# Phylogenetic analysis of Mycobacterium bovis reveals animal and zoonotic tuberculosis spread between Morocco and European countries

## TL;DR

This study uses genome sequencing to show how tuberculosis spreads between Morocco and Europe, highlighting the role of animal trade and human migration.

## Contribution

The study identifies two new M. bovis spoligotypes in Morocco and provides evidence of cross-border transmission between Morocco and European countries.

## Key findings

- Two new M. bovis spoligotypes were discovered in Morocco.
- Moroccan M. bovis clonal complexes are classified as European or Unknown, suggesting the Sahara Desert limits transmission to Sub-Saharan Africa.
- Close genetic links were found between M. bovis in Morocco and strains in Spain, France, Portugal, Germany, and humans in Italy, Germany, and the UK.

## Abstract

Livestock production is a fundamental pillar of the Moroccan economy. Infectious diseases of cattle and other species represent a significant threat to the livestock industry, animal health, and food safety. Bovine tuberculosis (bTB), mainly caused by Mycobacterium bovis, generates considerable direct and indirect economic losses, and an underestimated human health burden caused by zoonotic transmission. Previous studies have suggested likely M. bovis transmission links between Morocco and Southern Europe, however, limitations inherent with the methods used prevented definitive conclusions. In this study, we employed whole genome sequencing analysis to determine the genetic diversity of the first 55 M. bovis whole-genomes in Morocco and to better define the phylogenetic links between strains from Morocco and a large dataset from related and neighboring countries. With a total of 780 M. bovis sequences extracted from cattle, wildlife or humans and representing 36 countries, we discovered two new M bovis spoligotypes in Morocco and that the Moroccan clonal complexes are classified as belonging to Europe or Unknown, supporting previous studies that the Sahara Desert might be playing a key role in preventing M. bovis transmission between North Africa and Sub-Saharan Africa. Furthermore, our analysis showed a close M. bovis genetic relationship between cattle from Morocco and cattle from Spain, France, Portugal and Germany, and from cattle in Morocco and humans in Italy, Germany, and the UK. These results suggest that animal trade and human migration between Morocco and these countries might be playing a role in disease transmission. Our study benefits from a large sample size and a rich dataset that includes sequences from cattle, wildlife and humans from Morocco and neighboring countries, enabling the delineation of M. bovis genetic links across countries and host-species. Our study calls for further investigation of animal and zoonotic TB spread in Morocco and in other countries, which is important to inform future TB control measures at the animal-human interface.

Livestock production is a cornerstone of the Moroccan economy, but infectious diseases, particularly bovine tuberculosis (bTB), pose significant risks to animal health, and food safety. Predominantly caused by Mycobacterium bovis, bTB leads to substantial economic losses and an underestimated human health burden through zoonotic transmission. Previous research indicated possible M. bovis transmission links between Morocco and Southern Europe, though methodological limitations hindered conclusive findings. Here, we utilized whole genome sequencing to analyze the genetic diversity of the first 55 M. bovis genomes from Morocco, comparing them with a large dataset of 725 sequences from 36 countries, including cattle, wildlife, and human samples.

Our findings revealed two new M. bovis spoligotypes in Morocco and classified Moroccan clonal complexes as European or Unknown, suggesting the Sahara Desert limits transmission between North Africa and Sub-Saharan Africa. Additionally, we identified close genetic relationships between M. bovis from Morocco and strains from Spain, France, Portugal, Germany, and humans in Italy, Germany, and the UK, implying that animal trade and human migration might be contributing to disease spread.

This study, benefiting from a comprehensive dataset, underscores the need for further research on animal and zoonotic TB transmission to inform effective control measures at the animal-human interface.