Fig 1.
Leprosy patients diagnosed in the (BE-)-PEOPLE studies between 11/2021 and 07/2024.
Only leprosy patients diagnosed according to WHO criteria were included in this study. Patients could selectively refuse the collection of specific sample types. Patients without lesions or only lesions in the face were not included for skin biopsy sampling. The collection of tongue scrapes only started in 10/2023. For patients included after this date, tongue scraping was always performed after tongue swabbing. MB: multibacillary, PB: paucibacillary.
Table 1.
Positivity rates of the RLEP qPCR assay in different sample types.
Table 2.
Pairwise comparisons of positivity of the RLEP qPCR across sample types.
Fig 2.
Yield of positive RLEP qPCR results over different sample types.
The proportion of positive RLEP qPCR results was calculated per sample type and type of clinical diagnosis. For skin biopsies and tongue scrapes the results only represent the subset of patients for which the samples were available. The cutoff for positivity was set at a Cq-value of 40. MB: multibacillary, PB: paucibacillary.
Fig 3.
Median quantity of bacilli in the skin biopsies of patients belonging to different groups.
Boxplots depict the median and interquartile range of the log10-transformed bacterial load on the respective skin biopsies of patients belonging to the groups indicated on the x-axis. The results of a pairwise Wilcoxon Rank-Sum test are depicted, ****: p-value < 0.0001, ***: p-value < 0.001, ns: no significant. SB: skin biopsy, NS: nasal swab, TS: tongue swab, TScr: tongue scrape, + /-: positive/negative RLEP qPCR for respective sample.
Table 3.
Number of bacilli on skin biopsies and nasal swabs defined by RLEP qPCR, stratified by tongue swab positivity.
Fig 4.
Quantity of human mtDNA detected in swab-based samples.
Median mtDNA copies per samples type are depicted, stratified by positivity on the respective sample. Boxplots show the median of the log10-transformed mtDNA quantity per swab with interquartile range; black dots represent outliers. The results of a Wilcoxon Rank-Sum test are depicted, with ****: p-value < 0.0001, *: p-value < 0.05, ns: no significant. The red dot indicates the mean.
Fig 5.
Cq-values of SPC measured in the different sample types.
The plots in the top row (a - d) depict the Cq-values stratified by RLEP positivity in the sample. The plot on the bottom (e) depicts only the samples with a negative RLEP qPCR result. Boxplots show the median of the SPC Cq-values with interquartile range; black dots represent outliers. The results of a Wilcoxon Rank-Sum test are depicted for the skin biopsies, ****: p-value < 0.0001, ns: not significant.