Table 1.
List of environment variables used as predictors in multivariable analyses to identify risk factors for the Burundi RVF outbreak (May – November 2022).
Fig 1.
Spatiotemporal distribution of Rift Valley fever (RVF) cases in cattle, goats, and sheep in Burundi, May–November 2022.
Burundi shape file used to demarcate the boundaries was obtained from https://www.diva-gis.org/data.html. Administrative boundaries of Burundi were delineated using a shapefile obtained from the DIVA-GIS database.
Fig 2.
Weekly incidence of Rift Valley fever (RVF) cases by livestock species during the RVF outbreak in Burundi, May–November 2022.
Blue, black and brown bars represent sheep, cattle and goats, respectively.
Table 2.
RVFV positive genome cases by province and animal species (National Veterinary Laboratory of Bujumbura, Burundi).
Table 3.
Sequencing and GenBank data with associated metadata of the RVFV strains isolated in different districts, Burundi, 2022. *Sequences not submitted (<90 coverage).
Fig 3.
Evolutionary relationships of Rift Valley fever virus (RVFV) strains from the 2022 outbreak in Burundi within the East African regional context.
Maximum likelihood phylogenetic tree inference was performed using the medium (M) segment sequences and root-to-tip distance regressed against the collection time in the heterochronous sequences. (A) Temporal signal showing sufficient correlation (Correlation coefficient = 0.93) between divergence and time (years) in the dataset. (B) Migration model showing the most likely locations for internal nodes in the maximum likelihood tree inferred using TreeTime. (C) Time-calibrated maximum clade credibility (MCC) phylogenetic tree was retrieved and annotated from 10,000 trees after discarding 1001 trees as burn-in, here showing the clustering of Burundi, 2022 outbreaks samples alongside different heterochronous sequences from East Africa region. The tips/leaves of the phylogenetic trees are colored according to lineages.
Fig 4.
Distribution of meteorological variables used in the study.
Temporal distribution of wet months (top left) and minimum temperature (bottom left) before and after May 2022, the onset of the Rift Valley fever (RVF) outbreak. Maps (right panels) show cumulative rainfall (top right) and minimum temperature (bottom right) at the end of week 2 (January–February 2022). Burundi shape file used to demarcate the boundaries was obtained from https://www.diva-gis.org/data.html.
Fig 5.
Spatial distribution of environmental and demographic variables in Burundi, 2022.
Table 4.
Results of the univariable analysis used to assess the association between selected independent variables and the number of RVF cases in livestock in Burundi (May – November 2022).
Table 5.
Outputs of a random effects Poisson regression model used to identify risk factors for clinical RVF infections in livestock in Burundi (May – November 2022).