The Brazil Health Ministry is now reporting suspected yellow fever cases in the states of Goiás and Mato Grosso do Sul, this is in addition to the four states previously reported–Minas Gerais, Espírito Santo, Bahia, São Paulo (the suspect cases in Federal District have been ruled out).

Aedes albopictus/FotoshopTofs
Aedes albopictus/FotoshopTofs

Earlier this month, the World Health Organization (WHO) expressed concern that yellow fever could quickly spread from the outbreak’s ground zero to other states in the north and west because of the region’s low rates of vaccinations and mosquito-friendly environments.

Related: Brazil orders millions of yellow fever vaccines

As of Thursday, the Ministry of Health registered 550 suspected cases of yellow fever. Of the total, 455 cases remain under investigation, 72 were confirmed and 23 discarded. Of the 105 reported deaths, 40 were confirmed and 65 are still investigated.

Minas Gerais remains the state with the highest number of cases reported to date.