Behavioral, climatic, and environmental risk factors for Zika and Chikungunya virus infections in Rio de Janeiro, Brazil, 2015-16

Abstract

The burden of arboviruses in the Americas is high and may result in long-term sequelae with infants disabled by Zika virus infection (ZIKV) and arthritis caused by infection with Chikungunya virus (CHIKV). We aimed to identify environmental drivers of arbovirus epidemics to predict where the next epidemics will occur and prioritize municipalities for vector control and eventual vaccination. We screened sera and urine samples (n = 10,459) from residents of 48 municipalities in the state of Rio de Janeiro for CHIKV, dengue virus (DENV), and ZIKV by molecular PCR diagnostics. Further, we assessed the spatial pattern of arbovirus incidence at the municipal and neighborhood scales and the timing of epidemics and major rainfall events. Lab-confirmed cases included 1,717 infections with ZIKV (43.8%) and 2,170 with CHIKV (55.4%) and only 29 (<1%) with DENV. ZIKV incidence was greater in neighborhoods with little access to municipal water infrastructure (r = -0.47, p = 1.2x10-8). CHIKV incidence was weakly correlated with urbanization (r = 0.2, p = 0.02). Rains began in October 2015 and were followed one month later by the largest wave of ZIKV epidemic. ZIKV cases markedly declined in February 2016, which coincided with the start of a CHIKV outbreak. Rainfall predicted ZIKV and CHIKV with a lead time of 3 weeks each time. The association between rainfall and epidemics reflects vector ecology as the larval stages of Aedes aegypti require pools of water to develop. The temporal dynamics of ZIKV and CHIKV may be explained by the shorter incubation period of the viruses in the mosquito vector; 2 days for CHIKV versus 10 days for ZIKV.

Aspectos clínicos e epidemiológicos da introdução do vírus Chikungunya em Sergipe

“…Nesta localidade, a maioria dos casos esteve presente naqueles com idade entre 15 e 45 anos (47,7%) 12 . No Rio de Janeiro, durante a epidemia ocorrida nos anos de 2015-2016, observou-se dentre os casos confirmados laboratorialmente que 2,7% correspondiam a indivíduos com idade ≤ 9 anos, entretanto taxa significativa fora observada naqueles com mais de 60 anos, equivalendo a um total de 24,2% dos casos; indivíduos entre 20 e 59 anos representaram 68,2% do total, com maior incidência na população maior de 40 anos 14 .…”

Neurological complications associated with emerging viruses in Brazil

“…Nevertheless, the model based on Zika alone explained GBS cases better than the model based on Zika + dengue virus (arboviruses). Adding dengue virus to the model failed to improve goodness of fit because the epidemics that occurred in the early 2000s were not accompanied by an increase in GBS, and the incidence of dengue virus was low in 2015–2016 . The predictive model was more accurate in the metropolitan area of the city of Rio de Janeiro, which is primarily urban, than across the whole state of Rio de Janeiro, which encompasses urban and rural areas.…”

Zika Virus Vertical Transmission in Children With Confirmed Antenatal Exposure

“…Because ZIKV diagnostics in infants was considered investigational at the time, we did not collect specimens from infants born early on in the epidemic, which is when ZIKV was still circulating, which is a study limitation, as collection of early specimens in all children would have been ideal. In May 2016 we saw a dramatic decline in ZIKV circulation in Rio de Janeiro, which coincided with a Chikungunya outbreak [28][29] . For this reason, it is unlikely that the tested group of infants had a high chance of acquiring postnatal ZIKV infection, as by the time most of them were born, the virus was no longer circulating in Rio de Janeiro.…”