Yellow Fever outbreaks in unvaccinated populations, Brazil, 2008-2009.

Due to the risk of severe vaccine-associated adverse events, yellow fever vaccination in Brazil is only recommended in areas considered at risk for disease. From September 2008 through June 2009, two outbreaks of yellow fever in previously unvaccinated populations resulted in 21 confirmed cases with 9 deaths (case-fatality, 43%) in the southern state of Rio Grande do Sul and 28 cases with 11 deaths (39%) in Sao Paulo state. Epizootic deaths of non-human primates were reported before and during the outbreak. Over 5.5 million doses of yellow fever vaccine were administered in the two most affected states. Vaccine-associated adverse events were associated with six deaths due to acute viscerotropic disease (0.8 deaths per million doses administered) and 45 cases of acute neurotropic disease (5.6 per million doses administered). Yellow fever vaccine recommendations were revised to include areas in Brazil previously not considered at risk for yellow fever.

Registro de Aedes albopictus em áreas epizoóticas de Febre Amarela das Regiões Sudeste e Sul do Brasil (Diptera: Culicidae) / Aedes albopictus appearence in epizootic areas of jungle Yellow Fever in South-Eatern and Soutern Regions of Brazil (Diptera: Culicidae)

Durante estudo biológico e ecológico sobre mosquitos levado a cabo em área com registro de epidemia de febre amarela silvestre e epizootia em macacos, foram encontrados adultos de Aedes albopictus. A tendência da espécie para invadir ambiente extradomiciliar potencializada a chance de infecção natural, ao tempo em que evolui para formar um elo entre focos naturais dos vírus e o ambiente urbano. Esta nota técnica representa um alerta aos gestores dos três poderes públicos sobre perspectivas de mudanças no perfil epidemiológico atual da Febre Amarela no Brasil...

During biological and ecological study on mosquitoes carried out on area with registers of epidemic of jungle yellow fever and monkey epizootic were found some adults of Aedes albopictus. The tendency of this species to invade the extra-domicile environment brings out the possibility of natural infection, and at the same time evolving to form a link between natural focus of the virus and the urban environment. This Technical Note represents an alert to the three government levels about the perspectives of changes in the actual epidemiological profile of yellow fever in Brazil.

Clinical and epidemiological characteristics of yellow fever in Brazil: analysis of reported cases 1998-2002.

Yellow fever (YF), an arboviral infection of major public health importance in Brazil, is associated with high mortality and high epidemic potential. We analysed confirmed YF cases from the National Surveillance System from 1998-2002 and assessed risk factors for death among hospitalised patients. Variables assessed included age, gender, clinical signs and laboratory findings. A logistic regression model was used to identify independent predictors of death among hospitalised patients. From 1998-2002, among 2117 suspected YF cases reported to Brazil's Ministry of Health, 251 (11.9%) had confirmed YF, of whom 217 (86.5%) were hospitalised and the case fatality rate was 44.2%. Factors associated with higher mortality in univariate analysis included male gender (relative risk (RR) 1.96, 95% CI 1.17-2.28), age >40 years (RR 2.61, 95% CI 1.25-5.45), jaundice (RR 2.66, 95% CI 2.12-3.35), serum aspartate aminotransferase (AST) >1200 IU/l (RR 1.84, 95% CI 1.23-2.74), alanine aminotransferase >1500 IU/l (RR 2.09, 95% CI 1.38-3.17), total bilirubin >7.0mg/dl (RR 2.33, 95% CI 1.44-3.78), direct bilirubin >5.0mg/dl (RR 2.29, 95% CI 1.33-3.94) and blood urea nitrogen >100mg/dl (RR 5.77, 95% CI 1.43-23.22). In multivariate analysis, elevated AST and jaundice remained independently associated with higher mortality. These findings suggest that selected clinical and laboratory indicators may help clinicians recognise potentially fatal cases of YF.