Febre amarela silvestre: reemergência de transmissão no estado de São Paulo, Brasil, 2009

Abstract

METHODS: This is a descriptive study of a sylvatic yellow fever outbreak in the Southwestern region of the state from February to April 2009. Suspected and confirmed cases in humans and in non-human primates were evaluated. Entomological investigation in sylvatic environment involved capture at ground level and in the tree canopy to identify species and detect natural infections. Control measures were performed in urban areas to control Aedes aegypti. Vaccination was directed at residents living in areas with confirmed viral circulation and also at nearby cities according to national recommendation. RESULTS:Twenty-eight human cases were confirmed (39.3% case fatality rate) in rural areas of Sarutaiá, Piraju, Tejupá, Avaré and Buri. The deaths of 56 nonhuman primates were also reported, 91.4% were Allouatta sp. Epizootics was confirmed in two non-human primates in the cities of Itapetininga and Buri. A total of 1,782 mosquitoes were collected, including Haemagogus leucocelaenus, Hg. janthinomys/capricornii, and Sabethes chloropterus, Sa. purpureus and Sa. undosus. Yellow fever virus was isolated from a group of Hg. Leucocelaenus from Buri. Vaccination was carried out in 49 cities, with a total of 1,018,705 doses. Nine serious post-vaccination adverse events were reported. CONCLUSIONS:The cases occurred between February and April 2009 in areas with no recorded yellow fever virus circulation in over 60 years. The outbreak region occurred outside the original recommended vaccination area with a high percentage of susceptible population. The fast adoption of control measures interrupted the human transmission within a month and the confirmation of viral circulation in humans, monkeys and mosquitoes. The results allowed the identification of new areas of viral circulation but further studies are required to clarify the dynamics of the spread of this disease.

Prevalence and titers of yellow fever virus neutralizing antibodies in previously vaccinated adults

“…During the 2000s the transmission risk area has expanded, causing YF outbreaks in areas that were previously free of YF virus circulation in the South and Southeast of the country 2 , 3 , 4 . Nowadays, YF vaccine is recommended for those living in such regions, including the elderly that should receive their primary immunization.…”

Yellow Fever

“…However, in 200832 . However, in -2009, an outbreak of yellow fever reporting 56 deaths of non-human primates in southeast São Paulo, highlights the significance of surveillance and monitoring of epizootic events as an early indicator of viral circulation 43,44 .…”

“…This decision would increase vaccination coverage in Brazil with the future challenge to potentially universalize the vaccine across not only Brazil, but to every country internationally, in order to control yellow fever. However, a major barrier to mass vaccination is the shortage of vaccines 44 .…”

Novas Estratégias De Imunização Contra a Febre Amarela

“…A febre amarela (FA) é uma doença infecciosa de etiologia viral provocada por um arbovírus da família Flaviviridae e do gênero Flavivirus transmitida por mosquitos infectados nos ciclos epidemiológicos: silvestre e urbano (6,18,19,20) .…”

“…Dessa forma, o cuidado com a infestação do Aedes aegypti no perímetro urbano deve ser redobrado, sendo necessário controlar o mosquito e aumentar a cobertura vacinal (CV) (1,6,17,18,24) . Tais cuidados englobam ações de controle de proliferação dos mosquitos, eliminando reservatórios, entulhos e outras fontes de aglomeração destes mosquitos (3,6,24) .…”