In a follow-up on the yellow fever situation in Minas Gerais  in southeastern Brazil, the Brazil IHR NFP provided an update on the event on Thursday informing that a total of 110 suspected cases, including 30 deaths, had been reported from 15 municipalities of Minas Gerais: Ladainha (31 cases, 11 deaths), Caratinga (20 cases, 1 death), Imbe de Minas (14 cases, 1 death), Piedade de Caratinga (12 cases, 4 deaths), Poté (6 cases, 3 deaths), Ubaporanga (6 cases, 2 deaths), Itambacuri (5 cases, 3 deaths), Ipanema (4 cases, 1 death), Malacacheta (4 cases, 2 deaths), Entre Folhas (2 cases), Frei Gaspar (1 case), Inhapim (2 cases), São Domingos das Dores (1 case), São Sebastião do Maranhão (1 fatal case), and Setubinha (1 fatal case).

Public domain image/Deyvid Aleksandr Raffo Setti
Public domain image/Deyvid Aleksandr Raffo Setti

On Friday, a “state of emergency” was declared.

Serological tests for 19 suspected cases were positive for yellow fever. Among them, 10 deaths (CFR: 53%) were reported. The report also confirms that there had been epizootics in 13 municipalities of Minas Gerais. Six of these 13 municipalities have not so far reported human cases of yellow fever: Agua Boa, Durande, Ipatinga, Sao Pedro do Sacui, Simonesia, and Teófilo Otoni.

Yellow fever outbreak has previously been detected in Minas Gerais. The most recent outbreak occurred in 2002–2003, when 63 confirmed cases, including 23 deaths (CFR: 37%), were detected.

The current yellow fever outbreak is taking place in an area with relatively low vaccination coverage, which could favor the rapid spread of the disease. The concern is that transmission may extend to areas located in proximity of Minas Gerais, such as the state of Espírito Santo and the south of Bahia, which have favorable ecosystems for the transmission of the virus. These areas were previously considered to be at low risk of transmission and, consequently, yellow fever vaccination was not recommended.

The introduction of the virus in these areas could potentially trigger large epidemics of yellow fever. There is also a risk that infected humans may travel to affected areas, within or outside of Brazil, where the Aedes mosquitoes are present and initiate local cycles of human-to-human transmission. Response efforts are further complicated by the fact that it is occurring in the context of concomitant outbreaks of Zika virus, chikungunya and dengue.