Ticks are unlikely to play a role in leprosy transmission in the Comoros (East Africa) as they do not harbour M. leprae DNA

Introduction

Leprosy, one of the oldest known human diseases, continues to pose a global challenge for disease control due to an incomplete understanding of its transmission pathways. Ticks have been proposed as a potential contributor in leprosy transmission due to their importance as vectors for other infectious diseases.

Methods

In 2010, a sampling of ticks residing on cattle was conducted on the islands Grande Comore, Anjouan, and Mohéli which constitute the Union of the Comoros where leprosy remains endemic. To investigate the potential role of ticks as a vector in transmission of leprosy disease, molecular analyses were conducted.

Results

Out of the 526 ticks analysed, none were found to harbour Mycobacterium leprae DNA, as determined by a quantitative polymerase chain reaction (qPCR) assay targeting a family of dispersed repeats (RLEP) specific to M. leprae.

Discussion

Therefore, our results suggest that in the Union of the Comoros, ticks are an unlikely vector for M. leprae.

Hi-plex deep amplicon sequencing for identification, high-resolution genotyping and multidrug resistance prediction of Mycobacterium leprae directly from patient biopsies by using Deeplex Myc-Lep

BACKGROUND

Expansion of antimicrobial resistance monitoring and epidemiological surveillance are key components of the WHO strategy towards zero leprosy. The inability to grow Mycobacterium leprae in vitro precludes routine phenotypic drug susceptibility testing, and only limited molecular tests are available. We evaluated a culture-free targeted deep sequencing assay, for mycobacterial identification, genotyping based on 18 canonical SNPs and 11 core variable-number tandem-repeat (VNTR) markers, and detection of rifampicin, dapsone and fluoroquinolone resistance-associated mutations in rpoB/ctpC/ctpI, folP1, gyrA/gyrB, respectively, and hypermutation-associated mutations in nth.

METHODS

The limit of detection (LOD) was determined using DNA of M. leprae reference strains and from 246 skin biopsies and 74 slit skin smears of leprosy patients, with genome copies quantified by RLEP qPCR. Sequencing results were evaluated versus whole genome sequencing (WGS) data of 14 strains, and versus VNTR-fragment length analysis (FLA) results of 89 clinical specimens.

FINDINGS

The LOD for sequencing success ranged between 80 and 3000 genome copies, depending on the sample type. The LOD for minority variants was 10%. All SNPs detected in targets by WGS were identified except in a clinical sample where WGS revealed two dapsone resistance-conferring mutations instead of one by Deeplex Myc-Lep, due to partial duplication of the sulfamide-binding domain in folP1. SNPs detected uniquely by Deeplex Myc-Lep were missed by WGS due to insufficient coverage. Concordance with VNTR-FLA results was 99.4% (926/932 alleles).

INTERPRETATION

Deeplex Myc-Lep may help improve the diagnosis and surveillance of leprosy. Gene domain duplication is an original putative drug resistance-related genetic adaptation in M. leprae.

FUNDING

EDCTP2 programme supported by the European Union (grant number RIA2017NIM-1847 -PEOPLE). EDCTP, R2Stop: Effect:Hope, The Mission To End Leprosy, the Flemish Fonds Wetenschappelijk Onderzoek.

Evaluating TB diagnosis and care in the Union of the Comoros

SETTING

The Union of the Comoros has experienced a persistent notification gap in TB cases despite several strategic changes, including molecular diagnosis and contact investigation. We therefore performed a TB patient pathway analysis (PPA) under the National Tuberculosis Programme (NTP).

OBJECTIVE

To assess the alignment of healthcare-seeking behaviour and TB service availability to clarify the reasons for these missing cases.

DESIGN

Three primary data sources, including a national list of health facilities, TB surveillance data and care-seeking behaviour data, were analysed at the national and regional levels to determine access to TB diagnosis and the initial point of care-seeking. Summary data were visualised using the standardised PPA Wizard programme, and the analysis was completed using demographic and socio-economic data.

RESULTS

At the initial point of care-seeking, 18% of patients had access to TB services, available only in nine centralised public health facilities. Furthermore, 30% of patients initially consulted in the informal sector and 45% in the formal public or private sector in health facilities, both of which lacked the capacity for TB diagnosis or first-line treatment.

CONCLUSION

The concentration of and limited access to TB services at the intermediate and central levels of care indicate a need for decentralisation efforts.