Situation summary in the Americas
Since epidemiological week (EW) 1 to EW 14 of 2017, Brazil, Colombia, Ecuador, Peru, the Plurinational State of Bolivia, and Suriname have reported suspected and confirmed yellow fever cases.
Following is a summary of the situation in Brazil.
In Brazil, since the beginning of the outbreak in December 2016 up to 6 April 2017, there were 2,210 cases of yellow fever reported (604 confirmed, 1,054 discarded, and 552 suspected under investigation), including 302 deaths (202 confirmed, 52 discarded, and 48 under investigation). The case fatality rate (CFR) is 33% among confirmed cases.
According to the probable site of infection, the cases were reported in 342 municipalities, while the confirmed cases were distributed among 103 municipalities in 5 states (Espírito Santo, Minas Gerais, Pará, Rio de Janeiro, and São Paulo).
With regard to the confirmed fatal cases and their probable site of infection, 148 were in Minas Gerais, four in São Paulo, 43 in Espírito Santo, four in Pará, and three in Rio de Janeiro. In descending order, the CFR among suspected and confirmed cases by state is 100% in Pará, 80% in São Paulo, 34% in Minas Gerais, 29% in Espírito Santo, and 27% in Rio de Janeiro.
In the state of Minas Gerais, the downward trend in reported cases persists. The date of symptoms onset of the last reported case is 6 March 2017. In the state of Espírito Santo, since EW 9 of 2017, a new increase has been observed in the number of cases, the majority of which are being reported from the southern part of the state. Local and state authorities are investigating and characterizing this increase in cases while also intensifying immunization activities. Similarly, in the state of Rio de Janeiro, an increase in the number of suspected cases was observed between 15 and 25 March; it will be necessary to observe if this trend is maintained in the following weeks (Figure 1).
Moreover, since EW 13, four autochthonous cases of yellow fever were confirmed in the state of Pará, in the municipalities of Alenquer (3) and Monte Alegre (1).
To date, Aedes aegypti has not been reported to have a role in transmission. However, confirmed epizootics in large cities, such as Vitoria in Espírito Santo 3 and Salvador in Bahia, 4 represent a high risk for a change in the transmission cycle.
A recent study conducted by researchers from Brazil reported that the genomic sequencing of samples obtained from two southern brown howler monkeys (Alouatta guariba clamitans) found in the state of Espírito Santo belong to the South American genotype I. This genotype has been the most frequently found in Brazil during previous outbreaks.