Prospective hospital-based surveillance to estimate rotavirus disease burden in the Gauteng and North West Province of South Africa during 2003-2005.

BACKGROUND: Rotavirus is considered to be the most common cause of serious acute dehydrating diarrhea worldwide. However, there is a scarcity of information on rotavirus disease burden in sub-Saharan Africa. METHODS: We conducted prospective, hospital-based surveillance for rotavirus diarrhea among children <5 years of age at the tertiary care Dr. George Mukhari Hospital (DGM) and at the Brits district Hospital (BH) in the Gauteng and North West Provinces in South Africa; we estimated that up to 80% of children <5 years of age in their catchment areas who are hospitalized for diarrhea are admitted to one of these hospitals. RESULTS: At DGM, 2553 children <5 years of age were admitted for diarrhea from January 2003 through December 2005, and 852 children <5 years of age were treated for diarrhea at BH during 2004-2005. We examined stool specimens from 450 children (53%) at BH and from 1870 children (73%) admitted to DGM. An estimated 22.8% (95% confidence interval [CI], 21.2%-24.5%) of the children hospitalized with diarrhea at DGM were rotavirus positive, and the corresponding figure at BH was 18.2% (95% CI, 14.9%-22.1%). Among children <5 years of age admitted to DGM for any reason, an estimated 5.5% (95% CI, 5.1%-6.0%) had rotavirus diarrhea. Our incidence estimates suggest that 1 in 43-62 children in the area is likely to be hospitalized with rotavirus diarrhea by 2 years of age. CONCLUSIONS: Prevention of serious rotavirus illness by vaccination will substantially reduce not only the disease burden among young children but also the case load in South African health care facilities.

Determination of the G and P types of previously nontypeable rotavirus strains from the African Rotavirus Network, 1996-2004: Identification of unusual G types.

A total of 215 nontypeable rotavirus samples collected from children <5 years of age by members of the African Rotavirus Network were characterized using reverse-transcription polymerase chain reaction analysis and sequencing. The most predominant strain identified was P[8]G1 (46.9%). Genotypes P[8]G10, P[8]G8, P[6]G8, and P[7]G5 were also detected at frequencies varying from 0.5% to 2.3%. This study suggests that reassortment of unusual G types into a background of globally common genotype P[8] strains may be a major mechanism of generating rotavirus diversity. Nucleotide substitutions at the P[8], P[6], and G1 primer binding sites accounted for the failure to type these strains initially. Hence, these findings highlight the need for regular evaluation of rotavirus genotyping methods.

Emergence and characterization of serotype G9 rotavirus strains from Africa.

Serotype G9 strains have been detected sporadically and in localized outbreaks in various African countries, including South Africa, Botswana, Malawi, Kenya, Cameroon, Nigeria, Ghana, Guinea-Bissau, Libya, and Mauritius. Serotype G9 strains were analyzed to investigate genogroup characteristics, including subgroup specificity, electropherotype, and P and G genotypes. In addition, the antigenic composition of the South African G9 strains was assessed. African G9 strains were associated with both DS-1-like characteristics and Wa-like characteristics, indicating the predisposition of G9 strains to frequently reassort. Despite these reassortment events, serotype G9 strains appear to maintain antigenic character in the outer capsid protein, as evident with the reaction of the South African G9 strains with the G9-specific monoclonal antibody F45:1. Phylogenetic analysis clustered African G9 strains geographically, regardless of genogroup characteristics, into 1 lineage (IIId). Two groups of G9 strains, originating in India and Japan, were identified in this lineage. Continuous surveillance of circulating rotavirus strains in Africa is vital to prepare for future vaccine implementation on a continent that clearly needs such preventative medicines.

Novel human rotavirus genotype G5P[7] from child with diarrhea, Cameroon.

We report characterization of a genotype G5P[7] human rotavirus (HRV) from a child in Cameroon who had diarrhea. Sequencing of all 11 gene segments showed similarities to > or =5 genes each from porcine and human rotaviruses. This G5P[7] strain exemplifies the importance of heterologous animal rotaviruses in generating HRV genetic diversity through reassortment.

Detection of an unusual human rotavirus strain with G5P[8] specificity in a Cameroonian child with diarrhea.

Rotavirus strains detected as part of ongoing strain surveillance in Cameroon, and whose first-round reverse transcription-PCR product could not be genotyped by using conventional genotyping primers, were subjected to sequence analysis for strain characterization. We detected for the first time in Africa a human rotavirus with G5 specificity. The Cameroonian G5 strain had a short electrophoretic pattern and was of VP6 subgroup I specificity and a VP4 P[8] type. The VP7 gene shared a higher nucleic acid and amino acid homology with the porcine G5 strain CC117 (90 and 96%, respectively) than with human G5 strain IAL-28 (86 and 92%, respectively). Phylogenetic analysis showed Cameroonian strain MRC3105 clustered together in the same lineage as two other reported porcine G5 strains. The Cameroonian G5 strain, the first to be reported in humans outside of Latin America, may be a natural reassortant between animal and human rotavirus strains.