{"id":509527,"date":"2024-05-07T17:05:14","date_gmt":"2024-05-07T20:05:14","guid":{"rendered":"https:\/\/revistapesquisa.fapesp.br\/?p=509527"},"modified":"2024-05-07T17:05:14","modified_gmt":"2024-05-07T20:05:14","slug":"yellow-fever-virus-has-been-circulating-uninterrupted-in-southern-brazil-for-seven-years","status":"publish","type":"post","link":"https:\/\/revistapesquisa.fapesp.br\/en\/yellow-fever-virus-has-been-circulating-uninterrupted-in-southern-brazil-for-seven-years\/","title":{"rendered":"Yellow fever virus has been circulating uninterrupted in southern Brazil for seven years"},"content":{"rendered":"

On April 30 this year, a 44-year-old man from S\u00e3o Jo\u00e3o da Boa Vista, a town 210 kilometers north of the S\u00e3o Paulo state capital, died of yellow fever. It was the second fatality from the disease in 2023 in the state, where for three years previously there had been no recorded human cases. After the most intensive phase of the current outbreak \u2014 the biggest in decades, which between 2016 and 2020 afflicted some 2,300 people and killed more than 600 in the Brazilian Southeast, Midwest and South \u2014 yellow fever began to relent. Its incidence fell sharply, but circulation of the virus that causes it continued. According to data from the Pan American Health Organization (PAHO), between July 2022 and mid-March 2023 there were 300 suspected cases in Brazil, of which three were confirmed, with one death; the second fatality in S\u00e3o Paulo occurred subsequently. During the same period, hundreds of monkeys were found dead in forests close to urban regions, suspected of having been infected with the virus, which can cause lesions in the liver, kidneys, and heart, killing up to half of the people contracting the serious form of the disease.<\/p>\n

\u201cThis is the first time there has been such a long-lasting outbreak outside Amazonia: almost 7 years of active transmission, at some stages with two varieties of the virus circulating simultaneously,\u201d explains virologist Camila Zanluca, a researcher at the Carlos Chagas Institute, a unit of the Oswaldo Cruz Foundation in Paran\u00e1 State (ICC\/FIOCRUZ-PR). Zanluca and Italian virologist Marta Giovanetti, from FIOCRUZ in Rio de Janeiro, are the lead authors of an article published in the journal Science Advances <\/em>in September, describing the dynamics around the recent spread of the virus in the country. Researchers from 46 Brazilian and overseas institutions sequenced the genome of 147 samples of the virus obtained from humans, monkeys, and mosquitoes infected between 2015 and 2022, and compared these with 296 other genomes from specimens of the pathogen that circulated in recent decades in Central and South American countries \u2014 yellow fever is endemic in 13 countries across the region and in a further 34 on the African continent.<\/p>\n

Analysis of such a large number of virus genomes \u2014 the biggest ever conducted on Brazilian samples \u2014 provided some unexpected findings. The first is that in this current outbreak, the yellow fever agent arrived in southcentral Brazil two or three years before originally thought, from somewhere in Amazonia. \u201cCurrent data indicate that the virus arrived in southeastern Brazil between the end of 2013 and the beginning of 2014,\u201d reports virologist Luiz Carlos J\u00fanior Alc\u00e2ntara, a researcher at the Rene Rachou Institute in Minas Gerais State, also a unit of FIOCRUZ, and a coordinator of the current study. Alc\u00e2ntara collaborated on previous research, published in 2018 in the journal Science<\/em>, which, based on analysis of 62 genomes, had calculated that the virus was believed to have reached the region, more specifically the state of Minas Gerais, only at the end of 2016.<\/p>\n

The second piece of news in the Science Advances <\/em>article is that in the last seven years, three variants of the virus circulated in southcentral Brazil, two of which concurrently at certain times. Given the technical name Clados Ia, IIb, and IIIc, all are part of the South American I genotype, the most common in the country. However, they differ due to individual alterations, particularly in the gene that codes an enzyme which assists in the replication of the virus\u2019s genetic material within the host cells (mosquito, monkey, or human).<\/p>\n

