatial and temporal analysis.
Purpose of the Study:
- To estimate the prevalence of congenital microcephaly in Pernambuco state, Brazil.
- To identify spatial and temporal patterns of microcephaly during the Zika outbreak.
- To map the distribution of microcephaly cases for public health intervention.
Main Methods:
- Utilized the Registro de Eventos em Saúde Pública (RESP) surveillance system (August 2015–August 2016).
- Defined microcephaly as neonatal head circumference below the 3rd percentile of Intergrowth standards.
- Employed a Bayesian conditional autoregressive (CAR) spatial and first-order autoregressive temporal model for prevalence mapping.
Main Results:
- Identified a total of 742 congenital microcephaly cases.
- Detected high and early occurrences in the Recife Metropolitan Region and a coastal area.
- Observed a north-south band of high prevalence approximately 300 km inland.
- Reported overall prevalence exceeding 0.5% in substantial parts of the state.
Conclusions:
- The study provides a detailed spatial and temporal analysis of congenital microcephaly prevalence in Pernambuco during the Zika outbreak.
- High prevalence was noted in both coastal and inland regions, with inland reasons remaining unclear.
- Findings highlight the need for continued surveillance and investigation into geographical risk factors for Zika-related microcephaly.
