Marcio Roberto Teixeira Nunes , Nuno Rodrigues Faria , Janaina Mota de Vasconcelos , Nick Golding , Moritz UG Kraemer , Layanna Freitas de Oliveira , Raimunda do Socorro da Silva Azevedo , Daisy Elaine Andrade da Silva , Eliana Vieira Pinto da Silva , Sandro Patroca da Silva , Valéria Lima Carvalho , Giovanini Evelim Coelho , Ana Cecília Ribeiro Cruz , Sueli Guerreiro Rodrigues , Joao Lídio da Silva Gonçalves Vianez Jr , Bruno Tardelli Diniz Nunes , Jedson Ferreira Cardoso , Robert B Tesh , Simon I Hay , Oliver G Pybus , Pedro Fernando da Costa Vasconcelos
30 April 2015
In December 2013, an outbreak of Chikungunya virus (CHIKV) caused by the Asian genotype was notified in the Caribbean. The outbreak has since spread to 38 regions in the Americas. By September 2014, the first autochthonous CHIKV infections were confirmed in Oiapoque, North Brazil, and in Feira de Santana, Northeast Brazil.
We compiled epidemiological and clinical data on suspected CHIKV cases in Brazil and polymerase-chain-reaction-based diagnostic was conducted on 68 serum samples from patients with symptom onset between April and September 2014. Two imported and four autochthonous cases were selected for virus propagation, RNA isolation, full-length genome sequencing, and phylogenetic analysis. We then followed CDC/PAHO guidelines to estimate the risk of establishment of CHIKV in Brazilian municipalities.
We detected 41 CHIKV importations and 27 autochthonous cases in Brazil. Epidemiological and phylogenetic analyses indicated local transmission of the Asian CHIKV genotype in Oiapoque. Unexpectedly, we also discovered that the ECSA genotype is circulating in Feira de Santana. The presumed index case of the ECSA genotype was an individual who had recently returned from Angola and developed symptoms in Feira de Santana. We estimate that, if CHIKV becomes established in Brazil, transmission could occur in 94% of municipalities in the country and provide maps of the risk of importation of each strain of CHIKV in Brazil.
The etiological strains associated with the early-phase CHIKV outbreaks in Brazil belong to the Asian and ECSA genotypes. Continued surveillance and vector mitigation strategies are needed to reduce the future public health impact of CHIKV in the Americas.