Ecological distribution and phylogenetic diversity of measles virus genotypes in West Africa, 2001 to 2020

Introduction

Measles remains a significant threat to public health in developing countries, particularly among children under the age of 5. A pivotal aspect of the measles eradication initiative involves the genetic characterization of wild-type viruses to better understand transmission patterns and inform vaccination strategies.

Objective

This study aims to investigate the ecology and genotype diversity of the measles virus in West Africa from 2001 to 2020, utilizing available sequence data from the GenBank.

Methodology

We conducted a comprehensive analysis using maximum-likelihood phylogenetics, focusing on the N450 fragment from measles virus isolates found in West Africa between 2001 and 2020. Additionally, pairwise sequence comparison analysis was carried out to determine the evolutionary divergence of various genotypes in West Africa and their genetic distance from vaccine strains.

Results

Our findings indicate that over the past 2 decades, B3, D3, and D8 isolates have been circulating in various West African countries. Notably, B3 isolates have been identified as the primary contributors to endemic transmission, as evidenced by the concurrent presence of the same isolate in different countries within the subregion. Furthermore, our analysis reveals a significant shift in the circulation of D3 and D8 isolates, which were originally reported exclusively in New Guinea over 15 years ago but are now dominated by the B3 genotype.

Conclusion

Over the past 2 decades, B3, D3, and D8 measles virus genotypes have circulated in 10 West African countries. Particularly, B3.1 isolates currently dominate, especially in Nigeria, indicating endemic transmission. However, despite the informative value of N450, complete genome sequencing data is highly needed to accurately understand the evolutionary dynamics of the measles virus in West Africa.