Measles virus genotype B2 is not inactive: Evidence of continued circulation in Africa

Abstract

This study describes two measles outbreaks--one in Cape Town, South Africa in November 2002, and the other in Luanda, Angola in March 2003. The outbreaks were notable because they were caused by closely related genotype B2 viruses. This genotype was first described in an outbreak in Libreville, Gabon in the 1980s and was labeled as inactive by the World Health Organization in 2003 because it had not been detected for over 15 years. As the first three cases in the Cape Town outbreak were Angolan citizens who recently arrived from Angola, it appears likely that the source of the virus was Angola. Molecular analysis of specimens collected during the outbreak in Luanda provided direct evidence for the circulation of genotype B2 measles virus (MV) in Angola. This study clearly demonstrates that there is still active circulation of genotype B2 in Africa, and we propose that its apparent inactivity is merely the result of insufficient virologic/molecular surveillance in the region. These findings highlight the need for expanded molecular surveillance in Africa.

Genotyping of Measles Virus in Clinical Specimens on the Basis of Oligonucleotide Microarray Hybridization Patterns

“…Of the 55 samples in panel 1, 39 represented 14 different MV genotypes, including genotypes D1 and D2, which were not previously tested during assay evaluation (see Materials and Methods). (28) and the reference strain for genotype B2, isolated in 1983. Due to the 1.7 to 2.0% nucleotide difference between the recent wild-type strains and the reference sequence, the microarray mistakenly identified these samples as genotype B3.2.…”

Measles Virus Strain Diversity, Nigeria and Democratic Republic of the Congo

“…Therefore, genotype B2 was considered inactive, until recent variants of this genotype were found in the Central African Republic (2000), South Africa (2002), and Angola (2003) ( 13 , 35 ). Viruses obtained from these 3 countries had a minimum genetic distance of 6–8 nts in the MVN-HVR compared with the closest variant (MVi.Libreville.GAB/84[R102]) obtained from Gabon almost 20 years earlier.…”

Slow clearance of measles virus RNA after acute infection

“…Detection of RNA at follow-up was not more frequent in children with persistent IgM (11%) or undetectable IgM (26%; P = 0.29). The median % CD4 + T lymphocytes at study entry (26.5% versus 26.8%; P = 0.89) and at follow-up (30.9% versus 30.4%; (Muwonge et al, 2005;Smit et al, 2005;World Health Organization, 2003) known to be circulating throughout the African continent were included for comparison. Distances were calculated using the Kimura 2 parameter method.…”