Mayaro virus produces nonspecific, sublethal disease symptoms, often confused with dengue, but with symptoms of arthalgias that can cause incapacitating disability. Outbreaks have been localized and sporadic in the Pan-Amazonia forest since its first isolation in 1954 (Trinidad and Tobago). The literature available is scarce, diverse and dispersed. Mayaro virus is an alphavirus, phylogenetically related to the Semliki forest antigenic complex. UNA and Mayaro viruses are the only viruses of this complex that have been isolated in the New World. Mayaro consists of single-stranded RNA of positive charge, length of 12 kb, subdivided into genomic and subgenomic regions, which encode nonstructural and structural proteins respectively. Mayaro shows a great plasticity in vertebrate host infection, whereas high specificity in the family Culicidae (mosquitoes). Risk factors of infection are associated with forest areas of northern South America and the rainy season. Two genotypes of MAYV have been identified, L (Belterra, Brazil) and D (widely distributed in the Pan-Amazonia). The enzootic cycle is similar to the jungle cycle of yellow fever, which involves Haemagogus mosquitoes and monkeys as reservoirs. However, the involvement of other secondary vectors and other hosts may be important in spread of the virus. Humans may have high levels of viremia, and efficient experimental transmission has been demonstrated in Aedes aegypti, Aedes albopictus and Aedes scapularis, suggesting a significant risk to public health in urban, rural and peridomestic locations close to enzootic foci of Mayaro virus.