The evidence of ZIKV infection documented by RT-PCR among patients with the Guillain-Barré syndrome during the outbreak of ZIKV infection in Colombia lends support to the role of the infection in the development of the Guillain-Barré syndrome. (Funded by the Bart McLean Fund for Neuroimmunology Research and others.).

Background Colombia began official surveillance for Zika virus disease (ZVD) in August 2015. In October 2015, an outbreak of ZVD was declared after laboratory-confirmed disease was identified in nine patients. Methods Using the national population-based surveillance system, we assessed patients with clinical symptoms of ZVD from August 9, 2015, to April 2, 2016. Laboratory test results and pregnancy outcomes were evaluated for a subgroup of pregnant women. Concurrently, we investigated reports of microcephaly for evidence of congenital ZVD. Results By April 2, 2016, there were 65,726 cases of ZVD reported in Colombia, of which 2485 (4%) were confirmed by means of reverse-transcriptase-polymerase-chain-reaction (RT-PCR) assay. The overall reported incidence of ZVD among female patients was twice that in male patients. A total of 11,944 pregnant women with ZVD were reported in Colombia, with 1484 (12%) of these cases confirmed on RT-PCR assay. In a subgroup of 1850 pregnant women, more than 90% of women who were reportedly infected during the third trimester had given birth, and no infants with apparent abnormalities, including microcephaly, have been identified. A majority of the women who contracted ZVD in the first or second trimester were still pregnant at the time of this report. Among the cases of microcephaly investigated from January 2016 through April 2016, four patients had laboratory evidence of congenital ZVD; all were born to asymptomatic mothers who were not included in the ZVD surveillance system. Conclusions Preliminary surveillance data in Colombia suggest that maternal infection with the Zika virus during the third trimester of pregnancy is not linked to structural abnormalities in the fetus. However, the monitoring of the effect of ZVD on pregnant women in Colombia is ongoing. (Funded by Colombian Instituto Nacional de Salud and the Centers for Disease Control and Prevention.).

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ObjectiveSince the 1980s, dengue incidence has increased 30‐fold. However, in 2017, there was a noticeable reduction in reported dengue incidence cases within the Americas, including severe and fatal cases. Understanding the mechanism underlying dengue's incidence and decline in the Americas is vital for public health planning. We aimed to provide plausible explanations for the decline in 2017.MethodsAn expert panel of representatives from scientific and academic institutions, Ministry of Health officials from Latin America and PAHO/WHO staff met in October 2017 to propose hypotheses. The meeting employed six moderated plenary discussions in which participants reviewed epidemiological evidence, suggested explanatory hypotheses, offered their expert opinions on each and developed a consensus.ResultsThe expert group established that in 2017, there was a generalised decreased incidence, severity and number of deaths due to dengue in the Americas, accompanied by a reduction in reported cases of both Zika and chikungunya virus infections, with no change in distribution among age groups affected. This decline was determined to be unlikely due to changes in epidemiological surveillance systems, as similar designs of surveillance systems exist across the region. Although sudden surveillance disruption is possible at a country or regional level, it is unlikely to occur in all countries simultaneously. Retrospective modelling with epidemiological, immunological and entomological information is needed. Host or immunological factors may have influenced the decline in dengue cases at the population level through immunity; however, herd protection requires additional evidence. Uncertainty remains regarding the effect on the outcome of sequential infections of different dengue virus (DENV) types and Zika virus (ZIKV), and vice versa. Future studies were recommended that examine the epidemiological effect of prior DENV infection on Zika incidence and severity, the epidemiological effect of prior Zika virus infection on dengue incidence and severity, immune correlates based on new‐generation ELISA assays, and impact of prior DENV/other arbovirus infection on ZIKV immune response in relation to number of infections and the duration of antibodies in relation to interval of protection. Follow‐up studies should also investigate whether increased vector control intensification activities contributed to the decline in transmission of one or more of these arboviruses. Additionally, proposed studies should focus on the potential role of vector competence when simultaneously exposed to various arboviruses, and on entomological surveillance and its impact on circulating vector species, with a goal of applying specific measures that mitigate seasonal occurrence or outbreaks.ConclusionsMultifactorial events may have accounted for the decline in dengue seen in 2017. Differing elements might explain the reduction in dengue including elements of immunity, increased vector control, and even vector and\or viruses changes or adaptations. Mo...

Adherence to infection control recommendations is critical to prevent spread of this novel yeast.