案件的令人不安的上升Febre Amarelahas Brazilians queueing around vaccination centres around the country, as people urgently seek protection from the infection. Yellow fever is a viral haemorrhagic disease transmitted by the bite of a mosquito, and manifests with non-specific symptoms such as fever, muscle pain, nausea and vomiting. Although most recover after this, around 15% of people go on to the more toxic phase: a characteristic yellowing of the skin (jaundice), vomiting and bleeding which can result in death in half of cases. And although no antiviral drugs exist against yellow fever (treatment is symptomatic), it is a vaccine-preventable disease.

在南美，有两个疾病周期。在城市黄热病中，该病毒通过咬伤从人到人传播埃及埃及，在国内环境中蓬勃发展。该周期可能会导致最高伤亡人数，但在巴西尚未记录since 1942。In sylvatic yellow fever, ‘wild’ mosquitoes (haemoagogusandSabethes属）在森林地区的猴子之间传播病毒；人们进入这些生态系统时会意外感染。

Fractional dosing: making the most of vaccine stocks

根据Brazil’s Ministry of Health从2017年7月至2018年1月之间，Sylvatic传播是该国213例已确认的黄热病案件的来源。不幸的是，到目前为止，有81人死亡，而另外435例案件仍在调查中。建议高风险地区的居民（现任圣保罗，米纳斯·格拉斯（Minas Gerais）和里约热内卢（Rio de Janeiro））避免了林区和休闲公园，除非已接种疫苗。

有一种安全有效的疫苗抵抗黄热病，其中一种剂量赋予了终身免疫力。在接种疫苗后的30天内，99％的接种疫苗are protected. In Brazil, the magnitude of the yellow fever outbreak has forced health authorities to分馏疫苗较小剂量以增加风险领域的人口覆盖范围：自2017年以来74,4 million doses已经管理。

部分剂量有什么影响？

世界卫生组织说，在“分数给药”中五分之一的疫苗可以提供与至少12个月的全剂量相同的保护。But there is evidence it could be even longer. A学习conducted in 2017 byBio-Manguinhos/Fiocruz，随后在2009年以不同剂量的疫苗接种的900名参与者中，有319名参与者。他们的结果证实，减少的分数可以至少提供8年的全部保护，从而进一步支持这种疫苗接种策略。但是，全剂量is still given to children between 9 months and 2 years, pregnant women in high-risk areas, and travellers to countries that require a vaccination certificate. It should also be noted that although the vaccine is considered to be safe, it is禁忌in some cases, and medical guidance should always be provided.

建议将分数剂量用于控制暴发，但疫苗接种必须成为更大的控制策略的一部分。2017年，几个巴西健康社会写了打开信封to the authorities, addressing the need to take stronger action against an imminent risk of yellow fever urbanization and its devastating consequences. They urged the establishment of short- and medium-term policies, including the reinforcement of both vaccine production and strict vaccination campaigns, as well as updated surveillance data that would allow control measures to be changed as needed. Furthermore, the letter advocated for a collaboration between different institutions including health authorities, research centres, and the media.

爆发的环境影响

“Yellow fever exterminates all 17 families of howler monkeys in Horto” was the不幸的标题今年1月初在巴西每日报纸上出版。据一位研究人员称，他们采访了报纸，在病毒到达之前，有86只猴子住在森林城市公园。卫生当局在2017年10月被警报了他们的第一次动物死亡后关闭了公园：猴子比人类对病毒更敏感，并且该事件在该地区宣布了黄热病的流通。但这不是新事物。在整个巴西，不同物种的灵长类entire populations。自617年爆发开始于2016年7月,革命制度党mates have fallen ill or dead with the virus. Cities like Sao Paulo and Rio de Janeiro, which are part of the current outbreak, are reporting primate casualties.

Sadly, not only the virus is killing the monkeys. As the public is aware these animals can also get yellow fever, some people poison or beat them to death out of fear they will give them disease. Apart from disseminating information on yellow fever vaccination and prevention, education campaigns by health authorities are reminding Brazilians that it is the mosquito that transmits the yellow fever virus, and not the monkeys. Their protection is particularly valuable since, aside from their ecological importance, the presence of the primates helps authorities in their surveillance of this disease.