São Paulo (SP), a densely populated state in southeast Brazil that contains one of the world´s largest urban regions, has experienced its largest yellow fever virus (YFV) outbreak in decades. Surveillance in non-human primates (NHP) is important in order to detect YFV early during an epidemic or epizootic, to quantify the magnitude of the outbreak in NHP, and to evaluate the risk of YFV spillover infection in human populations. To better understand the genetic diversity and spatial distribution of YFV during the current outbreak in southeast Brazil, we generated 46 new virus genomes from YFV positive cases identified in 18 different municipalities in SP, mostly sampled from non-human primates between April 2017 and February 2018. Our data show that most NHP cases in São Paulo state were likely caused by the introduction of a single YFV lineage from Minas Gerais to São Paulo. Phylogenetic and phylogeographic analyses of these data indicate that YFV spread southwards from Minas Gerais into São Paulo state at a typical rate of <1km per day. These results shed light in the sylvatic transmission of yellow fever in highly fragmented forested regions in São Paulo state and highlight the importance of continued operational research and surveillance of zoonotic pathogens in sentinel populations.
São Paulo, a densely inhabited state in southeast Brazil that contains the fourth most populated city in the world, recently experienced its largest yellow fever virus (YFV) outbreak in decades. YFV does not normally circulate extensively in São Paulo, so most people were unvaccinated when the outbreak began. Surveillance in non-human primates (NHPs) is important for determining the magnitude and geographic extent of an epizootic, thereby helping to evaluate the risk of YFV spillover to humans. Data from infected NHPs can give more accurate insights into YFV spread than when using data from human cases alone. To contextualise human cases, identify epizootic foci and uncover the rate and direction of YFV spread in São Paulo, we generated and analysed virus genomic data and epizootic case data from NHPs in São Paulo. We report the occurrence of three spatiotemporally distinct phases of the outbreak in São Paulo prior to February 2018. We generated 51 new virus genomes from YFV positive cases identified in 23 different municipalities in São Paulo, mostly sampled from NHPs between October 2016 and January 2018. Although we observe substantial heterogeneity in lineage dispersal velocities between phylogenetic branches, continuous phylogeographic analyses of generated YFV genomes suggest that YFV lineages spread in São Paulo at a mean rate of approximately 1km per day during all phases of the outbreak. Viral lineages from the first epizootic phase in northern São Paulo subsequently dispersed towards the south of the state to cause the second and third epizootic phases there. This alters our understanding of how YFV was introduced into the densely populated south of São Paulo state. Our results shed light on the sylvatic transmission of YFV in highly fragmented forested regions in São Paulo state and highlight the importance of continued surveillance of zoonotic pathogens in sentinel species.
Polymyxin resistance is a public health concern -present in humans, animals and the environment -caused by chromosomal-encoding or plasmid-encoding mechanisms. Chromosomal alterations in MgrB are frequently detected in Klebsiella spp., but not yet reported and characterised in Klebsiella variicola ( K. variicola ). This study performed microbiological and genomic characterisation of three polymyxin- resistant K. variicola isolates (M14, M15 and M50) recovered from the microbiota of migratory birds in Brazil. The isolates were submitted to SpeI-PFGE, broth microdilution and whole genome sequencing us- ing Illumina MiSeq for analysis of genetic relatedness, sequence typing and detection of antimicrobial- resistance genes. K. variicola isolates belonged to two clones, and susceptibility tests showed resistance only for polymyxins. Sequences of chromosomal two-component systems (PmrAB, PhoPQ, RstAB, CrrAB) and MgrB were evaluated by blastN and blastP against a polymyxin-susceptible K. variicola (A58243), and mutations with biological effect were checked by the PROVEAN tool. K. variicola isolates belonged to two clones, and susceptibility tests showed resistance for polymyxins. In M14 and M15, phoQ deleterious mutations (D90N, I122S and G385S) were identified, while an mgrB variant containing a single deletion (C deletion on position 93) leading to the production of a non-functional protein was detected in M50. mgrB complementation studies showed restoration of polymyxin susceptibility (64 to ≤ 0.25 mg/L) as a wild-type mgrB was inserted into the mgrB-deficient M50. This study confirmed the role of a non-functional mgrB variant in conferring polymyxin resistance, stressing the role of this regulator in K. variicola and drawing attention to novel polymyxin resistance mechanisms emerging in wildlife.