Rapid diversification of measles virus genotypes circulating in Morocco during 2004-2005 epidemics

Measles virus strains circulating in six different regions in Morocco during 2004-2005 were analysed. They were genotyped using two different methods: the recently developed method based on real-time PCR amplification and melting curve analyses, and the conventional method based on nucleic acid sequencing and phylogenetic analysis of 456 nucleotides of the 3'-region of the nucleoprotein (N) gene sequence. Five genotypes (A, B3.2, C2, D7 and D8) were shown to be circulating during this period. Previous studies on measles virus genotypes in Morocco (1998-2003) showed that only the genotype C2 was present and was considered to be endemic. Sequence comparison of the 2004-2005 viruses with other measles strains suggests that measles strains belonging to genotype B3.2 were probably imported from West Africa, whereas those belonging to genotypes D7 and D8 were imported from Europe. These studies which identify the route of importation of measles are important for developing strategies for measles elimination in Morocco.