The northeast (NE) region of Brazil commonly goes through drought periods, which favor cyanobacterial blooms, capable of producing neurotoxins with implications for human and animal health. The most severe dry spell in the history of Brazil occurred between 2012 and 2016. Coincidently, the highest incidence of microcephaly associated with the Zika virus (ZIKV) outbreak took place in the NE region of Brazil during the same years. In this work, we tested the hypothesis that saxitoxin (STX), a neurotoxin produced in South America by the freshwater cyanobacteria Raphidiopsis raciborskii, could have contributed to the most severe Congenital Zika Syndrome (CZS) profile described worldwide. Quality surveillance showed higher cyanobacteria amounts and STX occurrence in human drinking water supplies of NE compared to other regions of Brazil. Experimentally, we described that STX doubled the quantity of ZIKV-induced neural cell death in progenitor areas of human brain organoids, while the chronic ingestion of water contaminated with STX before and during gestation caused brain abnormalities in offspring of ZIKV-infected immunocompetent C57BL/6J mice. Our data indicate that saxitoxin-producing cyanobacteria is overspread in water reservoirs of the NE and might have acted as a co-insult to ZIKV infection in Brazil. These results raise a public health concern regarding the consequences of arbovirus outbreaks happening in areas with droughts and/or frequent freshwater cyanobacterial blooms.

中文翻译：

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蓝藻石房蛤毒素会加剧寨卡病毒引起的神经细胞死亡和脑畸形。

巴西东北部（NE）地区通常会经历干旱期，这有利于蓝藻的繁殖，能够产生影响人类和动物健康的神经毒素。巴西历史上最严重的干旱发生在 2012 年至 2016 年之间。巧合的是，同年，与寨卡病毒 (ZIKV) 爆发相关的小头畸形发病率最高的发生在巴西东北部地区。在这项工作中，我们测试了这样的假设：石房蛤毒素 (STX) 是南美淡水蓝藻 Raphidiopsis raciborskii 产生的一种神经毒素，可能导致了全世界描述的最严重的先天性寨卡综合症 (CZS)。质量监测显示，与巴西其他地区相比，东北地区人类饮用水中的蓝藻数量和 STX 发生率更高。在实验中，我们描述了 STX 使人脑类器官祖区中 ZIKV 诱导的神经细胞死亡数量增加了一倍，而在妊娠前和妊娠期间长期摄入被 STX 污染的水会导致 ZIKV 感染的免疫活性 C57BL/6J 后代的大脑异常。老鼠。我们的数据表明，产生石房蛤毒素的蓝藻在东北部水库中广泛传播，可能是巴西寨卡病毒感染的共同危害。这些结果引起了公众健康的关注，即在干旱和/或淡水蓝藻频繁繁殖的地区发生虫媒病毒爆发的后果。