By combining the genetic characteristics of the samples with the location from which they were collected, the researchers were able to partially reconstruct the pathways taken by each variant of the virus. From northern Brazil, members of Clado Ia entered the Southeast via Minas Gerais around the beginning of 2014, although the first cases in monkeys and humans were only detected at the end of 2016. From there they moved on to Esp\u00edrito Santo State, and then spread to the states of Rio de Janeiro and Bahia, the latter in the Northeast, as indicated in an article published in 2019 in the Journal of Virology<\/em>, from a study also coordinated by Alc\u00e2ntara.<\/p>\n<\/div>

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Almost simultaneously, Clado IIb broke out in the midwestern state of Goi\u00e1s, and a year later arrived in Minas Gerais, from where it spread to S\u00e3o Paulo State. It then went on to reach southern states, where it remains in circulation. \u201cWe are still receiving virus samples extracted from nonhuman primates, primarily from the South, which belong to Clado IIb,\u201d confirms virologist Claudia Nunes Duarte dos Santos, head of the Molecular Virology Laboratory at ICC\/FIOCRUZ-PR and a coordinator of the current study.<\/p>\n

There is less information on Clado IIIc, since there were fewer than 20 genomes available. We know it is genetically closer than the other two to an ancestral variety detected in the northern state of Roraima in 2002. This emerged in the North of Brazil in 2017, and then moved through the Midwest to the Southeast.<\/p>\n

\u201cCirculation of the yellow fever virus along the North-South axis has already been suggested by other authors based on empirical observations,\u201d recalls virologist Renato Souza, a yellow fever specialist at the Taubat\u00e9 unit of the Adolfo Lutz Institute, who did not participate in the study. \u201cThe current article is based on high-quality genetic sequencing data to reconstruct the background of the virus diffusion in space and time, enabling the more likely spread routes to be tracked,\u201d he says.<\/p>\n

Infectologist Marcos Boulos, of the University of S\u00e3o Paulo (USP) and advisor to the S\u00e3o Paulo State Health Department\u2019s Disease Control Center, believes that the study reveals much in demonstrating that the virus has remained constantly in circulation since the beginning of the current outbreak. \u201cClinical case analyses would not enable this to be observed so evidently,\u201d he comments. \u201cThis result widens scientific knowledge on the behavior of the virus, but does not change the treatment.\u201d<\/p>\n

Some 90% of people infected present no or very few symptoms and don\u2019t even know that they\u2019ve had the virus. The other 10% include mild and serious cases. The most effective way of preventing the disease is through vaccination. Produced with a live, weakened virus of an African variant, the vaccine is safe and provides lifelong protection. Brazil\u2019s National Immunization Program recommends an initial dose at 9 months of age, with a booster at 4 years.<\/p>\n

Scientific articles<\/strong>
\nGIOVANETTI, M. et al.<\/em> Genomic epidemiology unveils the dynamics and spatial corridor behind the yellow fever virus outbreak in Southern Brazil<\/a>. Science Advances<\/strong>. vol. 9, no. 35. sept. 1, 2023.
\nFARIA, N. R. et al.<\/em> Genomic and epidemiological monitoring of yellow fever virus transmission potential.<\/a> Science<\/strong>. aug. 23, 2018.
\nGIOVANETTI, M. et al.<\/em> Yellow fever virus reemergence and spread in Southeast Brazil, 2016-2019.<\/a> Journal of Virology<\/strong>. vol. 94, no. 1. dec. 12, 2019.<\/p>\n","protected":false},"excerpt":{"rendered":"The disease vector arrived in the country\u2019s southeast two to three years earlier than previously thought","protected":false},"author":16,"featured_media":509528,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_exactmetrics_skip_tracking":false,"_exactmetrics_sitenote_active":false,"_exactmetrics_sitenote_note":"","_exactmetrics_sitenote_category":0,"footnotes":""},"categories":[159],"tags":[229,237,242],"coauthors":[105],"class_list":["post-509527","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-science","tag-epidemiology","tag-genetics","tag-immunology","keywords-vaccine","keywords-virology"],"acf":[],"_links":{"self":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/posts\/509527","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/users\/16"}],"replies":[{"embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/comments?post=509527"}],"version-history":[{"count":2,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/posts\/509527\/revisions"}],"predecessor-version":[{"id":509541,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/posts\/509527\/revisions\/509541"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/media\/509528"}],"wp:attachment":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/media?parent=509527"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/categories?post=509527"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/tags?post=509527"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/coauthors?post=509527"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}