Risk of death following chikungunya virus disease in the 100 Million Brazilian Cohort, 2015-18: a matched cohort study and self-controlled case series.

BACKGROUND: Chikungunya virus outbreaks have been associated with excess deaths at the ecological level. Previous studies have assessed the risk factors for severe versus mild chikungunya virus disease. However, the risk of death following chikungunya virus disease compared with the risk of death in individuals without the disease remains unexplored. We aimed to investigate the risk of death in the 2 years following chikungunya virus disease. METHODS: We used a population-based cohort study and a self-controlled case series to estimate mortality risks associated with chikungunya virus disease between Jan 1, 2015, and Dec 31, 2018, in Brazil. The dataset was created by linking national databases for social programmes, notifiable diseases, and mortality. For the matched cohort design, individuals with chikungunya virus disease recorded between Jan 1, 2015, and Dec 31, 2018, were considered as exposed and those who were arbovirus disease-free and alive during the study period were considered as unexposed. For the self-controlled case series, we included all deaths from individuals with a chikungunya virus disease record, and each individual acted as their own control according to different study periods relative to the date of disease. The primary outcome was all-cause natural mortality up to 728 days after onset of chikungunya virus disease symptoms, and secondary outcomes were cause-specific deaths, including ischaemic heart diseases, diabetes, and cerebrovascular diseases. FINDINGS: In the matched cohort study, we included 143 787 individuals with chikungunya virus disease who were matched, at the day of symptom onset, to unexposed individuals using sociodemographic factors. The incidence rate ratio (IRR) of death within 7 days of chikungunya symptom onset was 8·40 (95% CI 4·83-20·09) as compared with the unexposed group and decreased to 2·26 (1·50-3·77) at 57-84 days and 1·05 (0·82-1·35) at 85-168 days, with IRR close to 1 and wide CI in the subsequent periods. For the secondary outcomes, the IRR of deaths within 28 days after disease onset were: 1·80 (0·58-7·00) for cerebrovascular diseases, 3·75 (1·33-17·00) for diabetes, and 3·67 (1·25-14·00) for ischaemic heart disease, and there was no evidence of increased risk in the subsequent periods. For the self-controlled case series study, 1933 individuals died after having had chikungunya virus disease and were included in the analysis. The IRR of all-cause natural death within 7 days of symptom onset of chikungunya virus disease was 8·75 (7·18-10·66) and decreased to 1·59 (1·26-2·00) at 57-84 days and 1·09 (0·92-1·29) at 85-168 days. For the secondary outcomes, the IRRs of deaths within 28 days after disease onset were: 2·73 (1·50-4·96) for cerebrovascular diseases, 8·43 (5·00-14·21) for diabetes, and 2·38 (1·33-4·26) for ischaemic heart disease, and there was no evidence of increased risk at 85-168 days. INTERPRETATION: Chikungunya virus disease is associated with an increased risk of death for up to 84 days after symptom onset, including deaths from cerebrovascular diseases, ischaemic heart diseases, and diabetes. This study highlights the need for equitable access to approved vaccines and effective anti-chikungunya virus therapeutics and reinforces the importance of robust vector-control efforts to reduce viral transmission. FUNDING: Brazilian National Research Council (CNPq), Fundação de Amparo à Pesquisa do Estado da Bahia, Wellcome Trust, and UK Medical Research Council. TRANSLATION: For the Portuguese translation of the abstract see Supplementary Materials section.

Mortality from Congenital Zika Syndrome - Nationwide Cohort Study in Brazil.

BACKGROUND: Prenatal exposure to Zika virus has potential teratogenic effects, with a wide spectrum of clinical presentation referred to as congenital Zika syndrome. Data on survival among children with congenital Zika syndrome are limited. METHODS: In this population-based cohort study, we used linked, routinely collected data in Brazil, from January 2015 through December 2018, to estimate mortality among live-born children with congenital Zika syndrome as compared with those without the syndrome. Kaplan-Meier curves and survival models were assessed with adjustment for confounding and with stratification according to gestational age, birth weight, and status of being small for gestational age. RESULTS: A total of 11,481,215 live-born children were followed to 36 months of age. The mortality rate was 52.6 deaths (95% confidence interval [CI], 47.6 to 58.0) per 1000 person-years among live-born children with congenital Zika syndrome, as compared with 5.6 deaths (95% CI, 5.6 to 5.7) per 1000 person-years among those without the syndrome. The mortality rate ratio among live-born children with congenital Zika syndrome, as compared with those without the syndrome, was 11.3 (95% CI, 10.2 to 12.4). Among infants born before 32 weeks of gestation or with a birth weight of less than 1500 g, the risks of death were similar regardless of congenital Zika syndrome status. Among infants born at term, those with congenital Zika syndrome were 14.3 times (95% CI, 12.4 to 16.4) as likely to die as those without the syndrome (mortality rate, 38.4 vs. 2.7 deaths per 1000 person-years). Among infants with a birth weight of 2500 g or greater, those with congenital Zika syndrome were 12.9 times (95% CI, 10.9 to 15.3) as likely to die as those without the syndrome (mortality rate, 32.6 vs. 2.5 deaths per 1000 person-years). The burden of congenital anomalies, diseases of the nervous system, and infectious diseases as recorded causes of deaths was higher among live-born children with congenital Zika syndrome than among those without the syndrome. CONCLUSIONS: The risk of death was higher among live-born children with congenital Zika syndrome than among those without the syndrome and persisted throughout the first 3 years of life. (Funded by the Ministry of Health of Brazil and others.).

The Epidemic of Zika Virus-Related Microcephaly in Brazil: Detection, Control, Etiology, and Future Scenarios.

We describe the epidemic of microcephaly in Brazil, its detection and attempts to control it, the suspected causal link with Zika virus infection during pregnancy, and possible scenarios for the future. In October 2015, in Pernambuco, Brazil, an increase in the number of newborns with microcephaly was reported. Mothers of the affected newborns reported rashes during pregnancy and no exposure to other potentially teratogenic agents. Women delivering in October would have been in the first trimester of pregnancy during the peak of a Zika epidemic in March. By the end of 2015, 4180 cases of suspected microcephaly had been reported. Zika spread to other American countries and, in February 2016, the World Health Organization declared the Zika epidemic a public health emergency of international concern. This unprecedented situation underscores the urgent need to establish the evidence of congenital infection risk by gestational week and accrue knowledge. There is an urgent call for a Zika vaccine, better diagnostic tests, effective treatment, and improved mosquito-control methods.

Risk factors for the incidence of dengue virus infection in preschool children.

OBJECTIVE: To estimate the seroincidence of dengue in children living in Salvador, Bahia, Brazil and to evaluate the factors associated. METHODS: A prospective serological survey was carried out in a sample of children 0-3 years of age. A multilevel logistic model was used to identify the determinants of seroincidence. RESULTS: The seroprevalence of dengue was 26.6% in the 625 children evaluated. A second survey detected an incidence of 33.2%. Multilevel logistic regression showed a statistically significant association between the seroincidence of dengue and age and the premises index. CONCLUSION: In Salvador, the dengue virus is in active circulation during early childhood; consequently, children have heterotypic antibodies and run a high risk of developing dengue haemorrhagic fever, because the sequence and intensity of the three dengue virus serotypes currently circulating in this city are very similar to those that were circulating in Rio de Janeiro, Brazil, in 2008. Therefore, the authors strongly recommend that the health authorities in cities with a similar epidemiological scenario be aware of this risk and implement improvements in health care, particularly targeting the paediatric age groups. In addition, information should be provided to the population and actions should be implemented to combat this vector.